Darwinian Theories of Human Nature
(This is my summary of a section of a book I often used in university classes: Thirteen Theories of Human Nature, Oxford Univ. Press. There is also an outline of the material at the end of the post. And if for some reason you doubt that evolution is true beyond see
“Is Evolution True? Yes, and the World is Round Too.“)
What does modern biology say about human nature? To understand the answer to this question let us look the history of evolutionary ideas.
Evolutionary Theory, Stage I: Darwin and his Contemporaries – Before Darwin came along scientists in the 18th and 19th century realized the world was much older than the Judeo-Christian tradition had assumed. Geologists like Charles Lyell realized that layers of rocks or soil were formed by processes like eruption, sedimentation, and erosion over vast periods of time. Scientists before Darwin had also discovered fossils of creatures that no longer existed. Many thinkers, including Darwin’s Grandfather Erasmus Darwin, had realized that the organisms that exist now had come from predecessors through a series of small changes. [Even some pre-Socratic philosophers had theories of evolution.]
Darwin on Natural Selection – Of course, it is one thing to realize that something had happened but quite another to show how it had happened. What Darwin realized was that natural selection was the mechanism for evolution. The most prominent theory about how this had happened before was Lamarck’s theory. Lamarck believed in the “inheritance of acquired characteristics.” If animals, for example, stretch their necks they might pass on long necks to their offspring. [Or if you lift weights you might pass on your muscles to your offspring.] Darwin, who came to Cambridge to study first medicine and then theology, found himself most fascinated with biology and geology—which led to his getting a position as the naturalist about the HMS Beagle on its five-year trip around the world.
During his excursion, he found bones of huge, extinct animals, the fossilized remains of sea creatures, an earthquake in Chile that uplifted earth, and other evidence of the processes of geological change. And of course, he saw the birds and other animals in the Galapagos Islands, which were similar to those of the mainland but differed from one island to another. Even the beaks of little finches differed from one island to the other, in each case so as to help them get food on that island. Shortly after his return to England, he came up with the idea of natural selection, but he did not publish the idea for almost twenty years since they were so controversial. Finally, after Alfred Wallace had arrived at the same conclusions, his friends encouraged him to publish so that he could get the credit.
The basic idea of evolution can be logically deduced from 4 basic empirical facts:
1) Variation of traits exists among individuals in a given species [look at other humans]
2) Traits of parents are passed on to offspring [look at people’s parents]
You can easily see both of the above by looking around you. This is how we have bred animals and plants for thousands of years. Just like humans artificially select to modify species—hence all those different dogs walking around—so too does nature select. And that’s called natural selection. Here are the other two facts:
3) The population of species can increase quickly, and
4) An environment’s resources typically cannot support such increases.
Fact #3 can be confirmed when you realize that any pair of organisms can produce more than two offspring, in some cases thousands of offspring. Along with fact #4, this means that only a small portion of offspring reach maturity and reproduce and that there is a competition to survive and reproduce. Given fact #1 we can logically infer that some individuals, because of their differences, have a better chance to survive and leave offspring than other individuals. Thus the traits of those individuals that reproduce will be passed on. This means that the characteristic of populations gradually change and, given enough time, this will lead to new species. All you need is natural selection working on individuals with different traits. (Darwin also recognized sexual selection, the process of selecting for traits that help individuals reproduce—color of birds, antlers of the stag, or a peacock’s tail.)The Origin of Species is basically 700 pages of evidence to support his logical inference—evidence from selective breeding, natural history, paleontology, and more.
Darwin on Human Evolution – While others immediately saw the implications of his theory for human bodies, Darwin waited another 12 years to publish The Descent of Man. In it he used anatomical, medical, embryological, and behavioral evidence to support the thesis that the human body has a common ancestry with other animals. Today biological evolution is acknowledged as a fact beyond any reasonable doubt by biologists. The overwhelming evidence for this today comes from literally dozens of sciences including but not limited to: comparative anatomy, botany, embryology, biochemistry, genetics, anthropology, geology, molecular biology, chemistry, mathematics, population ecology, zoology, and more. This is as well established as anything in science.
