Featured Research

from universities, journals, and other organizations

Anthropologists confirm link between cranial anatomy and two-legged walking

Date:
September 26, 2013
Source:
University of Texas at Austin
Summary:
Anthropologists confirm a direct link between upright two-legged (bipedal) walking and the position of the foramen magnum, a hole in the base of the skull that transmits the spinal cord.

Comparison of the skeletons of three bipedal mammals: an Egyptian jerboa, an eastern gray kangaroo and a human.
Credit: Image courtesy of University of Texas at Austin

Anthropology researchers from The University of Texas at Austin have confirmed a direct link between upright two-legged (bipedal) walking and the position of the foramen magnum, a hole in the base of the skull that transmits the spinal cord.

The study, published in a forthcoming issue of the Journal of Human Evolution, confirms a controversial finding made by anatomist Raymond Dart, who discovered the first known two-legged walking (bipedal) human ancestor, Australopithecus africanus. Since Dart's discovery in 1925, physical anthropologists have continued to debate whether this feature of the cranial base can serve as a direct link to bipedal fossil species.

Chris Kirk, associate professor of anthropology and co-author of the study, says the findings validate foramen magnum position as a diagnostic tool for fossil research and sheds further insight into human evolution.

"Now that we know that a forward-shifted foramen magnum is characteristic of bipedal mammals generally, we can be more confident that fossil species showing this feature were also habitual bipeds," Kirk says. "Our methods can be applied to fossil material belonging to some of the earliest potential human ancestors."

The foramen magnum in humans is centrally positioned under the braincase because the head sits atop the upright spine in bipedal postures. In contrast, the foramen magnum is located further toward the back of the skull in chimpanzees and most other mammals, as the spine is positioned more behind the head in four-legged postures.

As part of the study, the researchers measured the position of the foramen magnum in 71 species from three mammalian groups: marsupials, rodents and primates. By comparing foramen magnum position broadly across mammals, the researchers were able to rule out other potential explanations for a forward-shifted foramen magnum, such as differences in brain size.

According to the findings, a foramen magnum positioned toward the base of the skull is found not only in humans, but in other habitually bipedal mammals as well. Kangaroos, kangaroo rats and jerboas all have a more forward-shifted foramen magnum compared with their quadrupedal (four-legged walking) close relatives.

These particular mammals evolved bipedal locomotion and anteriorly positioned foramina magna independently, or as a result of convergent evolution, says Gabrielle Russo, who is a postdoctoral research fellow at Northeast Ohio Medical University and lead researcher of the study.

"As one of the few cranial features directly linked to locomotion, the position of the foramen magnum is an important feature for the study of human evolution," Russo says. "This is the case for early hominin species such as Sahelanthropus tchadensis, which shows a forward shift of the foramen magnum but has aroused some controversy as to whether it is more closely related to humans or African apes."


Story Source:

The above story is based on materials provided by University of Texas at Austin. Note: Materials may be edited for content and length.


Journal Reference:

  1. Gabrielle A. Russo, E. Christopher Kirk. Foramen magnum position in bipedal mammals. Journal of Human Evolution, 2013; DOI: 10.1016/j.jhevol.2013.07.007

Cite This Page:

University of Texas at Austin. "Anthropologists confirm link between cranial anatomy and two-legged walking." ScienceDaily. ScienceDaily, 26 September 2013. <www.sciencedaily.com/releases/2013/09/130926111903.htm>.
University of Texas at Austin. (2013, September 26). Anthropologists confirm link between cranial anatomy and two-legged walking. ScienceDaily. Retrieved September 17, 2014 from www.sciencedaily.com/releases/2013/09/130926111903.htm
University of Texas at Austin. "Anthropologists confirm link between cranial anatomy and two-legged walking." ScienceDaily. www.sciencedaily.com/releases/2013/09/130926111903.htm (accessed September 17, 2014).

Share This



More Fossils & Ruins News

Wednesday, September 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Researchers Explore Shipwrecks Off Calif. Coast

Researchers Explore Shipwrecks Off Calif. Coast

AP (Sep. 16, 2014) — Federal researchers are exploring more than a dozen underwater sites where they believe ships sank in the treacherous waters west of San Francisco in the decades following the Gold Rush. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Museum Traces Fragments of Star-Spangled Banner

Museum Traces Fragments of Star-Spangled Banner

AP (Sep. 12, 2014) — As the Star-Spangled Banner celebrates its bicentennial, Smithsonian curators are still uncovering fragments of the original flag that inspired Francis Scott Key's poem. (Sept. 12) Video provided by AP
Powered by NewsLook.com
Spinosaurus Could Be First Semi-Aquatic Dinosaur

Spinosaurus Could Be First Semi-Aquatic Dinosaur

Newsy (Sep. 11, 2014) — New research has shown that the Spinosaurus, the largest carnivorous dinosaur, might have been just as well suited for life in the water as on land. Video provided by Newsy
Powered by NewsLook.com
Meet Spinosaurus, the First-Known Water Dinosaur

Meet Spinosaurus, the First-Known Water Dinosaur

AFP (Sep. 11, 2014) — Spinosaurus aegyptiacus was adapted for both land and water, and an exhibit featuring a life-sized model, based on new fossils unearthed in eastern Morocco, opens at the National Geographic Museum in Washington on Friday. Duration: 01:02 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

      Technology News



      Save/Print:
      Share:  

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile iPhone Android Web
      Follow Facebook Twitter Google+
      Subscribe RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins