DNA reveals clues to the Siberian ancestors of the first Americans | Science News for Students

DNA reveals clues to the Siberian ancestors of the first Americans

Previously unknown Ice Age travelers crossed a land bridge from Russia into North America
Jul 10, 2019 — 6:45 am EST
a photo of a researcher at a Russian excavation site
DNA from teeth unearthed at this Russian site came from a population of people who migrated to Siberia around 38,000 years ago.

Elena Pavlova

New findings offer a clearer picture of the ancestors of modern Siberians — and Native Americans. They come from groups that lived long ago in Asia. Some of their members mixed and then later spread into North America.

Three distinct groups of people migrated to Siberia. During the later Ice Age, some of them migrated into North America.That’s the finding of a new study. Clues to those migrations can be seen today in the genes of Siberians and Native Americans.

The story of these peoples is complex. Each incoming group largely replaced people already living in an area. But some mating between the newcomers and old-timers also took place, notes study leader Martin Sikora. An evolutionary geneticist, he works at the University of Copenhagen in Denmark.

His team’s findings appeared online June 5 in Nature.

Sikora’s group analyzed DNA from 34 people. All had been buried between 31,600 and 600 years ago in Siberia, in East Asia or in Finland. Sikora’s group compared their DNA with DNA collected earlier from very ancient and modern people who had lived across Europe, Asia and North America.

Two teeth proved important. They had been dug up at a Russian site. Known as Yana Rhinoceros Horn. This site was some 31,600 years old. The teeth there came from an unknown group of people. The researchers named this population the Ancient North Siberians. Around 38,000 years ago, these people migrated to Siberia from Europe and Asia. They adapted quickly to the region’s frigid Ice Age conditions, the team reports.

a photo of 31,600-year-old fossil teeth
DNA from two 31,600-year-old teeth (two views of each tooth shown) in Russia helped identify a group of Siberians who trekked into North America.
Russian Academy of Sciences

Some 30,000 years ago, ancient North Siberians traveled onto a land bridge. It linked Asia and North America. There, these people mated with East Asians who also had moved to the land bridge. Their mixing created another genetically distinct group. The researchers named them the Ancient Palaeo-Siberians.

Over the next 10,000 years the climate warmed. It also became less harsh. At this point, some of the Ancient Palaeo-Siberians returned to Siberia. There, they slowly replaced the Yana people.

Other Ancient Palaeo-Siberians trekked from the land bridge into North America. Over time, rising waters swamped the land bridge. Later, between 11,000 and 4,000 years ago, some of their relatives returned to Siberia by sea. They became the ancestors to many of today’s Siberians.

A nearly 10,000-year-old Siberian man held the key to linking all these groups. His DNA helped identify genetic similarities between Ancient Palaeo-Siberians and modern peoples.

Power Words

(more about Power Words)

climate     The weather conditions that typically exist in one area, in general, or over a long period.

DNA     (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. It is built on a backbone of phosphorus, oxygen, and carbon atoms. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

evolutionary     An adjective that refers to changes that occur within a species over time as it adapts to its environment. Such evolutionary changes usually reflect genetic variation and natural selection, which leave a new type of organism better suited for its environment than its ancestors. The newer type is not necessarily more “advanced,” just better adapted to the conditions in which it developed.

gene     (adj. genetic) A segment of DNA that codes, or holds instructions, for a cell’s production of a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.

ice age     Earth has experienced at least five major ice ages, which are prolonged periods of unusually cold weather experienced by much of the planet. During that time, which can last hundreds to thousands of years, glaciers and ice sheets expand in size and depth. The most recent ice age peaked 21,500 years ago, but continued until about 13,000 years ago.

land bridge     A narrow region of land linking two large masses of land. In prehistoric times, a major land bridge connected Asia and North America across the Bering Strait. Scientists believe early humans and other animals used it to migrate between the continents.

migration     (v. migrate) Movement from one region or habitat to another, especially regularly (and according to the seasons) or to cope with some driving force (such as climate or war). An individual that makes this move is known as a migrant.

native     Associated with a particular location; native plants and animals have been found in a particular location since recorded history began.

Native Americans     Tribal peoples that settled North America. In the United States, they are also known as Indians. In Canada they tend to be referred to as First Nations.

online     (n.) On the internet. (adj.) A term for what can be found or accessed on the internet.

population     (in biology) A group of individuals from the same species that lives in the same area.

sea     An ocean (or region that is part of an ocean). Unlike lakes and streams, seawater — or ocean water — is salty.

Siberia     A region in northern Asia, almost all of which falls within Russia. This land takes its name from the language of the Tatar people, where Siber means sleeping land. This region is vast. It has become famous for its long, harsh winters, where temperatures can fall to −68° Celsius (−90° Fahrenheit).

Citation

Journal: M. Sikora et al. The population history of northeastern Siberia since the Pleistocene. Nature. Vol. 570, June 5, 2019, p. 182. doi: 10.1038/s41586-019-1279-z.