[Evolution is as well established as that gravity or atoms exist! It is every bit as certain as that the earth is (roughly) round and goes around the sun! Anyone who tells you that evolution is false is either a) lying; or b) scientifically illiterate. The only way to imagine it is false is if intelligent aliens or deceptive gods are playing tricks with our minds! But you don’t have to trust me. Here is a link to a statement on the issue from the National Academy of Sciences, the most important scientific body in the world. You could also visit hundreds of other scientific websites to confirm this claim. Even better, major in biology at a good university and you can learn to understand this fact first hand. ]
Social Darwinism – But what are the social, ethical, or religious implications of the theory? Specifically, can a scientific fact imply anything about values? Can you get an ought from an is? It seems not. For example, it may be a scientific fact that penicillin cures certain bacterial infections, but that doesn’t mean that you ought to take penicillin (unless you value health.) Or it may be a fact that large amounts of energy are released when we split atoms, but that doesn’t imply that you ought to split atoms. Similarly, the fact of evolution doesn’t tell us what we ought to do. (Defenders of this view say that those who think you can get facts from values commit the naturalistic fallacy.)
Still others say that since evolution implies the most biologically fit survive and reproduce, and since biological success might be thought of as the ultimate value, those who survive must be the most valuable. They take Darwinism to imply that we should do everything we can to survive, that greed is good, etc. [Not surprisingly Ayn Rand, the matron of today’s Republican Party in the USA, titled her work on ethics: The Virtue of Selfishness.] In other words, those who survive are not the biological fittest, but basically the fittest in a larger sense. [In the USA today this is generally taken to mean those with the most money.]
This also implies that charity, health-care, social security, public education, child care, etc are pointless. You must let the inferior die; they cannot possibly be as valuable as the idle rich! Many thinkers in the USA in the 19th century adopted this attitude, and it was as common among the robber barons at that time as it is among large elements of today’s Republican Party in America. It advocates competition to weed out the 47% who are Ayn Rand’s or Mitt Romney’s or US Senator Paul Ryan’s moochers. It is but a small step from social Darwinism to racism and genocide. But it doesn’t follow that those who are biologically fit—like cockroaches—are morally, artistically, intellectually, spiritually, or psychologically fit. Those who have the most children or the most money aren’t necessarily the best in other ways. And social Darwinism was not Darwin’s idea, nor did he subscribe to it. The idea came from the philosopher Herbert Spencer and was embraced by the wealthy in America in the 19th century, as it still in large part is. [How ironic that so many of the opponents of biological Darwinism in the American political arena, primarily from the right, are supporters of social Darwinism. They disbelieve what we know to be true, and believe what we know to be false.]
Darwin’s Own Values – Darwin suggested that not only had human bodies evolved from lower forms but so too had our intelligence, language, emotions, morality, and religion. [Today we know that Darwin was right about all this. He was, I believe, the most important human being who has yet lived.] Darwin knew he was speculating by extending evolution from human bodies to their minds and behaviors. And some of his ideas, especially about selection operating at the level of the group—group selection—are still matters of controversy today. [Yes there are controversies about how evolution happened, but none about that it happened.] He also realized that culture, as well as biology, influenced ethical values and religious beliefs. Darwin believed that human sympathy and compassion were noble. By all accounts, he was a humble man, dedicated father, and affectionate husband.
The reply to social Darwinism is that evolution has given us sympathy and concern for our fellows, and the intelligence to make a just and moral world. This is every bit as natural as a survival of the fittest. But in the end, the appeal to the ethics of Kant or Marx or Christianity at its best goes well beyond any biological imperative. As for religion, many pages have been spilled on the issue of Darwin’s religious beliefs. But anyone serious about discovering his views will conclude that by the end of his life he was almost certainly a closet atheist. He had come a long way from preparing for the clergy as a young man.
