Human-Caused 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.
The work was done by an international team of scientists from Sweden, Switzerland and the United Kingdom.
The researchers point out in the 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.
“The extinctions that we see in the fossils are often explained as the results of climatic changes but the changes in Africa within the last few million years were relative minor and our analyses show that climatic changes were not the main cause of the observed extinctions,” explains Søren Faurby, researcher at Gothenburg University and the main author of the study.
“Our analyzes show that 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,” adds Daniele Silvestro, computational biologist and co-author of the study.
Carnivores disappeared
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, we can 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,” he 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,” explains Søren Faurby
Humans today affect the world and the species that live in it more than ever before.
“But this does not mean that we previously lived in harmony with nature. Monopolization of resources is a skill we and our ancestors have had for millions of years, but only now are we able to understand and change our behavior and strive for a sustainable future. ‘If you are very strong, you must also be very kind’,” concludes Søren Faurby and quotes Astrid Lindgrens book about Pippi Longstocking.
I have to question whether there were enough homo Sapiens to affect extinctions on that scale.
Furthermore:
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And yet, those climatic changes were enough to produce the evolution, not just of our species, but of our genus as well (from Australopithecus).
I was hoping that study found that the extinctions were the result of the evolution of the first species ever that was capable of controlling — and ultimately, abusing — fire. We know, for example, that pre-Columbian aboriginal humans in North America would ignite entire forests in the hopes that the new green shoots would attract game for them to hunt. If conduced on a global scale for hundreds of thousands of years, this behavior would have *had* to have an impact on the climate and perhaps even made a major contribution to ending the last glaciation.
I read where it has been hypothesized that it was possible that a few of the carbon molecules from the very first fires lit by our hominid ancestors — possibly homo Habilis/Ergaster as many as two million years ago — are still floating around the atmosphere. If that’s the case, then its not difficult to see that hominids have been using fire to cause biodiversity decline long before we homo Sapiens arrived on the scene.