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Yohannes Haile-Selassie

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

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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." 

6 Pioneering Facts About Mary Leakey

Fossil bones and the earliest footprints of our human ancestors are just a few of Mary Leakey’s groundbreaking discoveries. Get to know the legendary paleoanthropologist, and learn how her serendipitous finds forever altered scientists’ understanding of human origins.


Mary Leakey (1913-1996), née Mary Nicol, was destined to be an explorer: Her father, Erskine Nicol, was a landscape painter, and the family traveled extensively through France, Italy, and Switzerland. While staying in a commune in southern France, 12-year-old Mary became interested in archaeology after meeting Elie Peyrony, a French prehistorian excavating a cave. Mary dug through his tiny finds—which included fine points, scrapers, and flint blades—and sorted them into an amateur classification system.


Leakey’s parents were artists, but hunting for fossils was part of her heritage: Her maternal great-great-grandfather was John Frere, an 18th-century English government official and antiquarian who’s credited with first recognizing Stone Age flint objects as early weapons and tools.


Leakey was intelligent, but she also had a rebellious streak. As a teen, she was expelled from several Roman Catholic convent schools—once for intentionally creating an explosion in a chemistry lab. Figuring she wasn’t cut out for a classroom, Leakey never finished high school, and decided to pursue independent studies in art, geology, and archaeology at the University of London instead. (“I had never passed a single school exam, and clearly never would,” the scientist later wrote in her 1986 autobiography Disclosing the Past.)


Mary Leakey—who inherited her father’s artistic skills— ended up working as an illustrator for archaeological digs. An archaeologist introduced her to Cambridge University paleontologist Louis Leakey, who needed an illustrator for his book Adam’s Ancestors (1934). The two became lovers, but their union resulted in scandal, as Leakey was still married at the time. The couple married in 1936, after Leakey divorced his first wife.


Mary Leakey's first major discovery came in 1948 when she found a fossil skull fragment of Proconsul africanus, an ancestor of apes and humans, which later diverged into two separate species. The fossil was thought to be more than 18 million years old.


In 1978, Leakey was on an expedition in Laetoli, in Tanzania, when members of her camp engaged in a spirited elephant dung fight. A scientist fell down, and he noticed strange indentations on the ground that had been recently exposed by erosion. They turned out to be tracks made around 3.7 million years prior, from animals that had walked over damp volcanic ash. Examining these prints took several years, but the team's efforts paid off when Leakey noted that one of the prints seemed to be made by a hominin. This discovery showed that early humans began walking upright long before scientists thought they had.

Additional source: Ancestral Passions: The Leakey Family and the Quest for Humankind's Beginnings, Virginia Morell

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Wikimedia Commons // Public Domain
Stones, Bones, and Wrecks
Researchers Unveil an Unusual New Theory For How Easter Island’s Statues Were Made
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Wikimedia Commons // Public Domain

The Moai statues of Easter Island present one of the world's greatest technical mysteries. The stone heads (actually full bodies) that dot the island in the South Pacific are massive and number in the hundreds, prompting archaeologists to wonder how they got there in the first place. Now, as Newsweek reports, a group of researchers believe they're closer to finding an answer.

European sailors first arrived on Easter Island in 1722 and were greeted by a native population of 1500 to 3000. Along with the residents were 900-odd statues carved from solid rock, meaning there were fewer than four people for every massive monolith.

How was such a thin population able pull off such an impressive feat of architecture? According to researchers from Chile, New Zealand, and the U.S., it's possible they had help. Their new study published in the journal Frontiers in Ecology and Evolution suggests that the statues were carved and erected at a time when Easter Island supported a much larger population. Using data from the island, they estimated just how high the island's numbers may have reached.

Easter Island has the agriculture potential to sustain a maximum population of 17,500, researchers say. This estimate is based on the weather and soil quality of the island, 19 percent of which is capable of growing the sweet potatoes that fed inhabitants. "Despite its almost complete isolation, the inhabitants of Easter Island created a complicated social structure and these amazing works of art before a dramatic change occurred," lead author Cedric Puleston said in a statement.

If the Moai were constructed by a much larger group than the Europeans encountered, that would clear up some of the mystery surrounding the island. But it would also raise more questions. How, for instance, did the population fall so quickly in the few centuries between the statues' construction and first contact with Europeans? One theory is ecocide, which happens when an area is exhausted of its resources faster than it can replenish them.

The mystery of how the towering monoliths were transported across the island after they were built still remains. The indigenous people told Dutch explorers that the Moai walked themselves, an explanation an MIT professor put to the test when he designed a 2000-pound sculpture that could be shimmied long distances. But despite the numerous theories, hard evidence related to the figures' origins remains scarce.

[h/t Newsweek]


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