Featured Research

from universities, journals, and other organizations

Direct ancestor of Homo genus? Fossils show human-like hand, brain and pelvis in early hominin

Date:
September 8, 2011
Source:
University of Zurich
Summary:
The Australopithecus sediba discovered in 2008 could be the direct ancestor of the Homo genus. That is the conclusion of an international team of scientists. The researchers describe in five papers why their finding is more likely to come into consideration than earlier discoveries, like Homo habilis.

Australopithecus sediba has a relatively long thumb. The hand suggests that he may have had the capacity to manufacture and use complex tools.
Credit: University of Zurich; Peter Schmid

The Australopithecus sediba discovered in 2008 could be the direct ancestor of the Homo genus. That is the conclusion of a team from the University of Witwatersrand, with participation by anthropologist Peter Schmid of the University of Zurich. The researchers describe in five publications in "Science" why their finding is more likely to come into consideration than earlier discoveries, like Homo habilis.

The fossil bones of the pre-human, excavated north of Johannesburg in Malapa, are 1.98 million years old. That figure was yielded by the latest analyses on the two skeletons MH-1 and MH-2, originating from a boy of approximately 10-13 years and a woman of approximately 30 years.

It was discovered that Australopithecus sediba unites various properties that were not yet seen in early ancestors of humans. The fossils show a surprisingly modern, yet small brain; a very modern, developed hand with long thumbs, like in humans; a very human-like pelvis; but a form in the foot and ankle shape that is both ape- and human-like. In light of these findings, Prof. Lee Berger, University of Witwatersrand, is of the opinion that Australopithecus sediba is the best candidate ancestor for our genus, the genus Homo.

One of the partial skeletons consists of a skull measured to have a brain volume of 420 cubic centimeters. Considering the growth zones on the long bones and the tooth formation, it must be the skull of a young individual who is 10-13 years old. The brain of an adult would therefore have a volume of ca. 440 cubic centimeters. "This very small volume is irritating, especially when one observes the thoroughly advanced facial features and the very human-like particularities in the locomotion system," observes Peter Schmid from the University of Zurich, co-author of the publications.

Beginnings of a Modern Brain

The extraordinarily well preserved skull made it possible to clarify whether the windings and grooves correspond to those of the earlier Australopithecus, or if it shows the properties of a modern brain. It was revealed that the frontal pole region and the olfactory bulb area are already similar to those in humans. This has led the researchers to postulate that neuronal reorganization of the forebrain must have occurred before the actual size increase in the brain.

New information was also facilitated by the oldest nearly complete hand of an early hominin ever found and described. This is significant because the hand is seen as the trademark of humanity. Throughout the course of human evolution, the hand was no longer used for locomotion, as is the case with apes, but rather to manipulate objects.

A Hand for Making Tools

Compared to earlier forms, Australopithecus sediba has shorter fingers, very long thumbs, and more robust metacarpal bones. Astonishingly, the Sediba's hand shows more modern properties than the hand fragments from an earlier find considered to be the origin of the tool-making human (Homo habilis, "handy man") and therefore to be the first representative of the Homo genus. "Australopithecus sediba should therefore have been even more capable of making tools," says Schmid. Since this hand is different from that of the Homo habilis, there must have been various hominins with various types of hands producing tools during the same time period.

The hand found is more complete than that of the Homo habilis, and therefore allows for more conclusions to be drawn. It is more modern, although Homo habilis is 200,000 to 300,000 years younger. The researchers are therefore of the opinion that Australopithecus sediba is an earlier toolmaker than Homo habilis, and therefore also better suited to be the morphotype of a basal hand.

In contrast to later forms of the Homo genus and several australopithecines, the hand of Australopithecus sediba conservedseveral modifications for tree life. While Sediba does appear to already be capable of using and making tools with his hands, those hands are also well suited for climbing.

