Darwinian View of Life
Roz
EvolutionforEveryoneChapters1-4.pdf
Evolution for Everyone
How Darwin’s Theory Can Change the Way We
Think About Our Lives
David Sloan Wilson
Distinguished Professor
Departments of Biology and Anthropology
Director of EvoS (http://bingweb.binghamton.edu/~evos/)
Binghamton University
Binghamton, New York 13902-6000
Tel: 607-777-4393 Fax: 607-777-6521
Representation:
Michelle Tessler
Tessler Literary Agency
27 West 20th Street, Suite 1003
New York, NY 10011
(212) 242-0466
www.tessleragency.com
To be published by Bantam Press in Spring 2007..
Table of Contents
1. The Future Can Differ From The Past 5
2. Clearing The Deck 14
3. A Third Way Of Thinking 19
4. Prove It! 23
5. Be Careful What You Wish For 29
6. Monkey Madness 36
7. How The Dog Got Its Curly Tail 41
8. Dancing With Ghosts 49
9. What Is The Function Of A Can Opener? How Do You Know? 55
10. Your Apprentice License 60
11. Welcome Home, Prodigal Son 63
12. Teaching The Experts 69
13. Murder City 76
14. How I Learned To Stop Worrying And Love Genetic Determinism 85
15. They’ve Got Personality! 92
16. The Beauty Of Abraham Lincoln 105
17. Love Thy Neighbor Microbe 114
18. Groups All The Way Down 121
19. Divided We Fall 126
20. Winged Minds 130
21. The Egalitarian Ape 138
22. Across The Cooperation Divide 149
23. The First Laugh 156
24. The Vital Arts 163
25. Dr. Doolittle Was Right 174
26. How Many Inventors Does It Take To Make A Light Bulb? 181
27. I Don’t Know How It Works! 193
28. Darwin’s Cathedral 209
29. Is There Anyone Out There? Is There Anyone Up There? 228
30. Ayn Rand: Religious Zealot 240
31. The Social Intelligence of Nations, or, Evil Aliens Need Not Apply 254
32. Mr. Beeper 266
33. The Ecology Of Good And Evil 274
34. Mosquitoes Under The Bed 281
35. The Return Of The Amateur Scientist 288
36. Bon Voyage 308
Acknowledgements 313
Endnotes 314
Bibliography 327
Websites 340
For H.
Chapter 1
The Future Can Differ From The Past
This is a book of tall claims about evolution: that it can become uncontroversial;
that the basic principles are easy to learn; that everyone should want to learn them, once
their implications are understood; that evolution and religion, those old enemies who
currently occupy opposite corners of human thought, can be brought harmoniously
together.
Can these claims possibly be true? Isn’t evolution the most controversial theory
the world has ever seen? Since it’s a scientific subject, isn’t it hard to learn? If the
implications are benign, then why all the fear and trembling? And how on earth can the
old enemies of evolution and religion do anything other than come out of their opposite
corners fighting?
I might be an optimist, but I am not naive. Allow me to introduce myself: I am an
evolutionist, which means that I use the principles of evolution to understand the world
around me. I would be an evolutionary biologist if I restricted myself to the topics
typically associated with biology, but I include all things human along with the rest of
life. That makes me an evolutionist without any qualifiers. I and my fellow evolutionists
study the length and breadth of creation, from the origin of life to religion. I therefore
have a pretty good idea of what people think about evolution, and I can report that the
situation is much worse than you probably think. Let me show you how bad it is before
explaining why I remain confident about accomplishing the objectives of this book.
Most people are familiar with the reluctance of the general public to accept the
theory of evolution, especially in the United States of America. According to the most
recent Harris Poll, 54% of U.S. adults believe that humans did not develop from earlier
species. That is up from 46% in 1994. Rejection of evolution extends to beliefs about the
origin of other species, the fossil record as evidence for evolution, and the constant
refrain that evolution is “just a theory.”
To make matters worse, most people who do accept evolutionary theory don’t use
it to understand the world around them. For them it’s about dinosaurs, fossils, and
humans evolving from apes, not the current environment or human condition. The polls
don’t measure the fraction of people who relate evolution to their daily lives, but it would
be miniscule.
It’s easy for scientists and intellectuals to smile at the ignorance of religious
believers and the general public, but the fact is that they’re not much better. The Ivory
Tower is more aptly named the Ivory Archipelago. It consists of hundreds of isolated
subjects, each divided into smaller subjects in an almost infinite progression. People are
examined less with a microscope than with a kaleidoscope—psychology, anthropology,
economics, political science, sociology, history, art, literature, philosophy, gender
studies, ethnic studies. Each perspective has its own history and special assumptions. One
person’s heresy is another’s commonplace. With respect to evolution, most scientists and
intellectuals would say that they accept Darwin’s theory, but many would deny its
relevance to human affairs or would blandly acknowledge its relevance without using it
themselves in their professional or daily lives. In effect, there is a wall within academia
that restricts the study of evolution to biology and a few human-related subjects such as
human genetics, physical anthropology, and specialized branches of psychology. Outside
this wall, it is possible for a person to get their PhD without a single course in evolution
or more than a casual reference to evolution in their other courses. That is why the term
“evolutionary biologist” sounds familiar while the more general term “evolutionist” has a
strange ring.
