Researchers used a technology developed at McMaster to rebuild the fluctuating animal and plant communities during the Holocene. Credit: Julius Csotonyi.
The soil pulled from Canada's permafrost is opening vast windows into ancient life in the Yukon, revealing rich new information and changing previous beliefs about the extinction dynamics, dates and survival of megafauna.
A 30,000-year record of past environments is presented in a new paper by researchers from the American Museum of Natural History and the Canadian government.
The changing animal and plant communities at different times during the last 11,000 years were isolated and rebuilt using the new technology developed at McMaster.
Billions of tiny soil samples contain billions of tiny genes from animal and plant species.
The analysis shows that mammoths and horses were already in decline before the instability, but they did not disappear immediately due to human overhunting. The mid-Holocene is when the woolly mammoth and North American horse were last seen, and the evidence shows that they were there for as long as 5,000 years ago.
The cored permafrost is from the central part of the country. Credit: Tyler Murchie.
The environment of the Yukon continued to change. The "Mammoth Steppe" was overrun with shrubs and mosses, species no longer held in check by large herds of mammoths, horses and bison. There are no megafaunal "ecological engineers" to manage grasslands in northern North America.
Evolutionary geneticist Hendrik Poinar, the lead author on the paper and director of the McMaster Ancient DNA Centre, says that the rich data provides a unique window into the population dynamics of megafuana.
The work builds on the research done by the scientists at McMaster who found woolly mammoths and the North American horse in the Yukon around 9,700 years ago. The date has been pushed forward because of better techniques and further investigation.
"Now that we have these technologies, we realize how much life-history information is stored in permafrost," says Tyler Murchie, a researcher in the Department of Anthropology at McMaster University.
Credit: McMaster University
He says that the amount of genetic data in permafrost is enormous and allows for a scale of ecology and evolutionary reconstruction that is unparalleled with other methods to date.
"Although mammoths are gone forever, horses are not" says Ross MacPhee of the American Museum of Natural History, another co-author. The horse that lived in the Yukon 5,000 years ago is related to the horse species we have today. The horse is a native North American mammal and should be treated that way.
Scientists stress the need to archive more permafrost samples, which are at risk of being lost forever as the temperature warms.
Nature Communications is a journal.
The ancient DNA found in soil samples shows that the mammoths and the wild horses were alive thousands of years longer than thought.
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