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Thomas Henley Huxley via Wikimedia Commons // CC BY 4.0
Thomas Henley Huxley via Wikimedia Commons // CC BY 4.0

We May Have Split from Our Ape Relatives 2 Million Years Earlier Than Thought

Thomas Henley Huxley via Wikimedia Commons // CC BY 4.0
Thomas Henley Huxley via Wikimedia Commons // CC BY 4.0

Researchers say the evolutionary split between humans and other apes may have happened 2 million years earlier than previously believed. The findings were published in the journal Nature.

The timing and location of specific events in primate evolution are the subject of some debate among scientists. Many believe that the great apes (including humans) first evolved in Eurasia, a belief supported by the scarcity of great ape fossils found in Africa. But in the last few decades, other researchers have found Ethiopia’s Chorora Formation to be a rich source of fossilized primate remains—including those of Chororapithecus abyssinicus, an early gorilla ancestor. 

The authors of the current study say the presence of C. abyssinicus in Africa proves that human and gorilla lineages must have split there. They also say the age of the C. abyssinicus fossils prove that the split must have happened much earlier than was previously believed.

These conclusions are drawn from analysis of the rock and sediment surrounding nine fossilized C. abyssinicus teeth. One technique called lithostratigraphy examined the order and placement of layers in the rock to estimate how old they were. The team used chemical fingerprinting and Argon dating (a process similar to carbon dating), as well as magnetostratigraphy, which measures how rock samples respond to magnetic fields. The results of all these tests marked the teeth as about 8 million years old, suggesting that gorillas are a more recent development than scientists had previously thought.

Gen Suwa

"Our new research supports early divergence: 10 million years ago for the human-gorilla split and 8 million years ago for our split from chimpanzees," study co-author Giday WoldeGabriel said in a press release. "That's at least 2 million years earlier than previous estimates, which were based on genetic science that lacked fossil evidence."

While impressive, these conclusions are still pretty speculative. Remains from another early primate ancestor, Nakalipithecus nakayamai, were also found in Africa, but scientists aren’t sure where in the family tree to put them. At about 9.8 million years old, N. nakayamai may be a common ancestor of humans and other apes, but it might also be a very early gorilla. If it’s the latter, then gorillas must have been around 9.8 million years ago. If it’s the former, the split was more recent, around 8 million years ago. 

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AFP, Stringer, Getty Images
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Stones, Bones, and Wrecks
The Most Complete Fossil of an Early Human Relative Goes on Display
AFP, Stringer, Getty Images
AFP, Stringer, Getty Images

Twenty years after it was discovered in an African cave, one of the most important fossils in the quest to demystify human evolution is finally on display. As Smithsonian reports, Little Foot, an Australopithecus specimen dating back more than 3 million years, was revealed to the public this month at the Hominin Vault at the University of the Witwatersrand’s Evolutionary Studies Institute in Johannesburg, South Africa.

Paleontologist Ron Clarke discovered the first bone fragments from the fossil in 1994. The pieces came from the remains of a young female’s feet, hence the nickname. Clarke and his team spent years excavating Little Foot bit by bit from the Sterkfontein cave system in South Africa until the bones were fully removed in 2012. The shattered remains had been embedded in a concrete-like material called breccia, making them incredibly tricky to recover. But the sum of the parts is monumental: Little Foot is the most complete Austrolopithecus fossil known to science.

The hominid genus Austrolopithecus played an essential early role in the chain of human evolution. Lucy, another famous hominid fossil, is a member of the same genus, but while Lucy is only 40 percent complete, Little Foot retains 90 percent of her skeleton, including her head. It’s also possible that Little Foot surpasses Lucy in age. Most paleontologists agree that Lucy lived about 3.2 million years ago, while one analysis places Little Foot’s age at 3.67 million years.

Austrolopithecus is believed to have spawned Homo, the genus that would eventually contain our species. The discovery of Lucy and other fossils have led scientists to designate East Africa as the cradle of human evolution, but if Little Foot is really as old as tests suggest, then South Africa may deserve a more prominent point in the timeline.

Following Little Foot’s public debut, the team that’s been studying her plans to release a number of papers exploring the many questions her discovery raises.

[h/t Smithsonian]

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Mark Golitko
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Stones, Bones, and Wrecks
6000-Year-Old Skull Might Belong to World's Oldest Tsunami Victim
Scientists speak to residents in Aitape.
Scientists speak to residents in Aitape.
Mark Golitko

Tsunamis and other natural disasters have taken a deadly toll on human populations for millennia, and now we may have the oldest example of that truth yet. An international team of anthropologists and environmental researchers recently analyzed a cracked skull that belonged to a person who likely died in a tsunami some 6000 years ago. They detail their find in a new study published in PLOS One.

The partial skull in question, known as the Aitape skull, was found in Papua New Guinea in 1929 during a geological survey by an Australian scientist named Paul Hossfield. It has since been dated to the mid-Holocene epoch, or around 6000 years ago.

For the current study, the scientists returned to the site of the 1929 discovery to sample and analyze the sediment there to find out more about what might have killed the person millennia ago. They had only Hossfield's basic field descriptions to go on, but University of Notre Dame anthropologist Mark Golitko, one of the study’s authors, says that based on those descriptions, they think they were able to sample within 100 yards or so of the skull's original location.

The top of a brown cracked skull against a pink background
Arthur Durband

Based on the grain size, chemical signature, and marine microalgae found within the sediment samples, they were able to determine that around the time that the skull was buried, the area was inundated with water, probably from a tsunami. At that time, the site, located near the present-day town of Aitape, would have been just along the shoreline. Aitape was also the site of a devastating tsunami in 1998, and the Holocene sediments resembled the ones associated with that disaster.

It's possible that the skull was buried before the tsunami hit, and the grave was ripped apart by the waters and the rest of the bones scattered. However, during the powerful 1998 tsunami that killed more than 2100 people in Papua New Guinea, bodies buried in modern cemeteries were not uprooted even as the sediment above them washed away, making it more likely that the ancient skull belonged to someone killed in the disaster.

The new analysis has "made us realize that human populations in this area have been affected by these massive inundations for thousands of years," study co-author James Goff of the University of New South Wales said in a press statement. "Given the evidence we have in hand, we are more convinced than before that this person was either violently killed by a tsunami, or had their grave ripped open by one."

Field Museum anthropologist John Terrell, another co-author of the study, said, "If we are right about how this person had died thousands of years ago, we have dramatic proof that living by the sea isn't always a life of beautiful golden sunsets and great surfing conditions."

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