Some intellectuals rival young earth creationists in their rejection of evolution
when it comes to human affairs. A 1997 article in The Nation titled “The New
Creationism: Biology Under Attack” put it this way:
The result is an ideological outlook eerily similar to that of religious
creationism. Like their fundamentalist Christian counterparts, the most
extreme anti-biologists suggest that humans occupy a status utterly
different from and clearly “above” that of all other living beings. And, like
the religious fundamentalists, the new academic creationists defend their
stance as if all of human dignity—and all hope for the future—were at
stake.
The famous metaphor of the mind as a blank slate captures the idea that we can
understand the human condition without any reference to basic evolutionary principles or
our own evolutionary past. The most extreme academic creationists reject not just
evolution but science in general as just another social construction, but they are only one
particularly fierce tribe that inhabits the Ivory Archipelago. Other tribes are fully
scientific but still manage to exclude evolutionary theory. In a 1979 survey of 24
introductory sociology textbooks, every one assumed that biological factors were
irrelevant for the study of human behavior and society. Fast-forwarding to the present,
political scientist Ian Lustick could say this about the human social sciences in a 2005
article:
Of course social scientists have no objection to applying evolutionary
theory in the life sciences—biology, zoology, botany, etc. Nevertheless,
the idea of applying evolutionary thinking to social science problems
commonly evokes strong negative reactions. In effect, social scientists
treat the life sciences as enclosed within a kind of impermeable wall.
Inside the wall, evolutionary thinking is deemed capable of producing
powerful and astonishing truths. Outside the wall, in the realm of human
behavior, applications of evolutionary thinking are typically treated as
irrelevant at best; usually as pernicious, wrong, and downright dangerous.
It might seem that the situation can’t get more bleak, but it does. Evolutionary
biologists are themselves conflicted about the study of our own species. When Harvard
evolutionary biologist Edward O. Wilson published his encyclopedic book Sociobiology
in 1975, his fiercest critics were fellow Harvard evolutionary biologists Stephen Jay
Gould and Richard Lewontin. Fast forwarding to the present, the National Science
Foundation’s most recent and ambitious effort to fund evolutionary research is called the
National Evolutionary Synthesis Center (NESCent), whose basic mission is to “help
foster a grand synthesis of the biological disciplines through the unifying principle of
descent with modification.” This language is not as grandiose as it might seem.
Biologists expect evolution to serve as a unifying theory, delivering “powerful and
astonishing truths” as Ian Lustick put it. Yet, as a curious complement to his diagnosis of
the social sciences, there is not a single member of NESCent’s scientific advisory board
representing a human-related subject, apart from human genetics. It seems that the
barrier separating the study of humans from the study of the rest of life is largely
respected on both sides, even by evolutionary biologists who are trying to foster a grand
synthesis.
Knowing all of this, I remain confident that there is a path around both walls of
resistance, the first denying evolution altogether and the second denying its relevance to
human affairs. Darwin provides an example for us to emulate: On any given day of his
life he might be found dissecting barnacles, minutely observing the behavior of his
children, or germinating seeds that had first been fed to mice, which in turn had been fed
to hawks at the London zoo. The same person who studied earthworms and orchids also
studied human morality. Darwin’s interests were so far flung that his mail came by the
wagonload from all corners of the globe. One letter about plant distributions in India
might be followed by another on the emotional expressions of African natives. Darwin’s
empire of thought was larger than the British Empire.
How was Darwin able to unite so many subjects and blend humans seamlessly
with the rest of life? Perhaps he was a genius. Perhaps there was less to know back then.
Perhaps, but the main reason is more interesting and relevant to our own situation. It was
primarily Darwin’s theory, not his personal attributes or time and place, that enabled him
to build his empire of thought. Moreover, his theory was powerful even in a rudimentary
form because Darwin knew so much less about the details of evolution than we do now.
The same theory enables modern evolutionists to build empires of their own. I’m
no Darwin but my own career shows what a good theory can do. I have studied creatures
as diverse as bacteria, beetles, and birds. I have studied topics as diverse as altruism,
mating, and the origin of species. I can understand and enjoy the work of my colleagues
who study an even greater range of creatures and topics. Please don’t think that I am
boasting about myself—that would be boring. I am boasting about the theory, and the
whole point of this book is to show how anyone can profit from it. It takes a great theory,
not great intelligence, to acquire this kind of synthetic knowledge.
If our own species can be included in this grand synthesis, there is every reason to
do so. It would be like a strange figure emerging from the shadows to enjoy the warmth
of a campfire with good company. My own career shows that this is possible. Just like
Darwin—not because I share his personal attributes but because I share his theory--I have
seamlessly added humans to the bestiary of animals that I study, on topics as diverse as
altruism, beauty, decision-making, gossip, personality, and religion. I publish in
anthropology, economic, philosophy, and psychology journals in addition to my
biological research. My books are on subjects that most people don’t associate with
evolution: Unto Others: the evolution and psychology of unselfish behavior (co-written
with a world-class philosopher named Elliott Sober), Darwin’s Cathedral: evolution,
religion, and the nature of society, and The Literary Animal: Evolution and the Nature of
Narrative (co-edited with a bold young literary scholar named Jonathan Gottschall).
These are not popular accounts watered down for a general audience. They are written for
the experts, most of whom spend their lives studying a much smaller range of subjects.
Evolutionists can stride across human-related subjects at the highest level of intellectual
discourse, in the same way that evolutionary biologists are already accustomed to striding
across biological subjects.
