Navigation Links
Some like it hot: Site of human evolution was scorching
Date:6/8/2010

If you think summer in your hometown is hot, consider it fortunate that you don't live in the Turkana Basin of Kenya, where the average daily temperature has reached the mid-90s or higher, year-round, for the past 4 million years.

The need to stay cool in that cradle of human evolution may relate, at least in part, to why pre-humans learned to walk upright, lost the fur that covered the bodies of their predecessors and became able to sweat more, Johns Hopkins University earth scientist Benjamin Passey said.

"The 'take home' message of our study," said Passey, whose report appears this week in the online early edition of Proceedings of the National Academy of Sciences, "is that this region, which is one of the key places where fossils have been found documenting human evolution, has been a really hot place for a really long time, even during the period between 3 million years ago and now when the ice ages began and the global climate became cooler."

Passey, an assistant professor in the Morton K. Blaustein Department of Earth and Planetary Sciences at the university's Zanvyl Krieger School of Arts and Sciences, says that conclusion lends support to the so-called "thermal hypothesis" of human evolution.

That hypothesis states that our pre-human ancestors gained an evolutionary advantage in walking upright because doing so was cooler (when it is sunny, the near-surface air is warmer than air a few feet above the ground) and exposed their body mass to less sunlight than did crawling on all fours. The loss of body hair (fur) and the ability to regulate body temperature through perspiration would have been other adaptations helpful for living in a warm climate, according to the hypothesis.

"In order to figure out if (the thermal hypothesis) is possibly true or not, we have to know whether it was actually hot when and where these beings were evolving," he said. "If it was hot, then that hypothesis is credible. If it was not, then we can throw out the hypothesis."

Evaluating whether the ancient Turkana Basin climate was, in fact, the same scorching place it is today has been difficult up until now because there are very few direct ways of determining ancient temperature. Efforts to get a handle on temperatures 4 million years ago through analysis of fossil pollen, wood and mammals were only somewhat successful, as they reveal more about plants and rainfall and less about temperature, Passey said.

Passey, however, previously was part of a team at the California Institute of Technology that developed a geochemical approach to the "temperature problem." The method involves determining the temperatures of carbonate minerals that form naturally in soil (including a sedimentary rock called "caliche" and hard pan, which is a dense layer of soil, usually found below the uppermost topsoil layer) by examining "clumps" of rare isotopes. (Isotopes are atoms of the same element that have different masses due to differences in the number of neutrons they contain.)

In the case of soil carbonates common in the Turkana Basin, the amount of rare carbon-13 bonded directly to rare oxygen-18 provides a record of the temperature during the initial formation of the mineral. It told the team that soil carbonates there formed at average soil temperatures between 86 and 95 degrees Fahrenheit, leading to the conclusion that average daytime air temperatures were even higher. In other words, it was hot way back then in what is now northeastern Kenya.

"We already have evidence that habitats in ancient East Africa were becoming more open, which is also hypothetically part of the scenario for the development of bipedalism and other human evolution, but now we have evidence that it was hot," Passey said. "Thus, we can say that the 'thermal hypothesis' is credible."


'/>"/>

Contact: Lisa DeNike
Lde@jhu.edu
443-287-9960
Johns Hopkins University
Source:Eurekalert

Related biology news :

1. East-African human ancestors lived in hot environments, says Caltech-led team
2. Scientists discover ancient viral invasion that shaped human genome
3. Innovative research reawakens human memories through intelligent textiles
4. New culture dish could advance human embryonic stem cell research
5. Powerful genome barcoding system reveals large-scale variation in human DNA
6. European Society of Human Reproduction and Embryology Annual Meeting
7. Early human habitat was savanna, not forest
8. UCI researchers create retina from human embryonic stem cells
9. Discovery of stem cell illuminates human brain evolution, points to therapies
10. Allen Institute for Brain Science launches Allen Human Brain Atlas
11. Co-discoverer of 4.4-million-year-old Ardi to give talk at UC Riverside on human evolution
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/3/2017)... 2017  Data captured by IsoCode, IsoPlexis ... a statistically significant association between the potency ... and objective response of cancer patients post-treatment. ... whether cancer patients will respond to CAR-T ... as to improve both pre-infusion potency testing and ...
(Date:3/30/2017)... 2017 Trends, opportunities and forecast in this ... technology (fingerprint, AFIS, iris recognition, facial recognition, hand geometry, ... end use industry (government and law enforcement, commercial and ... and others), and by region ( North America ... Asia Pacific , and the Rest of the ...
(Date:3/27/2017)... 27, 2017  Catholic Health Services (CHS) has ... Society (HIMSS) Analytics for achieving Stage 6 on ... . In addition, CHS previously earned a place ... an electronic medical record (EMR). "HIMSS ... of EMR usage in an outpatient setting.  This ...
Breaking Biology News(10 mins):
(Date:7/20/2017)... Minn., July 20, 2017   KCNQ2 Cure ... genetic evaluations company, today announced that they have ... a genetic mutation implicated in KCNQ2 epileptic encephalopathy. ... for a second case involving an additional KCNQ2 ... Cure Alliance and Pairnomix entered into a collaboration ...
(Date:7/18/2017)... ... July 18, 2017 , ... Genedata, ... a leading science and technology company, has implemented Genedata Biologics ™ to ... areas of Oncology, Immunology, and Neurodegenerative Diseases. , The need to systematically evaluate ...
(Date:7/17/2017)... (PRWEB) , ... July 17, 2017 , ... ... its drug delivery device testing capabilities to encompass the full series of ISO ... comprehensive evaluations of fittings for medical device and drug delivery systems. With this ...
(Date:7/17/2017)... ... July 17, 2017 , ... ... Ph.D. , recently participated in the BiG (Biomedical Innovation Group) annual meeting in ... discussions of CAR-T (chimeric antigen receptor T-cell) therapy, a rapidly developing highly personalized ...
Breaking Biology Technology: