The Domesticated Brain (2 page)

This is an old idea that has lately been re-seeded with new research and potential mechanisms. It first appeared under the guise of Social Darwinism in the nineteenth century – the idea that there were selective pressures that emerged from living together that changed the nature of the individuals. At first glance, it seems a bizarre hypothesis that living peacefully together caused the human brain to change, let alone shrink. After all, humans have been civilized for much longer than 20,000 years, with many earlier examples of societies, religions, art and culture. The recent discovery of stone artefacts on the Indonesian island of Flores that date to one million years ago tentatively indicate that an early hominin ancestor,
Homo erectus
, had inhabited the island.
¹⁰
If correct, that means that
Homo erectus
must have had considerable seafaring skills that would have required the cognitive capacity and social cooperation to coordinate such a voyage on early rafts because the land masses were separated by substantial amounts of open sea.
¹¹

Clearly our ancestors were cooperating and communicating well before the end of the last Ice Age. But there was a rise in the population around this time that could have increased pressure to adapt to cohabitation in larger groups.
¹²
Analysis of our species’s history reveals that the world’s population rose significantly in three continents well before the Neolithic period began around 12,000 years ago.
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When the ice sheets covering the northern continents began to melt around 20,000 years ago, the demographics of our species changed rapidly, creating social environments that required increased levels of skills to navigate. The process of selection for social traits must have started when our
hominid ancestors first began cooperating hundreds of thousands of years ago, when domestication first began to appear, but it could have undergone a sharp acceleration when they settled down to live together after the last great Ice Age.

Strength and aggression were advantageous for hunter-gatherer existence, but in these settled communities cunning, cooperation and trade were necessary. Humans now would have had to keep cool heads and even tempers. Those who prospered in this new selective environment would pass on the temperaments and social abilities that made them skilled at negotiation and diplomacy. Of course, there have been extreme violence and wars in the modern era and we have developed technologies to kill each other in vast numbers, but modern combat is typically orchestrated by groups; brute individual aggression was more prevalent in the smaller hunter-gatherer tribes of our prehistory.

By self-domesticating, we have been changing our species by promoting genes that produce relatively slowly developing brains in comparison to bodies. This would mean longer periods of development and social support that would have incurred more parental investment. It would require mechanisms that modulate temperaments and teach children how to behave in socially appropriate ways. Humans who lived together more peacefully in settled communities reproduced more successfully. They acquired skills that enabled them to cooperate, share information and eventually create our cultures.

Modern civilization arose not because we suddenly became more intelligent as a species, but rather because we learned to improve upon technologies and knowledge that
we inherited by sharing information that was a by-product of domestication. Long childhoods were useful for transferring knowledge from one generation to the next, but they originally evolved so that we could learn to get along with everyone in the tribe. It was the drive to learn to live together in harmony that enabled collective intelligence to thrive, not the other way around. By sharing knowledge we became more educated, not necessarily more intelligent.

In 1860, two intrepid Victorian explorers named Robert Burke and William Wills set out on an expedition to cross the Australian continent from Melbourne in the south to the Gulf of Carpentaria in the north – a distance of 2,000 miles. They were successful in reaching the north coast, but on the return journey they both succumbed to starvation. Burke and Wills were educated modern men, but they did not know how to survive in the Outback. They were living on a plentiful supply of freshwater shellfish and a plant known as ‘nardoo’ that the local Aboriginals ate. However, both contain high levels of an enzyme that destroys vitamin B1, which is a vital amine (hence ‘vitamin’) essential for life. By ignoring the traditional Aboriginal method of roasting the shellfish and wet grinding and then baking the nardoo, which neutralizes the toxic enzyme, Burke and Wills had failed to capitalize on the ancient cultural Aboriginal knowledge. They did not die because of a lack of things to eat, but of beriberi malnutrition. Aborigines did not know about vitamin B1, beriberi or that intense heat destroys enzymes; they just learned from their parents the correct way to prepare these foods as children – no doubt
knowledge that was acquired through the trial and error of deceased ancestors. Their cultural learning had provided them with critical knowledge that Burke and Wills lacked. As the two explorers’ fates show, our intelligence and capacity for survival depends on what we learn from others.

Learning through domestication entails the transfer of knowledge and practices that are not always evident, either in terms of their purpose or origin. In the case of roasting Australian ‘bush tucker’, this practice was how to safely prepare food, but other examples include hunting and childbirth, both potentially life-threatening activities associated with folk wisdom. Of course, much folklore also contains superstition and irrational beliefs, but as we will discover in the following chapters, there is a strong imperative to copy what those around you say and do, especially when you are a child.

As a developmental psychologist, it is my view that childhood plays a major role in understanding the cultural evolution of our species. I usually tell my students at the University of Bristol the oft-cited finding that animals with the longest rearing periods tend to be the most intelligent and sociable. They also tend to be found in species that pair-bond for life rather than those that have multiple partners and produce many self-sufficient progeny. So it should be no surprise that of all the animals on this planet, humans spend proportionally the longest period of their lives dependent on others as children, and then as parents investing large amounts of their time and effort in raising their own offspring. This is how our species has evolved.

