COPERNICUS took away our claim as humans to a special position at the centre of the Universe. Darwin forced us to take our place among the animals. Now the last refuges of mystery are being invaded as science begins to take apart human nature itself.
Psychologists of every hue 鈥 cognitive, linguistic, developmental, social and evolutionary 鈥 have been joined by neuroscientists, neurologists, ethologists, artificial intelligence experts, philosophers and economists in the rush to solve this last great problem. The scale and scope of activity is unprecedented.
Nor is anyone shy about announcing their findings to the public: never before have there been so many best-selling books on mind and brain from so many different thinkers. And no sooner has one proclaimed that a profound mystery 鈥 consciousness, say 鈥 has been explained, than half a dozen others counterclaim that the mystery has merely grown deeper.
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Amid this great rush, it would be impossible even to attempt some grand summing up of every area of research. Instead, this week and next we invite you to visit some of the hot spots, meet some of the most interesting researchers, and form your own opinions.
As the science of human nature advances, two old debates remain. The first comes in many shapes. Is our nature inbuilt or is it acquired? Are genes or environment more important in shaping us? Are we a blank slate upon which experience writes or will our intrinsic, evolved nature always assert itself? Is culture simply a product of individual human minds or is it a separate force that creates human minds? Philosophers characterise the difference as being between nativists and empiricists: was Plato right to argue that we come into the world equipped with innate knowledge, or do we have to learn all that we are, as Aristotle claimed?
The second great debate has a profound religious dimension. Does free will really exist or are minds merely a reflection of the mechanical workings of the brain? Hippocrates, who died in 377 BC, was one of the earliest to write that thoughts, feelings and perceptions were simply activities of the brain. But his appears to have been a lone voice in the Western world over the past 2500 years, especially since Christianity placed the existence of free will, and its consequent choices between right and wrong, heaven and hell, at the heart of its dogma.
The two debates are different in kind. The latter, to which we will return next week, remains a live issue for many people: either there is a separate soul or consciousness that ultimately controls our human decisions and is separate from the purely deterministic workings of our brain, or there is not. While a great many scientists live comfortably with the mechanistic view 鈥 and therefore with the death of the soul, and perhaps of God 鈥 others do not. We will return to this issue with comment from the philosopher Daniel Dennett, the Dalai Lama and neurobiologist Owen Flanagan, author of Dreaming Souls.
The first dispute is of an altogether different kind. The dichotomies on which it is built are ultimately false. Genes versus environment, nature versus nurture, innate versus acquired, individuals versus culture 鈥 none of these binary oppositions is of any profound value to researchers who are trying to unravel how human nature really works and develops.
But real or not, the questions underlying these two great debates have more than merely academic appeal. The lives and deaths of millions of people over the centuries have turned on them.
The F眉hrer and the Chairman
The study of human nature is not only scientifically challenging. False insights from it have the potential to be extraordinarily dangerous.
Hitler had a theory of human nature that was informed by the science of his day. Marx and his descendants, from Stalin to Chairman Mao and Pol Pot, had their theory of human nature too. For Hitler, eugenic theories helped create the idea of a master race, destined to rule over the rest and to extinguish the 鈥渨orst鈥 specimens. Marx鈥檚 descendants believed that if social circumstances were altered, human nature could be rewritten.
Both these opposing notions 鈥 of genetic determination and of a 鈥渂lank slate鈥 鈥 are wrong. Both led to the deaths of tens of millions of people. Of course, Hitler had no deep knowledge of genetic theory, nor did Mao know much of behaviourism. But the old excuse that scientists are in not in any way to blame for the crimes committed by such demagogues won鈥檛 wash. Maybe it鈥檚 true that unscrupulous politicians will always take what they want from science to further their own ends and ideologies. But in the area of human nature, scientists have had a more direct responsibility for acts for which we should now feel collectively ashamed.
