Featured Research

from universities, journals, and other organizations

Fossil Teeth Reveal Recent Origin Of Human Growth Pattern

Date:
December 7, 2001
Source:
Penn State
Summary:
The long period of development leading up to a modern human's adulthood arose relatively late in our evolutionary history, according to an analysis of growth patterns in fossil teeth in the 6 December issue of the journal Nature, written by Christopher Dean of University College, London, and colleagues including Alan Walker, distinguished professor of anthropology and biology at Penn State.

The long period of development leading up to a modern human's adulthood arose relatively late in our evolutionary history, according to an analysis of growth patterns in fossil teeth in the 6 December issue of the journal Nature, written by Christopher Dean of University College, London, and colleagues including Alan Walker, distinguished professor of anthropology and biology at Penn State.

Related Articles


"One of the things that sets modern humans apart from the living great apes is our long period of growth and development," Dean explains. "While humans take a good 18 to 20 years to grow up, other primate species like chimpanzees and gorillas take just 11 or 12 years." A supporting article, written by Jacopo Moggi-Cecchi of the University of Florence in Italy, is included in the "News and Views" section of the journal. The research was designed to determine when the prolonged growth period we have today arose during our long evolutionary history.

"Dental development is a good measure of overall growth and development," says Walker, who pioneered the study of living primates as a basis for the analysis of fossils and was one of the first to use scanning electron microscope studies of fossil teeth. "Teeth grow in an incremental manner like trees or shells, preserving a record of their growth with daily marks along the prisms that make up the enamel." By making thin sections of modern and fossil teeth, the researchers were able to count the daily incremental markings within the enamel of humans, apes, and fossil "hominin" species in the human lineage in order to calculate and compare their rates of enamel formation.

"Of the 13 fossil tooth fragments we studied--both those attributed to the earliest australopith hominins that lived roughly between 4 and 1 million years ago, and those of the earliest members of our own Homo genus that lived about 1.5 million years ago--none showed the slower pattern of modern human enamel growth," says Walker, who in 1984 was a key member of the team that discovered a juvenile skeleton in Kenya from one of the earliest species in the Homo genus, Homo erectus. "We found that the first dental evidence for a modern human-like growth period appears much more recently, in a Neanderthal fossil that lived about 120,000 years ago."

The results are surprising because researchers had expected that Homo erectus--the first fossil human ancestor to show a suite of modern human-like characteristics including body proportions, body weight, and small teeth and jaws--would show evidence of a modern human-like growth period. However, because the brain in Homo erectus was still not as large as a modern human's and because a long growth period is linked with the time needed to grow and learn to use a large brain, the researchers say these findings are compatible with predictions that could be made on the basis of brain size alone.

As part of their research, the scientists used the incremental growth markings to calculate the formation times of individual teeth as a clue in the solution to another mystery about the age at death of the Homo erectus fossil found in Kenya.

"Using these tooth-formation times, we can speculate about the age at which key teeth emerged into the mouth in Homo erectus," Dean explains. "It seems likely that the first permanent molar tooth, which erupts at around 6 years in modern humans and about 3.5 years in apes, erupted between 4 and 4.5 years in Homo erectus. Previously, most people accepted this boy was close to 11 or 12 years of age, but now it seems more likely he was closer to 8 years of age, which is a surprise because he was already 5 feet 3 inches tall."

"It seems our prolonged period of growth and development may be a more recent evolutionary acquisition that arose in step with our comparatively recent development of a larger, modern, human-sized brain," Walker says.

This research was supported by the Royal Society and the Leverhulme Trust.


Story Source:

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


Cite This Page:

Penn State. "Fossil Teeth Reveal Recent Origin Of Human Growth Pattern." ScienceDaily. ScienceDaily, 7 December 2001. <www.sciencedaily.com/releases/2001/12/011206073838.htm>.
Penn State. (2001, December 7). Fossil Teeth Reveal Recent Origin Of Human Growth Pattern. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2001/12/011206073838.htm
Penn State. "Fossil Teeth Reveal Recent Origin Of Human Growth Pattern." ScienceDaily. www.sciencedaily.com/releases/2001/12/011206073838.htm (accessed October 24, 2014).

Share This



More Fossils & Ruins News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Fossil Treasures at Risk in Morocco Desert Town

Fossil Treasures at Risk in Morocco Desert Town

AFP (Oct. 23, 2014) Hundreds of archeological jewels in and around the town of 30,000 people prompt geologists and archeologists to call the Erfoud area "the largest open air fossil museum in the world". Duration: 02:17 Video provided by AFP
Powered by NewsLook.com
Oldest Bone Ever Sequenced Shows Human/Neanderthal Mating

Oldest Bone Ever Sequenced Shows Human/Neanderthal Mating

Newsy (Oct. 23, 2014) A 45,000-year-old thighbone is showing when humans and neanderthals may have first interbred and revealing details about our origins. Video provided by Newsy
Powered by NewsLook.com
Weird-Looking Dinosaur Solves 50-Year-Old Mystery

Weird-Looking Dinosaur Solves 50-Year-Old Mystery

Newsy (Oct. 23, 2014) You've probably seen some weird-looking dinosaurs, but have you ever seen one this weird? It's worth a look. 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