The Rational Optimist_ How Prosperity Evolves - Matt Ridley [23]
The Boxgrove hominids of 500,000 years ago (who were members of Homo heidelbergensis) had their ecological niche. They had a way of getting food and shelter in their preferred habitat, of seducing mates and rearing babies. They walked on two feet, had huge brains, made spears and hand axes, taught each other traditions, perhaps spoke or signalled to each other grammatically, almost certainly lit fires and cooked their food, and undoubtedly killed big animals. If the sun shone, the herds of game were plentiful, the spears were sharp and diseases kept at bay, they may have sometimes thrived and populated new land. At other times, when food was scarce, the local population just died out. They could not change their ways much; it was not in their natures. Once they had spread all across Africa and Eurasia, their populations never really grew. On average death rates matched birth rates. Starvation, hyenas, exposure, fights and accidents claimed most of their lives before they were elderly enough to get chronically ill. Crucially, they did not expand or shift their niche. They remained trapped within it. Nobody woke up one day and said ‘I’m going to make my living a different way.’
Think of it this way. You don’t expect to get better and better at walking in each successive generation – or breathing, or laughing, or chewing. For Palaeolithic hominids, hand-axe making was like walking, something you grew good at through practice and never thought about again. It was almost a bodily function. It was no doubt passed on partly by imitation and learning, but unlike modern cultural traditions it showed little regional and local variation. It was part of what Richard Dawkins called ‘the extended phenotype’ of the erectus hominid species, the external expression of its genes. It was instinct, as inherent to the human behavioural repertoire as a certain design of nest is to a certain species of bird. A song thrush lines its nest with mud, a European robin lines its nest with hair and a chaffinch lines its nest with feathers – they always have and they always will. It’s innate for them to do so. Making a teardrop-shaped sharp-edged stone tool takes no more skill than making a bird’s nest and was probably just as instinctive: it was a natural expression of human development.
Indeed, the analogy with a bodily function is quite appropriate. There is now little doubt that hominids spent much of those million and a half years eating a lot of fresh meat. Some time after two million years ago, ape-men had become more carnivorous. With their feeble teeth and with finger nails where they should have had claws, they needed sharp tools to cut the skins of their kills. Because of their sharp tools they could tackle even the pachydermatous rhinos and elephants. Biface axes were like external canine teeth. The rich meat diet also enabled erectus hominids to grow a larger brain, an organ that burns energy at nine times the rate of the rest of the body. Meat enabled them to cut down on the huge gut that their ancestors had found necessary to digest raw vegetation and raw meat, and thus to grow a bigger brain instead. Fire and cooking in turn then released the brain to grow bigger still by making food more digestible with an even smaller gut – once cooked, starch gelatinises and protein denatures, releasing far more calories for less input of energy. As a result, whereas other primates have guts weighing four times their brains, the human brain weighs more than the human intestine. Cooking enabled hominids to trade