Charles Robert Darwin is buried in the north aisle of the nave of Westminster Abbey, not far from Sir Isaac Newton.
Evolutionary Theory, Stage II: The Reaction Against Biological Accounts of Human Nature
The Genetic Basis of Heredity – Darwin knew that there are variations between individuals and that these variations are inherited, but he didn’t know the mechanism of inheritance. This mechanism was discovered by Gregor Mendel who figured out that distinct casual factors—what we call genes—are passed from parents to offspring. We now know that sometimes genes change or mutate randomly, which accounts for genetic variation. Putting Mendelian genetics together with Darwinian natural selection along with precise mathematically modeling resulted in the “modern synthesis.” [This feat accomplished during the 1930s and 1940s is one of the greatest scientific achievements of all time.] To make the ideas even stronger, the biochemical basis of gene copying was uncovered with the discovery of DNA in 1953 by Crick and Watson. (And Rosalind Franklin, whose contributions to the discovery of the structure of DNA were largely recognized posthumously.) This ushered in the era of molecular biology so that we now understand evolution at a molecular level that Darwin couldn’t imagine. Today, in laboratories around the world, biological evolution is confirmed over and over every single day! Over and over and over; day after day after day!
Crick & Watson Rosalind Franklin
Eugenics, Racism, and Sexism – Many were led to the conclusion that evolution implied that there are innate differences between individuals, sexes, or races. Perhaps this implies that we should let the physically or mentally weak die or at least keep them from breeding. This led to the idea of eugenics, the study of how to produce fit offspring. In the early twentieth century, much of the western world was enamored with this idea. Yet even if this was ethically acceptable, it is practically impossible to know who has “bad” genes. Moreover, such judgments, as Darwin himself realized, were sociological, not biological. What we call different races are all the same species. Racism and sexism all emanate from prejudice against groups with no biological justification for such prejudice. [Race is not a justifiable biological concept. More genetic diversity exists within populations than between them.]
The Reaction in Favor of Culture and Education: Intelligence Tests, Sociology, and Anthropology – Many went further to suggest that women and some racial groups were intellectually inferior to white men. But this raises a number of questions. Is there some single thing called intelligence that can be measured? Even if there were how would it be measured. Are there different kinds of intelligence, say social or moral intelligence as compared to simply being good at math or language? And even if we had tests to measure this supposed intelligence how do we know if the results are due to innate ability or social opportunities? Today the whole idea of intelligence measurement is controversial.
Moreover, the burgeoning social sciences of the 19th century placed more emphasis on the influence of culture rather than biology to explain human behavior. (With the exception of some basic biological functioning.) Social scientists generally say that facts about human beings are: 1) physical; 2) psychological; and 3) social/cultural. Most importantly social facts are not reducible to psychological or physical facts. This means that social facts really exist just as physical things do. [There really are such things as sub-cultures or societies.] Social facts are facts about wholes that cannot be reduced to their parts. [Society is not just a collection of individuals.] The social world strongly affects the individual. Culture is not reducible to biology. [If you were raised in a non-English speaking culture, you would probably not have learned English.] However, none of this implies cultural relativism. Some cultures may be better than others, at least in certain ways.
John B. Watson
The Reaction Against Instinct Theory: Behaviorist Psychology – There was also a reaction against supposedly Darwinian ideas in psychology, especially the idea of instincts. To put psychology on a more scientific basis John B. Watson (1878-1958) proposed that psychology study observable behaviors and reject the appeal to vague notions like instincts, intentions, or other mental states. He was so adamant about the influence of the environment that he thought he could make any healthy child a world-class scholar, musician, or athlete if the right environment were provided. This program was carried forth by B.F. Skinner (1904 – 1990) at Harvard. Skinner argued the environment selects behaviors by rewarding them or eliminating behaviors by punishing them. [Classical and operant conditioning.] In other words, Skinner emphasized that behavior was explained by environmental causes. While there is some truth in all this, studies of identical twins reared apart—who share identical genomes—reveal the strong influence on the biological as compared to the environmental.
