Does evolution explain human nature?

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Does
evolution explain
human nature?
300 Conshohocken State Road, Suite 500
West Conshohocken, Pennsylvania 19428
Tel: 610.941.2828 | Fax: 610.825.1730
www.templeton.org
Obviously, says the monkey.
Frans de Waal
4
Except where it matters.
Simon Conway Morris
8
Quite well.
Lynn Margulis
12
Not entirely.
Francis Collins
16
More fully by the day.
Geoffrey Miller
19
Not yet…
Joan Roughgarden
23
In part.
Martin Nowak
26
Yes.
Robert Wright
29
Only up to a point.
Francisco J. Ayala
33
Yes, but…
Eva Jablonka
37
Totally, for a Martian.
Jeffrey Schloss
40
Yes and no.
David Sloan Wilson
44
A T E M P L E T O N C O N V E R S AT I O N
INTRODUCTION
he John Templeton Foundation serves as a philanthropic catalyst
for research on what scientists and philosophers call the Big
Questions. We support work at the world’s top universities in
such fields as theoretical physics, cosmology, evolutionary biology,
cognitive science, and social science relating to love, forgiveness, creativity,
purpose, and the nature and origin of religious belief. We encourage
informed, open-minded dialogue between scientists and theologians as
they apply themselves to the most profound issues in their particular
disciplines. And we seek to stimulate new thinking about wealth creation
in the developing world, character education in schools and universities,
and programs for cultivating the talents of gifted children.
and much-disputed subject, and they bring to bear — in civil, elegant
prose — a range of different perspectives. By assembling this “conversation”
and inviting the public to join in, we intend to spark a discussion
that transcends the familiar positions usually found in such debates. We
aim to turn discourse on the Big Questions in a more thoughtful,
considered direction. It is our hope that this booklet will be a lasting
resource for students, teachers, parents, political leaders, scientists, clergy,
and anyone else engaged with the great issues of human nature and
purpose. Additional copies of the booklet can be ordered by writing to
[email protected]
T
2
The Big Question posed in these pages celebrates the bicentenary
of the birth of Charles Darwin, the founding genius of modern biology.
We have focused on the long-standing debate over how well the theory of
evolution can explain human nature — a subject of heated contention in
Darwin’s day as in our own. An important new aspect of the discussion, as
many of our essayists emphasize, is the transformation that evolutionary
theory itself has undergone in recent decades. Researchers have concluded
that natural selection helps to explain the development of a range of
human emotions, behaviors, and capacities — and not just the stereotypically
“selfish” ones. Evolutionary theory has become a powerful tool in trying to
understand such traits as altruism, cooperation, religious belief, and moral
commitment. But is it sufficient for a full understanding of these
human qualities? And does evolutionary theory illuminate such intractably
difficult subjects as human consciousness, free will, and spirituality?
This booklet neatly embodies the approach that we take to the Big
Questions across all of the Foundation’s areas of interest. The contributors
are distinguished scientists and scholars, they address a perennial
Four previous conversations on Big Questions at the core of the
Foundation’s mandate may also be of interest to readers. They can be
found online at the following addresses:
Does the universe have a purpose?
www.templeton.org/purpose
Will money solve Africa’s development problems?
www.templeton.org/africa
Does science make belief in God obsolete?
www.templeton.org/belief
Does the free market corrode moral character?
www.templeton.org/market
3
A T E M P L E T O N C O N V E R S AT I O N
Frans de Waal
Obviously, says
the monkey.
4
Frans de Waal is
C.H. Candler Professor of
Psychology at Emory
University and conducts
research at the Yerkes
National Primate
Research Center. His
popular books include
Chimpanzee Politics,
Our Inner Ape, and The
Age of Empathy, which
will be published this fall.
Human nature simply cannot be understood in
isolation from the rest of nature. This evolutionary
approach is already difficult for many people to
accept, but it is likely to generate even more resistance
once its implications are fully grasped. After all,
the idea that we descend from long-armed, hairy
creatures is only half the message of evolutionary
theory. The other half is continuity with all other
life forms. We are animals not only in body but also
in mind. This idea may prove harder to swallow.
We are so convinced that humans are the only
intelligent life on earth that we search for other
intelligent beings in distant galaxies. We also never
seem to run out of claims about what sets us apart,
even though scientific progress forces us to adjust
these claims every couple of years. That is why
we do not hear any more that only humans make
tools, imitate each other, have culture, think ahead, are self-aware, or
adopt another’s point of view. It is the rare claim of human uniqueness
that holds up for more than a decade.
If we look at our species without letting ourselves be blinded by the
technological advances of the last few millennia, we see a creature of flesh
FRANS DE WAAL
and blood with a brain that, albeit three times larger than that
of a chimpanzee, does not contain any new parts. Our intellect may be
superior, but we have no basic wants or needs that cannot also be
observed in our close relatives. I interact daily with chimpanzees and
bonobos, which are known as anthropoids precisely because of their
human-like characteristics. Like us, they strive for power, enjoy sex, want
security and affection, kill over territory, and value trust and cooperation.
Yes, we use cell phones and fly airplanes, but our psychological make-up
remains that of a social primate.
To explain human behavior as a “mere” product of evolution, however,
is often seen as insulting and a threat to morality, as if such a view would
absolve us from the obligation to lead virtuous lives. The geneticist
Francis Collins sees the “moral law” as proof that God exists. Conversely,
I have heard people echo Dostoevsky’s Ivan Karamazov, exclaiming
that “If there is no God, I am free to rape my neighbor!”
Perhaps it is just me, but I am wary of anyone whose belief system is the
only thing standing between them and repulsive behavior. Why not
assume that our humanity, including the self-control needed to form a
livable society, is built into us? Does anyone truly believe that our
ancestors lacked rules of right and wrong before they had religion? Did
they never assist others in need or complain about an unfair share?
Human morality must be quite a bit older than religion and civilization.
It may, in fact, be older than humanity itself. Other primates live in
highly structured cooperative groups in which rules and inhibitions
apply and mutual aid is a daily occurrence.
Even without claiming other primates as moral beings, it is not hard
to recognize the pillars of morality in their behavior. These are summed
up in our golden rule, which transcends the world’s cultures and religions.
“Do unto others as you would have them do unto you” brings together
empathy (attention to the feelings of others) and reciprocity (if others
follow the same rule, you will be treated well, too). Human morality could
not exist without empathy and reciprocity, tendencies that have been
found in our fellow primates.
5
6
A T E M P L E T O N C O N V E R S AT I O N
FR ANS DE WA AL
After one chimpanzee has been attacked by another, for example, a
bystander will go over to gently embrace the victim until he or she stops
yelping. The tendency to console is so strong that Nadia Kohts, a Russian
scientist who raised a juvenile chimpanzee a century ago, said that when
her charge escaped to the roof of the house, there was only one way to
get him down. Holding out food would not do the trick; the only way
would be for her to sit down and sob, as if she were in pain. The young ape
would rush down from the roof to put his arm around her. The empathy
of our closest evolutionary relatives exceeds even their desire for bananas.
to negative behavior — when humans maim and kill each other, we are
quick to call them “animals”— but we prefer to claim noble traits
exclusively for ourselves. When it comes to the study of human nature,
this is a losing strategy, however, because it excludes about half of our
background. Short of appealing to divine intervention as an explanation,
this more attractive half is also the product of evolution, a view now
increasingly supported by animal research.
Reciprocity, on the other hand, is visible when chimpanzees share food
specifically with those who have recently groomed them or supported
them in power struggles. Sex is often part of the
mix. Wild males have been observed to take
great
risks raiding papaya plantations, returning
We never seem
to share the delicious fruit with fertile females
to doubt that
there is continuity in exchange for copulation. Chimps know how
to strike a deal.
between humans
and other animals
with respect to
negative behavior,
but we prefer to
claim noble
traits exclusively
for ourselves.
Our primate relatives also exhibit pro-social
tendencies and a sense of fairness. In experiments,
chimpanzees voluntarily open a door to
give a companion access to food, and capuchin
monkeys seek rewards for others even if
they themselves gain nothing from it. Perhaps
helping others is self-rewarding in the same
way that humans feel good doing good. In
other studies, primates will happily perform a
task for cucumber slices until they see others
being rewarded with grapes, which taste so much better. They become
agitated, throw down their measly cucumbers, and go on strike. A
perfectly fine vegetable has become unpalatable! I think of their reaction
whenever I hear criticism of the extravagant bonuses on Wall Street.
These primates show hints of a moral order, and yet most people still
prefer to view nature as “red in tooth and claw.” We never seem to doubt
that there is continuity between humans and other animals with respect
This insight hardly subtracts from human dignity. To the contrary,
what could be more dignified than primates who use their natural gifts
to build a humane society?