Anyone who doubts this can take a trip to the archives of the Cold Spring Harbor Laboratory on Long Island, New York, one of the world鈥檚 great centres for genetic research. At is the story of the eugenics movement in the US. Cold Spring Harbor was the centre for American eugenics research from 1910 to 1940. But as the laboratory now bravely confesses: 鈥淚n the archive you will see numerous reports, articles, charts, and pedigrees that were considered scientific 鈥榝acts鈥 in their day. It is important to remind yourself that the vast majority of eugenics work has been completely discredited. In the final analysis, the eugenic description of human life reflected political and social prejudices, rather than scientific facts.鈥
At the entrance to the archive are written the words of philosopher George Santayana: 鈥淭hose who cannot remember the past are condemned to repeat it.鈥 The study of human nature has been bedevilled by prejudice about race, temperament, character and sex differences, by narrow ideological theorising and by a rush to apply overambitious theories to social policy. And remember these figures: every individual human brain contains around 1012 (1 trillion) neurons and 1015 (1 quadrillion) synapses, capable of changing in milliseconds, and there are 6 脳 109 (6 billion) people on this planet, all potentially capable of interacting and influencing one another. Last year alone 1.6 脳 1011 (160 billion) minutes of international telephone calls were made between people talking at a rate of 120 to 150 words per minute.
Clearly we are still a long way from understanding how the brain, mind and society work.
Drop the dichotomies
The very act of talking about 鈥渉uman nature鈥 implies, of course, that humans do have a nature 鈥 that the way we are is not infinitely malleable, that it ultimately faces constraints. That statement is no more controversial than saying we are not birds, and that however hard we flap our arms we will not fly gracefully into the sky. It does not imply that everything we do is narrowly determined by our genes. The old dichotomies of genes versus environment, individuals versus culture, innate versus acquired need to go. That is a theme that runs through the contributions that follow this introduction.
In the first of them, Matt Ridley explains why our emerging knowledge of the genome has changed everything in the nature/nurture debate (鈥淕enes are so liberating鈥). No side wins as a result of our new knowledge. Instead, Ridley argues, molecular biology and genetics 鈥渆nriches the arguments from both ends until they meet in the middle鈥.
The second contribution, from archaeologist Steven Mithen, argues that the emergence of culture was a vital shaper of human nature (鈥淭horoughly mobile minds鈥). This is not the old view of culture as an independent force that creates human nature, nor the individualistic, free-market view that culture is just a product of individual humans. As Margaret Thatcher famously put it: 鈥淭here are individual men and women and there are families鈥 There is no such thing as society.鈥 Culture is a product of human desires, a shaper of them and a storehouse of the acquired knowledge of millions of minds: 鈥渂rain, body and material culture are all constituent elements of the human mind鈥.
There is little room for the third dichotomy, innate versus acquired, in the research of Alison Gopnik into infant minds (鈥淲hat every baby knows鈥). Babies are born with complex ideas and the innate ability to acquire more. They have both an initial 鈥渢heory鈥 about the world and the capacity to make inferences from their surroundings which they use to rewrite that theory. And Gopnik鈥檚 Bayes net model can incorporates both inborn starting states and new ideas, making it a 鈥渁 halfway point between classically nativist and empiricist approaches鈥.
Another key but empty dichotomy is tackled by philosopher Dominic Murphy, this time between the mind and the brain (鈥淏reaking out of the straitjacket鈥). This has important consequences for the millions of people worldwide diagnosed as having some sort of mental illness, who are forced to fit the current psychiatric model of mental illness as the result of biological disease. Murphy explores the possibility of a completely different model which has the roots of 鈥渕ental illness鈥 lying either in the malfunction of cognitive components of the brain, or in the function of evolutionarily adapted but now inappropriate models.
Down to earth
Talk of molecular biology and inferential learning theories sounds very distant from what people normally mean by human nature. Understandably, most people tend to insist that the details of their lives and experiences matter far more than any philosophical debate over a nature/nurture dichotomy.
Fair enough. But they are connected: these experiences that bring so much pleasure and pain do relate to broad-sweep theories in which it makes sense to talk about 鈥渉uman nature鈥. To demonstrate this we decided to analyse how Britain鈥檚 most watched TV soap opera, EastEnders (which has been on the air for the past 18 years, and whose four episodes a week are now watched by tens of millions around the world), uncannily merges theory with everyday life (see 鈥淪ex, lies and EastEnders鈥). There鈥檚 murder, death, sex, marriage, betrayal, vengeance, infidelity, uncertain paternity, infanticide, rape and struggle between the sexes. There鈥檚 also trust, love, altruism and cooperation.
These are the seemingly eternal themes that keep viewers glued to their TVs every week. They are also what our close primate relatives 鈥 chimpanzees and bonobos 鈥 would want to watch in soap operas too, with a few adjustments for sex and violence. If primatologists have it right, there would more sex for bonobos and more violence for chimpanzees. And, strangely, if social statisticians have it right for our own species, EastEnders needs to provide fewer murders and more children of dubious paternity. It is no accident that these are the big themes most likely to feature in research papers by scientists attempting to explain human nature.
Next week we will take a look at sex, sex differences and a little violence, and investigate how evolutionary psychology and understanding our primate relatives can help us understand ourselves. Contributions come from primatologist Sarah Blaffer Hrdy, social psychologist Anne Campbell, psychologist Simon Baron-Cohen and anthropologist Helen Fisher.
But what of the other end of the spectrum 鈥 trust, love, altruism and cooperation? Surprisingly, some of the most interesting discoveries have come from economists and mathematicians interested in rational choice and game theory. Even more surprising, given the fondness of economists for preaching the benefits of competition, self-interest and greed, their research has provided some of the biggest insights into why humans may be cooperative, moral animals (see 鈥淧lay fair, why don鈥檛 you?鈥),. That research on human nature can brings together insights from economists and neurologists has to be a hopeful sign for the future. There is even a brand new discipline of neuroeconomics (see New 杏吧原创, 10 May, p 32). Collaboration is the key.
E. O. Wilson, whose controversial book Sociobiology launched the biological study of human nature in 1975, wrote in his famous last chapter that for a zoologist visiting from another planet: 鈥渢he humanities and social sciences shrink to specialised branches of biology; history, biography and fiction are the research protocols of human ethology; and anthropology and sociology together constitute the sociobiology of a single primate species鈥.
The intensity of the disputes that ensued is hardly surprising. Twenty-five years later, Wilson seemed a little more conciliatory in a new introduction to the book: 鈥渢he line between the great branches of learning is not a line at all, but instead a broad, mostly unexplored domain awaiting cooperative exploration from both sides鈥.
With the enormous growth in budgets for the molecular and biological sciences, it鈥檚 those older branches of enquiry that are likely to be left crying out for help. We will soon know far more about our genome than our phenome. But to understand human nature, half the picture will not be enough.
Play fair, Why don鈥檛 you?
Given economists鈥 fondness for advocating the benefits of competition, self-interest and greed, it comes as a surprise that their research has provided some of the most interesting insights into humans as cooperative, moral animals.
Take the classic 鈥渦ltimatum鈥 game. Player 1 is given $10, part of which he has to share with Player 2. He can offer to hand over as much or as little as he likes, and Player 2 can accept what is offered or not. But if Player 2 turns the sum down, neither player gets anything. They play only once, and have no opportunity to get to know one another.
In this situation, Player 2 loses out by turning down any offer, no matter how small. Yet in reality, Player 2 frequently does reject 鈥渦nfair鈥 offers 鈥 on average anything less that $2.59 is rejected 鈥 and both lose out.
These and a host of similar laboratory games suggest that humans have a strong sense of fairness. They will, for example, punish cheats in more extended games even if doing so leaves them out of pocket. An ultimatum game reported this year in Nature (vol 422, p 137) by Ernst Fehr of the Institute for Empirical Research in Economics in Zurich shows that a desire for fairness extends further. When one player is given powers to fine the other, unfair use of the fine to enforce cooperation can turn out to damage it. On the other hand, cooperation can be enhanced if a player voluntarily refrains from using the fine.
Robert Frank of Cornell University has provided a broader argument that many human emotions are designed to lead people away from pure 鈥渃alculative rationality鈥. What better way to keep reciprocity going than for it to be known how angry you get if you are cheated? Rage deters cheats, guilt makes cheaters feel bad, compassion produces compassion and loyalty makes people keep agreements. In essence, emotions may be the brain鈥檚 way of making us do things 鈥 keeping our word, refusing to be cheated, cooperating 鈥 that will pay off for individuals long-term and stop us being what the economist Amartya Sen calls 鈥渞ational fools鈥.
Evidence from individuals with brain damage supports this view. One of neurologist Antonio Damasio鈥檚 well-known cases was of a man with damage to the prefrontal cortex who appeared to have lost connection to his emotions. In a specially designed gambling game he would inevitably pursue immediate short-term gain, even though it would lead to ultimate loss. The patient never seemed to be able to develop the 鈥済ut feel鈥 that told him to steer away from this strategy, and unlike normal people playing the same game successfully he failed to show the galvanic skin responses that indicate emotional arousal.
