Did climate change shape human evolution?

Apr 24, 2012 By David Funkhouser
Homo erectus, Museum of Natural History, Ann Arbor, Mich. Credit: Thomas Roche/San Francisco

(Phys.org) -- As human ancestors rose on two feet in Africa and began their migrations across the world, the climate around them got warmer, and colder, wetter and drier. The plants and animals they competed with and relied upon for food changed. Did the shifting climate play a direct role in human evolution?

The evidence so far is thin, said Richard Leakey, the renowned and who joined a score of scientists delivering their findings at a conference on and human evolution this week, held at ’s Lamont-Doherty Earth Observatory.

“Is there evidence for a direct connection between changing climate and human evolution?” Leakey asked during a keynote address Thursday. “The answer so far is no. I don’t see it yet.”

Still, a number of scientists are on the hunt. Speakers talked about changes in , and how fluctuations in temperature and rainfall would have altered the landscapes. They’re studying what carbon isotopes in soil can tell us about changing plant life and temperature; what hominid teeth suggest about changes in diet; and what sediment cores from the bottom of the ocean have to say about variations in monsoon rainfall.

What did all this mean for our ancestors? If the climate affected human evolution, “there should be a substantial adaptive response,” Leakey said. But with a limited fossil record, “We are stuck with this very, very narrow vision” of human evolution, Leakey said.

Leakey has been in the middle of the search for for decades, following in the footsteps of his famous parents, the archeologists Louis and Mary Leakey, whose work at Olduvai Gorge in northern Tanzania was key to the understanding of . He lives in Kenya, where he has been active in politics and conservation; he also is a professor of anthropology at Stony Brook University.

Leakey suggested the focus of research should be on trying to answer four key questions:

First, what would have prompted hominids to go bipedal – standing upright with the big toe pointing straight ahead?

“Standing upright on two legs is not only an odd way to be,” he said, “but a huge adaptation to what was going on.”

Second, what prompted our ancestors to begin using one tool to make another, and when: “The use of stone to make stone that can cut flesh is important. We’re not empirical things, we’re thinkers. … What was it that triggered that response?”

The third point has to do with the first of hominids out of Africa, when homo erectus spread into Asia and Europe. “At some point about 1.8 million years ago, a hominid shoes up in Europe. That implies experience with different environments, and that implies technology,” Leakey said. But, he asked, why didn’t that hominid continue to thrive?

Lastly, what drove the second migration of hominids — this time homo sapiens — out of ?

For more on the conference, visit the web site. Stay tuned for a video of the talks, which will be available at the site in the future. Professor Peter deMenocal, a paleoclimatologist at Lamont-Doherty and vice chairman of the Department of Earth and Environmental Sciences, organized the conference, which brought in scientists from around the world to talk about their latest research.

Explore further: Richard III's makeshift grave opens to public

Related Stories

Unraveling malaria's genetic mysteries

Dec 22, 2011

(PhysOrg.com) -- Simon Fraser University researchers in biology and computing sciences are starting to piece together a picture that may help scientists and doctors save more than a million lives annually.

New tool enhances view of muscles

Jan 23, 2012

Simon Fraser University associate professor James Wakeling is adding to the arsenal of increasingly sophisticated medical imaging tools with a new signal-processing method for viewing muscle activation details that have never ...

Warming of two degrees inevitable over Canada: study

Mar 04, 2012

(PhysOrg.com) -- Even if zero emissions of greenhouse gases were to be achieved, the world’s temperature would continue to rise by about a quarter of a degree over a decade. That’s a best-case ...

Recommended for you

West US cave with fossil secrets to be excavated

Jul 24, 2014

(AP)—For the first time in three decades, paleontologists are about to revisit one of North America's most remarkable troves of ancient fossils: The bones of tens of thousands of animals piled at the bottom ...

Radar search to find lost Aboriginal burial site

Jul 22, 2014

Scientists said Tuesday they hope that radar technology will help them find a century-old Aboriginal burial ground on an Australian island, bringing some closure to the local indigenous population.

User comments : 17

Adjust slider to filter visible comments by rank

Display comments: newest first

EdMoore
1 / 5 (13) Apr 24, 2012
Wow.

Two, two junk science ideologies rolled into one!

Doublemint deception!

plaasjaapie
1.1 / 5 (10) Apr 24, 2012
"Lastly, what drove the second migration of hominids this time homo sapiens out of Africa?"

Still trying to retail the old H. Sap. "our of Africa" notion, I see. I guess Leakey would have a hard time justifying his family's life and work otherwise.
foofighter
3.3 / 5 (7) Apr 24, 2012
lol - there is more evidence for evolution than there is for the bible's inerrancy. you creationist niggers talk as if your shit doesn't smell
Torbjorn_Larsson_OM
5 / 5 (10) Apr 24, 2012
@ EdMore:

Wow, not even climate denialists deny global warming! But they are often creationists, two crackpotisms in one package. You are going for the hat trick.

