Alaska frozen soil samples show that woolly mammoths may have survived in North America for thousands of years longer than previously thought. A new study shows that these furry animals probably existed until about 5,000 years ago in what is now the Canadian Yukon.
This conclusion is the result of fragments of mammoth DNA found in frozen soil samples that had been stored and forgotten in a laboratory freezer for a decade. Tyler Merki, a researcher in the Department of Anthropology at McMaster University and lead author of the study, said:
Organisms continuously lose their cells throughout their lives. For example, every hour, an average of 40,000 skin cells fall out of a human being. That is, we are constantly throwing pieces of our DNA into our surroundings.
The same is true of other forms of life. Inhuman animals, birds, fungi and microbes are constantly leaving tiny remnants everywhere. However, most of these genetic debris do not remain in the environment, and microbes consume most of the DNA fragments soon after disposal. The small amount of discarded DNA that remains may attach to small pieces of mineral sediment and be preserved. However, only a very small portion of what is dumped first remains for centuries to come. However, this small amount can be a window to the extinct world full of defective creatures. “In a tiny particle of soil, there is DNA in the whole ecosystem,” Merki said.
Artist image of furry mammoths. Scientists have discovered that hairy mammoths lived with humans in North America for thousands of years more than previously thought.
Merki analyzed soil samples taken from the frozen soil of the Central Yukon. Many specimens date from the Pleistocene-Holocene transition period (14,000 to 11,000 years ago). The period was characterized by rapidly changing climatic conditions in which many large mammals (such as dagger-toothed tigers, mammoths, and mastodons) disappeared from fossil records.
The DNA fragments in the specimen specimens were small and often no longer than 50 letters or bp. However, he was able to extract an average of about two million DND fragments from each sample. He indirectly observed the evolution of ancient ecosystems during this turbulent period by analyzing DNA from soil samples of various dates.
Researchers collect samples of frozen soil in the Yukon
The main advantage of studying ancient DNA is that researchers can observe organisms that are usually not well fossilized. “An animal has only one body and it is not very likely to fossilize,” Merki said. In addition, you must be able to find it. “But the same animal continuously dumps large amounts of DNA into the environment throughout its life.”
Soil samples (dating from 30,000 to 5,000 years ago) showed that mammoths and horses probably existed in this polar environment much more than previously thought. DNA data show that mammoths and horses experienced severe population decline during the Pleistocene-Holocene transition period, but not all of them disappeared at once due to climate change or overhunting.
A study published in the October issue of the journal Nature found that some mammoths were isolated on islands far from human contact until 4,000 years ago. However, the new study is the first to reveal that small populations of mammoths lived alongside humans until the Holocene and as far back as 5,000 years ago in mainland North America. Hendrik Poinar, lead author and director of the Ancient DNA Center at McMaster University, said:
The extinction of the Great Lakes in this period has been largely attributed to two causes: the hunting of ancient humans and the climatic catastrophe. The new study shifts the focus from this long-standing two-dimensional debate in paleontology.
According to Poinar, the new study provides evidence that the extinction of the great North American species is more detailed. There is no doubt that the animals were under the pressure of human predators and rapid climate change, but the question is how much they were hunted and whether hunting was really a turning point that led to their extinction.
Analysis of ancient DNA from soil can give us a great deal of knowledge about ancient life, and the Arctic frozen soil is ideal for this type of ancient DNA study because it preserves the freezing of ancient DNA well. But that may not be possible forever: As Arctic ice melts as temperatures rise rapidly, much of life history information is lost. In fact, this information disappears before anyone has a chance to read it.
The study is published in the journal Nature Communications.