7
A T E M P L E T O N C O N V E R S AT I O N
S I M O N C O N WA Y M O R R I S
of these developments have occurred independently and by the process
of evolution.
Simon Conway Morris
Except where
it matters.
8
Simon Conway Morris
is a professor of
evolutionary paleobiology
at the University of
Cambridge and a Fellow
of St. John’s College.
Elected to the Royal
Society in 1990, he is
the author, most recently,
of Life’s Solution:
Inevitable Humans in a
Lonely Universe.
As I write this essay, my fingers hold a pen and my
eyes scan the page — fingers that have evolved from
fins, eyes that have developed from little more than
pigmented spots. We may walk tall, but we cast a
long evolutionary shadow. At the same time, my ears
are distracted by bird-song from the yard outside.
But why should I bother to waste my time listening
to the birds? Why, indeed, should I be interested if
three separate families of birds — songbirds, parrots,
and hummingbirds — all evolved song independently,
and why should I care that the manner in which
some birds learn to sing is strikingly similar to the
way that language emerges from babble in children?
The answer is that I am naturally curious and also
that I appreciate beauty. The evolution of bird-song
is not only a striking example of evolutionary
convergence — that is, of unrelated organisms arriving
at very much the same biological solution — but it has a much wider
importance. It is an indication that at least some outcomes of the Darwinian process are more likely than others and, in some cases perhaps,
are actually inevitable. The capacity for song points to even more striking
similarities between birds and mammals in terms of overall cognitive
capacity, not least with respect to play and the manufacture of tools. All
So why quibble with the standard Darwinian formulation? Is it not
obvious that the roots of human behavior and cultural sophistication lie
in the rich loam of our evolutionary past? We are but a hair’s breadth
from our animal cousins. Such is evident in terms of their cognitive
world (which many believe encompasses, at least in apes and some birds,
a theory of mind), their capacity for self-recognition in mirrors, and the
glimmerings among them not just of culture and its transmission but of
crafted tools and even traits of personality. So what is the problem?
At one level, there is none. It would be strange if my fingers and eyes
were to have an evolutionary origin but not my capacity to speak, to
empathize, and even to deal with simple abstractions like numbers. And
yet, though we may be just a hair’s breadth away from a chimp — not
to mention a crow, a dolphin, an elephant, and even an octopus — we
humans are still utterly and stupendously different. A seamless extrapolation from one species to another? That is what Darwin proposed,
but pinning down how the glaring gaps — most obviously, language
— were actually bridged remains almost entirely obscure.
Should we look, then, to human exceptionalism, to a freak mutation
that suddenly propelled us into new worlds? It is possible, of course, but
there is not a shred of evidence for it. Could it just be an illusion?
Perhaps we think we are different, but the animals themselves know
better. Is that credible? Not really. So profound is the gulf between us
and the chimps that they might as well live in the Andromeda galaxy.
Have you seen a chimp make a fire, let alone go to the library?
The late David Stove, an Australian philosopher, wrote a wonderful
book entitled Darwinian Fairytales. How dare anybody use a word like
“fairytale” in the same breath as the venerated Darwin? (See how the
cage housing the ultra-Darwinists rocks and shudders, the occupants
hurling themselves against the bars with cries of outrage.) But Stove was
emphatically not a creationist or even a theist, let alone a Christian.
And he had no quarrel with evolution. For him, the question was not
9
A T E M P L E T O N C O N V E R S AT I O N
where we came from but who we are now. In a piercing critique, he
dismantled the Darwinian pieties purporting to show why we are so
extraordinarily altruistic (not to mention our love of animals), demolished
the absurdities of genetic determinism, exploded the naiveties of
sociobiology, and laid waste the myth that we are “just another species.”
But how did we come to be so different, in fact, so very odd? I would
propose a radical alternative. We live in a world riddled with symbols and
symbolic expression — a place where people kill for principle or engage
in reckless altruism, where thousands cheer their teams while others
choose monastic isolation. Our societies buzz with chatter, friendship,
and laughter, but they are also haunted by terrible, reflective silences,
echoing back through history for hundreds of years.
10
The world of
myth is not just a
set of superior
fairy stories but
rather an attempt
to use language
to describe our
cosmic engagement. Is all this
striving after
ultimate meaning
a massive
delusion?
Somehow we have intuited the ineffable,
matters that defy precise description but still
resonate at the deepest levels. The world of
myth is not just a set of superior fairy stories but
rather an attempt to use language to describe
our cosmic engagement. Is all this striving after
ultimate meaning a massive delusion, a gigantic
wish-fulfillment? Is this what happens when
the brain gets too big: the puzzled and frightened
ape stumbles across comprehension and just
as suddenly realizes that his existence is entirely
meaningless? Could our symbol-rich world
be of interest only to a pitiless nihilist? I do not
think so.
Suppose that the moral structure, the ethical
voice, the heart-wrenching aesthetic, the
haunting intuition that certain places are holy,
the endless yearning for a world made good are not the fantasies of a
deracinated ape but rather are signposts to deep realities in which our
destiny may be involved. Suppose that evolution is like a search engine,
always seeking the best solution. From this perspective, it is hardly
surprising that scattered across the evolutionary landscape, among the
S I M O N C O N WA Y M O R R I S
grunts and howls, the dawning intelligence and the scarcely articulated
emotions, we do indeed see the flickerings of ourselves.
The real question of how we came to be who we are does not revolve
around a process of creeping Darwinian emergence, whereby the various
components drifted together into a human whole with distinctive and
(let us be honest) very odd powers all of its own. Rather it is a true story
of discovery, of first detecting and then entering and finally enjoying
entirely new worlds that were waiting for us all the time. We could not
have arrived where we are except by evolution, and this is where we
need to be. As rational creatures we now not only know evolution but we
know how to transcend it.
11
A T E M P L E T O N C O N V E R S AT I O N
Lynn Margulis
Quite well.
12
Lynn Margulis is
Distinguished University
Professor in the
Department of Geosciences
at the University of
Massachusetts-Amherst
and, currently, the
Eastman Professor at
Balliol College, Oxford.
A member of the National
Academy of Sciences,
she is the author of, among
other books, Acquiring
Genomes and
Dazzle Gradually (both
with Dorion Sagan).
Ever since Bishop Wilberforce asked, in a debate
with Thomas Huxley, whether it was from his
grandmother or grandfather that he claimed descent
from a monkey, the sufficiency of evolutionary
theory to explain humanity’s spiritual and moral
qualities has been in question. Then, as now, the
evolution of humans was a touchy subject, and after
the publication of On the Origin of Species, Darwin
devoted a separate work, The Descent of Man, to
untangling how evolutionary understanding could
be applied to humans and their special traits.
Since his account of “descent with modification”
leaned heavily on natural selection of the individual,
Darwin wondered how moral behaviors — which
focus on others — evolved. When lying, cheating,
manipulation, greed, and other less than admirable
qualities seemed to benefit those individuals who
practiced them, how could their opposites evolve?
Pointing out that he “who was ready to sacrifice his
life … would often leave no offspring to inherit
his noble nature,” Darwin pondered how members of a tribe became
endowed with moral attributes.
His simple answers still apply. One who aids his fellows commonly
receives aid in return. Darwin called this a “low motive” because it is
LY N N M A R G U L I S
self-regarding. So-called reciprocal altruism — I’ll carry your baby if
you take my son on the hunt tomorrow at dawn — is operative in species
whose members are capable of recognizing each others’ faces. More
important is the praise we love and the blame we dread, instincts that
help bind tribe members who work together. Reciprocal acts of
kindness and aid underlie families, tribes, and religious groups; they
ensure survival and reproduction as “naturally selected” perpetuating,
living entities.
Our human sort of mutual care, along with the strong feeling of life
we have in the presence of sexual partners, family, friends, colleagues,
classmates, and fellow citizens (in short, in the company of meaningful
others), necessitates frequent communication: symbols, language, music,
teaching, learning, etc. Do these activities fundamentally distinguish
us from the non-human life forms with whom we share the planet and
upon whom we depend for our survival? I doubt it.
This may sound inadequate to true believers in human uniqueness,
especially on religious grounds. But religion serves an obvious evolutionary
function: it identifies, unifies, and preserves adherents. Admonitions
to desist from the seven deadly sins inhibit behaviors that threaten group
solidarity and survival. Greed, for example, privileges the individual
in seasons of limited resources. Lust — the biblical coveting of the
neighbor’s wife (in its male-centered perspective) — interferes with ideals
for the nurture of healthy children and effective warriors. Prohibiting
sloth enhances productive work intrinsic to survival and reproduction of
the social unit. Anger, perhaps useful in battle, destroys family and
other social relationships. Envy and pride promote individual interests
above those of the larger social unit. The survival value of prohibiting
sin seems obvious.
