From a conservation point of view, the recent study published on Plos Biology From two researchers at the University of Arizona and Harvard is almost dangerous. Contrary to what supported in other works, even recent, he denies the idea that the earth is crossing a mass extinction (the sixth, according to the most widespread interpretation).
So there would be nothing to worry, if not unnecessary false alarms? Not really: the imminent extinction of tens of thousands of species is a sad reality against which we are trying to fight. The point is that … the previous ones were worse.
The difference between extinctions. The extinction of mass known as the extinction of the olcene, or sixth extinction, or even the extinction of the anthropocene, is a phenomenon that began thousands of years ago:
The disappearance of megafaune was caused by our appearance on the planet, starting a phenomenon that intensified first in the colonial period, and then in the last century, reaching a rate of disappearance of the species that is between 100 and 1,000 times faster than the natural one. These are now proven facts that even the new study confirms.
But the key word to understand the news of the recent study is “species”. The mass extinctions are characterized not only by the disappearance of hundreds of thousands of species, but also and above all by the extinction of higher taxonomic categories, starting with genres.
The famous extinction that took away the Dinosaurs not Aviani, for example, led to the disappearance of 50% of all existing genres, and 17% of all families: from an ecological and biodiversity point of view losing an entire genre (or a family, or an even higher category) is more serious and devastating than the disappearance of the individual species.
A situation not to be underestimated. The analysis of the two experts has shown that, from 1500 to today, 102 different genres have been extinct, at least among those we have identified: it is 0.5% of the total of the genres described.
Not only that: half of these extinctions are concentrated between mammals and birds, three quarters of these are linked to insular species, and faster extinction rates have been observed between the late nineteenth and early twentieth centuries. In simpler terms, this means that the current extinction is taking away many species, but it is still irrelevant to gender level and higher categories.
What has been said does not mean that the current extinction of plants and animals is not a problem, on the contrary: the risks for biodiversity remain.
The study, however, wants to demonstrate that, compared to the previous five great extinctions, the current one has not (still) achieved the same levels of danger.
In short, we are not yet the insinction of entire taxonomic categories. A condition that does not exclude the worsening of things, this is why experts underline how the study should not become an excuse to loosen the guard.
