About 100,000 years ago, life on our planet looked a lot more impressive than it is today. Sloths were as long as a giraffe’s neck, bears were monstrous, and beavers were as heavy as an NFL player. However, in time, most of these animals disappeared in a mysterious way. Scientists have never been able to discover why this happened so quickly. Until now. According to a study which the journal Science recently published, the most important players who took part in this disappearance were hominins and humans, not some huge catastrophic events.
According to Felisa Smith, the lead author of this study, the team started by looking at the fossil records for the past 65 million years. They wanted to come up with an answer regarding whether or not has ever been a disadvantage to be big. They reached the conclusion that no, size doesn’t make an animal go extinct more quickly, it never has. But then a new predator came to be, the Homo erectus. About 1.8 million years ago, hominins who were once eating plants became dependent on meat. Wherever they spread, extinctions of large mammals followed. This is how it all began.
Humans are to blame for mammals’ smaller size
Our ancestors knew that they had to go big or go home. When they were hunting a rabbit, they were providing food for a family. But hunt a mammoth and you provide food for an entire village. Sometimes, these ancient humans were probably hunting the largest mammals as part of a competition. Then there’s the problem of reproduction. Bigger animals do not reproduce as fast as small ones. This probably contributed to their decrease in size too.
It’s worth noting that the average body mass in mammals today is just one-tenth than it was 125,000 years ago. This is a huge difference which can probably by explained by the aforementioned factors.
Image source: nps.gov