Featured Research

from universities, journals, and other organizations

Early Hominid First Walked On Two Legs In The Woods

Date:
October 8, 2009
Source:
University of Illinois at Urbana-Champaign
Summary:
Among the many surprises associated with the discovery of the oldest known, nearly complete skeleton of a hominid is the finding that this species took its first steps toward bipedalism not on the open, grassy savanna, as generations of scientists -- going back to Charles Darwin -- hypothesized, but in a wooded landscape.

Ambrose analyzed the teeth of two-dozen mammal species found in the same ancient soil layer as Ardipithecus in order to help reconstruct its environment. A modern hippopotamus tooth is pictured.
Credit: Photo by L. Brian Stauffer

Among the many surprises associated with the discovery of the oldest known, nearly complete skeleton of a hominid is the finding that this species took its first steps toward bipedalism not on the open, grassy savanna, as generations of scientists – going back to Charles Darwin – hypothesized, but in a wooded landscape.

“This species was not a savanna species like Darwin proposed,” said University of Illinois anthropology professor Stanley Ambrose, a co-author of two of 11 studies published this week in Science on the hominid, Ardipithecus ramidus. This creature, believed to be an early ancestor of the human lineage, lived in Ethiopia some 4.4 million years ago.

One of the crucial pieces of evidence to show that Darwin didn’t get it right, Ambrose said, was the analysis of carbon isotopes in the soil and in the teeth of Ardipithecus and other animals that lived at roughly the same time and in the same location.

The mass of carbon atoms in the atmosphere varies, and during photosynthesis, trees and tropical grasses absorb different proportions of carbon-12, the most common carbon isotope, and carbon-13, which is rare. These isotopes pass into the soil and into the bodies of animals that eat the plants, making it possible to accurately reconstruct the proportions of grass to trees on the landscape and in the diets of the animals that lived there.

Ambrose analyzed stable carbon isotope ratios in the soil in which the bones of 36 Ardipithecus individuals were found. He also analyzed the teeth of five Ardipithecus individuals and 172 teeth of two-dozen mammal species found in the same ancient soil layer.

The fossil-bearing layer, in the Afar Rift region of northeastern Ethiopia, spans a broad arc about 9 kilometers long. Sandwiched between two layers of volcanic ash that both date to about the same age, it provides a well-focused snapshot of an ancient African ecosystem.

The carbon isotope ratios of the soils indicated that in the time of Ardipithecus the landscape varied from woodland in the western part of the study zone to wooded grassland in the east. None of the Ardipithecus specimens were found in the grassy eastern part of the arc.

“Fossils of many species are common all the way across the landscape,” Ambrose said. “But this species is missing in action from the east side of the distribution.”

Isotopic analysis of teeth found on the site gave a more complete picture of the habitat of the animals that lived and died there, Ambrose said.

“The distribution of plant carbon isotope ratios conveniently separates out grasslands from forests,” he said. “And it also separates out grazing animals, like zebras, from browsing animals that eat the leaves off of trees, like giraffes.”

The distribution of the fossil browsers and grazers echoed that of the habitat, he said.

“On the west we find lots of Ardipithecus fossils and they’re associated with a lot of woodland and forest animals,” he said. “And then there’s a break; Ardipithecus and most of the monkeys that live in trees disappear, and grass-eating animals become more abundant.”

The carbon isotope ratios of the Ardipithecus teeth also tell the story of a woodland creature, he said.

“The diet of the Ardipithecus is much more on the woodland and forest side,” he said. “It’s got a little bit more of the grassland ecosystem carbon in its diet than that of a chimpanzee but much less than its fully bipedal savanna-dwelling descendents, the australopithecines.”

This evidence, along with the anatomical studies indicating that Ardipithecus could walk upright but also grasped tree limbs with its feet, suggests that this early hominid took its first steps on two legs in the forest long before it ventured very far into the open grassland, Ambrose said.

“Multiple lines of evidence now suggest that they were beginning to leave the trees before they left the forest,” he said.


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. "Early Hominid First Walked On Two Legs In The Woods." ScienceDaily. ScienceDaily, 8 October 2009. <www.sciencedaily.com/releases/2009/10/091008113341.htm>.
University of Illinois at Urbana-Champaign. (2009, October 8). Early Hominid First Walked On Two Legs In The Woods. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2009/10/091008113341.htm
University of Illinois at Urbana-Champaign. "Early Hominid First Walked On Two Legs In The Woods." ScienceDaily. www.sciencedaily.com/releases/2009/10/091008113341.htm (accessed July 28, 2014).

Share This




More Plants & Animals News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
Powered by NewsLook.com
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) Video provided by AP
Powered by NewsLook.com
Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Russia Saves Gecko Sex Satellite, Media Has Some Fun With It

Newsy (July 27, 2014) The satellite is back under ground control after a tense few days, but with a gecko sex experiment on board, the media just couldn't help themselves. 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:
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