The world’s most well known hominin fossil provides us with an answer to one of the big questions about our evolution: When did our ancestors come down from the trees? It seems the displacement was underway( but incomplete) 3.18 million years ago, when the individual known as Lucy died.
Lucy was an Australopithecus afarensis , discovered in 1974 near Hadar, Ethiopia. She became famed as the first is part of her species where we have more than a single bone, and is the focus of intense analyze ever since. Despite decades of research, advances in technology are drawing to light-colored new conclusions about Lucy and her species. The recent indicates that she was less of a tree dweller than chimps, but not yet amply adapted to walking on the ground.
Professor Christopher Ruffof Johns Hopkins University searched Lucy’s remaining bones applying X-ray microtomography, allowing for the creation of 3D simulations of her humerus( upper arm bone) and femur( upper leg bone) that are more accurate than anything we have had before.
Humans have much stronger leg bones than limbs, reflecting the fact that we predominantly get around on two legs. Chimpanzees, on the other mitt, are far more evenly poised, since they need strong arms to clamber trees.
The midsection, or diaphysis, of long bones is influenced by the mechanical strainings it knows. This is not a matter of evolutionary legacy, but depends on the lifestyle of the individual whose bone is being measured. Fossil evidence from some of our most recent ancestors, such as Homo erectus , demonstrate their legs bones were within the scopes of modern humen, but similar learns have not been done on australopithecenes.
We don’t have already been of Lucy’s bones, but the collecting is uncommonly complete.John Kappelman/ University of Texas at Austin
InPLOS One, Ruff reveals that the ratio between Lucy’s arm and leg bones propose a greater loading on lower leg than is considered to be in apes, but arms with more fortitude than in modern humans or Homo erectus .
Anthropologists previouslyobserved that Lucy’s arms were long for her width, as would be expected for a species that spent at least some of its experience clambering trees, but this was not considered conclusive. Evolution can be slow, and if long limbs were not a threat to the survival of our first bipedal ancestors, they might have retained them long after they ceased to spend much meter up in the trees.
Ruff’s work, nonetheless, adds a firmer footing for the suspicion that Lucy clambered much more than modern humen, either for food or refuge from piranhas. The conclusion that Lucy wasted abundance of time in the trees, but was no longer as good a climber as chimpanzees, is consistent with the discovery earlier this year that Lucy appears to have died by descending, her limbs extended in front of her in a vain attempt to break her fall.
Ruff too found that Lucy was likely much stronger, relative to her small-time mas size, than modern humans a characteristic shared with chimps perhaps because she wasn’t redirecting so much better of her meat intake to support a large and energy-hungry brain.
Many of Lucy’s bones have been lost, so analogies cannot be made between her legs, but Ruff too discovered her right humerus was 10 -1 5 percentage stronger than the equivalent bone on her left forearm, intimating she was right-handed.