There is no need to be experts to understand that domestication and human activities in general have had enormous consequences on the animals that we put at home (or in the fields): the selective breeding, in particular, has led us to select increasingly big and productive beasts, not to mention what he did to dogs and cats.
But what are the effects of our presence on wild animals? For the first time, a team from the University of Montpellier has studied the long -term effects of human activities both on pets (in particular the breeding ones), and on wild ones, discovering an opposite trend in the two categories. The study is published on Proceedings of the National Academy of Sciences.
There are those who grow up and those who shrink. The French study was conducted by analyzing and measuring more than 225,000 bones of pets and wild animals from 311 different archaeological sites in France. Volpi, rabbits, deer, hares on one side, goats, sheep, cows and pigs on the other, dating back to very different periods: in total, 8,000 years of data, since we have started to raise the first animals to date.
These biometric data, which tell us how the size of certain species have changed over the millennia, have been combined with climatic and ecological data relating to the areas where the fossils were found, and of course with the data relating to the human presence.
The results first say one thing: pets are becoming bigger and bigger, while wild ones are taking the opposite direction. Not only that: the moment when this disparity began to expand is placed around 1,000 years ago;
Before then, domestic and wild followed the same evolutionary trajectory, becoming larger or smaller depending on the climatic and environmental situation in which they were.
The impact of man on the dimensions of animals. 1,000 years ago, during what we call Middle Ages, we humans began to select pets more precisely, favoring the larger ones and therefore gave more meat, more milk or more eggs.
At the same time, our increasingly invasive presence led wild animals to shrink: hunting and destruction of the habitat are the two main factors of this reverse course. In short: about a thousand years ago we humans have become the first and most important evolutionary pressure for wild animals, which reacted to our expansion by reducing their size.
In the last century, then, global warming has exacerbated the situation: the increase in temperatures, and its consequences on ecosystems, are continuing to shrink wild animals.
Two years ago, for example, we told you about how too hot has been reducing the size of the bird’s brain, and for more than a decade we have known that the fish that are caught are increasingly smaller. If you have noticed that cows are larger than the past, and smaller hares, now you know why.