By contrast, “love thy neighbor,” interpreted from an evolutionary point
of view, is an algorithm for social connectedness. The touted virtues of
chastity, moderation, compassion, diligence, patience, moral commitment,
and humility provide touchstones for effective group action. The intellectual historian Karen Armstrong, a former nun and the author of books
on Christianity, Judaism, and Islam, argues that compassion is the crucial
13
14
A T E M P L E T O N C O N V E R S AT I O N
LY N N M A R G U L I S
link among the major religions. The golden rule of Jesus, Confucius, and
others is that we should not do to others what we would not want them
to do to us. Is this not a clear precept for the evolutionary perpetuation of
specific cohesive groups in familiar habitats?
the only documented cases of the “origin of species” in real time involve
not selfish genes but “selfless” mergers of different forms. Chemical
and genetic evidence suggests that even mitochondria, bodies inside all
of our cells that suffocate without oxygen, came from ancient mergers,
truces between oxygen-respiring bacteria and the nearly poisoned
cells of other kinds of microscopic beings. The mergers, naturally selected,
survived to thrive and spread across the planet.
We differ from other species in that fewer
rules of social behavior are communicated
only by shout, groan, touch, and facial expression and more by verbal explication. But
all tend to maintain and perpetuate unity of
the pack, gaggle, or herd. We people share
a linguistic version of the universal tendency
toward socio-ecological wisdom measurable
in life forms at every level. After my collaborative scientific work for over a half century to
detail the genetics, microscopy, and biochemistry of cells that adhere in their lives together,
I consider the neo-Darwinist overemphasis
on competition among selfish individuals
— who supposedly perpetuate their genes as if they were robots — to be a
Victorian caricature. Disease microbes that kill all their victims perish
themselves as a result of their aggression.
On a crowded
planet, there
has always been
a premium on
effective togetherness. Our moral
nature reflects
rather than
conflicts with
nature.
I disagree with neo-Darwinist zoologists who assert that the accumulation of random genetic mutations is the major source of evolutionary
novelty. More important is symbiogenesis, the evolution of new species
from the coming together of members of different species. Symbiogenesis
is the behavioral, physiological, and genetic fusion of different kinds
of being; it leads to the evolution of chimeric new ones. One example is
of originally pathogenic bacteria that invaded and killed many amoebae
in the University of Tennessee laboratory of Kwang Jeon in the 1970s.
He selected survivors, and eventually different amoebae with new species
characteristics appeared among them. These had retained 40,000
bacteria in each amoeba!
A new type of fruit fly evolved after it acquired an insect-loving bacterium
that prevented it from successfully mating with its old partners. Indeed,
Gifted with large brains that permit us great neurological processing
power, we humans plan further into the future. We recognize more
of our own kind with whom, now via global communication, we establish
relationships of identity and trust. But on a crowded planet, there
has always been a premium on effective togetherness. Our moral nature
reflects rather than conflicts with nature.
Free will may also be nature-deep. Large single-celled forams choose
from brightly colored sand grains the correct ones with which to make
shells. Aware of shape and color, they make choices and reproduce their
kind. Awareness in some form has been naturally selected for at least
550 million years. For me, our spirituality and moral nature help perpetuate
our living communities, just as similar attributes aided previous
living communities whose evolution is chronicled in the fossil record.
Photo credit: Mariana Cook.
15
A T E M P L E T O N C O N V E R S AT I O N
Francis Collins
Not entirely.
16
Francis Collins is a
physician and geneticist
noted for his leadership in
directing the Human
Genome Project. He is the
author of The Language
of God and the founder
and president of the
BioLogos Foundation
(www.biologos.org),
which seeks to promote
harmony between science
and faith.
The evidence in support of Darwin’s theory
of evolution is overwhelming. In my own field of
genomics, the digital record of the long history
of life on this planet — a complex and awesome story
of gradual change in DNA acted upon by natural
selection — provides incontrovertible proof of descent
from a common ancestor. As the noted geneticist
and evolutionary theorist Theodosius Dobzhansky
wrote several decades ago, “Nothing in biology
makes sense except in the light of evolution.” And
that includes humankind.
But Dobzhansky believed in God. And so do I.
Regrettably, much of the current culture in the
United States sees evolution as an aff ront to belief in
God. But the 40 percent of working scientists
who are believers have a different view. Most of us
are theistic evolutionists. We see evolution as
God’s method for creation — and what an elegant
method it is! Put another way, we see life (bios) as the consequence
of God’s Word (the Logos). Thus, I like to refer to theistic evolution
as “biologos.”
Scientists who share my view do not see evolution as incompatible with
the Bible, and we are puzzled and distressed that so many modern-day
Christians insist on an ultra-literal reading of Genesis, when thoughtful
FRANCIS COLLINS
believers down through the centuries have concluded that this story of
God’s plan for creation was never intended to be read as a scientific
textbook. We see science as the way to understand the awesome nature
of God’s creation and as a powerful method for answering the “how”
questions about our universe. But we also see that science is powerless to
answer the fundamental “why” questions, such as “Why is there something
instead of nothing?,” “Why am I here?,” and “Why should good and
evil matter?”
Let’s focus on this last question. One of the most notable characteristics
of humanity, across centuries, cultures, and geographic locations, is a
universal grasp of the concept of right and wrong and an inner voice that
calls us to do the right thing. This is often referred to as the moral
law. We may not always agree on what behaviors are right (which is heavily influenced by culture), but we generally agree that we should try
to do good and avoid evil. When we break the moral law (which we do
frequently, if we are honest with ourselves), we make excuses, only
further demonstrating that we feel bound by the moral law in our
dealings with others.
Evolutionary arguments, which ultimately depend on reproductive
fitness as the overarching goal, may explain some parts of this human urge
toward altruism, especially if self-sacrificing acts are done on behalf
of relatives or those from whom you might expect some future reciprocal
benefit. But evolutionary models universally predict the need for reflexive
hostility to outside groups, and we humans do not seem to have gotten
that memo. We especially admire cases in which individuals make
sacrifices for strangers or members of outside groups: think of Mother
Teresa, or Oskar Schindler, or the Good Samaritan.
We should be skeptical of those who dismiss these acts of radical altruism
as some sort of evolutionary misfiring. And if these noble acts are frankly
a scandal to reproductive fitness, might they instead point in a different
direction — toward a holy, loving, and caring God, who instilled the moral
law in each of us as a sign of our special nature and as a call to relationship
with the Almighty?
17
A T E M P L E T O N C O N V E R S AT I O N
Do not get me wrong. I am not arguing that the existence of the moral
law somehow proves God’s existence. Such proofs cannot be provided
by the study of nature. And there is an inherent danger in arguing that
the moral law points to some sort of supernatural intervention in the
early days of human history; this has the flavor of a “God of the gaps”
argument. After all, much still remains to be understood about evolution’s
influence on human nature. But even if radically altruistic human acts
can ultimately be explained on the basis of evolutionary mechanisms, this
would do nothing to exclude God’s hand. For if God chose the process
of evolution in the beginning to create humans in imago Dei, it would also
be perfectly reasonable for God to have used this same process to instill
knowledge of the moral law.
18
A deeper question raised by this debate is the fundamental nature
of good and evil. Does morality actually have any foundation? To be
consistent, a committed atheist, who argues that evolution can fully
account for all aspects of human nature, must also argue that the human
urge toward altruism, including its most radical and self-sacrificial
forms, is a purely evolutionary artifact. This forces the conclusion that the
concepts of good and evil have no real foundation, and that we have been
hoodwinked by evolution into thinking that morality provides meaningful standards of judgment. Yet few atheists seem willing to own up
to this disturbing and depressing consequence of their worldview.
On the contrary, the most aggressive of them seem quite comfortable
pointing to the evil they see religion as having inspired. Isn’t that
rather inconsistent?
I was once an atheist myself, and so I understand the temptation to
fall into a completely materialistic view of human nature. But seeing
all of humanity’s nobler attributes through the constricted lens of
atheism and materialism ultimately leads to philosophical impoverishment and even to the necessity of giving up concepts of benevolence
and justice. I found that a whole world of interesting questions opened
up for me once I accepted the possibility of a spiritual aspect to humanity.
GEOFFREY MILLER
Geoffrey Miller
More fully by the day.
Geoffrey Miller is an
evolutionary psychologist
at the University of
New Mexico. He is the
author of The Mating
Mind: How Sexual
Choice Shaped the
Evolution of Human
Nature and Spent:
Sex, Evolution, and
Consumer Behavior.
In the last two decades, evolutionary psychology
has cast new light on ever more facets of human
nature. And contrary to popular critiques of the field,
it has done so in ways that are ever more intellectually
thrilling, morally enlightening, spiritually satisfying,
and socially progressive. What we mean by “evolution”
and “human nature” continues to develop through
mutual interaction, like the passions of a whispering
couple in a close-embrace tango.
