Probably a combination of factors has led to a massive disappearance in large mammals as the ice age approached.
But a study published Thursday in the journal Science provides evidence that the main engines were humans and other hominids.
Today, as we all know, human activities expose larger animals to greater risk of extinction. However, this targeting of the largest species is not new.
Smith et al. It shows that the bias from large numbers of mammal species in ecosystems is a hallmark of the human impact of human migration since the Pleistocene.
If the current trend continues, land mammals will be smaller than in the past 45 million years.
Giant animal mammals have a major impact on the structure of ecosystems, so their losses can be particularly destructive.
Since the late Pleistocene, large mammals have been expelled from most of the planet. Although all of the inhabitable continents used to have giant mammals, the remaining several species are mainly confined to Africa.
This decline is consistent with the global expansion of humanity in the Quaternary period. Here, we quantify the mammalian extinction selectivity, continental size distribution and taxonomic diversity in five time periods, spanning the past 125,000 years and extending to the next approximately 200 years.
We show that size-selective extinctions have been carried out at the oldest intervals and occur on all continents, all nutritional patterns and all time intervals.
Moreover, the degree of selectivity is unprecedented in the 65 million mammalian evolution. The unique selectivity characteristics mean that human activities have become the main driver of classification loss and homogeneity of ecosystems.
Because megafauna have a disproportionate impact on the structure and function of ecosystems, the past and present demographics are reshaping the Earth’s biosphere.
View Full Text – “Body size downgrading of mammals over the late Quaternary”