Human skull evolved along with two-legged walking, study confirms
The evolution of bipedalism in fossil humans can be detected using a key feature of the skull—a claim that was previously contested but now has been further validated by researchers at Stony Brook University and The University of Texas at Austin.
|The evolution of human skull took place along with two-legged walking, researchers have confirmed |
Controversy has centered on the association between a forward-shifted foramen magnum and bipedalism since 1925, when Raymond Dart discussed it in his description of "Taung child," a 2.8 million-year-old fossil skull of the extinct South African species Australopithecus africanus. A study published last year by Aidan Ruth and colleagues continued to stir up the controversy when they offered additional criticisms of the idea.
of the positioning of the foramen magnum in a bipedal springhare (left)
and its closest quadrupedal relative,|
the scaly-tailed squirrel (right) [Credit: Russo and Kirk, Journal of Human Evolution]
|Comparison of the skeletons of three bipedal mammals: an Egyptian jerboa, an eastern gray kangaroo and a human |
[Credit: University of Texas at Austin]
To make their case, Russo and Kirk compared the position and orientation of the foramen magnum in 77 mammal species including marsupials, rodents and primates. Their findings indicate that bipedal mammals such as humans, kangaroos, springhares and jerboas have a more forward-positioned foramen magnum than their quadrupedal close relatives.
"We've now shown that the foramen magnum is forward-shifted across multiple bipedal mammalian clades using multiple metrics from the skull, which I think is convincing evidence that we're capturing a real phenomenon," Russo said.
Additionally, the study identifies specific measurements that can be applied to future research to map out the evolution of bipedalism. "Other researchers should feel confident in making use of our data to interpret the human fossil record," Russo said.
Source: University of Texas at Austin [March 17, 2017]