Darwin should be emulated in another respect. His interactions with people from
all walks of life were primarily respectful and cordial. We can learn from his humility
and good humor in presenting his theory to others, in addition to the theory itself. Since
writing Unto Others and Darwin’s Cathedral, I have spoken about evolution, morality
and religion to diverse audiences around the world. Perhaps my most memorable
experience was a televised conversation with a group of faculty and monks from St.
John’s University in Minnesota, a Catholic University and oldest Benedictine Monastery
in North America. My co-author Elliott Sober was invited to converse with His Holiness
the Dalai Lama, making me unspeakably jealous. These encounters are the very opposite
of the sterile “debates” that are staged between creationists and evolutionists. If this kind
of cordial dialogue can take place for evolution and religion, then surely it can take place
for evolution and any other human-related topic.
Indeed, evolution is increasingly being used to study all things human in addition
to the rest of life. I recently conducted an analysis of the highly respected scientific
journal Behavioral and Brain Sciences (BBS). The format of BBS is for a lengthy target
article to be followed by commentaries by other authors, providing a comprehensive
exploration of a particular topic. The topics covered by BBS are highly diverse, from
neuroscience to cultural anthropology. BBS articles are subject to a bruising review
process before they are accepted, not to speak of the scrutiny they receive in the
commentaries. They often have a large impact on subsequent research. According to a
formula that the scientific publishing industry uses to calculate the impact of its journals,
BBS is ranked first among 40 behavioral sciences journals and 7 th among 198
neuroscience journals. If anything qualifies as solid and trend-setting science, it is a BBS
target article.
My analysis shows that during the period 2000-2004, 31.5% of the BBS target
articles used the word “evolution” in the title or as a key word, for topics as diverse as
religion, schizophrenia, infant crying, language, food transfer in hunter-gatherer societies,
facial expression, empathy, vision, brain evolution, decision making, phobias, mating,
cultural evolution, and dreams. In other words, using evolution to study our own species
is not a future event or fringe science. It has already arrived.
Curious, I e-mailed a survey to the authors of these target articles to learn how
they acquired their evolutionary expertise. I discovered that most of them received their
formal training in other areas (such as psychology, anthropology, or linguistics) with little
or no exposure to evolution in college or graduate school, as might be expected from my
bleak portrayal of the Ivory Archipelago. Instead, they encountered evolutionary theory
on their own, often by happenstance, and gradually built up their expertise until it became
a guiding force in their research. The fact that they could train themselves so easily
indicates that the power of evolutionary thinking does not reside in a mass of technical
detail but something much simpler that perhaps anyone can learn. In many ways they
recapitulated the experience of Darwin, who built his empire of thought without the
benefit of the masses of technical detail available to us today.
Perhaps you can begin to see why I am confident about achieving the objectives
of this book, but it gets better. I am a teacher in addition to a scientist. Every year I teach
a course called “Evolution for Everyone” that is open to all students. Last year they came
from the following departments: Anthropology, Art, Biology, Business, Chemistry,
Cinema, Computer Science, Creative Writing, Economics, Education, Engineering,
English, History, Human Development, Linguistics, Management, Mathematics, Nursing,
Philosophy, Physics, Political Science, and Psychology. They included new students
fresh from high school, seasoned upperclassmen, and even more seasoned adults from the
community continuing their education. At the end of the semester the students are asked
to evaluate the class anonymously, so they have nothing to gain or lose by their
comments. Here is a sample of what they have to say:
“This course provides evidence that evolution is evident in everything. It revolutionized
my way of viewing problems.”
“This course changed the way I look at things in general. I try to see and understand
them from an evolutionary perspective now.”
“This course shows how positive evolution can be. It teaches you a great deal and
increases one’s interest.”
“I came into the class not knowing a lot about evolution. I now have an entirely new
outlook on how evolution can be applied to many aspects of life.”
“I had taken evolution classes in high school and never felt it was interesting. But this
class changed all my views upside down. The most boring theories became interesting
thoughts that I could relate to in my own day to day life.”
I wish that I could attribute these glowing comments to my prowess as a teacher, but once
again the credit goes to the theory. My contribution was to help the students recapitulate
the experience of Darwin, much as the BBS authors did on their own initiative. To learn
more about how my students responded to the course, I gave them a survey that measured
their political and religious values, science background, prior knowledge of evolution,
and general thinking skills. The details will be published in a technical journal for anyone
to scrutinize my methods, but here are the results:
• The majority of students, not just a select few, learned to think about evolution as a
powerful way to understand the world in general and especially their own interests and
concerns.
• A background in science or prior knowledge of evolution was not required. Freshman
English majors got the message just as strongly as senior Biology majors.
• The course succeeded across the entire range of political and religious beliefs, from
feminists to young republicans and from atheists to believers. It might seem incredible
that a religious believer can think positively about evolution, not with difficulty but just
as easily as anyone else, but this fact will make more sense as we proceed.
• The students increased their general thinking skills, not just their knowledge about
evolution. In plain language, they got smarter. It might seem incredible that learning
about evolution can make you more intelligent, but think about it: Darwin built his
empire of thought by applying a single set of principles to a vast diversity of subjects,
which comes close to a definition of general intelligence.
