UK: Ecology The Human Stain: Biodiversity Decline Started Millions of Years Ago
The human-caused biodiversity decline started much earlier than researchers used to believe. According to a new study published in the scientific journal Ecology Letters the process was not started by our own species but by some of our ancestors.
An international team of scientists from Sweden, Switzerland and the United Kingdom point out a in study that the ongoing biological diversity crisis is not a new phenomenon, but represents an acceleration of a process that human ancestors began millions of years ago. Søren Faurby, researcher at Gothenburg University and the main author of the study argues that the extinctions that can be seen in the fossils are often explained as the results of climatic changes. However, the changes in Africa within the last few million years were relative minor, Faurby points our. Also, new analyses showed that climatic changes were not the main cause of the observed extinctions. According to Daniele Silvestro, computational biologist and co-author of the study, the best explanation for the extinction of carnivores in East Africa is instead that they are caused by direct competition for food with our extinct ancestors.
Our ancestors have been common throughout eastern Africa for several million years and during this time there were multiple extinctions according to Lars Werdelin, co-author and expert on African fossils. By investigating the African fossils, the scientists could see a drastic reduction in the number of large carnivores, a decrease that started about 4 million years ago. About the same time, our ancestors may have started using a new technology to get food called kleptoparasitism, Werdlin explains.
Kleptoparasitism means stealing recently killed animals from other predators. For example, when a lion steals a dead antelope from a cheetah. The researchers are now proposing, based on fossil evidence, that human ancestors stole recently killed animals from other predators. This would lead to starvation of the individual animals and over time to extinction of their entire species.
This may be the reason why most large carnivores in Africa have developed strategies to defend their prey. For example, by picking up the prey in a tree that we see leopards doing. Other carnivores have instead evolved social behavior as we see in lions, who among other things work together to defend their prey.
Originally published on: science.gu.se
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