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Nature

Bones Of A Mysterious Hominin Child Shed Light On How Our Extinct Relatives Grew Up

author

Tom Hale

Senior Journalist

clockApr 2 2020, 13:06 UTC

Right jaw with permanent teeth of DH7. Debra R Bolter et al/PLOS ONE

In the depths of a winding cave system in South Africa, scattered in a pit of some 1,500 ancient bone fragments, archaeologists unearthed the remains of a young Homo naledi who met an untimely end around 250,000 years ago. 

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As the first example of a juvenile H. naledi, it’s hoped the fossilized remains could shed some much-needed light onto the early life and childhood of archaic hominin species.  

The remains were first unearthed in the 2013-2014 excavation season during archaeological work at the Rising Star cave system, an 800-meter-long (2,600 feet, or half a mile) cave system found in the Cradle of Humankind World Heritage Site in South Africa. After a series of wall and crawl spaces, the end of this cave system opens up into Dinaledi Chamber, a chamber filled with thousands of bone fragments belonging to extinct species of hominin dating between 335,000 and 226,000 years ago

In 2015, researchers discovered these remains belonged to a totally new species of archaic hominin, naming it H. naledi. Remarkably, this primitive small-brained hominin species lived at a time and place that means it’s likely they lived alongside Homo sapiens.

DH7's ischium, the lower and back part of the hip bone. Debra R Bolter et al/PLOS ONE

Among the scattering of bones, researchers have managed to identify at least 15 different individuals, one of which is now known as DH7. Reported in the journal PLOS ONE, researchers recently re-evaluated the remains of DH7 to discover its bones and teeth were not fully developed, meaning it was likely a juvenile, and remarkably it displayed similar growth patterns seen in modern humans. 

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Despite everything we know about the evolution and ancestry of early hominins, little is known about their growth and development from children to adults as most remains found have been adults.

It’s hard to say how old DH7 was when they died since we don’t know how quickly the species grew and matured, but based on what we know about other ancient hominins, the researchers estimate they were between 8 to 11 years old at death. If the species matured at an equally slow rate as humans, DH7 could have been as old as 15 years of age.

Regarding the specific age, it’s extremely rare to find juvenile skeletons from any ancient hominins, not least of the extremely elusive species H. naledi

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Indeed, since the species has only been discovered in this single cave system, we actually don't know very much about H. naledi in general. We do know they stood at around 143.6 centimeters (4 foot 9 inches) in height, roughly the size of a standing chimp, and weighed around 40 kilograms (88 pounds). Their skulls still possessed the small brains and “ape-like features” seen in Australopithecus and early hominins, not like the more refined large-brained skull of Homo Sapiens

It remains to be answered, however, what all of these remains were doing in Dinaledi Chamber. The bones don’t appear to be scavenged on or brought there by a hungry animal, and the lack of other species in the cave suggests they were not accidentally washed down here. 

So, were the individuals purposely buried in some kind of funerary ritual? It might seem unlikely a small-brained primate would be capable of such a feat, but that’s currently the most plausible answer. 

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Nature
  • human evolution,

  • history,

  • Homo,

  • homo naledi,

  • hominid,

  • homo sapien

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