During the 1990s, biologists developed a whole
new toolbox of ideas about the nature of evolution,
including theories based on life history, multi-level
selection, strong reciprocity, good-genes sexual
selection, and costly signalling. These terms may be
unfamiliar to non-specialists, but they represent
a revolution in Darwinian theory and have proven
their value again and again in understanding aspects of human nature
that defy simplistic “survival of the fittest” reasoning.
Likewise, our understanding of human nature has been growing
exponentially through work in evolutionary psychology, evolutionary
anthropology, human evolutionary genetics, and primate behavior. Our
model is no longer a tattered old treasure map of a few basic instincts
(hunger, fear, lust) but a topographically detailed Google Earth panorama
across a whole continent of familiar capacities (romantic love, moral
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A T E M P L E T O N C O N V E R S AT I O N
commitment, self-deprecating humor, conspicuous charity, and many
more). New theories have led researchers to acknowledge new aspects of
human nature, and recognizing previously overlooked aspects of human
nature has promoted new progress in evolutionary theory.
My own research has been inspired mostly by good-genes sexual selection
theory (the idea that animals choose their partners based on cues about
genetic quality) and costly-signalling theory (the idea that only animals in
good condition can afford seemingly pointless displays like extravagant
plumage). These theories have proved enormously useful in understanding
a range of human behaviors that have seemed to have no clear survival
payoffs, like music, dance, art, humor, verbal creativity, conspicuous
consumption, and altruism.
Consider a few examples of new empirical discoveries from research I
have done with various collaborators:
20
* Gil Greengross and I showed that women are more attracted to men
who use self-deprecating rather than other-deprecating humor during
courtship (but only if the men are fairly high in social status). This is
consistent with the costly-signalling idea that self-mockery is a virtue
that only the successful can afford.
* Martie Haselton and I showed that women at peak fertility, just before
ovulation, show a stronger preference for creativity as opposed to wealth
in potential mates. This supports the idea that creativity is an indicator of
“good genes” rather than of potential as a “good provider.”
* Vladas Griskevicius, several colleagues, and I showed that if men are
put in a romantic mood rather than a neutral mood, they are more likely
to spend money on conspicuous luxuries, whereas women spend more
time on conspicuous charity, such that each sex is signalling a trait (social
status or kindness) that is relatively more desired by the other sex.
Each new finding like this illustrates how new evolutionary theories can
lead to discoveries that were never predicted by the standard “blank slate”
view of human behavior.
GEOFFREY MILLER
Still, evolutionary psychologists must guard against complacency.
We should not imagine that we have discovered every important facet of
human nature, or that evolutionary theory as it exists circa 2009 has
told us everything we need to know about the selection pressures that
have shaped human nature.
Consider just one new development in biology: the whole new world of
RNA, which may help explain the unique behavioral flexibility of
the human brain. The “central dogma” of genetics since the 1950s was
that DNA is transcribed into RNA, which is translated into proteins,
which generate all the adaptive complexity of organic life. Thus, only
the DNA sequences that code for proteins are important, and only
evolutionary changes in protein-coding DNA are worth analyzing. When
journalists report that humans have “only” some 25,000 genes — just a
few more than the 20,000 of the C. elegans worm — they are referring to
these protein-coding genes.
This “central dogma” has guided the Human Genome Project, the
HapMap project, and even the genome-wide association studies that
dominate the human genetics journals these days. But the idea
has been decisively overturned in the last decade by new discoveries
about the diversity of RNA that is transcribed from DNA but that
is not, in turn, translated into proteins. Most of this “non-coding” RNA
seems to constitute a genomic regulatory system of vast complexity
— a system that determines the expression of different protein-coding
genes in different cell types, tissues, and organs at different times during
development and in response to different environmental changes. The
human genome has a vastly more complex RNA system than C. elegans.
The molecular biologist John Mattick and others have argued that the
evolution of this RNA system was crucial for three great innovations in
life on earth: the emergence of the eukaryotic cell, the Cambrian
explosion of multi-cellular life, and the complexity of the human brain.
In this view, humans differ from other great apes not so much at the
level of protein evolution but at the level of the RNA regulatory system
that orchestrates the spatio-temporal patterning of gene expression and
protein function. The inherited DNA that is translated into this RNA
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A T E M P L E T O N C O N V E R S AT I O N
J OA N RO U G H G A RD EN
regulatory system does not just determine “innate instincts” or “hardwired” behaviors; it also orchestrates dynamic changes in brain function
and behavior under different circumstances.
Indeed, it seems likely that RNA is crucial in all sorts of behavioral
flexibility that humans have, from feeling different moods (elation, love,
depression, ambition) to laying down new memories, to super-charging
our creativity, humor, and altruism when we are courting a new mate.
All of this may be mediated by complex changes in gene expression throughout the brain, over time scales ranging from hours to decades. We
are realizing that our genes do not just determine the blueprint for an
infant’s brain; they are working actively throughout our lives, governed
by this vast RNA regulatory system, giving us degrees of behavioral
creativity and flexibility that it will take us decades to understand.
22
Joan Roughgarden
Not yet…
In short, evolution explains human nature very well indeed, but we are far
from finished in the grand project of naturalizing human consciousness.
Joan Roughgarden is
professor of biology at
Stanford University. Her
books include Evolution’s
Rainbow: Diversity,
Gender, and Sexuality in
Nature and People
and The Genial Gene:
Deconstructing
Darwinian Selfishness.
and almost surely never. Although human nature,
like biological nature generally, results from a
continuing process of evolution, the question before
us is whether present-day evolutionary science
explains human nature. Does it explain our religious
beliefs and moral commitments as convincingly
as it explains our more prosaic traits like, say, why we
have four arms and legs instead of six? Obviously
not. Evolutionary science has much more work to do
before it can explain our more abstract traits. But
how much more?
Religious beliefs, moral commitments, consciousness,
and the free will to do right and wrong emerge
in a social context. These traits are not properties of
an individual like the ability to hear high notes
or to taste bitter flavors. Social behavior develops as
individuals acquire experience with one another. It is a system of traits
that forms when individuals interact. A white-crowned sparrow learns
its song by listening to others as it grows up. Unlike its vocal chords, a
bird’s song is a collective property belonging to its group.
What makes social behavior hard to understand is that interaction takes
place during development rather than after it. By contrast, consider some
socially important physical traits, like green or gray skin color in frogs.
These traits are formed not during social interaction but prior to it. In wet
23
24
A T E M P L E T O N C O N V E R S AT I O N
J OA N RO U G H G A RD EN
years, with green moss on the trees, green frogs are more camouflaged
and are able to fight longer for space than gray frogs before seeking
cover from predators, whereas in dry years, gray frogs are able to defend
their territory longer. The competitive balance point between green
and gray frogs changes from year to year, depending on the year’s rainfall,
favoring green frogs in wet years and gray frogs in dry years. At each
year’s balance point, the frogs occupy all of the living space according
to a color ratio such that a newly arriving frog of either color has no
advantage over another frog. Thus, the colors influence the outcome of
territorial interactions, but the colors themselves are not generated by
those interactions.
With this approach, we have been able to show, for instance, that sexual
conflict is not inevitable in the relationship between males and females
in nature, as some evolutionary biologists claim, and we have demonstrated that some forms of sexual intimacy may be interpreted as mechanisms to enable friendship and teamwork among animals. All in all,
our research suggests that the “selfish-gene” metaphor for evolution is
misleading and inaccurate.
The competitive balance between socially important traits was studied
by the late John Maynard Smith, a theoretical biologist who introduced
mathematical game theory into evolutionary biology. Maynard Smith
applied his analysis to the evolution of social behavior among competing
individuals, assuming that their behavioral inclinations or “strategies”
were already formed prior to their interaction. He famously discussed the
evolutionary outcome of competition between “altruists” who interact
with “selfish” individuals, as though the traits of altruism and selfishness
were permanent characteristics of the actors, just as green or gray body
coloration might be for a frog.
But in most social behavior, how an organism acts, whether it behaves
altruistically or selfishly, depends in large part on its experience
with others while maturing. Moreover, the Maynard Smith approach
stipulates that behavioral interactions are inherently competitive
because he considered their outcome to be a competitive balance point.
To go beyond the limitations of Maynard Smith’s model, my students
and I have introduced the idea of “social selection.” Our approach
decomposes the evolutionary theory of social behavior into two levels or
“tiers.” The “lower” tier analyzes the development of behavioral actions
using game-theory techniques but without Maynard Smith’s assumption
of inherently competitive behavior; we employ criteria for both cooperative and competitive endpoints. The “higher” tier analyzes the evolution
of behavioral tendencies using population-genetic techniques.
