Featured Research

from universities, journals, and other organizations

Birth Rate, Competition Are Major Players In Hominid Extinctions

Date:
February 28, 2007
Source:
Penn State
Summary:
Modern human mothers are probably happy that they typically have one, maybe two babies at a time, but for early hominids, low birth numbers combined with competition often spelled extinction. "The lineages of primates have some traits that make it hard for them to respond to rapid perturbations in the environment," says Dr. Nina G. Jablonski, professor of anthropology and department head at Penn State. "Through time we see a lot of lineages become extinct when environments where the species are found become highly seasonal or unpredictable."

Modern human mothers are probably happy that they typically have one, maybe two babies at a time, but for early hominids, low birth numbers combined with competition often spelled extinction.

"The lineages of primates have some traits that make it hard for them to respond to rapid perturbations in the environment," says Dr. Nina G. Jablonski, professor of anthropology and department head at Penn State. "Through time we see a lot of lineages become extinct when environments where the species are found become highly seasonal or unpredictable."

Primates evolved in the Paleocene and Eocene when worldwide climate was less seasonal. The beneficial environment allowed primates to evolve as relatively brainy animals that reproduce slowly. However, when climate changed so that tropical forests shrunk and the environment became patchy, many species including primate species became extinct.

"While past primate populations moved with the forest, early hominid cultures 2.5 million years ago show signs of the ability to live in marginal areas and live on more dynamic, seasonal landscapes," Jablonski told attendees today (Feb. 16) at the annual meeting of the American Association for the Advancement of Science in San Francisco.

Through time, the human lineage evolved to fill a wide variety of ecological niches, but those species that filled narrow environments, were less able to withstand the effects of climate change. Paranthropus boisei, a Pleistocene hominid, thrived around 2.5 million years ago, but disappears from the fossil record a million years ago. Paranthropus boisei became extinct when it was unable to compete with other mammals.

A specialized feeder, Paranthropus boisei dined on hard objects like seeds, tubers and bones. While it had a variety of food sources, they all required the crunching, grinding force of its teeth. Unfortunately, bush pigs and hyenas had great grinding and crushing teeth, too, and went after the same food. Paranthropus could not compete because it produced one offspring a year at most, while the others had large litters and could increase their populations at a much faster rate. Paranthropus simply could not compete reproductively and could not alter its choice of food.

"We find that the early members of the genus Homo who succeeded were super ecological opportunists," says Jablonski. "They would eat vegetation and scavenge, kill small animals and forage."

Cultural adaptations helped these opportunists to take advantage of whatever food was available. But culture did not seem to help the Neandertal. Tremendously successful from about 200 to 50 thousand years ago, they suffered a gradual decrease and extinction from about 30 to 26 thousand years ago.

"Neandertal was extremely adept culturally," says Jablonski. "They had big brains, a wide variety of tools and were extremely successful as active, aggressive hunters of large game. We see evidence of hunting, kill sites, butchery and even herding off cliffs. We find thrusting spears and butchering knives." The Neandertal encountered increasing environmental seasonality with longer cold seasons and shorter periods of warm weather. Leading up to and during the last glacial maximum about 18,000 years ago, the grassy plains disappeared, taking with them the animals that relied on large expanses of grass for grazing. These animals were the prime food source for Neandertal.

At the same time, modern Homo sapiens experienced the same reduction in large animal game, but switched to also fishing, snaring small mammals like rabbits and capturing turtles and birds.

"Rather than being a specialized large mammal predator, modern humans would eat anything they could get their hands on. They eked out a living even if it meant eating grasshoppers or whatever," says Jablonski. "Even with this, modern humans barely hung on from 12 to 16,000 years ago.

"Why did Neandertal not adapt culturally?" she asks. "Why did they not start eating bunnies? They did begin fishing."

Jablonski believes that competition from modern humans was already too strong. The environment was marginal and modern humans were already foraging and small-animal collecting.

"I think they were out-competed at the very end," says Jablonski. "Modern humans simply did it better, more nimbly."

She adds that modern humans may have had storage capabilities that Neandertal did not. There is evidence that modern humans did have the capacity to store food and water in the late Pleistocene. No evidence exists that Neandertal could store either.

Both Neandertal and modern humans suffered from the primate curses of single births widely spaced. For Neandertal, cultural adaptation was not sufficient to overcome and compete with modern humans, just as Paranthropus boisei could not compete with the likes of bush pigs and hyenas. " Can we, today, control our cultural behavior to ensure our environmental success," says Jablonski. "Can we control growth and population density, or come up with new technology to overcome the problems we will face from the global climate change we have created?

"We clearly have the cultural ability to do either," says the Penn State researcher. "But both require forethought and planning to face the demographic and climate change. A degree of honesty, our species is not known for."


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. "Birth Rate, Competition Are Major Players In Hominid Extinctions." ScienceDaily. ScienceDaily, 28 February 2007. <www.sciencedaily.com/releases/2007/02/070218141435.htm>.
Penn State. (2007, February 28). Birth Rate, Competition Are Major Players In Hominid Extinctions. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2007/02/070218141435.htm
Penn State. "Birth Rate, Competition Are Major Players In Hominid Extinctions." ScienceDaily. www.sciencedaily.com/releases/2007/02/070218141435.htm (accessed July 24, 2014).

Share This




More Fossils & Ruins News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Mint Gives JFK Coin a Face-Lift

Mint Gives JFK Coin a Face-Lift

AP (July 24, 2014) The U.S. Mint has re-designed the John F. Kennedy half dollar coin to better match the former president's likeness. (July 24) Video provided by AP
Powered by NewsLook.com
Raw: MD Church Built in 1773 Ravaged by Fire

Raw: MD Church Built in 1773 Ravaged by Fire

AP (July 22, 2014) Authorities say a 241-year-old church on the National Register of Historic Places has been ravaged by fire in Maryland. (July 22) Video provided by AP
Powered by NewsLook.com
Neil Armstrong's Post-Apollo 11 Life

Neil Armstrong's Post-Apollo 11 Life

Newsy (July 19, 2014) Neil Armstrong gained international fame after becoming the first man to walk on the moon in 1969. But what was his life like after the historic trip? Video provided by Newsy
Powered by NewsLook.com
A Centuries' Old British Tradition Is Far from a Swan Song

A Centuries' Old British Tradition Is Far from a Swan Song

AFP (July 19, 2014) As if it weren't enough that the Queen is the Sovereign of the UK and 15 other Commonwealth realms, she is also the owner of all Britain's unmarked swans. Duration: 02:18 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