Is that really you, Granny? Model restates fossil's human ancestry claim

08 April 2018 - 00:00 By TANYA FARBER

A stunning re-creation of one of South Africa's most beloved "rock" stars is lying in a crate thousands of kilometres from home. But when she was briefly taken out to be checked for damage, she sent a wave of "shock" across the room.
The University of Michigan ordered the female lifelike reconstruction of "an extinct human relative" - Australopithecus sediba - for a new natural history museum.
"She's gazing right into your eyes and looks like a living creature that has paused mid-step," said curator Michael Cherney.
Her shining eyes and hairy, upright body, standing just 114cm tall, make for an endearing ancestor, but whether she is truly a human relative is a question that has had palaeontologists scratching their heads since she was found a decade ago - two million years after she roamed what is now South Africa.
By the time she makes her public debut about a year from now, science journals the world over will have published different theories. She keeps appearing on our family tree, only to be erased, then pencilled in again.
The latest theory, published in the South African Journal of Science, says we can't write her off as our ancestor simply because of the age of the six skeletons discovered at the Malapa fossil site at the Cradle of Humankind.
"We correct a common misconception in palaeoanthropology that a species currently known only from later in time than another species cannot be ancestral to it," says lead author Chris Robinson of Bronx Community College in New York.
"On temporal grounds alone, one cannot dismiss the possibility that A. sediba could be ancestral to the genus Homo."
Simply put, the evolution that led to our existence as a species is not represented by a neat line of changes to a single species. It is a messy business - more of a tangled bush than a neatly drawn tree.Robinson and the team say the Malapa deposits containing the skeletons were evidence of "one particular moment in time when the species existed" - but not evidence that the species was absent at other times.
They say they are not arguing that A. sediba is definitely our ancestor, merely pointing out that it is premature to dismiss this possibility based on temporal criteria.
"We urge caution for all scientists involved in studies of human evolution to carefully think about how temporal data can, and should, be used in assessing hypotheses."
The specimens are at the centre of other academic controversies about the creature, which walked upright but lacked Homo sapiens's larger brain, flatter face and smaller teeth and jaws.Lee Berger of the University of the Witwatersrand found the fossils with his nine-year-old son in 2008, and two years later claimed A. sediba as the exclusive ancestor of Homo. Dissenting voices quickly emerged.
Not quite the missing link that came just before us, it was more of an evolutionary dead end, said Tim White of the University of California, adding: "An inadequate fossil record continues to obscure the origins of our genus."
William Kimbel of Arizona State University said while A. sediba provided "fascinating details", it did not "convincingly indicate its position on the evolutionary route to modern humans". Berger and others have stuck to their guns, holding up A. sediba as a missing piece of our ancestral puzzle.
Whoever is right, the outward appearance of this fascinating creature is not in question, and when the Michigan university commissioned the "full-body, fleshed reconstruction" from the Daynès Studio in Paris, it was tapping into a pool of experience that could really bring her to life. This is the same studio that created a breathtaking replica of Lucy, the Australopithecus afarensis found in Ethiopia in 1974."What the bones tell us is that they would have been fully erect, not crouched at the hip and knee like chimps and gorillas, and that's something we really wanted to get right in this model," according to palaeoanthropologist Laura MacLatchy at the University of Michigan.
Get it right, they did - and now it's up to the scientists to keep venturing beyond her skin-deep beauty.
MOVE OVER, LUCY
Up until April 2013, Lucy, left, was in the pound seats. She was the Australopithecus afarensis found in Ethiopia in 1974 and dated to 3.2 million years ago, and for four decades was considered the most likely immediate ancestor of our own genus (Homo). But then came Australopithecus sediba—and now, five years later, the scientific jury is still hung,
farbert@sundaytimes.co.za..

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