How and when did humans get to North America? It is arguably one of the most hotly debated topics in archaeology. There have been many theories and studies over the years, and a recent study suggests that sea ice may have played a role in one way for people to move farther south.&nbsp;

Traditionally, scientists have believed that around 13,000 years ago, Stone Age hunters made their way across a land bridge between eastern Siberia and western Alaska and eventually walked their way to an ice-free corridor that briefly opened between ice sheets during this time.&nbsp;

However, recent findings, including human footprints in New Mexico which date back to 23,000 years have once again reignited the debate since the discoveries suggest that people made their way onto the continent much earlier.

<h2>What does the recent study propose?</h2>

Research presented on December 15 at the American Geophysical Union Annual Meeting (AGU23) suggests that sea ice may have been one way for people to move thousands of years ago.&nbsp;

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While the idea that early Americans may have travelled along the Pacific Coast isn’t new, the conditions were not exactly favourable. In 2020, researchers noted that freshwater from melting glaciers at the time may have created a strong current which would make it difficult for people to travel along the coast.

In line with this, Summer Praetorius the United States Geological Survey (USGS) and her team tried to study climate proxies in ocean sediment from the coast. Archaeologists have previously found evidence of coastal settlements as early as 14,000 years ago.&nbsp;

Although most of the data for Praetorius’ study came from tiny, fossilised plankton, researchers also used climate models to check ocean currents at the time. The abundance and chemistry of these organisms helped scientists reconstruct ocean temperatures, salinity, and sea ice cover.

<h2>What did they find?</h2>

Praetorious’ team found that ocean currents were twice the strength they are today at the height of the last glacial maximum around 20,000 years ago due to glacial winds and lower sea levels, conditions which would have made travelling by boat nearly impossible.&nbsp;

ALSO READ |&nbsp;<a href="https://www.wionews.com/science/iss-astronaut-snaps-photos-of-icebergs-a-reminder-of-climate-change-670133">ISS astronaut snaps photos of icebergs - a reminder of climate change</a>

Therefore, Praetorius suggests that since&nbsp;people back then who were adapted to the cold, would “rather than having to paddle against this horrible glacial current, maybe they were using the sea ice as a platform.” Similar to how people living in the Arctic travel along sea ice on dog sleds and snowmobiles.&nbsp;

Early Americans could have used the ‘sea ice highway’ to get around and hunt marine mammals, slowly making their way into North America in the process, said Praetorius.&nbsp;

While proving this will be difficult given that most of the archaeological sites are underwater, the recently proposed theory does provide a new framework.&nbsp;

The USGS scientist also noted that the sea ice highway isn’t mutually exclusive with other human migrations which took place later since their models show the Alaskan current had calmed down by 14,000 years ago, making it easier for people to travel by boat along the coast.

(With inputs from agencies)

How and when did humans get to North America? It is arguably one of the most hotly debated topics in archaeology. There have been many theories and studies over the years, and a recent study suggests that sea ice may have played a role in one way for people to move farther south.

How and when did humans get to North America? It is arguably one of the most hotly debated topics in archaeology. There have been many theories and studies over the years, and a recent study suggests that sea ice may have played a role in one way for people to move farther south. Traditionally, scientists have believed that around 13,000 years ago, Stone Age hunters made their way across a land bridge between eastern Siberia and western Alaska and eventually walked their way to an ice-free corridor that briefly opened between ice sheets during this time. However, recent findings, including human footprints in New Mexico which date back to 23,000 years have once again reignited the debate since the discoveries suggest that people made their way onto the continent much earlier. What does the recent study propose? Research presented on December 15 at the American Geophysical Union Annual Meeting (AGU23) suggests that sea ice may have been one way for people to move thousands of years ago. ALSO READ | NASA’s tiny telescope discovers seven hot Jupiters millions of light-years away While the idea that early Americans may have travelled along the Pacific Coast isn’t new, the conditions were not exactly favourable. In 2020, researchers noted that freshwater from melting glaciers at the time may have created a strong current which would make it difficult for people to travel along the coast. In line with this, Summer Praetorius the United States Geological Survey (USGS) and her team tried to study climate proxies in ocean sediment from the coast. Archaeologists have previously found evidence of coastal settlements as early as 14,000 years ago. Although most of the data for Praetorius’ study came from tiny, fossilised plankton, researchers also used climate models to check ocean currents at the time. The abundance and chemistry of these organisms helped scientists reconstruct ocean temperatures, salinity, and sea ice cover. What did they find? Praetorious’ team found that ocean currents were twice the strength they are today at the height of the last glacial maximum around 20,000 years ago due to glacial winds and lower sea levels, conditions which would have made travelling by boat nearly impossible. ALSO READ | ISS astronaut snaps photos of icebergs - a reminder of climate change Therefore, Praetorius suggests that since people back then who were adapted to the cold, would “rather than having to paddle against this horrible glacial current, maybe they were using the sea ice as a platform.” Similar to how people living in the Arctic travel along sea ice on dog sleds and snowmobiles. Early Americans could have used the ‘sea ice highway’ to get around and hunt marine mammals, slowly making their way into North America in the process, said Praetorius. While proving this will be difficult given that most of the archaeological sites are underwater, the recently proposed theory does provide a new framework. The USGS scientist also noted that the sea ice highway isn’t mutually exclusive with other human migrations which took place later since their models show the Alaskan current had calmed down by 14,000 years ago, making it easier for people to travel by boat along the coast. (With inputs from agencies)