Because of the perversions of social Darwinism, racism, sexism and all the other immoral ideas attached to Darwinism, the biology of human nature was ignored until the 1960s. And while we acknowledge the horrors of racism and sexism and social Darwinism, we should also not ignore facts about our biology. In the last few decades, a new wave of thinkers rediscovered and extended the Darwinian paradigm further than Darwin could ever imagine. They have brought about a scientific revolution. We now turn to these ideas.
Evolutionary Theory, Stage III: The Return to Human Nature
Genes and Memes – Throughout the 1960s and 1970s evolution was further confirmed and understood at greater depths than ever before. Mathematical insights shed light on adaptation, kin selection [altruism toward close relatives], reciprocal altruism [directed toward away from relatives even toward other species], and the relevance of game theory to evolving populations [for example, non-human animals often find themselves in situations with the structure of a prisoner’s dilemma.]
This research meant that evolution could be understood at the level of the gene, an idea popularized by Richard Dawkins in his famous book, The Selfish Gene. The very title of the book helps us see evolution in terms of the competition of genes trying to survive. [With today’s mathematical modeling we can understand this in great detail.] At the end of the book, Dawkins argued that culture evolves analogously to biology only much faster. The elements of culture that are selected for are ideas, beliefs, practices, fashions, etc. Dawkins called these “memes.” Some memes catch on and survive–say a belief in gods or immortality or wings for aircraft—while others go extinct—like the idea of celibacy for everyone or wings attached to your arms. Like genes, memes are transferred from person to person, only rather than being transferred from one body to another, they are transferred from one brain to another. This means you can spread memes must faster than you can spread genes. Cultural evolution is very fast while biological evolution proceeds very slowly. [Cultural evolution also seems to be guided by Lamarckian “inheritance of acquired characteristics.” You inherit your religious or sports team loyalties from say your parents, who acquired them.]
The Rise of Ethology – In the mid-twentieth century a new discipline arose, ethology, which studies animal behavior in its natural environment. The key finding was that such behavior is physiologically innate or hard-wired. Many behaviors in animals can’t be explained by environmental conditioning. They exist independent of experience or learning, they are fixed. It seems evolution has designed species-wide behaviors. Regarding animal behavior, the great ethologist Niko Tinbergen discovered that the explanations usually were in muscle contractions, hormone secretions, fetal development, and previous learning with the goal of surviving and reproducing. In other words, animal behavior depends on causes that are innate to those animals.
Konrad Lorenz (1903 -1989) became famous for studying animal behavior, especially the imprinting of ducks to the first moving thing they see. He assumed imprinting was an innate feature of many animals, but he reached this conclusion too easily—how does one know which traits are learned and which are innate? Moreover, if anti-social behavior is innate, can it be eradicated or are we stuck with it? Lorenz did believe in group selection, but as we have seen the level or levels at which selection operates is still open to debate.
Chomsky and Cognitive Psychology – While B.F. Skinner thought that language could be explained by the social environment, the linguist Noam Chomsky showed that human facility with language is different from other animal behaviors. All normal humans can learn language and no animal language approaches the complexity of human language. Even chimps who use sign language fall far short of human language. Chomsky famously argued that the speed at which infants learn language and grammatical rules suggests that a capacity for language is innate. There is a universal human grammar, and it is a result of our evolutionary history. [This has been the most influential idea in 20th-century linguistics.] In short, our facility with language is an evolutionary adaptation, a feature selected for in our long evolutionary history. Language aids survival. Today research on this topic is pursued by linguists, neuroscientists, and evolutionary biologists.
[Today Chomsky is known mostly as a political philosopher and social critic, especially as a critic of American domestic and foreign policy. Despite writing voluminously on political topics, despite a fearless desire to debate anyone, anywhere, you will almost never see him on TV or noted in the mass media. His ideas are generally censored from the masses. Here is a collection of his essays: Masters of Mankind: Essays and Lectures, 1969-2013.]
