Like the ancient Greek philosophers, children infer that living things have something special inside that makes them uniquely alive. They assume that there are essences5 that define what a living thing is, that there are vital life energies6 that cause things to be alive, and that everything is connected by forces. In philosophy these different but related notions are called ‘essentialism’, ‘vitalism’, and ‘holism’. As far as they go, they are pretty good approximations of what we know from science about life. If you open any modern biology textbook, you will find that such beliefs are in fact scientifically valid. For example, DNA is a biological mechanism for identity and uniqueness, which are core components of essentialism. Within all living cells there is a chemical reaction known as Krebs’s cycle that produces measurable quantities of energy.7 This is the vital life force that keeps the cell alive. Symbiosis is the study of the interconnectedness of biological systems. The connectedness of living systems can be found in evolutionary theory, in symbiotic physiology, and, more recently, in James Lovelock’s ‘Gaia’ theory of ecology.8 No man – and for that matter no microbe – is an island; all must be understood as part of a complex system. Most of us are ignorant of these various discoveries and theories, but long before DNA, Krebs’s cycle, and symbiosis became mainstream science, humans naturally assumed their existence in the form of intuitive essentialism, vitalism, and holism. However, such intuitive reasoning also forms the core of the supersense because we infer essential, vital, and connected properties operating in the world that go beyond what has been scientifically proven.
Although we intuitively think of essences, life forces, and holism, we would be hard-pressed to describe what we mean. We can’t easily articulate these concepts because we often lack the appropriate terms or language. In Eastern cultures, such notions are recognized by ancient terms such as ‘chi’ (Chinese), ‘ki’ (Japanese), and ‘mana’ (Polynesian). In Europe we used to have the term ‘élan vital’ (life force), but this has been mostly abandoned. Having good or bad ‘vibes’ is the closest that most of us come to phrasing these concepts. We may have lost our words to describe them, but our behaviour and opinions reveal that essentialism, vitalism, and holism are still guiding our reasoning. When people respond negatively to wearing a killer’s cardigan, this is a reflection of their naive biological reasoning at work. The evil they think is imbued in the cloth is a reflection of the same mechanisms that children apply to infer the hidden properties of living things.
If such metaphysical beliefs are rarely discussed in the West and no one told us about them, then where did they come from? Once again, the most likely explanation can be found in the developing mind. They must come from our natural way of reasoning about life. In this way, children’s intuitive biology sows the seeds of adults’ supernaturalism, especially as our understanding about life influences much of our attitudes and beliefs.
KOSHER CATEGORIES
Jewish dietary law forbids the consumption of certain animals described in Leviticus of the Old Testament as unclean. At first, the lists seem rather arbitrary. Unclean animals include camels, ostriches, sharks, eels, chameleons, moles, and crocodiles. I have actually eaten three off this list without any ill effects. Some of the animals deemed fit for eating are even more unappetizing to modern tastes, such as gazelles, frogs, grasshoppers, and some locusts. On what basis did someone decide that sharks are unclean but most fish are acceptable? Sharks are fish after all.
Some people have suggested that avoiding certain taboo foods reduces the risk of infection. For example, there is a high risk of food poisoning from shellfish, which can spoil rapidly in hot climates. Undercooked pork can be a source of the parasitic infection trichinosis. However, such an explanation fails to account for many of the unclean animals.
One intriguing alternative is that originally the animals were deemed either clean or unclean depending on how well they fit properties of the group to which they belonged.9 In the case of mammals, it is clear that the clean or unclean judgement had something to do with how well each example fit general categories when it came to hooves and chewing the cud.
But this is what you shall not eat from among those that bring up their cud or that have split hooves; the camel, for it brings up its cud, but its hoof is not split – it is unclean to you; and the hyrax, for it brings up its cud, but its hoof is not split – it is unclean to you; and the hare, for it brings up its cud, but its hoof is not split – it is unclean to you; and the pig, for its hoof is split and its hoof is completely separated, yet it does not chew its cud – it is unclean to you. You shall not eat of their flesh nor shall you touch their carcass – they are unclean to you.
Leviticus 11:4–8
Any group of animals should share more properties compared to those from another. Biologists call this grouping ‘taxonomy’, after the Greek taxis, which referred to the main divisions of the ancient army. Today’s modern taxonomy is based on one originally devised by the Swedish biologist Carl Linnaeus in the eighteenth century, but prior to this, taxonomies were based on animals’ different modes of movement and their habitats.
All the various animals of the land, sea, and air share very similar bodily structures and forms of locomotion. Land animals have four legs and jump or walk. Fish have scales and swim. Birds have wings and fly. One suggestion is that unclean animals tend to be those that violate these properties of the general category to which they belong. Sharks and eels live in the sea, but do not have scales. Ostriches are birds, but do not fly. Crocodiles have legs that look like hands. Maybe some of the unclean animals are the freaks of their taxonomic group. The early Jewish scholars thought that such violations were abominations of the natural world.
Our inclination to understand the world leads us to chop it up into all the different categories we think exist. By looking for the structure in the natural world, we group natural things together into their various kinds. In doing so, we acknowledge that members of a group share the majority of characteristics compared to members of a different group. However, in categorizing the natural world, we become aware that some members do not fit neatly into one category or another. Unclean animals and human freaks are violations of the natural order of things, and that order is one that we construct as part of the intuitive biology we develop as children.
IS IT A BIRD? IS IT A PLANE?
Give a twelve-month-old infant a bunch of toy birds and planes to play with. Then sit back and watch as something quite extraordinary happens. After the initial examination with eyes and then mouth, the baby will start to touch each of the birds in sequence, followed by touching each of the planes. Even though they may have similar shapes, with long bodies and stuck-out wings, the infant is treating birds and planes as different types of things.10 More remarkable is that six-month-olds shown different pictures of cats and dogs can tell the difference even though no two animals look alike.11 This simple demonstration reveals some very important things about babies. For a start, they are naturally inclined to sort out the world. They are thinking about things and forming categories. They must be thinking, This is one type of thing, whereas that is another. It’s exactly the sort of observational technique that professional scientists use when trying to understand the world. By sorting, they are telling us that they understand that dogs are members of one category whereas cats belong to another. In short, they have a rudimentary biology.