New species joins human ancestral parade

IllustrationCourtesy José-Manuel Benitos via Wikimedia Commons
Fossil bones of two hominins
found in a cave in South Africa, could be those of a completely new species of human and fill in a gap in human ancestry. The remains, which were found within a yard of each other, are of an adult middle-aged female and juvenile male. Scientists speculate the two could even be a mother and its child, or at least members of the same tribe. Either way, they add valuable information to the very fragmentary record of human evolution.

Professor Lee Berger, lead researcher of the discovery, and a paleoanthropologist at the University of the Witwatersrand, says the remains are well preserved and between the two of them include a nearly complete skull, shoulder, arm, lower leg, and hand. The pelvis is well represented, too. The fossils were found in the Malapa cave not far from the Cradle of Humankind World Heritage Site near Johannesburg.

Named Australopithecus sediba, the new finds which are nearly two million years old, have characteristics common to both Homo (which includes us) and Australopithecus, early ape-like creatures, making it an important transitional fossil between the two genera. Photo link

“That period between 1.8 and just over two million years - is one of the most poorly represented in the entire early hominid fossil record. You're talking about a very small, very fragmentary record," said," lead scientist Lee Berger. "It's at the point where we transition from an ape that walks on two legs to, effectively, us.”

Berger is a professor of paleoanthropology at the University of the Witwatersrand in Johannesburg. First evidence of the find was actually found by his 9 year-old son, Matthew, who picked up a couple fossils bones, a collarbone and jawbone that had been discarded by miners. Further investigation led to the rest of the remains. Professor Berger had found the cave in 2008 using Google Earth.

Although clearly australopithecine in size and stature, and most closely similar to the species Australopithecus afarensis, the boy’s skull and jaw also contain features seen in the genus Homo, such as the facial structure (e.g. a slight bony chin), and the shape and size of the premolars and molars. The two creatures upper limbs were overly long, again a trait of Australopithecus, and means they were more-than-likely arboreal, and able to easily climb trees to seek refuge and food. But their pelvic structures share features found in the hips of the Homo genus, leaning toward more efficiency in walking or running. This means A. sediba fills in some of the gap between Australopithecus afarensis and Homo erectus. Professor Berger’s study appears in the journal Science.

Berger suspects the two A. sediba had been swept into the cave by a flash flood or some such disaster and buried fairly quickly. The dig site produced the remains of 25 other animals such as a horse, saber-toothed cat, wild dogs, and antelope. None of the remains appear to have been scavenged Fossils from two other hominid individuals were also found but have not yet studied.

Article at Science.
Video at Science
Podcast at Science
More pictures at NatGeo

Your Comments, Thoughts, Questions, Ideas

mdr's picture
mdr says:

Paleoanthropologist Donald Johanson - discoverer of Australopithecus afarensis (aka Lucy) - brings up some questions about Berger's A. sediba that you can read at Scientific American.

posted on Tue, 04/13/2010 - 10:02am

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