The Future of Humanity: "How Beauteous Mankind Is!" Said Miranda in the Tempest. but Can Natural Evolution or Our Own Genetic Engineering Improve on the Present Model? (the NS Essay)
Tudge, Colin, New Statesman (1996)
Are we it? Have we already seen the best of humanity? Was Plato or Shakespeare or Einstein or Buddha or Lao Tzu or the prophet Mohammed as clever as any human being is ever likely to be? Modern athletes with their minutely cultured hearts and limbs don't run the 100 metres significantly faster than Jesse Owens did in 1936. So is this as fast as people can ever be? In short: has our evolution stopped; and if so, why, and if not, what lies in store? Or might genetic engineering allow us to breed our own superspecies, if not in God's image, at least according to the demands of market forces?
To begin at the beginning. Darwin's great contribution in The Origin of Species was to propose not simply evolution, but a plausible mechanism: it happens, he said, "by means of natural selection". The individuals best able to cope at any one time are those most likely to survive and leave offspring. So as the generations pass, each lineage of creatures becomes more and more closely adapted ("fitted") to its particular surroundings. Natural selection requires an appropriate mechanism of inheritance - one that ensures "like begets like" (that cats have kittens, and horses give birth to foals), but also provides variation, so that not all kittens and foals are identical. Darwin's near contemporary, GregorMendel, working in what was then Moravia and is now the czech Republic, provided just what was needed: he showed that inheritance works by transmitting units of information, now known as genes. Genes encapsulate the characters of the parents, but they are recombined in the offspring through the machinations of sex and are also prone to random change, of the kind known as mutation. So they provide all the variation that is required.
Darwin did not know of Mendel's work (he had Mendel's account on his desk, but failed to cut the pages), but 20th-century biologists put the two together and, by the 1940s, generated "neo-Darwinism". Creatures that reproduce through sex continually swap and recombine their genes, so all the genes in all the individuals in a sexually breeding population form one great "gene pool". Natural selection operates on the pool as a whole (these neo-Darwinists said). It knocks out individuals who contain less helpful genes, but favours those whose genes are especially advantageous. Thus the "bad" genes tend to be lost as time goes by, while the ones that promote survival and reproduction spread through the pool. Over time, the composition of the gene pool changes and so the creatures change as well. The neo-Darwinian model has been modified somewhat, but that general picture obtains.
There is no destiny in evolution, Darwinian or neoDarwinian. Natural selection is opportunist and answers to the here and now; it has no mind for the distant future. The fossils tell us that our ancestors grew taller over the past five million years, from about a metre to nearly two, while our brains have puffed up from an apish 400ml or so to 1,400ml - easily the biggest in proportion to body weight of any animal. Perhaps this has made us more like God. But there is nothing in natural selection to suggest that our ancestors did more than adapt to whatever their surroundings threw at them, or to imply that we will grow more godlike as the future unfolds.
Neither will we go the way of The Eagle's Mekon, arch-enemy of Dan Dare: a green homunculus with a head as big as a dustbin and legs like cribbage pegs. Before Darwin, the Frenchman JeanBaptiste Lamarck proposed a different mechanism of evolution, through "inheritance of acquired characteristics". He observed rightly enough that bodies adapt to whatever is demanded of them, so that blacksmiths, say, acquire bigger muscles. But he was wrong to propose that a blacksmith passes on his hard-earned biceps to his children. If the children want to be tough, they have to do their own smithying. By the same token, thinking won't make our brains grow bigger, in any heritable way, and physical indolence will not shrink our descendants' legs. …