by Mark Pagel
The idea of stable alternative strategies tells us that genetic variety can exist and be maintained for good adaptive reasons because no one tactic, strategy, or role is always best. Combined with Ricardo’s ideas on the benefits of specialization, it provides a way to understand how societies can maintain variety in their ranks. Think of the Sienese contrade. It is reasonable to expect that they have lasted in a relatively stable form for so long because they feed off of each other in much the same way that rock, scissors, and paper do in the parlor game. When there is an abundance of carpenters, they cannot find enough work, so the number declines; too few carpenters and their numbers can increase; too many or too few bakers and the same thing happens. In this context, we call the force regulating the numbers who can “play” each of these strategies “supply and demand,” and it means that over the long run the variety of strategies can persist so long as there is some demand for their different services.
Variety alone does not say people differ in their innate abilities. People might end up in a particular profession merely by chance or perhaps because their parents introduced them to it, and then they get good at it from practice. It would be like the example we gave of a group of people ten of whom choose to play rock, another ten play scissors, and the final ten play paper. There are no initial differences among them, and they will all have equal returns over the long run. Alternatively, at the other extreme, one could imagine something like Aldous Huxley described in his futuristic novel Brave New World in which people were mass-produced to have different predispositions. In that world we are more like the side-blotched lizards, endowed with dispositions to adopt different behaviors or to perform different tasks. This is anathema to the modern liberal view, and no one suggests there are specific sets of genes for each of the many different roles in society. But those many different roles might rely on some smaller set of different talents and skills.
Look around you. Do people tend to settle into tasks they are predisposed to by dint of their genes or because of upbringing and hard work? Is being good at languages helpful for a job in journalism or technical writing? Is being good at spatial reasoning a boost to a career in architecture or design? Does being good at mathematics grant an advantage to being a notary or financier? Do scientists, inventors, and entrepreneurs have a psychological disposition to focus single-mindedly on a goal or to wonder if the world could be different? Do musicians have innate musical talent? Do children often follow their parents into similar walks of life because of the opportunities their parents provide, or conversely because of a lack of opportunities for social mobility? Or, might children often do what their parents do because they have inherited their parents’ temperaments and abilities? These might be uncomfortable questions and the truth will often be “some of each,” but they are not questions we can dismiss outright. Some combination of a slight genetic push combined with a win-stay, lose-shift strategy over long periods of time can sort people by their abilities, even if the contribution of genes is small.
The possibility of equally good but alternative strategies might even explain aspects of personality. For example, when people are asked what aspects of their cultures they are drawn to, they tend to divide into five broad categories ranging from aesthetic (drawn to creative culture) and cerebral (drawn to information) to communal (relationships and emotions), dark (intense and hedonistic pursuits), and thrill seekers. These categorizations must be treated with caution, but biologists are coming to realize that alternative and equally successful personality strategies can even arise in animals. For instance, people differ in how likely they are to take risks, and a hypothetical evolutionary scenario can give one reason why. Imagine you and I differ in our perceptions of what the future holds. You occupy a position of prestige and great reputation in society and consequently you have an expectation for a long and productive life. I am not so highly regarded and this makes me pessimistic about my future. If each of us is right in our assessments, then it might pay you to be averse to taking risks in order to ensure many future returns. Perhaps you will bypass the big mammoth we are hunting out of fear that one swipe from its large tusks could do us in, and wait for a smaller mammoth to kill. But the opposite will be true of me—I will be motivated to adopt a short-term view, to cash in on what is at hand, even if it means taking a risk of being gored. If I don’t take a risk, I might be injured or dead before I get another chance.
By some estimates, 5 percent of us might be sociopaths. Such terms are notoriously difficult to define and harder to judge, but it is said that to understand what it is like to be a sociopath, you need to imagine yourself without a conscience—no sense of guilt or shame, no remorse for your actions. In The Sociopath Next Door, Martha Stout says that lacking these emotions sociopaths are unscrupulous and manipulative, and capable of emotional and physical cruelty. They are often able to conceal this from others, and maybe even themselves. It is difficult to get them to change their behavior because they don’t respond to appeals to morality, disgrace, or shame—these are precisely what they lack. In extreme form, this sociopathy can tip over into the malevolent and often deadly violence of a psychotic killer. But most sociopaths are not like that and indeed might wander among us in society. It is suggested they are likely to be chief executives and other people in positions of power in organizations, people not troubled by the nagging voice of their conscience, because sociopaths don’t have this voice, or if they do it is easily overridden. In fact, as the joke goes, being a sociopath means “never having to say you’re sorry.”
Could sociopathy be an alternative strategy, a personality style that can exist on the margins of society, given that most people are not sociopathic? The cooperation on which human society rests depends upon exchanges among people, trust, and a sense of fairness, and so we expect those dispositions to be widespread. But of course the more widespread they are, the more they present a target for others to exploit. Lacking a conscience might make someone the perfect impostor, able to deceive others as to their intentions because they don’t struggle with—and therefore have no need to conceal—the normal feelings of remorse a conscience brings. And what if getting a difficult job done sometimes requires someone who doesn’t worry too much about the consequences to others? Maybe it is even the unpleasant job of attacking that tribe in the next valley that is competing with yours for resources. Societies might only ever have room for a few sociopaths; but those opportunities will always exist, and that might be why we always seem to find them lurking in boardrooms, running companies, or shouting from a dictator’s pulpit. On the other hand, they will limit each other’s numbers because when two sociopaths meet, there is bound to be trouble—like rock meeting rock in a game of rock-scissors-paper.
