Humans causing ‘profound changes’ to evolution around the world

Cities globally more similar to one another than they are to nearby rural habitats, reports Jane Dalton

Environmental conditions in the centre of Toronto are more like those in downtown Tokyo than surrounding farmland, the research found (Getty Images)

Humans reshape the environments where they live and alter the way life evolves, scientists have found.

Cities in particular are driving the evolution of life worldwide, according to the experts.

They studied white clover to carry out their research because it is one of the few organisms present in almost every city on Earth.

Evolutionary biologists at the University of Toronto Mississauga (UTM) examined whether parallel evolution is occurring in cities all over the world.

In findings published in the journal Science, the Global Urban Evolution Project (Glue) analysed data collected by 287 scientists in 160 cities in 26 countries, who sampled white clover.

The study found that environmental conditions in cities tend to be more similar to each other than to nearby rural habitats, so the centre of Toronto is more like downtown Tokyo than surrounding farmland and forests.

The scientists say that worldwide, the plant is evolving in direct response to environmental changes in urban settings.

White clover produces hydrogen cyanide as both a defence mechanism against herbivores and to increase its tolerance to water stress, and the team found that clover growing in cities typically produces less of it than clover in rural areas because it has adapted to urban environments.

“Cities are where people live, and this is the most compelling evidence we have that we are altering the evolution of life in them. Beyond ecologists and evolutionary biologists, this is going to be important for society,” said Rob Ness, who co-led the project.