Locomotion Changed the Pelvic Form

The pelvis is a mix of original, Australopithecus-like, and later, Homo-like properties. The modern features of the pelvis are surprising for the researchers, as Sediba has such a small brain. Previously, the assumption was that a size increase in the brain changed the demands on the pelvis to facilitate the birth of babies with larger brains. The researchers surmise that the pelvis adapted in at least one of the lines of earlier hominins before brain volume increased. The most likely scenario, according to Peter Schmid, is that locomotion on two legs changed the pelvis. That would mean that the model pelvic form can be traced to the requirements of the locomotion system and not those of the birthing process.

What is confusing, according to Schmid, is the foot. In contrast to the pelvis, the hand, and the skull, it is very ape-like. Compared to older ancestors, it is also much less modern. There are various properties that indicate erect, bipedal walking, while others are suitable for climbing.

Australopithecus sediba: Finding and Name

In August 2008, Matthew Berger, the son of paleoanthropogist Lee Berger, found the fragment of a human-like collar bone. The first excavations at the discovery site, Malapa, north of Johannesburg, were performed by a team from the Swiss Field School of the Anthropological Institute at the University of Zurich, under the direction of Peter Schmid.

The fossils did not match any previously known hominin species -- that is why they constitute a new milestone in humanity's history. Based on age and morphology, researchers carefully allocated the new hominin species to the Australopithecus genus and not to the Homo genus. They gave it the name Australopithecus sediba, which in the Sesetho language means "fountain" or "source."


Story Source:

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


Journal Reference:

  1. Tracy L. Kivell, Job M. Kibii, Steven E. Churchill, Peter Schmid, Lee R. Berger. Australopithecus sediba Hand Demonstrates Mosaic Evolution of Locomotor and Manipulative Abilities. Science, 2011; DOI: 10.1126/science.1202625

Cite This Page:

University of Zurich. "Direct ancestor of Homo genus? Fossils show human-like hand, brain and pelvis in early hominin." ScienceDaily. ScienceDaily, 8 September 2011. <www.sciencedaily.com/releases/2011/09/110908161446.htm>.
University of Zurich. (2011, September 8). Direct ancestor of Homo genus? Fossils show human-like hand, brain and pelvis in early hominin. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2011/09/110908161446.htm
University of Zurich. "Direct ancestor of Homo genus? Fossils show human-like hand, brain and pelvis in early hominin." ScienceDaily. www.sciencedaily.com/releases/2011/09/110908161446.htm (accessed September 2, 2014).

Share This




More Fossils & Ruins News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Did Neanderthals Play Tic-Tac-Toe?

Did Neanderthals Play Tic-Tac-Toe?

Newsy (Sep. 2, 2014) — Artwork found in a Gibraltar cave that was possibly done by Neanderthals suggests they may have been smarter than we all thought. Video provided by Newsy
Powered by NewsLook.com
Millions Of Historical Public Domain Photos Added To Flickr

Millions Of Historical Public Domain Photos Added To Flickr

Newsy (Aug. 30, 2014) — Historian Kalev Leetaru uploaded a large collection of historical photos, images that were previously difficult to collect. Video provided by Newsy
Powered by NewsLook.com
Minds Blown: Scientists Develop Fish That Walk On Land

Minds Blown: Scientists Develop Fish That Walk On Land

Newsy (Aug. 28, 2014) — Canadian scientists looking into the very first land animals took a fish out of water and forced it to walk. Video provided by Newsy
Powered by NewsLook.com
Huge Ancient Wine Cellar Found In Israel

Huge Ancient Wine Cellar Found In Israel

Newsy (Aug. 28, 2014) — An international team uncovered a large ancient wine celler that likely belonged to a Cannonite ruler. 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:

More Coverage


Fossil Discovery Could Be Our Oldest Human Ancestor

Sep. 8, 2011 — Researchers have confirmed the age of possibly our oldest direct human ancestor at 1.98 million years ... read more
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