Featured Research

from universities, journals, and other organizations

Origin Of Bipedalism Seems Most Closely Tied To Environmental Changes

Date:
May 9, 2002
Source:
University Of Illinois At Urbana-Champaign
Summary:
After an extensive study of evolutionary, anatomical and fossil evidence, a team of paleoanthropologists has narrowed down the number of tenable hypotheses to explain the origin of bipedalism and our prehuman ancestors' method of navigating their world before they began walking upright.

CHAMPAIGN, Ill. -- During the past 100 years, scientists have tossed around a great many hypotheses about the evolutionary route to bipedalism, and what inspired our prehuman ancestors to stand up straight and amble off on two feet.

Now, after an extensive study of evolutionary, anatomical and fossil evidence, a team of paleoanthropologists has narrowed down the number of tenable hypotheses to explain the origin of bipedalism and our prehuman ancestors' method of navigating their world before they began walking upright.

The hypothesis they found the most support for regarding the origin of bipedalism is the one that argues our ancestors began walking upright largely in response to environmental changes -- in particular, to the growing incidence of open spaces and the way that changed the distribution of food.

In response to periods of cooling and drying, which thinned out dense forests and produced "mosaics" of forests, woodlands and grasslands, it seems likely that "some apes maintained a forest-oriented adaptation, while others may have begun to exploit forest margins and grassy woodlands," said paleoanthropologist Brian Richmond, lead author in the new study. The process of increasing commitment to bipediality probably involved "an extended and complex opening of habitats, rather than a single, abrupt transition from dense forest to open savanna," he said.

Richmond, from the University of Illinois at Urbana-Champaign, with paleoanthropologists David Begun from the University of Toronto and David Strait from the New York College of Osteopathic Medicine, describe their findings, which involved a comprehensive review and analysis of the five leading hypotheses on the origin of bipedalism, in a recent issue of the Yearbook of Physical Anthropology. Other hypotheses that remain viable, according to the team: "freeing" the hands for carrying or for some kind of tool use, and an increased emphasis on foraging from branches of small fruit trees, which is the context in which modern chimpanzees spend the most time on two legs.

For their study, the researchers combined data from biomechanics -- movement, posture and stesses in bones and joints -- and from bone growth and development. They found that our prehuman ancestors had terrestrial features in the hands and feet, climbing features throughout the skeleton, and knuckle-walking features in the wrist and hand; that finger bone curvature is responsive to changes in arboreal activity during growth, lending support to the hypothesis that many early hominid species, although bipedal, still climbed trees. Evidence from the wrist joint "suggests that the earliest humans evolved bipedalism from an ancestor adapted for knuckle-walking on the ground and climbing in trees."

The YPA article, according to Richmond, is "the first attempt in decades to bring together all of the available evidence for the argument that the earliest human biped evolved from ancestors that both knuckle-walked and climbed trees, rather than from ancestors living exclusively in trees and 'coming down from the trees,' or walking on the ground in ways similar to modern baboons."


Story Source:

The above story is based on materials provided by University Of Illinois At Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Urbana-Champaign. "Origin Of Bipedalism Seems Most Closely Tied To Environmental Changes." ScienceDaily. ScienceDaily, 9 May 2002. <www.sciencedaily.com/releases/2002/05/020509074029.htm>.
University Of Illinois At Urbana-Champaign. (2002, May 9). Origin Of Bipedalism Seems Most Closely Tied To Environmental Changes. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2002/05/020509074029.htm
University Of Illinois At Urbana-Champaign. "Origin Of Bipedalism Seems Most Closely Tied To Environmental Changes." ScienceDaily. www.sciencedaily.com/releases/2002/05/020509074029.htm (accessed September 19, 2014).

Share This



More Plants & Animals News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

AP (Sep. 18, 2014) Grand the elephant has successfully undergone surgery to remove a portion of infected tusk at Tbilisi Zoo in Georgia. British veterinary surgeons used an electric drill to extract the infected piece. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Chimp Violence Study Renews Debate On Why They Kill

Chimp Violence Study Renews Debate On Why They Kill

Newsy (Sep. 17, 2014) The study weighs in on a debate over whether chimps are naturally violent or become that way due to human interference in the environment. Video provided by Newsy
Powered by NewsLook.com
Some Tobacco Farmers Thrive Amid Challenges

Some Tobacco Farmers Thrive Amid Challenges

AP (Sep. 16, 2014) The South's tobacco country is surviving, and even thriving in some cases, as demand overseas keeps growers in the fields of one of America's oldest cash crops. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

AFP (Sep. 16, 2014) Scientists say a female colossal squid weighing an estimated 350 kilograms (770 lbs) and thought to be only the second intact specimen ever found was carrying eggs when discovered in the Antarctic. Duration: 00:47 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