June 26, 2022
Mammoth Steppe foi um ecossistema único que hospedava vários animais de grande porte, como os mamutes, no Ártico

Mammoths and large Ice Age animals lived longer than previously thought

mammoth And other large Ice Age animals like the woolly rhinoceros lived longer than scientists thought, co-existing with humans for tens of thousands of years before disappearing forever. This conclusion was made possible after the results of an ambitious research project analyzed for ten years DNA From hundreds of soil samples found throughout the Arctic.

Scientists involved in the project collected 535 samples of permafrost and sediment from frozen lakes, at 73 frigid sites where mammoth genetic material was found in Siberia, Alaska, Canada and Scandinavia.

DNA analysis showed that mammoths lived on the Siberian mainland 3900 years ago – after the construction of the Great Pyramid of Giza in Egypt and the erection of the Sotenehenge megalith. Most mammoths died out about 10,000 years ago, with the exception of a very few populations that survived on remote islands throughout Siberia.

On the other hand, woolly rhinos have been living in the Arctic for 9,800 years, according to researchers. Previous studies showed that they became extinct about 14,000 years ago. However, the species has already become extinct after the last areas of steppe mammoth The unique Arctic ecosystem, which no longer exists today, gave way to peat bogs, as the climate became wetter and warmer.

“The authors provide several histories of mammoths, woolly rhinos, horses, and bison, which are also much smaller than the fossil record indicates, forming a stronger case for late survival in the Arctic than it was previously,” said Tory Herridge. , an evolutionary biologist and mammoth expert at the Natural History Museum in London.

“I am very excited to see how this work will develop, and what new data may emerge to support or refute it. I am sure it will come under thorough scrutiny,” continued Heridge, who was not involved in the research.

Most of the DNA is taken from bones or teeth (the oldest ever DNA sequence was from mammoth teeth and was over a million years old). The use of new technologies allows the analysis, sequencing and dating of genetic material preserved in soil.

All animals, including humans, constantly lose genetic material when urinating, defecating, bleeding, hair loss, and dead skin cells. This genetic material penetrates the soil, where it can survive for tens, hundreds or thousands of years, when in the right conditions, such as in permafrost.

“The animal shed millions of fragments of DNA continuously throughout its life in its feces, urine, skin and hair cells, as it roamed across the geographical range, but left only one skeleton after its death, reducing the likelihood of its preservation and recovery,” said one of the study’s authors, Yucheng Wang, a researcher. Associate in the Department of Zoology at the University of Cambridge in England.

“By sequencing only a few DNA molecules conserved in the environment, we can determine their presence and range. So it is not surprising that sedimentary DNA can produce a more accurate estimate of later extinction.”

Archaeologists have used this technology, known as environmental DNA, or eDNA, to illuminate older humans. The same method was used during the pandemic to test urban wastewater for detection and tracing COVID-19.

Megafauna puzzle

The study, published in the journal Nature, also detailed the Arctic ecosystem over the past 50,000 years. The environment in which the mammoth lived, known as steppe mammoth, was cool, dry and in a complex area, with distinct communities of plants consisting of grasses (a grass-like plant), flowering plants, and shrubs. As part of the research, the team for the first time sequenced the DNA of 1,500 plants in the Arctic.

Large grazing animals such as the mammoth, which are now extinct, have been the subject of debate for more than a hundred years, Wang said. There are two main theories: mammoths were hunted to death centuries after first contact with humans, or that they weren’t able to adapt quickly enough to climate change at the end of the Ice Age. Wang also cites that his research supports the theory that climate change, 12,000 years ago, played an important role.

Wang explains that the long interaction between humans and mammoths in the Arctic, along with a detailed understanding of the ecosystem and its rapid change, are reinforcements against the argument that humans were primarily responsible for the mammoth extinction.

“When the weather became wetter and the ice began to melt, this led to the formation of lakes, rivers, and swamps. The ecosystem changed and the biomass of plants decreased, and they may not have been able to support the mammoth herds,” Wang said.

“We showed that climate change, specifically precipitation, directly led to the change in vegetation – and humans had no effect on them based on our models,” he concludes.

real dynamics?

Tory Heridge of the Natural History Museum in London says more research needs to be done on human presence in steppe mammoth If any human involvement in the mammoth disappearance is ruled out.

In the models used in the article, according to Heridge, researchers used the rare presence of human remains in the archaeological record, and the existence of a climate suitable for humanity as one of the agent, not as nucleic acid. More accurate data is needed to understand if and when humans and mice actually met in these areas.

“Environmental DNA studies like this have a lot of potential to directly test the presence of humans in the Arctic, just as they did here with mammoths — that’s the kind of high-resolution data we need to unravel the true dynamics of mammoth extinction,” she said.

“Data overlays alone will not solve this, because it is not the last behemoth that matters. It discovers why the mammoth population has been dropping so much that it has been reduced to a few isolated and vulnerable populations.”

(This text has been translated. Read Here original in english)