For many students who take a course such as the one that I offer, learning about
evolution is like walking through a door and not wanting to return. Using it to think about
their interests and concerns becomes second nature, like riding a bicycle. They are eager
to develop their expertise in subsequent courses and disappointed by professors who do
not share their newfound perspective. In response to this demand, I and my colleagues at
Binghamton University created a program called EvoS that enables anyone to use
evolutionary theory to explore the pageant of life on earth, including the pageant of
human life (http://bingweb.binghamton.edu/~evos/ ). I like to think of EvoS as a new
island in the Ivory Archipelago, a tropical paradise, so to speak. A student describes it as
well as I can: “EvoS provides a stimulating atmosphere within which biologists,
psychologists, anthropologists, philosophers, social scientists, and even those in the arts
can transcend traditional academic boundaries and collaborate in addressing mutually
interesting questions. It creates a think-tank atmosphere of sorts, and it’s a beautiful
thing!”
Now I hope you can see why I am confident about accomplishing the objectives
of this book. In a sense they have already been accomplished. There is already a path
around the two walls of resistance, the first denying evolution altogether and the second
denying its relevance to human affairs. It is not a narrow path accessible to only a
courageous few, but a thoroughfare regularly traveled by many. In this book I have tried
to provide the barest of essentials so that you, the reader, can begin to travel the same
thoroughfare. Do not be misled by the simplicity of the chapters. Simplicity is a virtue
and the chapters cover the same issues discussed by evolutionists at the most advanced
level. I hope you will agree with me by the end that when it comes to evolution and its
widespread acceptance, the future can differ from the past.
Chapter 2
Clearing the Deck
Evolutionary theory is a ship that has weathered many storms. Lately it has been
buffeted by the winds of Creationism and its born-again cousin, Intelligent Design (ID),
but the enemies of evolution are tame compared to its friends. Herbert Spencer, an
intellectual giant of Darwin’s day, liked evolution because he thought it justified the
inequalities of British class society. The first half of Ronald Fisher’s classic The
Genetical Theory of Natural Selection is still read today but the second half on eugenics
(the improvement of society by selective breeding) is politely ignored. Hitler liked
evolution because he thought it justified the ultimate social inequality of genocide. Using
evolution to justify social inequality has become known as “Social Darwinism.” Darwin
himself was passionately against slavery and thought that social policy should be based
on compassion, which he regarded as “the noblest part of our nature,” but even he was
not a new age guy by modern standards. If we judge Darwin’s theory by some of the
company it has kept, especially during its early days, we would give it a wide berth.
I have an unromantic view of science and scientists. I regard science as a roll-up-
your-sleeves activity, like gardening or construction work. I regard scientists as just like
other folks. No one can be trusted on the basis of their job title—not scientists,
politicians, priests, or self-righteous intellectuals. Trust requires accountability. Some
individuals are accountable on their own but that’s not good enough at the institutional
level. An effective government, religion, or scientific culture must include mechanisms
that make everyone accountable. When I was immersing myself in the study of religion
to write Darwin’s Cathedral, I discovered that the strongest and most effective religions
owe their success in part to their accountability. As one example, the church started by
John Calvin in 16 th century Geneva was not run by one person but by a group of Pastors.
When they couldn’t agree, the decision-making circle was widened, not narrowed. Elders
assigned by the Church to oversee different sections of the city had to be approved by
those who were being overseen. Life-threatening jobs such as ministering the plague
hospital were assigned by lottery. Double bookkeeping methods were used to keep track
of charitable funds. Calvin’s church was trustworthy as an institution because it included
mechanisms that made it difficult for even the leaders to cheat—just what you’d expect
from a religion founded on the doctrine of original sin!
Science is largely a way to insure accountability for factual claims. In the last
chapter I made some factual claims about how students responded to my “Evolution for
Everyone” course. I am expected to provide the details of my survey to anyone who
wishes to scrutinize them. I abide by an honor code (never, ever deliberately falsify your
data) that is largely maintained and when broken results in punishment and exclusion.
People can freely disagree about the veracity or interpretation of my results. They can
reserve judgment until the study is repeated or the same claim is demonstrated using
different methods. When the process works well, it results in the accumulation of factual
claims that are supported, like a sturdy scaffold that we can stand upon with confidence
to build higher. But vigilance is required at all times, just as with priests and politicians.
This practical view of science can help us clear the deck of past controversies
about evolution to prepare for our own voyage. With respect to Hitler and others who
used evolution to advance their nefarious causes, it’s not as if the world was a nice place
before Darwin and became nasty on the basis of his theory. America was colonized
before Darwin and the pioneers used the principle of divine right to dispossess the
natives. While we’re at it, let’s not romanticize the natives. In many indigenous cultures,
the word for “our people” is “human” and outsiders are classified as a type of animal.
Before Darwin, religious tracts claimed that negroes don’t have souls and women are
designed by “God and Nature” for a life of domestic servitude. Is it a surprise that the
theory of evolution would be pressed into the same kind of service? Is that a reason to
reject the theory?
Science, religion, and politics all face the same problem. Some individuals are
driven to benefit themselves at the expense of others or their society as a whole. At a
larger scale, some groups are driven to collectively benefit themselves at the expense of
other groups. In science this problem takes the form of self-serving factual claims. I say
that something is true, not because it really is true but because it serves my interests. The
most important wrong ideas in science are not just bad guesses; they systematically serve
the interests of their proponents. One hundred years ago, respectable doctors and
scientists thought that women shouldn’t go to college because brain development
interferes with ovarian development. This wasn’t just a bad guess; it was a bad guess that
supported deeply held notions about the role of women in society. An anthropologist
friend who studies ethnic conflict tells me that some Catholics in Northern Ireland think
they can identify Protestants by their closely spaced eyes. Some Protestants have exactly
the same theory about Catholics. These aren’t just bad guesses about facial morphology;
they’re bad guesses that dehumanize the enemy.
To make matters worse, our hidden agendas need not be conscious. It’s not as if
we see the world clearly and then willfully distort it to serve our purposes. The world we
see clearly has already been distorted by unconscious mental processes. Believers in the
eye theory didn’t make it up, knowing it to be false. They really believe it to be true.
Fortunately, even if we cannot always detect our own biases, we can hold each other
accountable for our factual claims by scientific methods. It turns out to be just plain
wrong that college women have shriveled ovaries. The eye theory can be settled in a
single afternoon with a pair of calipers. If people can’t be held accountable for their
factual claims at such a basic level, there is little hope of agreeing on larger issues.
How should we respond to someone who uses a scientific theory to justify acts
that we regard as reprehensible? There are two lines of defense. One is to question the
alleged facts. The other is to question whether the facts justify the acts. Even if going to
college did cause ovaries to shrivel, we might decide that women have the right to choose
for themselves which organ to develop.
A third line of defense is to declare the theory off-limits. This is tempting in an
impulsive sort of way but makes no sense upon reflection. Imagine that someone runs
into your house shouting “There’s a horrible monster coming our way! Let’s pretend that
it has nothing to do with us!” That’s what someone is doing when they declare a theory
off-limits because they think it might lead to bad consequences. We need to pluck up the
courage to determine if the factual claims are wrong (usually because they serve
someone’s interests) or if they are right, in which case we must decide what to do about
them in a morally responsible fashion.
Not all factual claims are contentious. Sometimes there is everything to gain and
nothing to lose by knowing the truth of the matter, like what it takes to keep an airplane
in the air. Many facts revealed by evolutionary theory are of this type and anyone would
be a fool to ignore them. However, even the most contentious claims associated with
evolution are less threatening than you might imagine when you roll up your sleeves and
get to work on them. Self-serving claims usually make bad scientific theories, which can
be rejected easily enough upon close inspection. In my class and this book there are no
topics that are off-limits. My students are not threatened or offended and I’ll bet that you
won’t be either.
Darwin’s theory is nearing its 150 th birthday and it might seem that the most
important discoveries have already been made. Actually, this is a short time and so much
remains to be discovered in the future. The science of genetics didn’t get started until the
rediscovery of Mendel and his peas in 1904. At first “Mendelism” was regarded as an
alternative to “Darwinism” and they didn’t come together until 1918, thanks in part to the
aforementioned Ronald Fisher. DNA wasn’t discovered to be the code of life until 1953.
Using evolution to think about organisms in their natural environments didn’t really
gather steam until the 1960’s.
Even more remains to be discovered about our own species. For millennia we
have imagined ourselves as set apart from the rest of nature. Our thoughts about
ourselves are especially prone to self-serving biases. Our academic traditions have
developed without reference to evolution for over a century. In anthropology, one of the
great questions of Darwin’s day was why some people had become “civilized” while
others remained in the state of “savagery.” The modern approach to this question is
illustrated by Jared Diamond’s magnificent Guns, Germs, and Steel, but back then it
seemed reasonable to imagine a linear evolutionary progression that all cultures travel
along, with some more advanced than others. In reaction, other anthropologists declared
themselves “anti-evolutionists” and insisted that every culture should be studied and
appreciated on its own terms, a tradition that persists to this day. In psychology,
evolutionary theory was eclipsed by a tradition known as behaviorism, which claimed
that people could be shaped by learning to do almost anything. If the mind is a blank
slate, then who cares what happened during the Stone Age? The field of economics has
been dominated by something called rational choice theory, which claims that people
attempt to maximize self-interested values. The values are flexible and economists don’t
care much about what they might be, as long as they can employ their optimization
models. Evolutionary theory was forced into the shadows while these other theories
occupied center stage. Even the most talented and open-minded scientists in these fields
are handicapped by events that took place before they were born and became the basis of
their disciplinary training, as we saw in the case of the BBS authors who had to discover
evolution on their own.
A theory is merely a way of organizing ideas that seems to make sense of the
world. Scientific methods are merely ways of rejecting or supporting factual claims that
emerge from theories. We do not automatically perceive the world as it really is and we
are especially prone to self-serving biases. These biases are advantageous for some
people in the short run by definition, but they are often harmful to other people and even
to everyone in the long run. Agreeing to establish, protect, and abide by a body of factual
information therefore has a moral quality similar to the norms of a religion or a
democratic government. It’s not always easy, especially when one’s own interests appear
to be at stake, but facts never lead to actions all by themselves. They can only inform a
system of values. I would rather live in a society based on good facts interpreted by a
good value system than in any other kind of society.
So, what is this theory that seems to make such sense of the world and might even
enhance our understanding of ourselves? Now that we have cleared the deck of past
controversies, let’s raise the sails and begin our own voyage.
Chapter 3
A Third Way of Thinking
Darwin’s theory of natural selection is like a recipe with three ingredients. We
start with variation. Individuals such as you and I differ in just about anything that can be
measured, such as height, eye color, or quickness to anger. Then we add consequences.
The differences between you and I sometimes make a difference in our ability to survive
and reproduce. Perhaps your superior size enables you to take my stuff or even kill me
directly. Perhaps my inferior size enables me to survive the winter on less food. The
details depend upon our particular traits and the environments we inhabit. The final
ingredient, a sort of yeast that makes the recipe come to life, is heredity. For many traits,
offspring tend to resemble their parents. Darwin didn’t know how heredity worked in a
mechanistic sense but it was a very well established fact.
