According to Darwin, there are two pre-conditions for evolution by natural selection to work. One is that parents have more offspring than are needed to replace themselves, and that there is genetic variation between the young – which occurs through sexual mixing. The second is that those genetic variations affect individuals’ ability to cope with the conditions in their environment, most specifically, to find food and to breed. If an individual’s genetic suitability is so poor that it dies before it is able to reproduce, its particular genetic configuration is removed from the gene pool, it leaves behind no offspring with that configuration. This is the meaning of ‘survival of the fittest’, - simply that those genetic traits which pass to the next generation tend to be those which have the closest ‘fit’ to the conditions of the environment – not necessarily the strongest, or the biggest, maybe the smallest, or the best camouflaged – and, although ‘the struggle for survival’ is often conceptualised as a competition between individuals, it is more accurately dependent on the way in which the individual reacts with its environment.
Among people with a partial understanding , there is often an assumption that evolution is teleological and progressive, ie) that it leads towards a specific goal which is in some way an ‘improvement’ on what went before. But this is to superimpose an artificial evaluation onto an objective situation. And anyway, the adaptation is to a specific set of environmental conditions. If that environment changes, for whatever reason, whether initiated by the organism or due to external circumstances, the species (and note that here we are talking about species, not individuals) no longer necessarily has the combination of genetic traits which will allow it to be successful with respect to the changed environmental factors.
OK, so there is a widespread assumption that humanity is the ‘pinnacle of creation’, possibly inherited from the judeo-Christian tradition, possibly just a natural species-centrism – just as each of us as individuals consider ourselves to be the centre of our own universe. But homo sapiens as a species has been around a very short span of evolutionary time, and ‘civilisation’ for practically no time at all.
So, why should we assume that evolution has in some way come to a halt? It seems that way because we only see an infinitesimally short time scale. It would be like, say, a mayfly which hatches in the morning and dies before sunset believing (assuming it had the mental capacity to do such a thing) that daylight is the eternal state of the world – or the people in Asimov’s short story ‘Nightfall’.
But I digress. So, if we think about the mechanisms of evolution, how are they likely to impact on humanity in the future? I have some thoughts about that – but you’ll have to wait until the future (probably tomorrow) to find out what they are.