Still, the question remains whether evolutionary science, even after
these and other improvements take root, will ever explain features of
human behavior such as spirituality, morality, consciousness, free
will, and so forth. But why stop there? Will evolutionary science ever
explain most of the features of any species?
This question forces us to confront our own modest place in nature. The
natural world is infinite, and even if the aggregate number of people who
have ever lived were scientists working 24/7 on evolutionary research,
their aggregate effort would be finite, leaving a still infinite set of evolutionary mysteries. Do we know why the chameleon evolved to catch bugs
with its tongue instead of sneaking up and pouncing on them? No. Will
we ever? Probably not. Do we know why and how humans have come
to possess a sense of morality? Not yet. Will we ever? Almost surely not.
Scientific research requires the expenditure of scarce time and money,
and for most people, the value of discovering the origins of our moral sense
is dwarfed by the health benefits of curing cancer or the environmental
benefits of conserving tropical forests. Questions about the evolution of
morality seem destined to linger indefinitely on some back burner.
There is nothing inappropriate about asking how we evolved our sense
of morality or any other aspect of human nature. Indeed, I believe that
investigating how evolution occurs is a sacred calling and that our
appreciation for every aspect of human life is enriched by an evolutionary
perspective. But some parts of this enterprise are more practical than
others — and also are far more likely to succeed.
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A T E M P L E T O N C O N V E R S AT I O N
M A R T I N N O WA K
My position is very simple. Evolution has led to a human brain that can
gain access to a Platonic world of forms and ideas. This world is eternal
and not the product of evolution, but it does affect human nature deeply.
Therefore evolution cannot possibly explain all aspects of human nature.
Martin Nowak
In part.
I am deeply fascinated by evolution, and I wish to
expand the boundaries of the evolutionary explanation
as far as possible. Yet I do not think that all aspects
of human nature can be explained by evolution. The
question is subtle, and the answer depends on how
we choose to define “human nature.”
26
Martin Nowak is
professor of biology and
mathematics at Harvard
University, where he
directs the Program for
Evolutionary Dynamics.
He is the author of over
300 scientific publications
and two books, Virus
Dynamics (with Robert
May) and Evolutionary
Dynamics: Exploring
the Equations of Life.
I like to think of human nature as a collection of
thoughts, feelings, and actions that humans experience or perform. Language, for example, is a fundamental aspect of human nature. A child growing up
in an environment of speakers develops a language
faculty. The thoughts and ideas that are expressed
in the languages of the world are all part of human
nature. Similarly, we like to listen to music and
perform it. A few of us compose music. Music is part
of human nature. There is also something very
intuitive about numbers and geometric objects, and
the ability to do some basic math seems to be part of
human nature.
Yet the great theorems of mathematics are statements of an eternal truth
that comes from another world, a world that seems to be entirely independent of the particular trajectory that biological evolution has taken
on earth. The great symphonies of Beethoven and Mahler capture
glimpses of a beauty that is absolute and everlasting. Beyond the temporal, materialistic world there is an unchanging reality.
What is evolution? Evolution occurs whenever there is a population of
reproducing individuals. Reproduction at different rates leads to natural
selection. Mistakes during reproduction lead to mutation. Mutation and
natural selection are two fundamental “forces” of evolution.
Reproduction can be genetic or cultural. The former gives rise to genetic
evolution, which has molded life on earth over the last four billion years.
The latter is the most decisive factor shaping human society. Humans
with language invented a mechanism for nearly unlimited cultural
evolution. New ideas and behaviors can spread rapidly by learning, teaching, and imitation. Cultural evolution allows rapid innovation and is
responsible for the dramatic changes that have occurred on this planet in
the last few millennia.
Sadly, humans do not use their evolved traits only for good ends. They
wage wars of destruction. They fight each other, and they destroy the
environment that is essential for their survival. Despite all of this, a flame
of love is burning inside us that cannot be extinguished.
I am fascinated by questions concerning the evolution of cooperation
and altruistic behavior. Natural selection is based on competition between
individuals. It introduces conflict. Cooperation means that one individual pays a cost for another individual to receive a benefit. Cooperation is
opposed by natural selection unless specific mechanisms are in place.
For humans, the fundamental mechanisms encouraging cooperation are
direct and indirect reciprocity. Direct reciprocity is based on repeated
interactions between the same two individuals: my behavior toward you
depends on what you have done to me. Indirect reciprocity is based on
repeated interactions in a group: my behavior toward you also depends
on what you have done to others. Cooperation among humans is related
to altruistic behavior. Loving others and trying to help them are important aspects of human nature.
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A T E M P L E T O N C O N V E R S AT I O N
ROBERT WRIGH T
Cooperation is, in my opinion, another fundamental “force” of evolution.
Cooperation is needed for construction. Whenever evolution moves to
higher levels of organization, cooperation is involved. The emergence of
multi-cellular organisms, for example, requires cooperation among cells.
And human language would not have evolved without sustained cooperation among potential speakers and hearers.
28
There is a fascinating additional problem concerning our present
understanding of evolution. Evolution is a search process. Populations
of reproducing individuals “search” for short-term solutions, such as
adaptations to a new environment or modifications of a social system.
But the search process has to operate within a given space of possibilities.
This “search space” ultimately determines what can evolve. For example,
evolution can find intelligent life, if it is part of the search space, but it
cannot construct the possibility of intelligent life. For science to
fully “explain” intelligent life (or other fundamental properties of living
systems), we need not only a theory of evolutionary dynamics but
also a theory describing how the fundamental laws of nature span the
search space.
As a scientist, I could adopt the narrow position that I am exclusively
interested in those aspects of human nature that can be analyzed by
scientific methods. This is a valuable and useful perspective, and it will
continue to generate much scientific progress. But in my Faustian
search for truth, I realize that science does not give a complete analysis of
human existence. We are all confronted by questions concerning
the mystery and purpose of life, which cannot be answered by natural
science alone.
I subscribe to the ideas of what Leibniz called “perennial philosophy”:
there is an unchanging reality beneath the world of change; this reality is
also at the core of every human existence; and the purpose of life
is to discover this reality. In the context of my own Christian faith, the
fundamental aspect of human nature is our relationship with God
and our participation in God’s love and eternity. This particular aspect of
human nature is also not a product of evolution.
Photo credit: Erik Jacobs.
Robert Wright
Yes.
Two centuries after the birth of Darwin, the Darwinian explanation of human nature is essentially
complete. We now know why people everywhere
— notwithstanding differences of culture and
context — experience the same basic emotions,
the same kinds of hopes and fears, even the same
distortions of perception and cognition.
Ever since Darwin published On the Origin of Species
in 1859, it has been clear that natural selection could
explain the more obviously animal parts of human
nature. Things like hunger and lust are no-brainers:
genes that encourage you to ingest nutrients and
have sex do better in the Darwinian marketplace
than genes that counsel starvation and abstinence.
Nor is it any great mystery how humans came to be
socially competitive. High social status brings improved access to mates,
so genes that fuel the pursuit of status fare well.
Robert Wright is the
author of The Moral
Animal: Why We Are
the Way We Are and
Nonzero: The Logic of
Human Destiny. His
new book, The Evolution
of God, will be published
in June.
Much subtler legacies of evolution have come to light in recent decades
as the modern science of evolutionary psychology has emerged. Not just
animal appetites and drives, but fine-grained tendencies of emotion and
cognition can now be ascribed with some confidence to natural selection.
For example, genes inclining us to lower the social status of rivals by
spreading unflattering gossip or harsh moral appraisals would be favored
by natural selection. And, of course, the most effective propagandist is
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A T E M P L E T O N C O N V E R S AT I O N
someone who believes the propaganda, so our everyday moral evaluations of people may be skewed by our genes.
Maybe the biggest accomplishment of post-Darwin Darwinians has
come in explaining the mushy side of human nature: compassion,
empathy, and so on. These emotions make obvious Darwinian sense
only when they are directed toward those endearing little vehicles of
genetic transmission known as offspring. But what about when they
are directed toward collateral kin — siblings, cousins — or even non-kin?
Over the past half-century, two theories — the theory of kin selection
and the theory of reciprocal altruism, respectively — have answered
these questions.
30
The theory of reciprocal altruism has also illuminated several other big
parcels of the emotional landscape — gratitude, obligation, forgiveness,
and righteous indignation. Even the sense of justice — the intuition
that it is “right” for good deeds to be rewarded and for bad deeds to be
punished — now makes sense as a product of natural selection.
