Bruce Hood - The Domesticated Brain - A Pelican Introduction (Pelican Books)

Babies do not need to be taught how to speak; most children are fluent by three years of age, irrespective of where they grow up in the world, so long as there are people around speaking to them. The grammars of industrialized societies are no more complex than those of so-called primitive tribes and all languages share the same underlying linguistic rules that were only relatively recently discovered. Language can also be knocked out by certain head injuries, it activates specific networks of neural circuitry in the brain and some language disorders are genetically transmitted. Taken together, these facts indicate that the development of language belongs more to the realm of human biology than cultural invention, which is why language has been called an instinct. 46Language not only enabled humans to pass on information, but it allowed us to domesticate our children by instructing, scolding and encouraging those ideas and behaviours that would be most suited to getting on with others peacefully.

The architecture of the mind

Many scientists believe that language did not suddenly appear but rather must have evolved from a number of different sub-skills – almost like making a new machine by recycling other parts. Evolutionary psychologists Leda Cosmides and John Tooby propose that much of the mind must also be considered like a toolbox that has accumulated specialized skills over the millennia to deal with specific problems. 47Like every other aspect of the human body, they argue that the brain must have evolved to solve problems through the process of gradual adaptation. As Cosmides and Tooby quip, ‘the human brain did not fall out of the sky’, ready prepared to address all of life’s problems. Rather, it must have evolved in stages, dealing with one set of problems at a time. As humans evolved increasingly more complex lives, we also had to evolve new behaviours that provided the best opportunity for reproduction. We needed to find the best mate, refine attentive social skills and learn what was necessary to be accepted.

With these sorts of recurring problems, humans evolved a repertoire of coping skills that are passed on in our genes. Our ability to navigate, count, communicate, reason about the physical properties of objects and interpret expressions are just some of the candidate functions that might be part of our evolved behaviours. These can all be found in humans across the planet today, irrespective of where they live. If these functions are universal and largely independent of the culture or society, then this strongly suggests that they are wired into our biology and transmitted by our genes. However, this is where the theoretical arguments take place. To what extent is a particular human attribute an evolved adaptation and to what extent has it been created and transmitted in recent evolutionary history by culture? Is jealousy a cultural artefact of prevailing sexual attitudes or could it be something that conferred an adaptation in our evolutionary past? Even though we cannot go back to see how our ancient ancestors evolved, we can look for clues that support the idea that functions we possess are the legacy of natural selection.

Human evolution took place over millions of years and must have been gradual for a number of reasons. First, as an organism evolves from simple to more complex activities, the types of problems it encounters over time will change, spurring on the necessity for further adaptations. The complexity of the brain could not have resulted from one massive mutation in our DNA. Rather, the complexity would have had to emerge as each successive version of ancestors had to deal with a new set of problems. Second, adaptation works for solving specific problems, so a brain that was not especially equipped to deal with a problem would not be selected for. In effect, the brain had to have a collection of specialized problem-solving solutions rather than being a good all-rounder. If the brain had only been a good all-rounder problem-solving system, then it could never be as efficient as one made up of multiple specific skills. Different problems require different solutions with tailored mechanisms. In other words, a jack-of-all-trades is a master of none.

One way to imagine the mind is as a Swiss Army knife with lots of blades that perform different functions. You have blades for removing stones from a horse’s hoof (who uses that these days?), corkscrews, scissors and an assortment of other bespoke blades. In the same way, the brain has specific functions such as language, spatial navigation, face processing, counting and so on. If our mind was like our metaphorical knife but only had one general-purpose blade good for cutting but not good for opening bottles, then we would be limited in dealing with specific problems. For example, vervet monkeys have evolved an alarm-call system to identify three different types of predator: snakes, eagles and leopards. Each predator requires a different course of action: either standing on hind legs looking down at the grass around them (snake), looking up in the air and diving into a bush (eagles) or climbing up a tree (leopards). Get the response wrong and the vervet monkey becomes dinner. This is why they instinctively respond to different alarm calls. A general-purpose ‘Look out!’ would not have been a good adaptation.

This evolutionary approach has led to the view that the architecture of the mind is not a general problem solver but rather a collection of systems dedicated to addressing specific problems. In the same way that dedicated mechanisms for solving recurrent problems during human evolution could have emerged through the process of natural selection, culture-gene approaches to understanding human evolution propose that our species possess mechanisms that reliably seek out cultural input. 48In other words, there are genetic dispositions to learn efficiently. The reason for this is that culture changes faster than genes. Unlike examples of cultural learning in animals, humans continually refine, develop and expand on knowledge that is passed on. This is possible because we have brains that are evolved to learn from others. Our efficiency is guided not only from our capacity to communicate, but also by our biases to attend to specific aspects of others that signal who are most valuable as teachers. As we will learn in the coming chapters, babies are tuned into their mothers from the very start in a reciprocal relationship. But they also pay more attention to others who are older, who are the same sex, who are friendly and who speak the same language. Babies are born with dispositions encoded in their genes to learn from those who are going to be most useful to them in terms of acceptance by the group.

Cognition, cooperation and culture

Psychologist Mike Tomasello at the Max Planck Institute for Evolutionary Anthropology in Leipzig is one of the world’s leading experts on what makes us human. He studies the development of children and how they compare to other primates. He believes that the traits that distinguish humans from our primate cousins are our capacity to think about others, cooperate with them and share ideas and behaviours. All of these are necessary for cultures to thrive. Human culture differs from any other social groups in the animal kingdom because there is a cumulative build-up of knowledge and technologies that is passed on from one generation to the next. With every generation, our world becomes more complex because we educate and share information by cooperation. In this way, knowledge and understanding ‘ratchet up’, with each successive generation expanding and improving the complexity and collective knowledge of the group. 49

Other animals also live in groups and exhibit a host of social skills for working out what others are thinking, but these abilities are mostly restricted to situations where there is a potential fight or conflict. Most non-human primates are opportunists, only on the lookout for situations where they can take advantage of other members for either food or sex or to establish a better position in the dominance hierarchy. There are examples where chimpanzees will help others, but these are mostly situations where there is the potential for some personal gain. 50In contrast, people will sacrifice personal gain for others. They will even spontaneously help strangers who they will never meet again. The capacity for altruism seems to be characteristically human. Examples of animal altruism are rare and restricted to those species that exhibit strong codependence, such as marmosets. In these cases, it is strategically in their interests to be promiscuously prosocial to increase their likelihood of breeding. 51