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Yohannes Haile-Selassie
Yohannes Haile-Selassie

Scientists Say They've Found a New Species of Human Ancestor

Yohannes Haile-Selassie
Yohannes Haile-Selassie

Lucy, our famous human ancestor who for decades held the title of the oldest most-complete ancient hominin ever found, may have had some surprising neighbors in Ethiopia more than 3.3 million years ago. New research contends that Lucy’s species, Australopithecus afarensis, wasn’t the only ancient human relative in the area.

Based on the discovery of teeth and jawbones from between 3.3 and 3.5 million years ago, Yohannes Haile-Selassie of Case Western Reserve University and the Cleveland Museum of Natural History and his fellow researchers describe a new hominin species called Australopithecus deyiremeda in a new paper in the journal Nature. (Hominins include humans and their extinct relatives.) The bones were found just 20 miles from where Lucy was discovered in Ethiopia in 1974. 

The researchers argue that the size and shape of the teeth found are different enough from previously discovered human ancestors—including A. afarensis and other proposed species like Kenyanthropus platyops (found in Kenya) and Australopithecus bahrelghazali (found in Chad)—to be classified as a new species. “There is now incontrovertible evidence to show that multiple hominins existed contemporaneously in eastern Africa during the Middle Pliocene,” they write. Only a few years ago, the same researchers found a hominin foot fossil that also suggested another species besides Lucy—one that would not have walked upright. 

Image Credit: Haile-Selassie et. al, Nature, 2015

However, the issue of how many species of hominins existed at this time is far from solved. As evolutionary anthropologist Fred Spoor writes in a Nature article accompanying the research, “the increasingly rich fossil record of the middle Pliocene provides plenty of opportunity for lively debate,” which is a polite way of saying that plenty of anthropologists will be ready to duke it out for the next few years over the coexistence of multiple hominin species during this era.

Whether or not different species of human ancestors (and just how many) were around in addition to Lucy’s A. afarensis has been debated since the 1980s, with some anthropologists arguing that the diversity between some of the fossils discovered is too great for them to be one species. However, it can be difficult to determine how many species may have existed, because the bones that have been discovered have been only fragments of skeletons. (Lucy's skeleton is only 40 percent complete.) It can be hard to figure out how a particular species may have walked, for instance, if scientists have not found hip and foot bones. 

“It doesn’t really make sense for these four fossils to be isolated there as the only record of this species, when there are hundreds of fossils from the same time period so nearby,” anthropologist John Hawks explained via email. “If Haile-Selassie is right, then our fossil collection should already include some of this species, and a lot of what others have written about the evolution of early hominins in this part of the world will fall apart.”

This finding "undeniably shows that there’s more diversity than we thought in the early branches of human evolution,” says Brian Richmond, curator of human origins in anthropology at the American Museum of Natural History. “Early human evolution is more complicated than we thought." 

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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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