E. O. Wilson
E. O. Wilson and Sociobiology – But if language has a strong evolutionary component, then wouldn’t other human behaviors? The Harvard biologist E. O. Wilson was the first to argue convincingly and vehemently that the humanities and social sciences can be reduced to biology, and that all this leads to the new science of sociobiology. In his Pulitzer Prize-winning book, On Human Nature, Wilson offers biological explanations for human social behaviors like aggression, sex, ethics, and religion. [I think this is one of the most important books of the 20th century. And it is eminently readable.] Needless to say Wilson’s ideas have provoked controversy, especially from social scientists who don’t want to believe their fields can be biologized. Moreover, they fear that Wilson’s views give support to those who would misuse them for racist or sexist views. Even some biologists believe he is underestimating the influence of culture. The political implications of Wilson’s theories are thought by some to be so controversial, that this grey-haired grandfather once had a bucket of water dumped on his head at a conference!
But Wilson’s detractors were wrong. He clearly saw both biology and culture as influential on human nature, and he made this clear to anyone who read his books carefully. In fact, he wrote an entire book on gene-culture coevolution. Still, he may have been right when he said that, for the moment, “genes hold culture on a leash.” We are not that far removed from our evolutionary past; its imprint is apparent in our behaviors.
Cosmides/Tooby and the Integrated Causal Model – What Wilson called sociobiology goes by other names like evolutionary psychology or evolutionary anthropology. This school of thought applies Darwinian insights to the human mind and human behaviors. Key premises are: 1) universal human nature refers primarily to evolved psychological mechanisms; 2) these mechanisms are adaptations selected for over many generations that helped us survive and reproduce, (remember though what was formerly adaptive and what is now adapted can be different—going to college may now be adaptive, aggression may no longer be); 3) our minds contain adaptations from distant ancestors, all the way back to the Pleistocene. This final point has been challenged by evidence that genes may evolve faster than previously thought.
Cosmides and Tooby
Cosmides and Tooby, an anthropologist and psychologist respectively, also critique the standard social science emphasis on environmental factors. Because social scientists fear racist and sexist ideologies, they argue, they have been blind to the overwhelming evidence for evolutionarily produced cognitive mechanisms. Like Wilson, they propose that a complex web of causal factors produced human nature. Behind any human phenomena is 1) natural selection operating over eons of time producing innate cognitive structures; 2) historical development; 3) unique genes as the result of sexual reproduction; 4) physical, cultural, and social environments; and 5) information processing which leads to beliefs and desires.
What all this means is that there are innate mental modules resulting from natural selection that operated on our distant ancestors, especially regarding factors relevant to reproductive fitness like perception, language, cooperation, mate selection, parental care. [Harvard’s Steven Pinker and Rutgers’ Helen Fischer both write about these issues for popular audiences.] Still, all of this is open to further investigation. Human nature is complex and there is much more to be learned.
Evolutionary Theory, Part IV: Hope for Humanity
Trees and Bushes
There are many issues surrounding the connection between evolution and progress, ethics, hope, or religion. For instance, some Darwinists and philosophers think of the evolution of species as progressive, that some animals now are more complex or now have bigger brains. But Darwin generally used the term “descent with modification” which doesn’t connote progress. And some Darwinists deny that species change is necessarily progressive. In fact, natural selection doesn’t imply that species are better only that they are better adapted to their environment. More complex species may go extinct while simpler ones may survive. Evolution may not be like a tree sprouting upward, but more like a bush sprouting sideways.
Turning to progress in human history, Kant, Hegel, Marx, and other modern thinkers espoused progressive views of history that echoed the positive interpretations of history found in the Western monotheistic religions. But if we’ve generally lost hope in religious stories of progress, have we not also lost faith in secular progress as well? We might become smarter or more moral, but then again we might not.
Theism, Darwinism, or Both?
