Featured Research

from universities, journals, and other organizations

Study Identifies Energy Efficiency As Reason For Evolution Of Upright Walking

Date:
July 17, 2007
Source:
University of Arizona
Summary:
A new study provides support for the hypothesis that walking on two legs, or bipedalism, evolved because it used less energy than quadrupedal knucklewalking. Humans walking on two legs only used one-quarter of the energy that chimpanzees who knuckle-walked on four legs did.

Ground reaction force (GRF) vectors for humans and chimpanzees.
Credit: Copyright Cary Wolinsky

A new study provides support for the hypothesis that walking on two legs, or bipedalism, evolved because it used less energy than quadrupedal knucklewalking.

Related Articles


David Raichlen, an assistant professor of anthropology at The University of Arizona, conducted the study with Michael Sockol from the University of California, Davis, who was the lead author of the paper, and Herman Pontzer from Washington University in St. Louis.

Raichlen and his colleagues will publish the article, "Chimpanzee locomotor energetics and the origin of human bipedalism" in the online early edition of the Proceedings of the National Academy of Sciences (PNAS) during the week of July 16. The print issue will be published on July 24.

Bipedalism marks a critical divergence between humans and other apes and is considered a defining characteristic of human ancestors. It has been hypothesized that the reduced energy cost of walking upright would have provided evolutionary advantages by decreasing the cost of foraging.

"For decades now researchers have debated the role of energetics and the evolution of bipedalism," said Raichlen. "The big problem in the study of bipedalism was that there was little data out there."

The researches collected metabolic, kinematic and kenetic data from five chimpanzees and four adult humans walking on a treadmill. The chimpanzees were trained to walk quadrupedally and bipedally on the treadmill.

Humans walking on two legs only used one-quarter of the energy that chimpanzees who knuckle-walked on four legs did. On average, the chimpanzees used the same amount of energy using two legs as they did when they used four legs. However, there was variability among chimpanzees in how much energy they used, and this difference corresponded to their different gaits and anatomy.

"We were able to tie the energetic cost in chimps to their anatomy," said Raichlen. "We were able to show exactly why certain individuals were able to walk bipedally more cheaply than others, and we did that with biomechanical modeling."

The biomechanical modeling revealed that more energy is used with shorter steps or more active muscle mass. Indeed, the chimpanzee with the longest stride was the most efficient walking upright.

"What those results allowed us to do was to look at the fossil record and see whether fossil hominins show adaptations that would have reduced bipedal energy expenditures," said Raichlen. "We and many others have found these adaptations [such as slight increases in hindlimb extension or length] in early hominins, which tells us that energetics played a pretty large role in the evolution of bipedalism."


Story Source:

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


Cite This Page:

University of Arizona. "Study Identifies Energy Efficiency As Reason For Evolution Of Upright Walking." ScienceDaily. ScienceDaily, 17 July 2007. <www.sciencedaily.com/releases/2007/07/070716191140.htm>.
University of Arizona. (2007, July 17). Study Identifies Energy Efficiency As Reason For Evolution Of Upright Walking. ScienceDaily. Retrieved April 1, 2015 from www.sciencedaily.com/releases/2007/07/070716191140.htm
University of Arizona. "Study Identifies Energy Efficiency As Reason For Evolution Of Upright Walking." ScienceDaily. www.sciencedaily.com/releases/2007/07/070716191140.htm (accessed April 1, 2015).

Share This


More From ScienceDaily



More Fossils & Ruins News

Wednesday, April 1, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Giant Amphibian Fossils Found in Portugal

Giant Amphibian Fossils Found in Portugal

Reuters - Light News Video Online (Mar. 31, 2015) Scientists discover a new species of giant amphibian that was one of the largest predators on earth about 220 million year ago. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Ancient Egyptian Beer Making Vessels Discovered in Israel

Ancient Egyptian Beer Making Vessels Discovered in Israel

AFP (Mar. 30, 2015) Fragments of pottery used by Egyptians to make beer and dating back 5,000 years have been discovered on a building site in Tel Aviv, the Israeli Antiquities Authority said on Sunday. Duration: 00:51 Video provided by AFP
Powered by NewsLook.com
Party Like It's 3000 BC: Egyptian Beer Vessels Unearthed in Tel Aviv

Party Like It's 3000 BC: Egyptian Beer Vessels Unearthed in Tel Aviv

Reuters - Light News Video Online (Mar. 30, 2015) Israeli archaeologists unearth ancient Egyptian beer vessels in downtown Tel Aviv. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
New Arthropod Fossil Might Be Relative Of Spiders, Scorpions

New Arthropod Fossil Might Be Relative Of Spiders, Scorpions

Newsy (Mar. 29, 2015) A 508-million-year-old arthropod that swam in the Cambrian seas is thought to share a common ancestor with spiders and scorpions. Video provided by Newsy
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