Of course, that profile of extended parental rearing is not unique to humans, but we are exceptional in that we use
childhood to pass on vast amounts of accumulated knowledge. No other species creates and uses culture like we do. Our brains are evolved for it. As the leading developmental psychologist Michael Tomasello once quipped, ‘Fish are born expecting water, humans are born expecting culture.’ Other animals have the capacity to pass on learned behaviours such as how to crack nuts or use a twig for prodding a termite hill, but none have the same ability to transmit wisdom that increases with complexity from each generation to the next. Our ancient ancestors may have taught their children how to make a simple wheel, but now we can teach our children how to build a Ferrari.

The ability to transmit knowledge requires communication. Other animals can also communicate, but only limited and rigid information; humans, with our unique capacity for generating language, can tell limitless stories – even fantastical ones that are literally out of this world. We can also speak, write, read and use language to reflect on the past or think about the future. And it is not just the complexity and diversity of human language that is unique. Language had to build upon an understanding and desire to share knowledge with others who, like us in the first place, were willing to learn. It required understanding what others were thinking. Communication is part of our domestication – we had to learn to live peacefully and cooperatively with others for the collective good by sharing resources that include knowledge and stories. We do not just educate our children – we also socialize them so that they become useful members of society governed by all the rules and behaviours that hold it together.

Of course, this does not mean that our species is necessarily peaceful. There are always tensions and struggles in a world of limited resources and individuals will group together to defend their position against members from another tribe. However, for the conflicts that arise between groups and among individuals, modern societies govern with a greater level of control through our morality and laws than previously experienced in our history. To be an accepted member of society, each of us must learn these rules as part of our domestication.

We are such social animals that we are completely preoccupied with what others think about us. No wonder reputation is paramount when it comes to feeling good about ourselves. The social pressure to conform involves being valued by the group because, after all, most success is really defined by what others think. This preoccupation is all too evident in our modern celebrity culture, and especially with the rise of social networking, where normal individuals spend considerable amounts of time and effort in pursuit of recognition from others. Over 1.7 billion people on this planet use social networking on the Internet to share and seek validation from others. When Rachel Berry, a character in the hit musical series
Glee
, about a performing-arts school, said ‘Nowadays being anonymous is worse than being poor’, she was simply echoing our modern obsession with fame and our desire to be liked by many people – even if they are mostly anonymous or casual acquaintances.

We have always preferred others for what they can do for us. In the distant past, it may have been the individual
attributes of strength to bring home the bacon and fight off competitors or our capacity to bear and raise many children that were selected for, but those attributes are no longer essential in the modern world. In today’s society, it is as much strength of character, intellect and potential financial earning that most regard as desirable traits. Top of the list of qualities most of us would like to possess is high social status, which explains why many individuals who already are well off in every other domain of their life still seek the attention of others.

What others think about us is one of the most important motivations for why we do the things we do. Some of us may have moments of blissful solitude when we escape the rat race of modernity and pressure to conform, but most inevitably return to seek out the company and support of others. Deliberate ostracization can be the cruellest punishment to inflict on an individual, short of physical harm. Like domesticated foxes that escaped into the wild, we invariably need to return to the company of others.

Why is the group so important and why do we care about what others think?
The Domesticated Brain
shows that we behave the way we do because of how our brains evolved to be social. For humans, being social requires skills of perception and comprehension when it comes to recognizing and interpreting the activity of others but it also requires changing our own thoughts and behaviours to coordinate with theirs so that we can be accepted. This domestication as a species took place over the course of human evolution as self-selecting mechanisms shaped social behaviours and temperaments that were conducive to living in communities,
but we continue to domesticate ourselves during the course of our own lives and especially during our most formative years as children.

Our brains evolved for living in large groups, cooperating, communicating and sharing a culture that we passed on to our children. This is why humans have such a long childhood: during this formative period, our brains can become acclimatized to our social environment. The need for social learning requires babies to pay special attention to those around them but also enough flexibility to encode cultural differences over the course of childhood. This enables each child to recognize and become a member of its own group. A child must learn to navigate not just the physical but the social world by understanding others’ unseen goals and intentions. We have to become mind readers.

We need to develop and refine skills that make us capable of reading others in order to infer what they are thinking and most importantly, what they think about us. Where possible, evidence from comparative studies is considered to reveal the similarities and differences we share with our closest biological cousins, the non-human primates. And of course, we focus on human children. Developmental findings that reflect the interplay between brain mechanisms and emergence of social behaviour are the key to understanding the origins and operations of the mechanisms that keep us bound together.

That analysis could rely solely on the costs and benefits of social behaviours, but then we would miss the important point that people are emotional animals with feelings. It is not enough to read others and synchronize with them
in some coordinated tango to achieve optimal goals. There is also an imperative to engage with others through positive and negative emotions that motivate us to be social in the first place. Taking that perspective casts a better light on understanding why humans seem to behave so irrationally because sometimes they care too much about what others think.

One of the more controversial issues that
The Domesticated Brain
addresses is the extent to which early environments can shape the individual and even pass on some acquired characteristics to their offspring. For most Darwinians committed to the theory of natural selection, whereby the environment alone operates to select genes that confer the best adaptations, this idea sounds heretical. Yet we examine the evidence that early social environments leave a lasting legacy for developing our temperaments through what are known as epigenetic processes – mechanisms that change the expression of our genes that can affect our own children.