It must be emphasized that there is no good evidence one way or the other that cultures have sorted us according to genetic predispositions, at least beyond the commonplace observations we all have made. Even so, when we look at how natural selection has molded differences among people who inhabit different parts of the world—differences in skin color, eye shape, stature, hair color—we can be sure it has had the time and ability to differentiate us within societies. Modern genetic technologies make it increasingly easy to collect evidence relevant to this question, but it is an issue we approach as a society the way we would approach Pandora’s box, and for the same reasons. Even among those prepared to ask such questions, the hunt for specific genes related to differences in lifetime performance is still in its infancy. The simple reason is that no one knows in advance which genes to examine. It will only be with the collection of large numbers of human genomes that cohorts of people with differing outcomes can be compared. This is not different from the approach that attempts to find genes for various medical risks, and the technology is becoming available to sequence human genomes cheaply and in large numbers.
If our societies have for millennia been sorting us by our talents, even if weakly so, this is something society might benefit from knowing about.
Most of us would agree that a society that promotes “equality of opportunity” is a desirable one. But we must also recognize that if there are inherent differences among individuals that make them more or less suited to a particular role or job in society, an inevitable consequence of equality of opportunity is to produce a society differentiated by innate predispositions, a genetic meritocracy. It will produce this meritocracy because equality of opportunity merely ensures that everyone has a fair chance of being delivered to the doorstep of a job or role in society, but does not ensure that everyone has an equal chance of being good at those roles. Inevitably, then, and the more so the greater the equality of opportunity, competition with others will sort people by their genetic predispositions. Or, as the sociologist Peter Saunders has written, the “essence of a meritocratic society is that it offers individuals equal opportunities to become unequal. There is open competition for the most desirable, responsible and well-rewarded positions, and the most able and committed people generally succeed in attaining these positions.”
CULTURE AND THE SELECTION OF OUR GENES
WHAT is staring us in the face is that there is now striking evidence that, coinciding with the advent of culture, our genes appear to have undergone an exceptionally rapid rate of adaptive evolution. This could, as mentioned, be evidence that recently evolved genes are still moving through our populations, but it could also mean that culture has been sorting us—the genetic phenomena themselves do not as yet clearly distinguish between these two alternatives. The evidence pointing to an increase in rates of evolution exploits the fact that our genes are arrayed on long strings of DNA called chromosomes. Humans have twenty-three pairs of chromosomes, one of each pair inherited from the mother and one from the father. This means that each of us has two copies of most genes, called alleles. The alleles might be the same or slightly different versions of the same genes. You might, for example, inherit a gene for brown eyes from your mother and blue eyes from your father. At another place along the same chromosome, you might have inherited a gene for long fingers from your mother but a gene for short fingers from your father. Now, if one allele of a gene—say blue eyes—is always found in combination with some other allele for a different gene—say short fingers—this tells us natural selection has acted strongly and quickly on that region of the chromosome to cause what is called a linkage between the two alleles. It is merely a physical linkage, not necessarily having anything to do with what these genes are for.
The reason that linkage identifies strong natural selection is that our pairs of chromosomes (the maternal and paternal copies) sometimes exchange some genes between them when we produce egg or sperm cells. Eggs and sperm carry just half our genes, and they are a random assortment of our maternal and paternal alleles. As a baby, you might have inherited the blue eyes and short fingers alleles from your father, but later in life one of these alleles might get exchanged with the alleles you inherited from your mother when you produce sperm or eggs. The process, known as recombination, occurs infrequently, so the probability of it splitting up a given pair of genes is low. This means that if something can propel a gene through a population rapidly it may come to be inherited by everyone before recombination has had a chance to separate it from other genes on that chromosome. That force is of course natural selection, and when it strongly favors an allele—because the allele confers a large advantage to survival and reproduction—the genes on this chromosome will become linked: they become more likely to be found together than expected for genes not undergoing strong selection.
When researchers study blocks of human DNA, they find thousands of linked genes that appear to have been subject to strong forces of natural selection. It is possible to attach estimates of the timings of these events of evolution, and the conclusion is that humans began to experience unusually rapid evolutionary changes to many of their genes beginning sometime around 40,000 years ago. One possibility is that this represents the limit of how far back in time this kind of genetic analysis can go. But the period beginning 40,000 years ago is also the period coinciding with the rapid expansion of human cultural groups around the world and with a flowering of human cultural innovations. It is possible, then, that the blocks of linked regions could be the signature of culture ushering us into different roles within our societies that favored particular combinations of genes. On the other hand, these strongly linked regions could just be the signature of widespread adaptation of entire groups of people to new environments. Forty thousand years ago was a time when humans were spreading out around the world, adapting to hot and cold climates, to new diets, and fossils show it was a time of rapid changes to our body size and shape. There were also new diseases such as smallpox, malaria, and yellow fever. Genes for brain size, pigmentation, immune responses, olfaction, nervous system regulation, and body size and shape all show signs of changing around this time. One intriguing finding is that genes associated with hearing seem also to have been subject to strong effects of natural selection. This could reflect the increasing importance in human societies of language and communication.
