Featured Research

from universities, journals, and other organizations

Lucy and Selam's species climbed trees: Australopithecus afarensis shoulder blades show partially arboreal lifestyle

Date:
October 25, 2012
Source:
California Academy of Sciences
Summary:
Australopithecus afarensis was an upright walking species, but the question of whether it also spent much of its time in trees has been the subject of much debate. For the first time, scientists have thoroughly examined the two complete shoulder blades of the fossil "Selam." Analyses of these rare bones showed them to be quite apelike, suggesting that this species was adapted to climbing trees in addition to walking bipedally when on the ground.

Selam's skull (top) and right shoulder blade (bottom).
Credit: Zeray Alemseged

Australopithecus afarensis (the species of the well-known "Lucy" skeleton) was an upright walking species, but the question of whether it also spent much of its time in trees has been the subject of much debate, partly because a complete set of A. afarensis shoulder blades has never before been available for study.

Related Articles


For the first time, Midwestern University Professor David Green and Curator of Anthropology at the California Academy of Sciences, Zeresenay Alemseged, have thoroughly examined the two complete shoulder blades of the fossil "Selam," an exceptionally well-preserved skeleton of an A. afarensis child from Dikika, Ethiopia, discovered in 2000 by Dr. Alemseged. Further preparation and extensive analyses of these rare bones showed them to be quite apelike, suggesting that this species was adapted to climbing trees in addition to walking bipedally when on the ground. "The question as to whether Australopithecus afarensis was strictly bipedal or if they also climbed trees has been intensely debated for more than thirty years," said Dr. Green. "These remarkable fossils provide strong evidence that these individuals were still climbing at this stage in human evolution."

The new findings are published in the October 26 issue of the journal Science.

Dr. Alemseged, assisted by Kenyan lab technician Christopher Kiarie, spent 11 years carefully extracting the two shoulder blades from the rest of the skeleton, which was encased in a sandstone block. "Because shoulder blades are paper-thin, they rarely fossilize--and when they do, they are almost always fragmentary," said Dr. Alemseged. "So finding both shoulder blades completely intact and attached to a skeleton of a known and pivotal species was like hitting the jackpot. This study moves us a step closer toward answering the question 'When did our ancestors abandon climbing behavior?' It appears that this happened much later than many researchers have previously suggested."

Selam was a three-year-old A. afarensis girl who lived about 3.3 million years ago, and she represents the most complete skeleton of her kind to date. After freeing the shoulder blades from the surrounding rock, Green and Alemseged digitized them using a Microscribe, and then took detailed measurements to characterize their shape and function, comparing them to the rare shoulder fossils of other early human relatives: Homo ergaster ("Turkana Boy"), Homo floresiensis ("The Hobbit"), A. africanus, and two adult specimens of A. afarensis. They also made comparisons with an extensive modern sample of juvenile and adult chimpanzee, gorilla, orangutan, and human specimens.

The analysis of the shape and function of the bones revealed that A. afarensis shoulder blades are apelike, indicating a partially arboreal lifestyle. Drs. Green and Alemseged also found that, like living apes, the shoulder anatomy of juvenile and adult representatives of A. afarensis were quite similar. "Human scapulae change shape throughout ontogeny in a significantly different manner than closely related apes," said Dr. Green. "When we compared Selam's scapula with adult members of Australopithecus afarensis, it was clear that the pattern of growth was more consistent with that of apes than humans." At the same time, most researchers agree that many traits of the A. afarensis hip bone, lower limb, and foot are unequivocally humanlike and adapted for upright walking. "This new find confirms the pivotal place that Lucy and Selam's species occupies in human evolution," said Dr. Alemseged. "While bipedal like humans, A. afarensis was still a capable climber. Though not fully human, A. afarensis was clearly on its way."


Story Source:

The above story is based on materials provided by California Academy of Sciences. Note: Materials may be edited for content and length.


Journal Reference:

  1. D. J. Green, Z. Alemseged. Australopithecus afarensis Scapular Ontogeny, Function, and the Role of Climbing in Human Evolution. Science, 2012; 338 (6106): 514 DOI: 10.1126/science.1227123

Cite This Page:

California Academy of Sciences. "Lucy and Selam's species climbed trees: Australopithecus afarensis shoulder blades show partially arboreal lifestyle." ScienceDaily. ScienceDaily, 25 October 2012. <www.sciencedaily.com/releases/2012/10/121025150353.htm>.
California Academy of Sciences. (2012, October 25). Lucy and Selam's species climbed trees: Australopithecus afarensis shoulder blades show partially arboreal lifestyle. ScienceDaily. Retrieved November 22, 2014 from www.sciencedaily.com/releases/2012/10/121025150353.htm
California Academy of Sciences. "Lucy and Selam's species climbed trees: Australopithecus afarensis shoulder blades show partially arboreal lifestyle." ScienceDaily. www.sciencedaily.com/releases/2012/10/121025150353.htm (accessed November 22, 2014).

Share This


More From ScienceDaily



More Fossils & Ruins News

Saturday, November 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

US Returns Looted Artifacts to Thailand

US Returns Looted Artifacts to Thailand

AFP (Nov. 19, 2014) — The United States has returns over 500 vases, bowls, axes, and other ancient artifacts mostly from the Ban Chiang archaeological site which were illegally looted from Thailand decades ago. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
How To Search Through Every Public Tweet Sent Since 2006

How To Search Through Every Public Tweet Sent Since 2006

Newsy (Nov. 19, 2014) — Twitter has announced improvements to its search index that allow users to search through every public tweet sent since its inception in 2006. Video provided by Newsy
Powered by NewsLook.com
Professor Unlocks the Mystery of Paintings

Professor Unlocks the Mystery of Paintings

AP (Nov. 19, 2014) — Richard Johnson, a computer and engineering professor at Cornell University, is using technology to uncover mysteries about the age and authenticity of historic paintings by artists like Johannes Vermeer and Vincent Van Gogh. (Nov. 19) Video provided by AP
Powered by NewsLook.com
Napoleon Memorabilia to Be Sold at Auction

Napoleon Memorabilia to Be Sold at Auction

AFP (Nov. 14, 2014) — Napoleon's personal possessions, including his iconic cocked hat, are being auctioned off this weekend at a special sale at Fontainebleau Castle. Buyers are expected to bid hundreds of thousands or even millions of euros. Duration: 01:13 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:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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