The European forest elephant was a colossus. Bulls reached a shoulder height of more than four meters and weighed up to eleven tons, so the animals were about a third larger than today’s elephants and two to three times as heavy. Fossils of these giants have been found all over Europe and in the Near East, including in Germany, for example in the Geiseltal in Saxony-Anhalt. The animals lived in the Ice Age Pleistocene, and they could also cope with cold, then they probably grew a fur. But they had a downside – and scientists say that may have been one of the reasons why the European forest elephant went extinct but not its smaller relatives in Asia and Africa, at least not yet. Compared to their overall size, their brains were small.
Researchers from Tel Aviv and Naples have looked not only at the European forest elephant, but also at 50 species of large animals that have become extinct in the past 120,000 years, including giant sloths and American mastodons, saber-toothed cats and Australian marsupial lions. All of these animals died out during cold periods, because of the climate, because they were pushed out by other animals, or because they were hunted by humans and eventually became extinct. But why did they die out while other large animals survived, such as elephants and rhinos, hippos and leopards?
To answer this question, the scientists compared the proportions of the extinct animals to 291 surviving species of a similar size. And how they are now in the magazine Scientific Reports to reportthey found: The surviving species had significantly more space in their skulls.
The larger an animal species was, the more likely it was to become extinct
“We found that the surviving species had, on average, 53 percent larger brains than evolutionarily closely related extinct species of similar body size,” says Tel Aviv University zoologist Shai Meiri, co-author of the study. The informative value of the analysis with regard to individual species is limited because fossil finds are often sparse. But the same picture emerged across all animal species. The dominant factor that decided the future of a species was its body size: the larger an animal species was, the more likely it was to become extinct – large animals reproduce more slowly. But species with relatively large brains still survived, despite their size.
More gray matter could also have turned out to be a disadvantage: the larger the brain, the more energy an animal needs, and the longer it takes for a young animal to mature and become capable of reproduction. Both actually increase the risk of extinction. But their comparatively large brain probably gave the animals an advantage, suspects the main author of the study, zoologist Jacob Dembitzer, who is currently doing his doctorate in Naples. Humans are often responsible for the extinction of large animals. Animals with larger brains, however, would probably have been better able to adapt to its attacks.
According to Dembitzer, these results could also help to solve another mystery: Why did almost everything larger than a vicuña or a red kangaroo go extinct in South America and Australia, while larger animals were able to survive elsewhere? The climate has changed particularly drastically on the two continents, and people have raged there violently, it is said so far. But apparently there was another factor: the large animals there also had relatively little on their minds.