The Domesticated Brain (3 page)

Every child at some point has been told that they must ‘behave’ and when they do not, they are ‘misbehaving’. What parents really intend when they scold their children for misbehaving is that they must learn how to control their thoughts and actions that conflict with the interests or expectations of others. Self-control is a feature of our developing frontal lobes of the brain and is central to our capacity to interact with others. Without self-control we would never be able to coordinate and negotiate by suppressing the urges and impulses that could interfere with social cooperation. This capacity for self-control is critical when it comes to being accepted and without it we are likely to
be rejected – labelled anti-social because we fall foul of the moral and legal codes that hold our societies together.

That danger of rejection is the flipside of the benefit of living in a group and the devastating consequence of becoming an outsider. Ostracism and loneliness not only register as pain in our brain but also make us both psychologically and physically ill. Rejection can make individuals behave in destructive ways not only against themselves when they self-harm, but also against others. We may be more connected through social networking on the Internet, but this digital village also makes it much easier to become isolated.

Considering the vast size of the different territories covered in
The Domesticated Brain
, from human evolution, brain growth and child development to genetics, neuroscience and social psychology, any attempt to bridge these regions will be ambitious – yet it is a goal worth pursuing. When we recognize the importance of others in shaping who we become and how we behave, we can begin to understand what makes us human.

‘Why
do you need a brain?’ Initially, this seems like a silly question with an obvious answer. ‘You need a brain to stay alive,’ is a fairly common response and indeed this is true.
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You would be dead without your brain. When someone is ‘brain dead’, they lack the vital signs of breathing and a heart beat – functions that are automatically controlled by structures deep at the core of the brain. However, keeping you alive is neither the sole function nor responsibility of the brain. There are many other organs you need to keep you alive. There are also many living things that do not have brains, such as simple organisms like bacteria, plants and fungi.

When you take a closer look at our planet and consider all its different life forms, it soon becomes apparent that the original reason why living things evolved brains was for movement. Life forms that do not move or those that are swept around by the ocean currents or carried in the wind or even transported on or inside the bodies of other animals do not need to have brains. In fact, some start off with brains that they later abandon.

The best example of this is the sea squirt that begins life as a tadpole-like creature, swimming around the ocean in
search of a suitable rock upon which to attach. It has a rudimentary brain to coordinate movements and even a simple eye spot to ‘see’, but when it finally attaches to the rock, it no longer needs to search for a home and so loses its own brain.
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Brains are expensive things to operate so if you no longer need one, why keep it?

Arguably, the main reason that the brain evolved was to navigate the world – to work out where you currently are, remember where you have been and decide where you are going next. The brain interprets the world as patterns of energy that stimulate the senses, generating signals that stream up into our brain where they are analysed and stored. With experience, these patterns become learned so that the brain knows how to respond more appropriately in preparation for future encounters. As you progress up the tree of life to animals with increasingly complex brains, you find that they have a much larger library of patterns they have stored. This provides greater flexibility, giving the animal more skills and knowledge to deal with potential problems rather than being stuck with a limited set of actions. Without the ability to act, organisms would be completely at the mercy of the environment. They would be easy pickings for any predator, unable to forage or capture their own food and vulnerable to the elements. Some creatures live their lives like this – the inevitable food for others – but many evolved a brain to lash out at the world or scamper away if the threat was too fierce.

The human brain, on the other hand, is not just for solving practical problems of finding food and avoiding danger; it is also a brain exquisitely engineered to interact with other brains. It evolved to enable humans to seek out others who
are similar to form social relationships. Many of its specialized operations address the complexities of the social spheres we inhabit. We require a brain with finely honed skills to process different individuals who may be family, friends, workmates or the multitude of strangers we encounter in everyday situations.

In our ancestral past, these encounters would have been few and far between, but in the modern era we need to be expert socializers. We need to recognize who people are, what they are thinking, what they want and how to cooperate – or not – with them. We have to read others in order to understand them. These social skills that may seem trivially easy for many of us turn out to be some of the most complicated calculations our brains can perform. Some people never master them, such as individuals with autism, and others lose these capabilities through the effects of damage and disease to their brains. Our brain may have initially evolved to cope with a potentially threatening world of predators, limited food and adverse weather, but we now rely on it to navigate an equally unpredictable social landscape. The human brain enables each of us to learn about, and from, each other – to become domesticated.

Our brain is equipped with the mental machinery to live together, to breed, to raise our children and to pass on information about how to become a valued member of society. Many animals live together in groups but only humans have brains that enable them to transmit knowledge and understanding from one generation to the next in a way that is unparalleled in the animal kingdom. We can learn the rules about how to behave in ways that are acceptable to the
group. We can adopt a moral code about what is right and wrong. We raise our children not only to survive to an age where they are capable of reproduction themselves but also to benefit from the collective wisdom of others that is passed on as culture.