The evolutionary roots of human nature have not been “proved” in the
sense that theorems are proved, and they are not as firmly corroborated
as, say, the first law of thermodynamics. But they grow increasingly
plausible as more psychological experiments are done from a Darwinian
angle, more evolutionary dynamics are modeled by computer, and the
biochemical links between genes and behavior become clearer. One
chemical alone — oxytocin — has been implicated in maternal bonding,
romantic bonding, and the trust that undergirds friendship.
None of this is to say that no puzzles remain or that there are no
disagreements among Darwinians. Spats between “group selectionists”
and “individual selectionists,” though often overstated and in some
cases merely semantic, do sometimes have real consequences. Still, this
infighting results from a surplus of serviceable Darwinian theories,
not a shortage. There can no longer be reasonable doubt that the emotions and inclinations that people everywhere share are the legacy
of natural selection. Darwin’s theory has illuminated and explained the
fundamental unity of human experience.
ROBERT WRIGH T
Many people find it depressing that some of our noblest impulses are
reducible to genetic self-interest — and, worse, that this self-interest
can subtly corrupt our moral evaluations and our conduct. As it happens,
the fact that they find this depressing is itself explicable in Darwinian
terms. Natural selection has inclined us to present ourselves as publicspirited and even selfless, and in the service of that goal we are inclined
to convince ourselves that we really are
public-spirited and even selfless. In other
Maybe the
words, we naturally consider ourselves
biggest
noble, not just “noble.”
accomplishment
of post-Darwin
Darwinians
has come in
explaining the
mushy side
of human nature:
compassion,
empathy, and
so on.
But this points to the sense in which the
Darwinian explanation of human nature is not
depressing. If we are naturally inclined to
overestimate our goodness, then a theory that
exposes us to a truer view of ourselves has the
potential to inspire self-improvement. What
should depress us is how much time we spend
deluding ourselves about our goodness, not the
fact that we now have a chance to escape
delusion and make amends.
Another dubious source of Darwinian depression is the idea that an evolutionary explanation
of human nature leaves us with no great awe-inspiring mysteries about
the human condition. Actually, Darwinism, while solving the mystery of
human nature per se, has revealed deeper mysteries that it has no hope
of solving.
For example: how on earth did the universe wind up generating an
algorithm (natural selection) that turns an imperative of utter selfishness
at the genetic level into altruism at the individual level? An algorithm
this elegant is at least as awe-inspiring as more direct means of creating
humanity and other species. Charles Kingsley, an Anglican clergyman
and a naturalist, wrote in a letter to Darwin, “I have gradually learnt to
see that it is just as noble a conception of Deity, to believe that He
created primal forms capable of self-development into all forms needful
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A T E M P L E T O N C O N V E R S AT I O N
F R A N C I S C O J. AYA L A
pro tempore and pro loco, as to believe that He required a fresh act of
intervention to supply the lacunas which he himself had made. I question
whether the former be not the loftier thought.”
Finally, there is the mystery of consciousness. I have said that natural
selection readily explains emotions like compassion and indignation.
Strictly speaking, it does not. It explains the behaviors with which
compassion and indignation are correlated and the neural programs that
govern those behaviors. Why these behaviors and this neural governance
should have emotional correlates — why there is subjective experience at
all — is actually a mystery. Only a few Darwinian thinkers, such as
Steven Pinker and the late John Maynard Smith, have appreciated this
problem. Daniel Dennett and others deny the mystery, but in doing so,
they sometimes veer perilously close to denying the existence of consciousness itself.
32
Subjective experience, of course, is what gives life meaning. A planet
full of robots that have no interior life but behave and speak as we do is
not a planet worth caring about. If none of these robots can feel pain,
what is wrong with smashing them? If none can feel joy — or anything
else — what is good about “life” on this planet?
What Darwinism tells us is how natural selection gave human life its
distinctively rich texture of meaning. Darwinism can also give us
guidance as we try to better ourselves and make that meaning richer still.
What Darwinism does not tell us is why there is meaning at all.
Francisco J. Ayala
Only up to a point.
Francisco J. Ayala is
University Professor
and Donald Bren
Professor of Biological
Sciences at the University
of California, Irvine. A
former president of the
American Association for
the Advancement of
Science and a winner of
the National Medal of
Science, he is the author
of Darwin’s Gift to
Science and Religion.
Evolution explains human origins. We know that
humans share recent ancestors with the apes. Our
lineage separates from that of the chimpanzees,
our closest living relatives, six or seven million years
ago. Scientists call members of this lineage “hominins.” The first fossil of a hominin was discovered
on the island of Java in 1894, twelve years after the
death of Charles Darwin, who had predicted
that such remains would eventually be found. That
hominin belonged to the species Homo erectus
and lived more than a million years ago.
Over the past century, thousands of other hominin
fossils have been discovered. The oldest of these
belong to species quite different from modern humans,
classified with exotic names that usually refer to
where they were unearthed. Sahelanthropus tchadensis,
found in Chad in Central Africa, lived between six
and seven million years ago. Australopithecus afarensis,
found in the Afar region of East Africa, lived
between three and four million years ago. And Homo heidelbergensis, first
found in Germany, lived between 500,000 and one million years ago.
For several million years, hominins had a small brain, similar to that of a
chimpanzee and weighing about one pound. Brain size started to
increase about two million years ago, with the species Homo habilis, the
first of the hominins to make stone tools. It seems likely that smarter
individuals with somewhat larger brains would have been able to make
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A T E M P L E T O N C O N V E R S AT I O N
better tools, which was advantageous for hunting, fighting, and so on.
As a result, smarter individuals would have left behind more descendants.
Gradually, over the last two million years, brain size tripled, reaching
about three pounds in the average modern human.
Evolution also allows us to trace the origin and migration of human
populations. Modern humans evolved in tropical and subtropical
Africa about 150,000 years ago. They colonized much of Africa and parts
of Asia and Europe starting about 100,000 years ago, and America
about 15,000 years ago. As one would expect from so recent a diaspora
(recent, that is, on the evolutionary scale), humans from different parts of
the world are genetically quite similar, despite their conspicuous differences in skin color, body configuration, hair, and other traits that help us
to distinguish people from different parts of the world.
34
Over the past decade, evolutionary geneticists have started to decipher
the genomes of humans and chimps. Surprisingly, in the genome regions
shared by the two species, nearly 99 percent of the DNA is identical.
But we also have discovered distinctive human features. Genes active in
the development of the brain, for instance, have changed more in the
human lineage than in the chimp lineage, and so has the gene called FOXP2,
which relates to speech. In fact, researchers have identified 585 genes
that have evolved faster in humans than in chimps. But there is still much
that we do not know about what makes us so different from apes.
Fortunately, we have been searching in earnest only for a decade, and
discoveries will continue to accumulate.
Evolutionary neurobiology has made similar advances. We now know a
great deal about which parts of the brain have become more differentiated
in humans than in apes, and what functions they play in memory, speech,
hand articulation, and so on. Much has been learned as well about how
light, sound, temperature, resistance, and other impressions are transmitted
to the brain by our sense organs. Still, despite all this progress, the field
remains in its infancy. Those questions that matter the most to us remain
shrouded in mystery: how physical phenomena (the chemical and
electric signals by which neurons communicate) become feelings, sensations, concepts, and all the other elements of consciousness, and how the
F R A N C I S C O J . AYA L A
mind, a reality whose properties include free will and self-awareness,
emerges from the diversity of these experiences.
Humans also have opened up a new mode of
evolution: adaptation by technological
manipulation and culture. We have developed
the capacity to modify hostile environments
according to the needs of our genes. The
discovery of fire and the fabrication of clothing
and shelter have allowed us to spread from
the warm tropical and subtropical regions of
the Old World, to which we are biologically
adapted, to most of the Earth. Humans
did not wait until genes evolved that would
provide anatomical protection against cold
temperatures by means of fur or hair.
Nor have we bided our time in expectation
of wings or gills: we have conquered the air and seas with artfully
designed contrivances. It is the human brain (or rather, the human mind)
that has made humankind the most successful — by most meaningful
standards — of living species.
Science is a way
of knowing, but
it is not the only
way. Evolution
tells us much,
but certainly not
everything, about
human experience
and the human
predicament.
But culture includes much more than adaptation to the environment
and much more than science and technology. Culture includes art
and literature; history and political organizations; economic and legal
systems; philosophy, ethics, and religion. These all-important components of human nature transcend evolutionary biology and every
other science. Science has nothing decisive to say about values, whether
economic, aesthetic, or moral; nothing to say about the meaning of
life and its purpose; and nothing to say about religious beliefs — except,
of course, in those cases when these values and activities transcend
their proper scope and make demonstrably false assertions about the
natural world.
