Print 79 comment(s) - last by BillyBatson.. on Jan 3 at 4:04 PM

Adversity breeds strength -- and perhaps human intelligence

It's a widely held hypothesis that ecological and climatological changes had a crucial driving role in evolution throughout history.  Now Penn State University geoscience professor Katherine Freeman and her graduate student, Clayton Magill, have put forth an intriguing study, which suggests that chaos in the ecosystem of East Africa drove mankind's ancestors to radically evolve 2 million years ago.

I. Life on the Chaotic Savanna

Mr. Magill comments, "The landscape early humans were inhabiting transitioned rapidly back and forth between a closed woodland and an open grassland about five to six times during a period of 200,000 years.  These changes happened very abruptly, with each transition occurring over hundreds to just a few thousand years."

To examine the ecological transition that coincided with this crucial phase of hominid evolution the researchers traveled to the Olduvai Gorge in northern Tanzania, collecting lake sediments.  Filtering the sediments of different ages, they performed biochemical analysis looking for fossilized chemical traces of grasses and trees.

Specifically, they sifted through sediments looking for leaf waxes, hardy biochemicals that tend to resist breakdown and survive, even over millions of years.  By performing gas chromatography and mass spectrometry analyses on the various waxes, the researchers were able to pinpoint both the foliage and composition to within a couple centuries.

Tanzania Gorge
Biochemical analysis of local sediments in a Tanzania gorge have offered key clues as to the evolutionary path of mankind's hominid ancestors. [Image Source: Gail Ashley]

What they discovered was that the "Great Drying", which is widely proven to have occurred in Africa around 3 million years ago, was not as much of a one-way process as was previously thought.  Rather, the sediments showed that the local ecosystem appears to have gone through a chaotic transition period in which the climate would fluctuate between wet and dry, before eventually gravitating fully to drier savanna.

To better understand the source of such strange and chaotic cycling, the researchers used statistical and mathematical models to formulate a hypothesis on the causes.  

Explains Professor Freeman, "The orbit of the Earth around the sun slowly changes with time.  These changes were tied to the local climate at Olduvai Gorge through changes in the monsoon system in Africa. Slight changes in the amount of sunshine changed the intensity of atmospheric circulation and the supply of water. The rain patterns that drive the plant patterns follow this monsoon circulation."

"We found a correlation between changes in the environment and planetary movement.  We find complementary forcing mechanisms: one is the way Earth orbits, and the other is variation in ocean temperatures surrounding Africa."

II. Adversity Breeds Evolved Intelligence

The chaos would obviously cause great stress on hominids living in the region forcing them to adapt to different food sources, different landscape, and different predators.  Mr. Magill and Professor Freeman suggest this was a key driver of the evolution of human intelligence.

Comments Mr. Magill, "Early humans went from having trees available to having only grasses available in just 10 to 100 generations, and their diets would have had to change in response.  Changes in food availability, food type, or the way you get food can trigger evolutionary mechanisms to deal with those changes." 

"The result can be increased brain size and cognition, changes in locomotion and even social changes -- how you interact with others in a group. Our data are consistent with these hypotheses. We show that the environment changed dramatically over a short time, and this variability coincides with an important period in our human evolution when the genus Homo was first established and when there was first evidence of tool use."

human intelligence
The papers suggest chaotic climate changes triggered the rise of human intelligence.
[Image Source: Pace J. Miller]

The research was published as a pair of papers [abstracts] in the prestigious peer-reviewed journal The Proceedings of the National Academy of Sciences (PNAS).  Among the other researchers working on the team was Rutgers University earth and planetary sciences professor Gail Ashley.  The research was funded by a National Science Foundation (NSF) grant.

Sources: PNAS [1], [2]

Comments     Threshold

This article is over a month old, voting and posting comments is disabled

RE: I don't think so...
By ppardee on 12/28/2012 7:46:32 PM , Rating: -1
Evolution is more than what you cite with bacterial strains becoming resistant to antibiotics. There are some major leaps that CAN'T be explained by natural selection.

Modern humans have larger brains. That along with standing upright and the changes in the hips/pelvis those required made child birth VERY dangerous. The idea of natural selection would say that these changes would have been weeded out. They aren't off-set by a greater intelligence since there is no evidence of that until long after the physiological changes.

That and natural selection doesn't generate new traits. The bacteria already had some resistance to antibiotics, which is why you can't just take one dose and be done with it. And again with the skin color: Human skin was capable of producing melanin already, changing the amount of melanin produced is not anything spectacular or evolutionary.

The transitional fossils are pretty pathetic. I'm willing to suspend disbelief a little bit and say that it is possible that the changes between Ardipithecus and Australopithecus could have happened in one generation (one gene - or set of genes - changed) but not to the point where I'd claim it as proof of anything... There should be quite a few steps between the two, which seems unlikely since they were essentially contemporary.

RE: I don't think so...
By retrospooty on 12/28/2012 8:40:49 PM , Rating: 4
"Evolution is more than what you cite with bacterial strains becoming resistant to antibiotics. There are some major leaps that CAN'T be explained by natural selection.

Of course it is more than that. That is one small example we have seen over the century or so since Penecillin was developed.

"Modern humans have larger brains. That along with standing upright and the changes in the hips/pelvis those required made child birth VERY dangerous. The idea of natural selection would say that these changes would have been weeded out."

That's not how it works. Try more like this. As trees in Africa became more and more scarce there were less and less places for us to hide and the distance between 2 safe places farther and farther. This pushed our tree dwelling ancestors to have to walk to get to the next bunch of trees. Over 100's of thousands of years, those that were faster and able to stand up higher on 2 feet managed to live better, and their offspring did the same and so on and eventually we were erect. This freed up our hands to hold tools that helped us to become hunters that helped us get the protien to facilitate larger brains. Its over 100's of thousands of years.

"That and natural selection doesn't generate new traits."
See previous section or google it FFS!. The info is out there. I didnt make it up.

"The transitional fossils are pretty pathetic."
We have thousands of fossils that document every step of the way with backing data from our own DNA, and archaeological and geological evidence that all paint the same picture. This is why every scientist on Earth knows we evolved and anyone that thinks otherwise is either uninformed or in denial... period. As I said, the debate is long over.

RE: I don't think so...
By Mitch101 on 12/29/2012 8:35:21 AM , Rating: 2
I tell you all I know from watching Discovery Channel and History Channel is everything I learned in School some 20+ years ago is utter BS. I want a regrade.

Hopefully there will be a nice 1-2 hour program on those channels that I can watch that brings me into the 20th century with what the latest theory/facts are.

Until then its aliens.

"What would I do? I'd shut it down and give the money back to the shareholders." -- Michael Dell, after being asked what to do with Apple Computer in 1997

Copyright 2014 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki