In 200 years, only cows will remain … No rhinos, no elephants … the largest land animal on Earth will be the cow. And it is that e l Homo sapiens, Neanderthals and other recent human relatives are responsible for a long period of extinction, according to a new study published in the journal Science.
The research, led by the State University of New Mexico in Albuquerque (USA), warns that, if the trend continues and after analyzing the evolution of the size of terrestrial mammals in the last 125,000 years, within 200 years the cow it will be the largest mammal on the earth’s surface. The selective extinction of large mammals on all continents began after the arrival of humans in each region with the end of the glaciation and the rise in temperatures that transformed the environment and allowed humans to multiply from Africa by all the planet.
Thus, the spread of hominids (early humans and relatives such as Neanderthals) from Africa coincided with the extinction of mammals such as mammoths, the saber-toothed tiger, and the glyptodon , an armadillo-like creature the size of a car that lived during the Pleistocene epoch.
Humans apparently attacked large species for meat, while smaller creatures like rodents escaped, according to the report.
In North America, for example, the average body mass of land mammals dropped to 7.6 kg from 98.0 after the arrival of humans. At least 125,000 years ago, the average African mammal was already 50% smaller than those on other continents , despite the fact that larger land masses can generally support larger mammals.
If the trend continues, “the largest mammal on Earth in a few hundred years may be a domestic cow weighing about 900 kg,” the authors wrote.
That would mean the loss of creatures like elephants, giraffes, and hippos. Recall that the last male northern white rhino died in Kenya in March.
Thomas Brooks, chief scientist at the International Union for Conservation of Nature (IUCN), who was not involved in the study, said the projection of smaller and smaller mammals was a “fatality.”
Of course, the Science study excludes marine mammals, such as the blue whale, the largest creature that ever existed. It is in danger, but populations are increasing after a moratorium on hunting. Additionally, the IUCN Red List of Threatened Species lists some wild mammals about the size of a cow, such as the African buffalo or brown bear, that are not endangered.
Be that as it may, depending on the job, the average body mass would plummet to less than 10 pounds, about the size of a Yorkshire terrier.
“If this trend continues and all currently threatened mammals are lost, then the energy flow and taxonomic composition will be completely restructured. In fact, the body size of mammals around the world will go back to what the world looked like. 40 million years “.
The restructuring could have “profound implications” for the world’s ecosystems . Large mammals tend to be herbivores, devouring large amounts of vegetation and effectively transporting associated nutrients around an ecosystem. If they continue to disappear, he said, the remaining mammals would prove to be poor substitutes for important ecological roles.
“Ecosystems are going to be very, very different in the future. The last time mammalian communities looked like this and had such a small average body size was after the extinction of the dinosaurs,” concludes Felisa Smith, leader of the work. .
Referencia: F.A. Smith at University of New Mexico in Albuquerque, NM el al., “Body size downgrading of mammals over the late Quaternary,” Science 20 Apr 2018: Vol. 360, Issue 6386, pp. 310-313 DOI: 10.1126/science.aao5987
