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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]



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diamonds are forever.
By drycrust3 on 12/27/2012 11:57:45 PM , Rating: -1
quote:
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.

Ok, so let me get this right: leaf wax somehow sat on the ground for 2 million years? How can leaf wax survive 2 million years of daily UV radiation? I think diamonds are one of the few things around that might actually have survived that long.
Oh, that's right, this leaf wax was actually under the ground for "2 million years". So what they mean is these leaves were buried very quickly by some extinction event, you know, one of those events where billions of dead things were buried by water, and covered by rocks all over the planet. Historical records from antiquity, as well as tribal legends from all over the planet do actually mention one such event like that, but of course I doubt they'd be interested in knowing this, especially as these leaves were almost certainly buried in that event.
Do you know what I think? I think if they bothered to carbon 14 date the stuff they'd get a result, and it wouldn't be 2 million years old. Oh, that's right, it wasn't actually 2 million years, they got a "within a couple of centuries" result, but we aren't told what the actual date determined was.
You know what else I think? I think if they look around in those sediments they might actually find some seeds with DNA in them.




RE: diamonds are forever.
By finetsky on 12/28/2012 4:50:13 AM , Rating: 2
"You know what else I think? I think if they look around in those sediments they might actually find some seeds with DNA in them."
What an advise... :-D you can be sure they took all they could possibly find and analyzed it.
BTW what are you suggesting as a real event? Big flood orchestrated by god? I hope not...
"I think if they bothered to carbon 14 date the stuff they'd get a result, and it wouldn't be 2 million years old."
Of course they bothered with dating! In case they wouldn't nobody would care about such a research. You tell them what should they do and what should they find but you have no basic understanding. Do you realize how stupid that is?


RE: diamonds are forever.
By gladiatorua on 12/28/2012 4:54:04 AM , Rating: 2
quote:
Oh, that's right, this leaf wax was actually under the ground for "2 million years". So what they mean is these leaves were buried very quickly by some extinction event, you know, one of those events where billions of dead things were buried by water, and covered by rocks all over the planet.
No, all this means is the chance of some kind of burial event like landslide is high if you take a large area and long period of time.
quote:
Historical records from antiquity, as well as tribal legends from all over the planet do actually mention one such event like that, but of course I doubt they'd be interested in knowing this, especially as these leaves were almost certainly buried in that event
Yes, because local floods are sooo rare. And word of mouth information storage is sooo precise.
quote:
Do you know what I think? I think if they bothered to carbon 14 date the stuff they'd get a result, and it wouldn't be 2 million years old.
Exactly! Because carbon 14 dating has quite limited range. Do you know how carbon 14 dating works? It has a half life of ~5730 years and has natural concentration of 1 part per trillion, so after 57300 years the concentration is reduced by 2^10=1024 times.
quote:
You know what else I think? I think if they look around in those sediments they might actually find some seeds with DNA in them.
Scientists would be happy to ha 2 million year old live seeds.


RE: diamonds are forever.
By EvL OnE on 12/31/2012 11:28:33 AM , Rating: 1
If we can explain how all the animals evolved then man can’t be far off. What was before the big bang and does it = the big collapse....


RE: diamonds are forever.
By Piiman on 12/31/2012 5:03:24 PM , Rating: 2
I like that big collapse thing. Once we stop expanding from the big bang there is no reason gravity won't start pulling us all back. It could be a big endless cycle.


RE: diamonds are forever.
By wgbutler on 12/31/2012 5:14:35 PM , Rating: 2
quote:

I like that big collapse thing. Once we stop expanding from the big bang there is no reason gravity won't start pulling us all back. It could be a big endless cycle.


I know you like it, because it caters to your emotional desire for atheism to be true. Your problem is that one of the leading cosmologists in the world has already discredited the "endless cycle" hypothesis and says that all the scientific evidence points to the universe having a distinct beginning.

http://www.uncommondescent.com/intelligent-design/...

quote:

Disorder increases with time. So following each cycle, the universe must get more and more disordered. But if there has already been an infinite number of cycles, the universe we inhabit now should be in a state of maximum disorder. Such a universe would be uniformly lukewarm and featureless, and definitely lacking such complicated beings as stars, planets and physicists – nothing like the one we see around us.

One way around that is to propose that the universe just gets bigger with every cycle. Then the amount of disorder per volume doesn’t increase, so needn’t reach the maximum. But Vilenkin found that this scenario falls prey to the same mathematical argument as eternal inflation: if your universe keeps getting bigger, it must have started somewhere.


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