Nature’s Genius
In this extract from his hopeful and surprising new book Nature’s Genius: Evolution’s Lessons for a Changing Planet, professor David Farrier explains how some animals can adapt to cities – something that may have implications for life on Earth
Cities are islands – places of refuge where life congregates and thrives – and like islands they can emerge astonishingly suddenly. In fact, by far the greatest number of new islands are born on land. From Songdo, a ‘city in a box’ built from scratch on cleared ground in South Korea between 2000 and 2015, to the still-incomplete $100-billion Forest City in Johor, Malaysia, new metropolises have arisen across the globe like atolls of concrete and glass. Since 1949, China alone has built at least 600 new cities, each with a population numbering in the millions. The environmental effects are typically devastating, involving razing forests or reclaiming land from the ocean. But cities also, in a sense, replace what they destroy. Cities occupy just 0.5 per cent of global land, but they mimic nearly every environment on Earth: skyscrapers and tall buildings replace hills and cliffs; metro lines stand in for cave systems; reservoirs, ponds and culverts are substitutes for natural waterways.
Cities offer an alternative to lost habitats, with plentiful food and shelter. The urban heat island effect – whereby the excess heat generated by people and machines can raise the temperatures several degrees above the surrounding environment – even provides some cities with their own microclimate, attracting plants and animals like moths to a flame. Each city is both island and archipelago, a patchwork of niches that different organisms can exploit. And the networks of trade, culture and information that connect them – as well as the increasing homogeneity found in cities as distant as Minneapolis and Mumbai – mean they also form a planetary archipelago.
Like islands, all cities, both new and old, are evolution engines – hot-houses of plasticity and speciation, where a host of creatures learn to adapt to city life. Urban snails in the Netherlands have lighter-coloured shells, to cope with the heat island effect; urban lizards in Los Angeles have larger scales for the same reason. Orb weaving spiders from Australia to Belgium are making tighter, denser webs to compensate for the fact that there are, in general, fewer insects to catch in cities. Fish called creek chub in Raleigh, North Carolina, are changing their body shape to cope with faster currents in urban waterways, while house finches in Tucson, Arizona, have developed larger beaks with a stronger bite as a result of foraging sunflower seeds from urban birdfeeders, which are harder to break than food sources in the surrounding desert. Some species seem to swap traits: urban bridge-dwelling spiders have evolved an attraction to artificial light to catch insects, while ermine moths have lost their attraction to light entirely. City birds around the world are changing their tune: in Melbourne and Sydney, silvereyes (pictured above) sing in shorter bursts to cope with urban echoes, while the dawn chorus begins earlier along the stretch of the Jarama River that passes Madrid airport, to avoid air traffic noise.
In The City We Became, N. K. Jemisin’s fantasy novel in which New York City itself has become sentient, there is a sound so faint only a few can hear it – ‘beneath the others, the pillar supporting them, the metronome giving them rhythm and meaning: breathing. Purring.’ If we watch and listen closely, our island cities are also alive: respiring not just with the tick of day and tock of night, the oscillation of work and rest, but with countless small lives, fitting themselves as we do to the demands of urban living.
Nature’s Genius by David Farrier is out now, published by Canongate. You can order a copy (including signed copies) by clicking here.
Cityscape by Sebastian Kurpiel on Unsplash. Silvereye by Alison Griffiths, also on Unsplash
