One way to find out what is happening to us is to study the effect of urban life on other animals who cohabit our cities. Menno Schilthuizen, a Dutch evolutionary biologist, ecologist, professor and permanent research scientist at Naturalis Biodiversity Centre in Leiden, The Netherlands, makes it clear that evolution in cities is happening, and happening at a faster scale than in the countryside because animals, plants and birds have to adapt to survive.
“Animals and plants evolve faster if the natural selection process is strong. If challenged by matters of life and death. You see that in the cities. If there is evolution that tends to happen very quickly in comparison to evolution that happens outside of the cities. …The conditions are so different there that they have to adapt. Some species cannot adapt and they simply disappear.”
If evolution is something that can happen over hundreds of years, it means that our whole concept of evolutionary change is wrong, we used to think that this was something that happened over thousands if not hundreds of thousands of years, at least that is what our school textbooks told us. “I think we have known this for quite a while, but in people’s minds, evolution is still something that happens slowly. But the speed of evolution differs from species to species, depending on how many years there are between generations. …Spiders, for example, evolve quickly because their generational cycle is very fast, two generations a year.”
Human beings have quite long generational cycles, so it is more difficult to observe changes. “It is mistake to think that human beings have stopped evolving” Menno Schilthuizen says. “We live in a very protective environment that we have created for ourselves, so it seems that we are free from natural selection and more affected by social selection. Because we live in large societies, which is a new phenomenon, as until quite recently we lived in very small communities of only a few dozen people, at the most a few hundred people. We had a whole system set up, where we had a system of favours, but that has all ended. We have moved into vast communities but the adaptation in our minds has not really taken place yet. Now there are so many people, that the DNA changes needed for evolutionary changes are probably taking place. If you have a lot of people, you have more chance of new mutations taking place.”
“In the future, people who are going to be most successful in terms of producing offspring by making use of these new conditions that urban society offers.” Menno Schilthuizen argues.
Discussion in the latter part of the programme focusses on the creation of borders between urban evolved species and non-urban evolved species. It will become more difficult for these two groups to intermingle. “We already know that, for example, birds sing at a different pitch and sing different songs in the city to attract mates, because the noise in the city demands different pitches to be audible. That also means that a bird from the countryside may not be recognised as belonging to the same species. On the other hand, cities may become so large that there are not enough animals left in the untouched countryside to provide an alternative. This is what makes urban evolution so fascinating because it is happening right here and right now.”
