Oldest Homo sapiens bones ever found shake foundations of the human story | Science | The Guardian
Researchers have dated the oldest known human fossil in Western of two new techniques that bypassed the limitations of carbon dating. Researchers were unable to use carbon-dating on the fossil have been confirmed as the oldest known species of human fossil ever found in. Earliest modern human fossil found outside Africa has been dated to Radioactive dating places the fossil and tools at between , and.
The researchers also had to check that the fossil had uniform levels of uranium and that none of the uranium has leached into the ground.
Ancient Bones Spark Fresh Debate over First Humans in the Americas - Scientific American
This is the same technique used to date larger mammals, although it was refined to keep it from damaging the skeleton. Who Is The Homo Antecessor? Early genetic studies at the Max-Planck Institute of Evolutionary Anthropology claimed that modern-day humans split off from the Neanderthalsyears ago.
However, the findings made by Duval's team means the split must have happened earlier, estimated aroundtoyears ago. As the original ancestor to the homo sapiens, the homo antecessor displayed a combination of primitive and modern characteristics. An average male homo antecessor stood around 5. His brain was significantly smaller than the modern brain at 1, to 1, cc, which is marked by a low forehead and an occipital bun protruding from the back of his skull.
His projecting nose and hollowed out cheekbones are decidedly modern, as well as the depression in his canine fossa, or the canine teeth. The homo antecessor was right-handed, which is a peculiar trait among early hominins. They likely lived in groups, moving from place to place to follow their food, and shared a symbolic language. Paleontologists excavated the remains in the early s from a site in San Diego County that was discovered during the course of highway improvements to State Route The researchers recovered bones of a number of different ice age species from different stratigraphic levels in the site.
For the new study, Steven Holen of the San Diego Natural History Museum and his colleagues focused on the partial skeleton of a male mastodon found in this location, dubbed the Cerutti Mastodon site for its discoverer, study co-author Richard Cerutti, also at the museum.
Such fractures typically occur when force is applied to fresh bone. The ends of some of the bones were also broken off, and several large, battered stone cobbles lay nearby.
When the team experimentally broke bones from the carcasses of large modern-day mammals using hammerstones and anvils, the resulting damage resembled that seen on the bones and stone cobbles from site. Together, the pattern of damage evident on the bones and stones, and the proximity of the rocks to the bones suggest to the team humans were pounding the bones with the rocks to get to the nutritious marrow inside or to make bone tools.
None of that would be remarkable in and of itself. Such behaviors have been well documented at archaeological sites around the world.
What makes the discovery a big deal is the supposed age of the remains. The team determined the age of the mastodon bones by applying a technique called uranium series dating, which uses the radioactive decay of uranium to measure the passage of time.
The results indicated the bones areyears old, give or take 9, years—more thanyears older than the oldest commonly accepted archaeological sites in the Americas.
Today the Cerutti Mastodon site sits in the middle of an urban setting. Butyears ago during the last interglacial period it was a meandering stream in a flood plain near the coastline.
Camels, dire wolves and capybara roamed there. If Holen and his colleagues are correct about the age and nature of the finds, researchers will need to rethink everything they thought they knew about the peopling of the New World, including which human species was the first to colonize it.
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Most researchers agree humans came to the Americas from northeastern Asia. Atyears ago, the authors argue, H. They could have crossed Beringia on foot prior toyears ago, when sea levels were sufficiently low.
List of first human settlements
Otherwise, they could have traveled by boat, following the coasts of Asia, Beringia and North America to reach the latitude of the Cerutti Mastodon site. During the press teleconference Holen said the new find should encourage other archaeologists to go out and look for more sites of this age—something he says they had not done previously because no one expected humans to be in the Americas so early.
Were pieces found 15 feet apart or 15 centimeters apart? Such information is important for reconstructing how the bones broke and what, if any, relationship existed between the bones and the rocks.
Although the researchers were able to experimentally reproduce the damage on the remains by processing fresh bone with stone tools, critics observe, the team did not rule out alternative causes. It is quite another to show that people, and people alone, could have produced those modifications.
Other commenters explained the team needs to look at many more fossil assemblages of large mammal bones, to see if natural causes could explain the breakage patterns evident in at the Cerutti Mastodon site.