New scientific discoveries indicate that humans arrived in the Americas at least 7. years earlier than it was previously estimated.
Research around the time when the American continent began to be populated from Asia on have raised deep debates for decades. Many researchers are skeptical of evidence for the human presence in North America far beyond 16 a thousand years ago.
Now, a team of scientists working in the state of New Mexico, in the southwestern US, has found human footprints that have been dated between 20 thousand and 21 thousand years ago.
This discovery has the potential to transform what is known and what is thought about when the continent was populated. It suggests the existence of large migrations that we know nothing about and raises the possibility that these populations may have gone extinct.
The footprints that led to this new timeline were formed in a soft mud on the shores of a lake that is now part of White Sands National Park.
To estimate the “age” of the footprints, the US Geological Survey team did carbon dating of sediment layers above and below the footprints found. And so they were able to determine the “age” of the footprints themselves.
Based on the sizes of these marks, scientists suspect that they are from teenagers or children who came and went, sometimes accompanied by a adult.
It is not clear to scientists what exactly these people were doing there, but possibly they were helping adults in a hunting modality that would be seen later in indigenous cultures in America. North. It is known as buffalo jumping and consists of leading wild animals to a cliff.
These animals “need to be cleaned and prepared for transport in a very short period of time”, explains paleontologist Sally Reynolds , researcher at the University of Bournemouth (United Kingdom). “I need to light the fires, separate the fat accurately.” Children and teenagers there may have helped the adults to collect water, firewood or other supplies.
‘Age’ of footprints
The dating of the discovery is central to the debate. This is because it is not the first time that some new evidence has been announced about the previous human presence in the Americas. But practically all of them end up being contested in some way.
In general, the debate revolves around the following: the stone tools found in an ancient site are in fact what they appear to be or if are they simply rocks broken by some natural process, such as falling off a cliff?
These possible artifacts are sometimes less obvious than spear points 12 thousand years that were exquisitely crafted and later found in North America. This leaves the door open to final disputes and conclusions.
“One of the reasons why there is so much debate is that there is a real lack of very solid and unambiguous data. That’s what we think is likely we now have (about the presence of humans on the continent almost 7. years earlier than previously thought)”, says Professor Matthew Bennett, first author of the Bournemouth University article, BBC News.
“Footprints are not like stone tools. A footprint is a footprint and not can be moved up and down .”
While the nature of the physical evidence here is more difficult to be dismissed or challenged like a spearhead, the researchers needed to ensure that the dating was literally watertight (completely closed to liquids) .
A potential complication pointed out by Science, the scientific publication in which the findings were published, in the early stages of the review of the discovery, was the “reservoir effect”. old carbon can sometimes be recycled in aqueous environments, interfering with radiocarbon results by making a site look older than it actually is.
The researchers, however, say they have investigated this possibility and they believe it is not significant here.
Tom Higham, professor and specialist in radiocarbon dating at the University of Vienna, said: “They did some checks on material dates near the footprint site and found that totally terrestrial samples ( coal) produced similar ages as the aquatic material that dated closer to the footprints.”
“They also argued, I think reasonably, that the lake must have been shallow at the time the people walked there, mitigating the impact of reservoir effects introduced by old carbon sources.”
According to Higham, the consistency of the results and the support of a different dating technique applied to the site of the discovery reaffirmed the validity of the results.
“I think that, taken together, this is a sequence of 20 thousand – a thousand years”, states Higham BBC News.
Disputes in early American archeology have a lot to do with the historical development of the scientific field.
During the second half of the century 20, a consensus emerged among North American archaeologists that the peoples belonging to the Clovis culture were the first to arrive in the Americas. .
These great hunters are believed to have crossed a land bridge over the Bering Strait, which connected Siberia to Alaska during the last ice age, when the sea level was very high. lower.
The name Clovis was that of a so-called archaeological site, discovered in 1939, also in New Mexico. At the site, chipped stone artifacts were found, dated 13, 4,000 years old. According to this theory, mainly defended by the American archeological community, the arrival would have occurred about 12 a thousand years ago. consensus consolidated, on the other hand discoveries of older human presences ended up being discarded as unreliable. This has even led some archaeologists to actually stop looking for signs of previous occupation.
But in the decade of 1939 this orthodoxy began to be called into question.
In the decade of 1970, solid evidence has emerged of a human presence 13, 5,000 years ago in Monte Verde, Chile.
And since the years 1970, other pre-Clovis sites have become widely accepted, such as the Buttermilk Creek Complex, with 14, 5,000 years old, in central Texas, and the Cooper’s Ferry site, with 16 thousand years old, in Idaho. Both in the United States.
Now, the footprints of New Mexico suggest that humans had reached the interior r from North America at the height of the last Ice Age.
Gary Haynes, professor emeritus at the University of Nevada, said “he couldn’t find fault with the work that was done or the interpretations of it. article, which is important and provocative.”
“The trails are so far south of Bering’s terrestrial connection that we now have to ask ourselves (1) whether the people or their ancestors (or other people) ) made the crossing from Asia to the Americas much earlier, (2) whether people moved quickly across continents after each crossing, and (3) whether they left any descendants.”
Andrea Manica, a geneticist at the University of Cambridge, said the discovery about the footprints in New Mexico would have important implications for the history of the population of the Americas.
“I cannot comment on how reliable the dating, because it’s out of my specialty, but solid evidence of humans in North America for 20 a thousand years ago is at odds with genetics, which shows there is clearly a division of Native Americans from Asians into approximately 20 thousand to 16 a thousand years ago,” said BBC News.
“This suggests that America’s first settlers were replaced when the ice corridor formed and another wave of settlers entered. But we have no idea how that would have actually happened.”