“An extraordinary advance in human origins research reveals evidence of the emergence of the upright human body plan over 15 million years earlier than most experts have believed. More dramatically, the study confirms preliminary evidence that many early hominoid apes were most likely upright bipedal walkers sharing the basic body form of modern humans.”
Extract from Science Daily article: Early Apes Walked Upright 15 Million Years Earlier Than Previously Thought, Evolutionary Biologist Argues
…The critical event involves a dramatic embryological change unique to the human lineage that was not previously understood because the unusual human condition was viewed as “normal.”
“From an embryological point of view, what took place is literally breathtaking,” says Dr. Aaron Filler, a Harvard-trained evolutionary biologist and a medical director at Cedars Sinai Medical Center’s Institute for Spinal Disorders.
In most vertebrates (including most mammals), he explains, the dividing plane between the front (ventral) part of the body and the back (dorsal) part is a “horizontal septum” that runs in front of the spinal canal. This is a fundamental aspect of animal architecture. A bizarre birth defect in what may have been the first direct human ancestor led to the “transposition” of the septum to a position behind the spinal cord in the lumbar region. Oddly enough, this configuration is more typical of invertebrates.
The mechanical effect of the transposition was to make horizontal or quadrupedal stance inefficient. “Any mammal with this set of changes would only be comfortable standing upright. I would envision this malformed young hominiform — the first true ancestral human — as standing upright from a young age while its siblings walked around on all fours.”
The earliest example of the transformed hominiform type of lumbar spine is found in Morotopithecus bishopi an extinct hominoid species that lived in Uganda more than 21 million years ago. “From a number of points of view,” Filler says, “humanity can be redefined as having its origin with Morotopithecus. This greatly demotes the importance of the bipedalism of Australopithecus species such as Lucy (Australopithecus afarensis) since we now know of four upright bipedal species that precede her, found from various time periods on out to Morotopithecus in the Early Miocene.”
Citation: Filler AG (2007) Homeotic Evolution in the Mammalia: Diversification of Therian Axial Seriation and the Morphogenetic Basis of Human Origins. PLoS One 2(10): e1019. doi:10.1371/journal.pone.0001019,http://www.plosone.org/doi/pone.0001019
Extracts from an article in Live Science: Human Ancestors Walked Upright, Study Claims by
“the other great apes we see now, such as chimps or gorillas or orangutans, might have descended from human-like ancestors,” researcher Aaron Filler, a Harvard-trained evolutionary biologist and medical director at Cedars-Sinai Institute for Spinal Disorders in Los Angeles, told LiveScience….
Filler analyzed how the spine was assembled in more than 250 living and extinct mammalian species, with some bones dating up to 220 million years old.”I am getting the feeling that a revolution in our thinking about the origins of bipedality is now under way,” said evolutionary anthropologist Robin Crompton at the University of Liverpool in England.
He discovered a series of changes that suggest walking upright-and not with our knuckles-might actually have been the norm for the ancestors of today’s great apes…
“Humanity can be redefined as having its origin with Morotopithecus,” Filler said. He detailed his findings online Oct. 10 in the journal PLoS ONE.
This research pushes back the date for the origins of bipedalism roughly 15 million years, to before the last common ancestor of humans, chimps, gorillas and orangutans, as well as lesser apes such as gibbons…