Science is a way of knowing, but it is not the only way. Evolution tells
us much, but certainly not everything, about human experience and the
human predicament. In The Myth of Sisyphus, Albert Camus asserted
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A T E M P L E T O N C O N V E R S AT I O N
that we learn more about ourselves and the world from a relaxed evening
gazing at the starry heavens and taking in the scent of grass than from
science’s reductive ways. This may be literary exaggeration, but there can
be no doubt that we learn about human nature by reading Shakespeare’s
King Lear, contemplating the self-portraits of Rembrandt, and listening
to Tchaikovsky’s Symphonie Pathétique. We humans judge our actions
toward others according to systems of morality, and we derive meaning
and purpose from religious beliefs. Evolution may explain our capacity to
hold these principles and beliefs, but it does not explain the principles
and beliefs themselves.
E VA J A B L O N K A
Eva Jablonka
Yes, but…
we have to qualify what we mean by “human nature,”
by “explain,” and by “evolution.”
36
Eva Jablonka is an
evolutionary biologist and
a professor at the Cohn
Institute for the History
and Philosophy of Science
and Ideas at Tel Aviv
University. Her books
include Animal
Traditions (with Eytan
Avital) and Evolution in
Four Dimensions
(with Marion Lamb).
If, like Aristotle, we see “human nature” as something
that depends on a basic animal nature, which in
turn depends on a nature that is common to all living
things, then the answer to the question is long
and complicated. It has to include the evolution
of the goal-directed, teleological systems underlying
the origin of life and the acquisition of a mentality
that endows every animal with a will, as well
as the evolution of the unique aspects of the human
mind. An answer would amount to re-writing
Aristotle’s De Anima using a 21st-century evolutionary framework.
But I think that the question being asked is a more
modest one, highlighting the uniqueness of human
nature as compared, for example, with the nature
of our evolutionarily close relative, the chimpanzee. Many people are
ready to accept that evolution explains chimpanzee nature, but not that it
explains human nature. They assume that at some definite point in
evolutionary history, God intervened and endowed the human lineage
with something that has set humankind apart from all other animals.
So let us consider these more limited questions: Is there a line of demarcation between humans and chimpanzees that makes humans very
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A T E M P L E T O N C O N V E R S AT I O N
E VA J A B L O N K A
different? And can we explain human nature as a product of an evolutionary
process, without miracles? I believe that the answer to both questions is “yes.”
Dobzhansky famously defined evolution as “change in the genetic
constitution of populations over time,” but this definition is too narrow
and, therefore, misleading. We have to think about more than genes.
My colleague Marion Lamb and I have suggested that evolution should
be redefined as the “set of processes that lead to changes in the nature
and frequency of heritable types in populations over time.” Heritable types
include: genotypes, types of transmissible epigenetic (that is, developmentally acquired) variations, types of socially learned animal behavior,
and types of symbol-based transmitted information.
Much has been written about how humans are unique or special, but I
favor the philosopher Ernst Cassirer’s views on the matter. He maintained
that what sets us apart is symbolic systems, most notably, our capacity
to think and communicate using language. This, he argued, is the foundation of our rationality and religiosity and for creating long-term goals
and abstract concepts like justice and truth, which organize human psychology and social life. Cassirer is right, I believe — but none of this
changes the fact that our capacity to use symbols is a product of evolution.
Describing the evolution of this capacity is an incredibly difficult task,
because it has complex and multiple social, cognitive, and emotional bases.
But during the last fifteen years great progress has been made in understanding it, especially with regard to our linguistic capacity. Although we
are only at the beginning of this great intellectual journey, the framework for explaining the origins and evolution of symbolic systems is now
in place.
At this point I also must qualify what I mean by “explain,” in particular,
how an evolutionary account can be said to be explanatory. If we
can describe the biological basis for the appearance of a new trait in a
population, describe how and why it spreads, and how, over time, it
becomes increasingly more sophisticated, we may claim to have provided an evolutionary explanation of this trait. Evolutionary biologists
recognize that at present there are only partial evolutionary descriptions
of most complex behavioral traits. Evolution explains cooperation
among ants, for instance, but we are still far from being able to give a full
causal account of how cooperation is instantiated in the biology of ants
and of how every aspect of such cooperation has evolved. The situation
is similar but even more difficult with respect to the human ability to
use language and other symbols. But the question is tractable and answerable within an evolutionary framework.
Here I must qualify yet another term, “evolution.” The evolutionary
framework that we need to use in this case is much wider than the one to
which we are accustomed. The great evolutionary biologist Theodosius
With humans, the transmission of information via symbols has resulted
in a very rich cultural evolution. This transmission is of major importance
not only for our cultural history but also for our genetic evolution. Under
the appropriate ecological and social conditions, even a crude ability to
communicate using symbols, similar to that seen in trained chimpanzees,
can trigger greatly accelerated genetic evolution of the capacity to use
symbolic systems. This, in turn, will lead to more elaborate symbol-based
cultural evolution, which will favor further genetic changes, and so on.
Recognizing this positive feedback loop between genetic and cultural
evolution may help us to understand how human language evolved and
how other cognitive and emotional features specific to humans — artistic
ability, rationality, religiosity — emerged and became consolidated
during our evolutionary history.
The original question therefore needs to be rephrased in a clumsier but
less ambiguous way: Can an expanded evolutionary framework account
for the specifically human features that set us apart from chimpanzees
and that most of us recognize as constituting human nature? The answer
is “yes.” Indeed, I believe that we can answer this question affirmatively
even if we are committed to the more ambitious Aristotelian concept
of human nature, which includes not only the nature of much simpler
animals endowed with wills but the nature of life itself. There is historical
continuity among the different “natures” that culminate in human nature.
Giving a fuller account of the continuous evolution of these goal-directed
systems is one of the great scientific challenges of this century.
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A T E M P L E T O N C O N V E R S AT I O N
JEFFREY SCHLOSS
cooperate on a scale far beyond that of any other species on the planet.
For all of these varied but crucial features of humanity, evolution
provides a single, empirically assessable account in terms of a principle
— natural selection — that also explains the features of other living
organisms. Evolution locates human nature securely within the confines
of nature itself.
Jeffrey Schloss
Totally, for a Martian.
40
Jeffrey Schloss is
distinguished professor
and chair of biology at
Westmont College. He is
the co-editor of several
books on evolutionary
themes, including The
Believing Primate:
Scientific, Philosophical,
and Theological
Perspectives on the
Origin of Religion (with
Michael Murray).
Humans bear the stamp of a fascinating evolutionary
past, and theories elucidating our biological origins
immensely enrich our understanding of what it
is to be human. But, no, evolution does not “explain
human nature.” In fact, the power of evolutionary
theory to illuminate our humanity derives importantly
both from what it is able to penetrate and from
what remains opaque to it.
So what does evolutionary theory explain well?
For starters, it provides one-stop shopping for many
of the universal or nearly universal features of
our species. It presents compelling accounts of our
intense need to give and receive parental and social
care; of our wide-ranging emotions and the ability
to recognize them facially; of our shared cognitive
biases, phobias, and desires; and of our capacities to
form lifelong social attachments and aversions,
to fall in love, and to envision not just the future but
also other minds, including supernatural minds.
Evolutionary analysis also helps us to understand why human groups are
structured around kinship and reciprocity, why they are monogamous or
polygamous but rarely polyandrous, why they are averse to incest, reliant
on the division of labor, and universally inclined to punish violations
of fairness, to accumulate and transmit extra-genetic information, and to
Though many of the attributes that I have listed above are universal
among humans, not all of them are. Evolutionary theory helps us to
understand this too, by reformulating biological notions of “human
nature” in terms of central tendencies rather than inevitabilities. It
navigates between naïve assertions of organically unconstrained cultural
relativism, on the one hand, and fixed and universal biological nativism,
on the other. The upshot of explaining the statistically normal while
eschewing the normative is that evolution cannot provide counsel for
what humans should be (work done by traditional concepts of human
nature from Aristotle on) and only posits accounts of how humans
came to be what we are.
It turns out, though, that even this more modest goal is not fully attained
by evolutionary theory. In the first place, evolution is absolutely necessary
but not sufficient for explaining just the most straightforward aspects of
an organism. Bat wings, for example, only make sense as evolved derivations of mammalian forelimbs. But to understand them fully also requires
concepts outside of evolution, like the principles of aerodynamics
and gravity. Evolution is a search engine that combs possibility space,
but to explain what it comes up with, we need to understand both
the engine and the space. Like a Shakespearian play, the evolutionary
drama is determined not only by the playwright (in this case, natural
selection, a very dumb author) but also by the constraints of an Elizabethan theater company. To understand the human and our place in
nature, we must understand the budget and the bounties of the world
that made humans possible.
