This item in last week’s New Scientist
about ‘evolution operating with a vengeance in the urban environment as animals struggle to adapt to novel conditions and cope with ‘evolutionary illusions’’
has been bugging me. It’s not just that it sometimes uses ‘evolution’ when it means ‘selection’ (selection is what operates on individuals, as in selection for an Olympics team; if it operates on enough individuals with enough consistency over enough time, so that those individuals with one genetically determined quality produce more offspring that other individuals of the same species, then evolution kicks in . . . but that doesn’t seem to be going on in the examples quoted). Or that at least one example, of sea turtles fatally mistaking city lights for the gleam of moon- or star light on the ocean, doesn’t have any evolutionary content; so far, we don’t have any evidence that those foolish turtles are evolving to live on land, although to be fair perhaps turtles that use other cues than light to navigate them towards the moon-dappled sea may survive more often, and thus the sea turtle species evolves). It’s also because it assumes that the urban environment is a novel niche, which it may not always be (squirrels occupy parks and gardens with trees - what’s novel about that?), and it doesn’t address the question of why some species live in cities and some don’t, perhaps because it raises the spectre of ‘preadaptation’, or colonisation of empty niches. After all, if you plant some trees in a city, don’t be surprised if species associated with trees turn up. And it makes no mention of the one species on which urban living may consistently operate at an evolutionary level: human beings.
On the other hand, the analyses of the effects of urban living on animal behaviour are fascinating, and the scientists quoted in the article are quite right to be excited: they seem to have found an empty research niche to colonise, and one which seems to be tremendously productive. Already, more than fifty per cent of human beings alive today live in cities, and cities are using up more and more of the countryside around them, not only as sites for buildings and roads, but also for industrialised agricultural production and leisure. In Britain, there are now very few areas which are in their original ‘natural’ state; almost all British fauna and flora have already adapted, and perhaps evolved, to cope with human intrusion, or are surviving in shrinking island niches.