Study suggests first people reached North America via ‘sea ice highway’ around 24,000 years ago

Genetic sequencing of human remains dating back 45,000 years has revealed a previously unknown migration into Europe and showed intermixing with Neanderthals in that period was more common than previously thought.

The research is based on the analysis of several ancient human remains,&nbsp;including a whole tooth and bone fragments, found in a cave in Bulgaria last year.

Genetic sequencing found the remains came from individuals who were more closely linked to present-day populations in East Asia and the Americas than populations in Europe.

<div class="videoWrapper trancodeVideo"><iframe allowfullscreen="" autoplay="1" class="includeVideo" frameborder="0" height="350" src="https://www.wionews.com/videos/neanderthals-disappeared-earlier-than-previously-thought-369570/embed" style="width:100%;max-width:560px;" width="560"></iframe></div>

"This indicates that they belonged to a modern human migration into Europe that was not previously known from the genetic record," the research, published Wednesday in the journal Nature, said.

It also "provides evidence that there was at least some continuity between the earliest modern humans in Europe and later people in Eurasia", the study added.

The findings "shifted our previous understanding of early human migrations into Europe", said Mateja Hajdinjak, an associate researcher at Germany's Max Planck Institute for Evolutionary Anthropology who helped lead the research.

"It showed how even the earliest history of modern Europeans in Europe may have been tumultuous and involved population replacements," she said.

One possibility raised by the findings is "a dispersal of human groups that then get replaced (by other groups) later on in West Eurasia, but continue living and contribute ancestry to the people in East Eurasia", she added.

The remains were discovered last year in the Bacho Kiro cave in Bulgaria and were hailed at the time as evidence that humans lived alongside Neanderthals in Europe significantly earlier than once thought.

Genetic analysis also revealed that modern humans in Europe at that time mixed more with Neanderthals than was previously assumed.

All the "Bacho Kiro cave individuals have Neanderthal ancestors five-seven generations before they lived, suggesting that the admixture (mixing) between these first humans in Europe and Neanderthals was common," said Hajdinjak.

Previous evidence for early human-Neanderthal mixing in Europe came from a single individual called the Oase 1, dating back 40,000 years and found in Romania.

"Until now, we could not exclude it being a chance find," Hajdinjak said.

"Our study suggests... (it) must have been common."

Human history 'lost in time'

The findings were accompanied by separate research published Wednesday in the journal Nature Ecology and Evolution involving genome sequencing of samples from a skull found in the Czech Republic.

The skull was found in the Zlaty kun area in 1950, but its age has been the subject of debate and contradictory findings in the decades since.

Initial analysis suggested it was older than 30,000 years old, but radiocarbon dating gave an age closer to 15,000 years.

Genetic analysis now appears to have resolved the matter, suggesting an age of at least 45,000 years old, said Kay Prufer of the Max Planck Institute's department of archaeogenetics, who led the research.

"We make use of the fact that everyone who traces their ancestry back to the individuals that left Africa more than 50,000 years ago carries a bit of Neanderthal ancestry in their genomes," he said.

These Neanderthal traces appear in short blocks in modern human genomes, and increasingly longer ones further back in human history.