When these ingredients are combined they lead to a seemingly inevitable
outcome. As an example, imagine a population of moths that vary in their coloration (1 st
ingredient). Some are more easily spotted and eaten by predators, removing them from
the population (2 nd ingredient). The offspring of the survivors resemble their parents (3
rd
ingredient), so the entire offspring generation is more cryptic, on average, than the
parental generation. If we repeat the process over many generations, and if nothing else
happens to complicate our story, the moths will become very hard for predators to spot. If
we could print a picture of each generation on a page and use the stack of pages like a
flipbook, the moths would seem to melt into their background. They have acquired a trait
that helps them to survive in their environment. In evolutionary parlance, they have
increased their fitness and become well adapted.
Is that all there is? Just about. Learning about natural selection is like having a
premature orgasm. You think it will take a long time and lead to a tremendous climax,
but then it’s over almost as soon as it began!
The main question about natural selection is not “What is it?” or “Does it
happen?” but “Why is it such a big deal?” To answer this question, imagine that I place
an object in your hand, perhaps a glittery rock or a furry mouse, and ask you to explain
how it obtained its properties. Before Darwin you would have had only two options. You
could say that God designed it according to his intentions. Perhaps the rock is glittery to
please the eye and the mouse is a pest to teach us humility. Or you could dismantle it and
explain the whole as a product of its parts. Perhaps the rock is glittery because it has
quartz crystals and the mouse’s fur is made of keratin. The big deal about natural
selection is that it provides a third way of explaining the properties of the mouse,
although not the rock. You could say that the mouse is endowed by natural selection with
the properties that enable it to survive and reproduce in its environment.
It is obvious that the natural selection explanation differs from the theological
explanation. The fact that it also differs from the material explanation is a bit more subtle.
Suppose that I place a clay sculpture in your hand and asked you how it obtained its
properties. You would spend most of your time talking about the shape imposed by the
artist, not the properties of clay. The clay permits but does not cause the properties of the
sculpture. In just the same way, heritable variation turns organisms into a kind of living
clay that can be molded by natural selection. Evolutionists such as myself routinely
predict the properties of organisms without any reference to what they are made of, not
even their genes.
To illustrate the power of this way of thinking, consider the subject of infanticide.
Since natural selection is all about having offspring, it might seem pathological to kill
them. Nevertheless, with a little effort you might be able to think of some environmental
situations that make infanticide adaptive. In my class I have the students turn to their
neighbors to discuss possibilities for a few minutes before telling me their suggestions.
They reliably identify the following situations that make infanticide adaptive.
The first is lack of resources. If a mother can’t feed herself and care for her
existing offspring, then it will not increase her fitness to have new offspring. The second
is poor offspring quality. It will not increase the fitness of a parent to raise an offspring
that itself is unlikely to survive and reproduce. The third is uncertain parentage. With
some important exceptions (read on!), it will not increase the fitness of a parent to raise
someone else’s offspring. This third situation is confronted primarily by males in
mammals such as ourselves, but female birds can also be “duped” by another female who
lays eggs in her nest.
My students (and perhaps you) did very well, since these are indeed the “big
three” situations that favor the evolution of infanticide, according to scientists who
actually study the subject. The message of this exercise is simple but profound: How did
my students become so smart? They hadn’t read anything on infanticide and I certainly
hope that they hadn’t experienced it for themselves. Their evolutionary training had only
just begun but even a tiny bit enabled them to become experts, honing in like heat-
seeking missiles on the predictions that are made by the experts. That is the power of
natural selection thinking that makes it such a big deal.
My students had also become taxonomic experts. They didn’t need to be
entomologists, ichthyologists, herpetologists, ornithologists or mammalogists to say
something important about insects, fish, reptiles, birds, and mammals. Natural selection
thinking is based on the relationship between an organism and its environment, regardless
of its taxonomic identity.
Even better, my students became experts without any knowledge of the physical
make-up of organisms. In any particular species, infanticidal behavior will be caused by
physical mechanisms that work through certain pathways, but we don’t need to know this
to predict the occurrence of the behavior. As long as we have the living clay of heritable
variation, we can make predictions based on the shaping influence of natural selection.
Finally, we can repeat the exercise to become expert on an infinite number of
other subjects. Why are males larger than females in some species and the reverse in
others? Why are there two sexes in the first place? Why are males and females born in
equal proportions in some species but not others? Why do some organisms reproduce
once and then die while others reproduce at repeated intervals? Why do some plants live
three weeks and others 3000 years? Why are some organisms social and others solitary?
Among social organisms, why do some individuals cooperate and others cheat?
Questions such as these are truly without end.
Soon I will add some qualifiers to the power of natural selection thinking but for
now we should pause to appreciate its amazing explanatory scope. I began this book by
saying that just about anyone can become an evolutionist by learning to think like
Darwin. This might have seemed crazy but now I hope you can see that it is a very
sensible and down-to-earth suggestion. It is the core idea of natural selection that we need
to learn and it is powerful even in its most rudimentary form. This was true even for
Darwin, who recalled his moment of insight as if struck by a bolt of lightning.
I can remember the very spot in the road, whilst in my carriage, when to
my joy the solution occurred to me…The solution, as I believe, is that the
modified offspring of all dominant and increasing forms tend to become
adapted to many and highly diversified places in the economy of nature.