In addition, when it comes to the most distinctive aspects of humanity — language, morality, religious belief, altruism, even our capacity for
science itself — we do not yet have complete or even agreed-upon
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A T E M P L E T O N C O N V E R S AT I O N
evolutionary explanations. This does not signal a need to give up on
evolutionary accounts. Indeed, there has been a recent flowering of
promising proposals for each of these qualities. Among the alternative
evolutionary explanations are theories based on sexual selection,
cooperative adaptation, dominance displays, group-level function, and
traits as byproducts. All of these contending accounts are consistent
with the process of genetic selection that operates in other species.
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What can we
learn about the
nature of being
human from an
account that in
principle could be
developed by an
alien intelligence
without access to
human interiority
or any interest
in humanity’s
most enduring
questions?
But how do we engage the thorny issue of why
our species so often makes choices that do not
maximize or even contribute to our reproductive fitness? One possibility is the idea of
“memes” (that is, transmitted units of cultural
information), which may involve a distinctly
human and non-genetic form of evolution.
Since being proposed by Richard Dawkins to
explain behaviors that “we alone on earth”
exhibit, the idea has been criticized by some as
too vague, too dualistic, too culturally reductionistic, or too assertive of human uniqueness.
Whatever the precise character of the
mechanism, however, one thing seems clear:
genetic selection has sprouted an organism
whose behavior is not fully reducible to
genetic selection.
The very existence of these fascinating
debates constitutes an instructive example of
how evolution illuminates the distinctively human by what it is both able
and not yet able to explain. This does not mean that we will not close the
gap. But science does not give credit for future understanding. At present,
evolution does not explain these important aspects of humanity.
Even if we achieve a fully adequate evolutionary account of things like
morality, religious belief, love, and sentience (perhaps the most difficult
question of all), it still would not tell us what these things are or what it is
JEFFREY SCHLOSS
to experience them as humans. This is not a deficiency of evolutionary
theory. To the contrary, it is a limitation directly related to its potency as
an empirical science. But not all questions that we humans ask about
ourselves are scientific ones.
On my bookshelf, I have an extensive collection of classic (and often
conflicting) volumes on evolution and human nature. It is uncanny
how many of them begin with the same affirmation of the objective nature
of their approach: their accounts, they suggest, are of just the sort
that Martian biologists or intelligent visitors from another planet would
develop. Several even claim that all of humanity’s own ideas about our
nature prior to evolutionary theory are “worthless” and that we would be
better off to “ignore them completely.” Indeed, one of the most prominent
accounts — Richard Dawkins again — asserts that, if extraterrestrial
intellects were to visit earth, it is unlikely they would be interested in
music or religion, and Shakespeare might “mean nothing,” but
they would revere Darwin, whose ideas “really matter in the universe.”
Given biology’s rejection of disembodied Cartesian rationality and
our understanding of how reason is deeply intertwined with emotions and
values, the Darwin versus Shakespeare dichotomy is probably just plain
wrong. Nor is much gained by invoking a sort of interplanetary argument
from authority: “E.T. believes me — so should you!” But the real problem
with so starkly objective an approach is what is left out. What can we
learn about the nature of being human from an account that in principle
could be developed by an alien intelligence without access to human
interiority or any interest in humanity’s most enduring questions?
Pretty much everything a Martian scientist might want to know.
Does evolution explain human nature? No. Does it enrich our understanding of the human? Most profoundly. But so does Shakespeare.
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A T E M P L E T O N C O N V E R S AT I O N
David Sloan Wilson
Yes and no.
When we say that a species has a “nature,” we
are referring to its evolved properties. For a lactosedigesting bacteria, digesting lactose is part of its
“nature.” If we turn it into a new genetic strain unable
to digest lactose, we will have changed its “nature.”
Similarly, domesticated animals have different
“natures” from their wild ancestors.
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David Sloan Wilson
directs EvoS, Binghamton
University’s evolutionary
studies program and
the hub of a nationwide
consortium. His latest
book is Evolution for
Everyone: How Darwin’s
Theory Can Change
the Way We Think
About Our Lives.
My simple formula equating “nature” with evolved
properties might seem boring at first, until we
realize that there is more to evolution than genetic
evolution. Genes are only one mechanism of inheritance. Some immunological, psychological, and
cultural processes also count as evolutionary. They
too rely on the open-ended variation and selective
retention of traits, but they are based on non-genetic
inheritance mechanisms.
People and cultures shaped by these fast-paced
evolutionary processes no longer have the same “nature,” any more than
two bacterial strains that have diverged by genetic evolution. In this
fashion, my simple and seemingly boring formula can be understood to
say that humanity as a whole does not have a single “nature.” Instead,
each and every person and culture has its own “nature.”
This is not just idle word play. We are only beginning to appreciate the
fact that human cultural diversity is fundamentally like biological
D AV I D S L O A N W I L S O N
diversity. Humanity is more like a multi-species ecosystem than a
single biological species. A culture, like a species, has a historical
phylogeny (that is, a sequence of events in its evolutionary trajectory)
and is adapted to its local environment. The body of knowledge
that members of Arctic cultures must learn and transmit to survive in
their harsh environment is mind-boggling when understood in
detail — and very different from the equally extensive body of knowledge
that members of desert cultures must master. In what sense do
they have the same “nature,” any more than a polar bear and a camel?
This is equally true of modern cultural diversity. Only a few decades
ago, American psychologists confidently assumed that their studies of
college students revealed a universal human nature. Economists treated
individual utility maximization as a grand explanatory principle. Moral
philosophers assumed that their own intuition was representative of
everyone’s intuition. The failure of these grand generalizations has been a
humbling experience. As the social psychologist Richard Nisbett put it,
“Psychologists who choose not to do cross-cultural psychology may
have chosen to be ethnographers instead.” Or, in the immortal words of
George Bernard Shaw, “Forgive him, for he is a savage and believes
that the customs of his tribe are the laws of nature.”
But this is not the whole story. Only some immunological, psychological,
and cultural processes qualify as evolutionary in their own right. Immunologists distinguish between the “innate” and “adaptive” components of
the immune system. The innate component consists of fixed responses to
invading organisms, such as the ability of macrophages to recognize
and engulf bacteria based on their surface properties, recruit other macrophages to wound sites, and so on. These highly sophisticated responses
developed through genetic evolution, but they are not open-ended
evolutionary processes. They are species-typical, in contrast to the unique
suite of antibodies that evolves in every individual, thanks to the adaptive
(that is, open-ended evolutionary) component of the immune system.
In addition, the adaptive component of the immune system requires
an elaborate architecture that is genetically innate and therefore part of
the “nature” of our species. Species-typical mechanisms create the
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A T E M P L E T O N C O N V E R S AT I O N
If we want to
change for
the better as
individuals and
societies, we
must learn how
to manage
fast-paced
evolutionary
processes to
take us where
we want to go.
46
diversity of antibodies, distribute them
throughout the body, cause those that successfully bind to antigens to reproduce, keep them
around for a long period of time as a “memory,”
and so on. The neurobiologist and evolutionist
William H. Calvin coined the term “Darwin
machine” to describe any fast-paced process
of evolution built by the slow-paced process of
genetic evolution. Darwin machines must
include a genetically evolved architecture (the
“machine”) if open-ended evolutionary
processes are to achieve biologically adaptive
outcomes.
What holds for the immune system also holds
for psychological and cultural processes.
For example, immediate threats to a person
result in automatic psychological defense responses analogous to
macrophages rushing to a wound site. These responses are highly adaptive
products of genetic evolution, but they are not open-ended evolutionary
processes in their own right. Calling them part of our “nature” should
be uncontroversial. In addition, our open-ended behavioral flexibility, as
individuals and as cultures, requires a genetically evolved architecture
no less than the immune system. A more poetic metaphor than a “Darwin
machine” is a musical instrument. It can produce an infinite number of
songs but also has a single “nature.”
Why do we ask questions about human nature in the first place? Many
people are interested primarily in human potential, our capacity as
individuals and societies to change for the better. For some, saying that
we have a nature is threatening because it seems to deny our capacity
for change, raising the specter of genetic determinism. For others, saying
that we have a nature is enticing because it promises the same kind of
understanding for humanity that evolutionary theory currently offers for
the rest of life.
D AV I D S L O A N W I L S O N
Answering “yes and no” to the question offers the best of both worlds. We
do not have a single nature as a species because we are actively evolving,
thanks to the rapid processes of evolution that employ non-genetic
inheritance mechanisms. Yet, a sophisticated knowledge of evolution is
required to understand both our genetically evolved nature and our
capacity for change. Indeed, just because we have a capacity for change
does not mean that we will necessarily change for the better. Evolution
frequently results in outcomes that are highly undesirable for long-term
human welfare. If we want to change for the better as individuals and
societies, we must learn how to manage fast-paced evolutionary processes
to take us where we want to go. Might this be possible in the foreseeable
future? The answer to that question is “yes.”
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