"In older individuals, such as the 45,000-year-old Ust'-Ishim man from Siberia, these blocks are much longer," Prufer said.

"We find that the genome of the Zlaty kun woman has even longer blocks than those of the Ust'-Ishim man. This makes us confident that she lived at the same time, or even earlier."

Despite dating from around the same period as the Bacho Kiro remains, the Zlaty kun skull does not share genetic links to either modern Asian or European populations.

Prufer now hopes to study how the populations that produced the two sets of remains were related.

"We do not know who the first Europeans were that ventured into an unknown land," he said.

"By analysing their genomes, we are figuring out a part of our own history that has been lost in time."

(With inputs from agencies)

Genetic sequencing of human remains dating back 45,000 years has revealed a previously unknown migration into Europe and showed intermixing with Neanderthals in that period was more common than previously thought.

Genetic sequencing of human remains dating back 45,000 years has revealed a previously unknown migration into Europe and showed intermixing with Neanderthals in that period was more common than previously thought. The research is based on the analysis of several ancient human remains, including a whole tooth and bone fragments, found in a cave in Bulgaria last year. Genetic sequencing found the remains came from individuals who were more closely linked to present-day populations in East Asia and the Americas than populations in Europe. "This indicates that they belonged to a modern human migration into Europe that was not previously known from the genetic record," the research, published Wednesday in the journal Nature, said. It also "provides evidence that there was at least some continuity between the earliest modern humans in Europe and later people in Eurasia", the study added. The findings "shifted our previous understanding of early human migrations into Europe", said Mateja Hajdinjak, an associate researcher at Germany's Max Planck Institute for Evolutionary Anthropology who helped lead the research. "It showed how even the earliest history of modern Europeans in Europe may have been tumultuous and involved population replacements," she said. One possibility raised by the findings is "a dispersal of human groups that then get replaced (by other groups) later on in West Eurasia, but continue living and contribute ancestry to the people in East Eurasia", she added. The remains were discovered last year in the Bacho Kiro cave in Bulgaria and were hailed at the time as evidence that humans lived alongside Neanderthals in Europe significantly earlier than once thought. Genetic analysis also revealed that modern humans in Europe at that time mixed more with Neanderthals than was previously assumed. All the "Bacho Kiro cave individuals have Neanderthal ancestors five-seven generations before they lived, suggesting that the admixture (mixing) between these first humans in Europe and Neanderthals was common," said Hajdinjak. Previous evidence for early human-Neanderthal mixing in Europe came from a single individual called the Oase 1, dating back 40,000 years and found in Romania. "Until now, we could not exclude it being a chance find," Hajdinjak said. "Our study suggests... (it) must have been common." Human history 'lost in time' The findings were accompanied by separate research published Wednesday in the journal Nature Ecology and Evolution involving genome sequencing of samples from a skull found in the Czech Republic. The skull was found in the Zlaty kun area in 1950, but its age has been the subject of debate and contradictory findings in the decades since. Initial analysis suggested it was older than 30,000 years old, but radiocarbon dating gave an age closer to 15,000 years. Genetic analysis now appears to have resolved the matter, suggesting an age of at least 45,000 years old, said Kay Prufer of the Max Planck Institute's department of archaeogenetics, who led the research. "We make use of the fact that everyone who traces their ancestry back to the individuals that left Africa more than 50,000 years ago carries a bit of Neanderthal ancestry in their genomes," he said. These Neanderthal traces appear in short blocks in modern human genomes, and increasingly longer ones further back in human history. "In older individuals, such as the 45,000-year-old Ust'-Ishim man from Siberia, these blocks are much longer," Prufer said. "We find that the genome of the Zlaty kun woman has even longer blocks than those of the Ust'-Ishim man. This makes us confident that she lived at the same time, or even earlier." Despite dating from around the same period as the Bacho Kiro remains, the Zlaty kun skull does not share genetic links to either modern Asian or European populations. Prufer now hopes to study how the populations that produced the two sets of remains were related. "We do not know who the first Europeans were that ventured into an unknown land," he said. "By analysing their genomes, we are figuring out a part of our own history that has been lost in time." (With inputs from agencies)

Gene sequencing of human remains reveals ancient migration in Europe unknown till now

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Study suggests first people reached North America via ‘sea ice highway’ around 24,000 years ago

Gene sequencing of human remains reveals ancient migration in Europe unknown till now