[Animals] Climate change behind megafauna extinction

[SnO]

Mazen Al-Najjar
A new study reported that climate change towards warming in the Pleistocene era 12,000 years ago caused a change in the vegetation cover of North America, which led to the destruction and extinction of large animals such as mammoths, and to the prosperity of humans and livestock species.

About 13,000 years ago, the world's climate began to change. Sea levels rose, ice masses retreated, and ecosystems began to transform.

 

 

At about the same time, humans began to arrive in North America, attracted by migratory hunting animals and birds and fertile new land, and over the next few thousand years many large animals such as mammoths became extinct.

environment or human?
Scientists have long disagreed about climate warming or human hunting activity, which is responsible for the extinction of megafauna of the Pleistocene era (the closest modern).

The new results of the radiocarbon dating tests support the climate-environmental explanation.

Dale Guthrie, a polar biologist at the University of Alaska in Fairbanks, compiled the epochs from radiocarbon dating of fossils from the Permafrost layer in the Arctic.

The fossils belong to five types of animals of the Pleistocene era, namely mammoths, horses (extinct), bison (American bull), moose and wobbets (American deer), as well as humans who were present in the lands of Alaska and Yukon.

Mammoths and horses disappeared from North America about 12,000 years ago, while the other four species proliferated and spread.

Vegetation
Guthrie found that the extinct Equus ferus horses had died out long before humans arrived in North America, disappearing 1,000 years before the disappearance of mammoths.

This overthrows Keystone's theory, according to which humans hunted mammoths to extinction, and caused a change in the vegetation cover of the continent, which later led to the extinction of other animals.

The persistence of mammoths after the arrival of humans for more than 1000 years indicates a weak explanation for the increase in excessive hunting.

But Guthrie sees vegetation change as key to understanding the radical shifts in animal life.

Before climate warming, this region of the world lacked trees and only provided some fodder. This gave a competitive advantage to mammoths, horses and the like because they could secure sufficient nutrients from large quantities of low-value forage.

But with the shift in climate, the mammoth steppe became the environment known today for its shrubs, tundra, and forests.

This type of feed is suitable for most livestock animals such as bison, wallabies, and moose. There is no evidence of the existence of these species older than 13,000 years, but they seem to have spread rapidly after that.

According to Guthrie's study, published last week in the journal Nature and presented by Scientific American, the archaeological excrement clearly shows the significant impact of human settlement on the resources of large mammals (such as bison and wallabies), as well as migratory waterfowl and salmonids in the Holocene.

However, these new data indicate that humans may not have played a major role in the decline of the mammoth steppes in the Pleistocene era, as what brought them to the region was a unique case of abundance of natural resources.

https://www.aljazeera.net/misc/2006/5/15/تغير-المناخ-وراء-انقراض-الحيوانات