Gone but not forgotten
Details of how people killed off species in the past may have implications for whether they do so in the future
Jan 25th 2010 | From The Economist online
Between 50,000 and 5,000 years ago roughly half of the earth’s larger mammals (species that were sheep-sized or bigger) went extinct. The distribution of these extinctions in time and space suggests strongly that humans were responsible. Large mammals in Africa, which had evolved alongside humans for millions of years, were for the most part spared. The species which died out elsewhere—178 of them, possibly more—tended to do so at around the time that they first encountered modern humans coming forth out of Africa with pointy sticks, good throwing arms and large appetites. Ecologists have shown that wiping out big animals is surprisingly easy, since big animals reproduce slowly, which means that a small increase in the rate at which predators pick them off can have a large effect on the population, especially if the predators prefer hunting juveniles. Hence the now widely accepted argument that humans come with original ecological sin built in.
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As a large and recent extinction event this topic would be worth studying even if it did not have implications for how people think about themselves. When extinction is becoming commonplace, a better understanding of its mechanisms is prudent. Research in this area has recently been throwing up some surprising and intriguing complexities. In North America, new evidence suggests that both mammoths and horses co-existed with humans a lot longer than had previously been expected, suggesting the extinctions could not have been simple wham-bam-yummy-leg-of-lamb affairs. Evidence from bones and teeth has led to researchers accepting that mammoths and native horses last roamed America between 15,000 and 13,000 years ago, which fits nicely with humans turning up about 14,000 years ago. But saying when the last of a species roamed on the basis of bones is an error-prone affair; the chances that the last of a dying race will pass away in some sort of ready-made ossuary are slim.
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Read more here/Leia mais aqui: The Economist
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NOTA CAUSTICANTE DESTE BLOGGER:
Eu não consigo entender a Lógica Darwinista 101. As extinções não são mecanismos evolutivos? O mais apto é o que sobrevive? Ora, então por que chorar as pitangas pelos animais extintos e que irão ser extintos, se isso faz parte do processo evolutivo?
Pô, mano, sejamos epistemologicamente coerentes com Darwin, o homem que teve a maior ideia que toda a humanidade já teve...
