Wednesday , April 21 2021

Researchers Examine How Dogs Arrived in the Americas | State and Regional



URBAN – Your poodle may have a French pedigree, but Siberia played an important role in introducing dogs to the Americas.

This is part of research conducted at the University of Illinois and the Illinois State Archaeological Survey, based on dog remains, including two dogs buried on their backs in an Illinois location across the Mississippi River from St. Louis.

That loving and ceremonial burial and about 50 fossilized dogs help tell the story, according to The News-Gazette.

This genetic code tells us not just about dogs, but about humans who crossed a land bridge that existed between Siberia and Alaska, said Ripan Malhi, a professor of anthropology and the School of Integrative Biology.

The Archaeological Survey of the State of Illinois had found several locations with dogs in them.

Not wanting to destroy valuable scientific and cultural relics, Malhi's team collected samples of domesticated dogs that may be almost 10,000 years old, probably the oldest in America.

"The amount removed is about the size of a (dental) cavity," he said.

Malhi worked closely with Kelsey Witt Dillon, who led the work of the mitochondrial DNA genome, following the maternal line of dogs as a graduate student here. (She is now a postdoctoral researcher at the University of California-Merced.)

In a clean room – not a trace of contaminants – the researchers extracted the DNA. It was then sequenced in another laboratory to create a "genomic library".

"DNA will give us millions of bits of DNA," Malhi said, some of them long contaminated by microbes or even human interference.

These first dogs in the Americas arrived from Siberia, Malhi said, and largely disappeared after European contact, an extreme version of the population decline with the Native Americans after contact.

During the Ice Age (which lasted about 14,500 years ago), sea levels were lower and the region between western and eastern Siberia was the entire land, rather than the Bering Strait that we know today. The region is known as "Beringia" and people (and dogs) managed to cross the land bridge because of the lower sea level, added Witt Dillon.

Scientists debate how native dogs have generally fallen from genetic patrimony: our ancestors may have killed them to prevent interbreeding with the dogs they have already raised for hunting and herding, or they could have been eaten in times of famine.

Illness is the most common cause, since the same thing happened to Native Americans.

In the journal Science, the researchers argued that the first dogs in the Americas were not domesticated as American wolves.

Most likely, they wrote, the dogs followed fellow humans by a land bridge that once connected northern Asia through Siberia to the Americas.

At an archaeological site near Cahokia called Janey B. Goode, other researchers found dogs with marks on their shoulders.

Malhi said the brands could mean that dogs were not only our best friends but our co-workers helping to pull carts for supplies or else other work similar to their continuous use with sleds in the Northwest.

Malhi's specialty is to trace the genetic history, so that his articles have titles like "Distribution of Y chromosomes among Native Americans: a study of the history of the population of Athapaskan."

He worked closely with the First Nations peoples in British Columbia and Alaska, including studying an invaluable food resource, salmon.

Nuclear DNA and mitochondrial DNA tell stories in different ways.

Nuclear DNA is the kind of DNA that most people probably think – its 23 pairs of chromosomes are all nuclear DNA, and you inherit half of them from your mother and half of them from your father, "explained Witt Dillon.

"Her mitochondrial DNA is inherited from her mother," she said, "and it is found in many more copies per cell than its nuclear DNA, so it is easier to find in old DNA samples that are usually degraded and fragmented" .

There are questions about when and where dogs were domesticated.

"Dogs were probably domesticated between 15,000 and 21,000 years ago, somewhere in Europe or Asia," said Witt Dillon. "Europe, the Middle East, Southeast Asia and Central Asia have been suggested as places of origin for dogs, but we still do not have a clear answer."

Possibly the dogs appeared in several places "of birth".

By the way, that shit that ends with every dog ​​walking? A pain for you, but of great value to science as fossilized coprolites.

UI anthropology student, Karthik Yarlagadda, is analyzing the microbiomas of the coprolites, working with Malhi.

In modern studies, he knows, tested samples contain a large number of microbes that reflect various factors, including genetics, diet and host environment.

"Because coprolytes represent an ancient fecal sample, they probably still contain some residual DNA from the microbes living in dogs at that time. This is particularly interesting because ancient microbiomes give us an additional view of an individual's life history." Yarlagadda said.


Source link