Some scientists are not so impressed with our human capacity for culture. Primatologist Frans de Waal argues that other animals also have culture because they can learn from others and transmit that learning on to the next generation.
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Famous examples of animal culture include the nut-cracking chimpanzees of Africa
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or the Japanese macaques who wash the sand off sweet potatoes given to them by researchers.
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In each case, juveniles have learned to copy what they observed in older animals. Just recently, three different neighbouring communities of chimpanzees living in the same habitat of the Ivory Coast have been shown to have distinct patterns of tool use to crack open Coula nuts.
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At the beginning of the season, when the nuts are hard, stone hammers are used by all; but later in the year when the nuts become softer and more amenable, one group switches to using wooden hammers or tree anvils. A third group makes this transition more rapidly. These distinct behaviours can only be explained by learning, as all tools are potentially available to each group.

There can be little quibble with the evidence in these examples of animal tool use, but this imitation is not the same as the cultural transmission that occurs when we teach our children. There is no solid evidence that cultural learning in animals has led to technologies that are improved upon, modified and developed from each new generation to the next. We return to this issue in later chapters when we
explore how human children not only copy an adult’s tool use to solve a problem, but also faithfully copy rituals that have no objective purpose; something that animals have not been observed doing.

The debate about culture in animals is contentious, and our concern here is instead with what animal studies teach us about how humans are different. By addressing social mechanisms that most of us take for granted because they seem so natural and effortless, we examine how our brain has evolved to become domesticated, concentrating on childhood because this is when the major building blocks of domestication are laid down. But first, we must consider some of the basic processes that shaped the human brain to be capable of learning to become social.

Evolution in a nutshell

The only reasonable answer to where our brain came from is evolution by natural selection as famously described by Charles Darwin in the nineteenth century. Following from Darwin, most scientists today believe that life started out billions of years ago as simple chemical compounds in a primordial soup that somehow (we still don’t really know how) developed the ability to copy themselves. These early replicators were the precursors of life, eventually developing structures called cells. Clusters of these cells in time collected together, evolving into the ancient life forms known as bacteria that are still with us today.

Everywhere you look, from the deepest oceans to the highest mountains, from the frozen tundra to the desert
furnace, or even in the volcanic acid pools that would strip the skin off most animals, you will find bacteria that have adapted to the most extreme conditions that can be found on our planet. Through the process of evolution, life forms continued to change and develop in ways that enabled them to survive different environments. But why evolve?

The answer is that there is no reason behind evolution, it just happens. Organisms evolve as adaptations to aspects of the environment that pose threats to survival and, more importantly, reproduction. When living organisms reproduce, their offspring carry copies of their genes. Genes are chemical molecules of deoxyribonucleic acid (DNA) encoded within each living cell that carry information about how to build bodies. The biologist Richard Dawkins famously likened bodies to simple vehicles for carrying genes around.
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Over time, various mutations arise spontaneously in the genes, creating slightly different bodies that lead to variations in the repertoire of adaptive fit. Some of these variations produce offspring who are better suited to the changing demands of the environment. The offspring who survive go on to produce further offspring with those inherited characteristics which worked so well, and so that adaptation becomes programmed into the genetic code that is passed on to future generations.

Through the relentless culling of those least suited for survival as natural selection dictates, the tree of life sprouted ever-increasing branches of diverging species that gradually evolved adaptations better suited to reproduce. This continuous winnowing process produced the diversity and accumulation of complex life forms that now fill the
various niches of our planet – no matter how unforgiving they may be.

The ability to move our bodies purposefully around the world may have been the initial reason that brains evolved, but clearly humans are more complex than sea squirts.

Complexity suggests purpose and goals whereas evolution is a blind process driven by an automatic selection that chooses the best variations that spontaneously arise as part of the copying process. It is for this reason that Dawkins calls evolution ‘The Blind Watchmaker’.
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Any complexity that an animal has is usually sufficient to deal with the problems they need to solve. However, as environments are constantly changing, animals need to keep evolving or become extinct – which, when you look back on the course of life on earth, has happened to most. One estimate
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suggests that of all the species that have lived on the Earth since life first appeared here some 3 billion years ago, only about one in a thousand is still living today – that’s only 0.1 per cent.

There may be some controversies over the exact details and dates of this brief history of evolution, but as far as science is concerned, the origin of the species by natural selection is the only game in town when it comes to explaining the diversity and complexity of life on Earth. Whether we like it or not, we are related to all other life forms – including those with and without brains. However, human brains have enabled us, like no other animal on the planet, to bend the rules of natural selection because of our capacity to change our environment. That manipulation is largely a product of our domestication as a species.

The cost of big brains

When
you consider that humans can survive in the hostile environment of outer space, where there is lethal radiation and no atmosphere, it is clear that we have considerable capacity for adaptation. When our early hominid ancestors first appeared some 4–5 million years ago, the environment was undergoing rapid changes and fluctuations that required a brain capable of versatility to deal with complex situations.
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We have brains that can think up solutions to overcome the physical limits of our bodies so that we can live under water, fly through the sky, enter outer space and even bounce around on the surface of an alien planet that has no atmosphere suitable for life. However, the processing power to solve complex problems is costly.