Evolution is so well confirmed that it is essentially a fact in the same way that the earth is round or goes around the sun. (Anyone who tells you otherwise is either lying or scientifically illiterate.) Still, many religious fundamentalists refuse to accept the science and prefer their creation myths instead. Somewhat more sophisticated believers suggest that their god didn’t create things literally, but used cosmic evolution to create us. (A strange way for an omnipotent being to proceed—that took about 14 billion years!)
Others argue that biological evolution reduces us to being just animals. But Darwin himself didn’t draw that conclusion. We may be human-animals, but that doesn’t mean that ethical or aesthetic standards no longer apply to us. We are at least special kinds of animals. So even if there was no exact moment at which humans became different in kind from their evolutionary ancestors, we can still say that we are vastly different now. Or consider that though our brains are products of evolution, that doesn’t imply the truth of our beliefs. In short, our values as persons needn’t be undermined by considerations of our origins.
Ethical Values and Evolution
Religious objections to evolution surely emanate from concerns that evolution implies that values are no longer objective or life no longer meaningful. But the fact that there are biological underpinnings to human altruism, for example, doesn’t mean that all altruism can be reduced to biology. While there are many reasons to doubt the objectivity of ethics, facts about our origins aren’t one of them. In the end, while our brain states affect our values, our values affect also our brain states. We can choose our values independent of any considerations of our origins.
My Final Thoughts
Darwin himself was a scientist who was unafraid of the truth:
[Humans in their] arrogance think [themselves] a great work worthy the interposition of a deity. More humble and I think truer to consider [them] created from animals.
Yet at the same time he was an artist who saw beauty in that truth:
There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.
He was also, by all accounts, a wonderful father and husband too.
Charles Darwin and his wife Emma Wedgewood
Finally, allow me to reiterate that Darwin is one of my greatest intellectual heroes, and he may have been the most influential person in human history. Today multiple sciences converge on his basic insight—which is true beyond any reasonable doubt. He gave us the greatest idea we have, and perhaps will ever have, an idea applicable to everything from the cell to the cosmos. Without a basic understanding of evolution, one lives in intellectual darkness. Before encountering Darwin that’s where I lived, and I thank him for showing me the light.
- Biological evolution was in the air in the 19th century.
- Darwin was the first to realize the mechanism—natural selection.
- He supported his claim with mountains of evidence.
- He didn’t publish the results—that non-human animal bodies evolve—for about 20 years.
- He later extended the argument to human-animal bodies.
- Today we know that biological evolution is true beyond any reasonable doubt.
- Scientific facts seem independent of values. Is doesn’t imply ought.
- But social Darwinists say if individuals survive, they must be better people.
- This attitude is reflected in political attitudes—winners are good people; losers are bad people.
- But why does biological survival or money make you a better person?
- Darwin was not a social Darwinist.
Laws of Inheritance and Genes
- Mendel discovered the laws of inheritance.
- The modern synthesis united Darwinian natural selection & Mendelian genetics.
- This was one of the greatest scientific achievements of all time.
- The exact molecular structure of the gene was discovered in the 1950s.
- Today biologists understand evolution all the way down to the molecular level.
The Reaction Against Biology – Eugenics, Racism, Sexism, Behaviorism
- Eugenics is about producing fit offspring.
- Some people think that certain races or sexes are less intelligent or have bad genes.
- But Darwin recognized these were sociological judgments.
- And race is a weak proxy for the relationship between ancestry and genetics.
- Also, the social and cultural play a large role in influencing traits.
- Watson and Skinner believed that our nature was primarily shaped by our environment.
Biology Ascends Again
- We now have detailed mathematical modeling of genetic evolution.
- Cultural ideas and beliefs evolve too—as memes.
- Lorenz found that many animal behaviors are hard-wired by genes.
- Chomsky showed that the ability to learn human language is hard-wired.
- E. O. Wilson argued that all human social behaviors have largely biological explanations.
- Others argue that social scientists generally reject biological explanations for human behavior because they associate those explanations with racism and sexism. But biology largely determines our nature.