So, with current knowledge, we can’t say much more than that our genes have been undergoing strong selection in recent times, but another feature of our societies also leads us to believe that latent differences among us might still be being revealed. Human population sizes have been increasing over the last 40,000 years. Natural selection operates more efficiently in larger populations because when populations are small, chance or random events from one generation buffet the population of genes, making it hard for natural selection to pick out the varieties it prefers. This is the phenomenon of random drift discussed in Chapter 1. Equally it will be less effective at removing other varieties that are less beneficial. This means that the small early human populations might have carried many different genetic varieties owing to random genetic drift. These varieties—sometimes referred to as evolutionary debris—would have been increasingly revealed to the honing effects of natural selection as populations grew. In the presence of cultural opportunities and larger groups, what was once debris might have become the raw materials of our differences.
Some of this debris may surface in the modern world in unexpected ways. Dyslexia is a heritable condition often associated with difficulties in reading and writing. It might have gone unnoticed before the emergence of writing because it did not affect any capabilities that mattered, and it is even possible that it granted some benefit in times past. For instance, we know that in modern society many dyslexics are good at mathematics, spatial reasoning, and computer programming. Autistic people often have profound deficits in understanding others’ motives and feelings, can be infuriatingly literal-minded, and are often socially withdrawn and isolated from others. Autism is also heritable and about four times more common in boys than girls. The psychologist Simon Baron-Cohen suggests that autism might represent the extreme end of a normal continuum of abilities to focus on and single-mindedly persevere at a task to the exclusion of others—he calls it the extreme male brain. The dispositions that produce the extreme male brain might have been useful in our evolutionary past, for tasks such as warfare or hunting large game that might demand a concentrated and unempathetic commitment to tracking down and then executing one’s prey. Baron-Cohen also suggests that boys might be more prone to what he terms systemizing, and this is seen in hobbies such as collecting things, bird-spotting, repairing cars and motorbikes, becoming a pilot, or sailing, but also in interest in mathematics and computer games and computer programming.
In our current environment, autism is an awkward condition and at its worst it can be disabling. The brilliant early twentieth-century physicist Paul Dirac is sometimes compared to Einstein for the intellectual depth of his discoveries. Dirac was also autistic, and some biographers speculate that his single-mindedness and ability to shut out or not even be aware of those around him might have benefitted his scientific work. Dirac was awkward and he would exasperate colleagues by not speaking for days. He wou
ld often go on long country bicycle rides with his daughter and not utter a word. One time after giving a lecture he agreed to take questions and a man raised his hand to say he didn’t understand the equation in one of Dirac’s slides. Dirac stood motionless for about a minute and a half, at which point the moderator asked him if he was going to answer the question. Dirac replied that it wasn’t a question.
THE PUSH OF OUR GENES AND THE GENTLE PULL
OF THE FUTURE
TO SOME, the idea that cultural innovations unlock differences among us that quietly await their destinies in finding a task or role they are good at might suggest that we have been on a preordained trajectory, an unfurling, or inevitable march to modernity. Some social anthropologists see in this a tendency to believe there is an inherent superiority to modern society, it being further along the path of inevitable progress. But this is a view that confuses different senses of the idea of progress. Cultural evolution has produced increased technological complexity, and most would probably agree it has raised our standards of living, even if unequally so around the world. If improved health and well-being makes modern societies superior, then these social anthropologists are correct, but then again one would not wish to see this as a bad thing. Biological evolution has also been progressive in this sense of producing greater complexity. The first life, starting billions of years ago, comprised simple, single-celled organisms; only later did natural selection discover how to build big, complex things like elephants.
But neither cultural nor biological evolution has been progressive in the sense of working toward some predetermined or preordained goal. Both merely lumber along producing new varieties of things, some of which catch on and some of which don’t. Nevertheless, we might have to accept that there is at least some broad inevitability to the outcomes of both cultural and natural selection. Given the physical nature of our planet, were we to rerun the tape of biological evolution it is highly likely the plants would evolve again, and if they did, it is highly likely we would see things like birds, fish, and land animals evolving to make use of the oxygen they released. These new forms might not be identical to the ones we have now, but there is good reason to expect that the broad outlines would reemerge. We know this because evolution has already played the tape independently many times on the plants and animals we do have. Penguins, seals, otters, porpoises, and fish have all independently evolved similar streamlined shapes for coursing through water. Birds, insects, bats, and some fish have all evolved wings for flight. Consider that in any world that produced insects that flew in the air, it is highly likely something like a bat or insect-eating bird would evolve to catch them. And if trees evolved, things would evolve to climb them, or giraffelike, acquire long legs and necks to eat their upper leaves.