@ plaasjaapie:

I'm not sure what you are referring to here, OOA is the reigning model. href="http://en.wikiped...n_humans : "In paleoanthropology, the recent African origin of modern humans, frequently dubbed the "Out of Africa" theory, is the most widely accepted model describing the origin and early dispersal of anatomically modern humans."
plaasjaapie
1.4 / 5 (8) Apr 24, 2012
...except that the oldest H. Sap. fossils by a long shot have been found in Israel, not Africa.
NotParker
1 / 5 (10) Apr 24, 2012

"the climate around them got warmer, and colder, wetter and drier"

Perfect AGW! It encompasses all possibilities. Therefore it can never be wrong.

Which makes it a cult, not a science
Calenur
4.5 / 5 (8) Apr 24, 2012

Perfect AGW! It encompasses all possibilities. Therefore it can never be wrong.

Which makes it a cult, not a science


.....ummm...elephant in the room? That perfectly describes religion.
nkalanaga
5 / 5 (8) Apr 24, 2012
NotParker: How could climate change a million years ago BE "AGW"? Since we had no technology back then, and there were very few of us, any climate variations have to be natural. Unless you're denying that the climate has ever changed for any reason?
rwinners
5 / 5 (2) Apr 25, 2012
I'd guess that every environmental variable that prehistoric 'humanity' experienced over a significant period of time effected human evolution.
nkalanaga
4 / 5 (5) Apr 25, 2012
More than likely, as that's how evolution works. Those that survive the change reproduce. Those that don't, don't. Thus, the offspring, as a group, are better adapted to the change. Repeat long enough, and the species is very well adapted. Then, if conditions change back, the process repeats. If the species has adapted too well, it may not have enough genetic variation to change back, and it goes extinct. Species that survive multiple changes tend to be more variable than those that live in a single stable environment.

In H.sapiens case, we can adapt mentally and through tools rather than by genetic changes, which gives us an added advantage - so far.
PeterKinnon
2.5 / 5 (2) Apr 25, 2012
An oft-overlooked source of selection pressure for the remarkable encephalization of our species is that of intra-species warfare.

This has strong positive feedback potential for both biological and technological "arms race" scenarios. Greatly potentiated by tool-use and also productive of stronger intra-group social organization and bonding.

This model is outlined in my freely downloadable e-books which are to be found at the "Unusual Perspectives" website
NotParker
1.5 / 5 (8) Apr 25, 2012
NotParker: How could climate change a million years ago BE "AGW"? Since we had no technology back then, and there were very few of us, any climate variations have to be natural. Unless you're denying that the climate has ever changed for any reason?


The climate always changes. Naturally. It has never needed man. And man has no effect. Except for the Urban Heat Island that surrounds our towns and cities and thermometers and raises temperatures by as much as 9C in the summer. And causes the gullible to think the globe has warmed because of CO2.
LariAnn
1 / 5 (3) Apr 25, 2012
No matter what kind of changes take place, in order for adaptation to take place, the genetic material must be present, either as a recessive or inactive gene(s) or as part of an active genome. If there is no genetic material present that can code for, say, thick fur. the organism won't survive under conditions where thick fur is required for survival. No "evolution" will change this, especially if adaptation is required within the span of a human lifetime or generation! By contrast, in huge populations of microorganisms, resistance to an antibiotic can manifest in a few generations. Ancient human populations were sure to be vastly smaller in numbers than microbe populations, precluding this kind of rapid adaptation to sudden change.
kaasinees
1 / 5 (3) Apr 25, 2012
"Lastly, what drove the second migration of hominids this time homo sapiens out of Africa?"

Still trying to retail the old H. Sap. "our of Africa" notion, I see. I guess Leakey would have a hard time justifying his family's life and work otherwise.

Ik hoop van harte dat jij geen nederlander ben want ls dat wel zo is ga ik mij kapot schamen voor mijn volk dat iemand zo als jij bestaat.
Egleton
2 / 5 (4) Apr 29, 2012
@ kaasie
Hey Kaaskop. Jy moet in Engles scruif. Ek kannie jou taal verstaan nie.
NotParker
1 / 5 (4) Apr 29, 2012
"Lastly, what drove the second migration of hominids this time homo sapiens out of Africa?"

Still trying to retail the old H. Sap. "our of Africa" notion, I see. I guess Leakey would have a hard time justifying his family's life and work otherwise.

Ik hoop van harte dat jij geen nederlander ben want ls dat wel zo is ga ik mij kapot schamen voor mijn volk dat iemand zo als jij bestaat.


Ik ben blij dat ik heb geen nederlanders in mij. Als je een represenative van de nederlandse dan zijn ze dom. Natuurlijk, wanneer ik in Nederland een bezoek aan een lange tijd geleden waren ze heel mooi. Uiteraard hebben ze meer manieren en hersenen dan jij. Ik mis rijsttafel.
DarkHorse66
1 / 5 (1) Apr 30, 2012
I may not speak Dutch, but I can guess at some of the conversation. If I have interpreted correctly, Egleton is calling kaasinees a 'cheesehead'(kaas=cheese, kop=head) for not writing in English. As for the other two; you might like 'having Nederlander within you', but don't you think that, as your country's 'resprentatives', you should be showing off your better 'manieren'(manners) by communicating in the official communal language of this site? Or use the PM option in your accounts? You could also use this to exchange email addresses privately and talk Dutch to each other in that way. Either that, or provide a proper translation. I suspect that in this regard, I speak for many on this site. Best Regards, DH66.