Before this insight, Darwin had been struggling with thousands of bits of information that
refused to fit together. Then he saw how they could become one big picture like a jigsaw
puzzle. No wonder that he used the word “joy” to describe the experience!
I also experience joy as I survey the length and breadth of creation, dropping in on
subjects and organisms that strike my fancy: Shyness and boldness in fish on Monday,
egg laying in birds on Tuesday, human gossip on Wednesday. It’s a joy just to think
about such different things as part of a single picture, but it’s a special joy to work on
them at the professional level, discovering new pieces and how they fit together for the
first time. How amazing that virtually anyone can begin to expand their horizons and fit
the pieces of their world together on the basis of such a simple idea.
Chapter 4
Prove it!
Evolution is a great theory for predicting the properties of organisms but no
theory is guaranteed to be correct. Unless the predictions can be tested by scientific
methods, progress grinds to a halt. Depending upon who has your ear, you might think
that evolutionary theory remains unproven after all these years. Even someone as
distinguished as the President of the United States (George W. Bush) has declared that
the jury is still out. Let me show you how silly this is, once you take a roll-up-your-
sleeves approach to science.
I have studied infanticide in a wonderful insect called the burying beetle (Family
Silphidae, Genus Nicrophorus). If you want to see a burying beetle for yourself, take a
piece of raw meat about the size of an egg and tie a 24” piece of dental floss tightly
around it. Place it on the ground in a wooded area and come back the next day. There is a
good chance that the meat will be gone but the dental floss will still be visible. Follow the
dental floss to where it disappears into the ground, remove the soil gently with a spoon,
and you will probably find the meat with two large beetles in Halloween colors, orange
and black. Look closer and you will see mites on their backs like passengers on an
airplane.
Burying beetles are carrion feeders that specialize on small carcasses, such as
mice and baby birds that fall out of their nests. They are one of a very few insects that
practice family values; both the mother and the father stay to raise their offspring.
Working together, they drag the carcass to a suitable spot and bury it in an underground
chamber for protection. This by itself is a remarkable feat because the carcass can be
many times their own weight and the soil contains impediments such as roots and stones.
Once the carcass is buried, the female lays her eggs in the surrounding soil and the couple
sets about preparing the carcass for their brood. This involves removing the fur or
feathers, rolling it around and around in the crypt until it assumes a spherical shape, and
covering it with a secretion that inhibits microbial growth. The parents must tend the
carcass continuously because if you remove them a beard of fungus and bacteria grows at
once.
When the eggs hatch the young larvae are actually called to the carcass by the
parents, who make a sound by rubbing their hard wing covers against their abdomen.
Rather than feeding upon the carcass directly, the larvae cluster around their parents, who
regurgitate predigested food. When they become larger the larvae feed on the carcass
itself, reducing it to bones while they become fat white grubs. As soon as the larvae
tunnel into the soil to transform into adults, the parents fly off separately in search of
other carcasses.
This might seem like a heart-warming tale but there is a dark side. The carcass
can vary in size from a baby mouse to an adult squirrel. Do the burying beetles adjust the
size of their brood to the size of the carcass, and if so, how is it accomplished? It turns
out that they do make the adjustment and it is accomplished by infanticide. At the same
time that they are nurturing some of their offspring, they are munching on others until
they have reduced their brood to a size appropriate for the carcass. This illustrates the
first environmental situation that favors the evolution of infanticide; lack of resources.
How can I state these facts with such confidence? I went to K-Mart and purchased
a lot of plastic shoeboxes and potting soil. I filled the shoeboxes with soil and placed a
pair of beetles and a dead mouse in each one. Half of the mice were small and the other
half were large. I dismantled a third of the boxes after the eggs had been laid and before
they had hatched. I counted the eggs and discovered that females who bury small mice
lay just as many eggs as females who bury large mice. I dismantled another third during
the larval stage and discovered that brood size had become proportionate to carcass size. I
allowed the offspring to complete their development in the last third and discovered that
there was no difference in the size of beetles grown on small and large carcasses. In other
words, offspring number had been regulated with remarkable precision such that average
offspring size remained constant.
The regulation takes place after the egg stage. How is it accomplished? It might
be infanticide, offspring competition, or conceivably even suicide. Direct observation
settled the issue. Adults can be easily seen nurturing some offspring and munching on
others until brood size is proportionate to carcass size. Their adaptive strategy is to
overproduce at the egg stage and cut back at the larval stage. Infanticide is as much a part
of this strategy as parental care.
Another question that interested me was why both parents remain to take care of
their young. There are many possibilities. After all, being a burying beetle is hard work.
You have to drag something that can be several hundred times larger than yourself, bury
it, work tirelessly to prevent microbial growth, and so on. I and my colleagues who study
this marvelous creature did numerous experiments of the sort that I have described for
brood regulation, in both the laboratory and their natural habitat. Remarkably, we
discovered that “single moms” did just as well as “intact families” in most respects. We
didn’t expect this and I still don’t entirely believe it, but that is what the results indicate.
The main situation that requires Dad in addition to Mom involves repelling intruders.
It turns out that of all the hardships faced by burying beetles, the most dangerous
is other burying beetles. With their exquisite sense of smell, they can detect a buried
carcass and when they find one a battle ensues. Males and females are equally fierce and
there is no average difference in size. If the intruder wins, he or she kills the offspring to
make room for his or her own. The resident member of the same sex is expelled and the
resident member of the opposite sex dutifully mates with the killer of his or her children.
This is the third environmental situation that favors the evolution of infanticide; when the
infants are not your own.
How about the second environmental situation that favors the evolution of
infanticide--poor offspring quality? If the parents are reducing the size of their brood,
wouldn’t it make sense for them to assess their quality to retain the best? I can’t answer
this question because the appropriate experiment has not yet been done. However, I’ll bet
you can imagine how it might be designed. Go to K-Mart and get more shoeboxes and
potting soil. In half of the boxes, intercept the young as they are arriving at the carcass
and reduce the brood size yourself by removing some at random. Let the parents do it
their way in the other half of the boxes. Compare the quality of the offspring that emerge
(their ability to survive and reproduce) and celebrate your newly documented fact with a
beer.
This roll-up-your-sleeves kind of science documents facts the way a brick factory
produces bricks. A brick is a humble object, of little use by itself, but it is durable and
becomes great in combination with other bricks. So it is with the facts documented by
scientific methods. A fact such as “burying beetles regulate brood size but not at the egg
stage” is humble and amounts to little by itself. However, assuming that it survives the
scrutiny of other scientists, it is durable and will be as true 500 years from now as it is
today. The idea that science is hard to do and facts can never become reliable is incorrect
at the brick level.
Big theories such as evolution and creationism are evaluated not by a single
decisive experiment but by how well they interpret the countless facts that lie around us
like piles of bricks. Creationism fails as a theory in part because it is so unhelpful. Does
anyone know God’s will for burying beetles? Natural selection thinking, by contrast,
delivers very specific predictions, such as “infanticide should be expected primarily in
three situations.” The predictions might be right or wrong but at least they tell us what to
look for. When a detailed prediction is confirmed, it provides support for the theory that
issued the prediction—never decisive, only cumulative. You might not be convinced
about natural selection writ large, but you must admit that it did a very good job telling us
where to find infanticide in burying beetles.
And not just burying beetles. Scientists are busy people and they have been
churning out durable facts about infanticide in all sorts of species. If you have access to
the Internet, go to Google Scholar (http://www.scholar.google.com/), a specialized
branch of Google that searches the scientific literature. Type “infanticide” and you will
get over 11,000 hits providing information on dozens and dozens of species, from other
insects to the Mountain Gorilla. Overwhelmingly, infanticide occurs in the “big three”
situations that my students were able to identify with just an ounce of knowledge about
natural selection.
You will also find plenty of information on infanticide in our species. Are you
curious to know if we stand apart from the rest of nature or if we fit the same pattern? My
students are, but I must keep you in suspense until a future chapter.
You might be surprised that a burying beetle with a brain the size of a mustard
seed is capable of such sophisticated behavior. Dragging, burying, modifying,
assessing—doesn’t all of that require intelligence? Isn’t intelligence something that we
have and they don’t? Evolutionary theory does not make a strong prediction on this
question. At first glance, it is plausible that sophisticated behaviors require big brains. If
so, then creatures with small brains would behave in unsophisticated ways (such as laying
eggs but not regulating brood size), creatures with big brains would behave in
sophisticated ways (such as regulating brood size) and we would be most sophisticated of
all. Most evolutionists 50 years ago probably expected this to be the case, but the facts
told a different story. It turns out that most species are very, very good at solving the
problems relevant to their survival and reproduction, as we have seen in the case of
burying beetles. Animal mental abilities can vastly exceed our own for specific tasks.
Some ants can find their way home across a featureless landscape by using the sun as a
compass. Can you do that? A chickadee can remember the location of thousands of food
items that it stored during the fall and recovers during the winter, whereas we have
trouble finding our keys. However, we are indeed special in the flexibility of our
intelligence. Our species can solve brand new problems in a way that other species
cannot.
This fact was elegantly established for burying beetles over a century ago by the
great French naturalist Jean Henri Fabre. To show that burying beetles do not have
human-like intelligence, he tied one end of a wire to a dead mouse and the other end to a
stick stuck in the ground. The beetles couldn’t chew through the wire, so to bury the
mouse they needed to topple the stick by excavating under it. This was not a difficult task
because the beetles are masters at soil excavation. However, it was a new task because
the beetles are accustomed to excavating under the mouse. A person would quickly solve
the new problem but the beetles were dumbfounded. They just mechanically kept doing
what they were programmed to do without a glimmer of awareness or creativity.
Fabre was a master experimentalist who established facts like these by the dozen,
as solid today as when they were first documented. He was also a creationist, as most
naturalists were at the time, although creationism back then bore little resemblance to its
current form. Darwin admired him and called him “that inimitable observer.” Darwin
knew that facts are common property that can be used by any theory. His theory was so
superior at explaining the facts, even way back then, that support for creationism rapidly
waned. This was not a conspiracy against religion, since the evolutionists were vastly
outnumbered. It was the way the facts fell. Fabre’s facts will last forever but the way he
interpreted them evaporated like the morning mist.
What I have shown for infanticide can be repeated for innumerable other subjects.
In fact, my primary interest in studying burying beetles was not infanticide or even the
beetles. It was the mites that you might notice if you look closely at the beetles. They too
are specialized carrion feeders but lacking wings, they require the beetles to travel from
carcass to carcass. There can be more mites on a single beetle than passengers on a jumbo
jet, but that’s another story.
