Versus 
Image Credit: Wikipedia Image Credit: Anne Knock
From Live Science:
At Olduvai Gorge, where excavations helped to confirm Africa was the cradle of humanity, scientists now find the landscape once fluctuated rapidly, likely guiding early human evolution.These findings suggest that key mental developments within the human lineage may have been linked with a highly variable environment, researchers added.
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Scientists had long thought Africa went through a period of gradually increasing dryness — called the Great Drying — over 3 million years, or perhaps one big change in climate that favored the expansion of grasslands across the continent, influencing human evolution. However, the new research instead revealed “strong evidence for dramatic ecosystem changes across the African savanna, in which open grassland landscapes transitioned to closed forests over just hundreds to several thousands of years,” researcher Clayton Magill, a biogeochemist at Pennsylvania State University, told LiveScience.
The researchers discovered that Olduvai Gorge abruptly and routinely fluctuated between dry grasslands and damp forests about five or six times during a period of 200,000 years.
“I was surprised by the magnitude of changes and the rapid pace of the changes we found,” Freeman told LiveScience. “There was a complete restructuring of the ecosystem from grassland to forest and back again, at least based on how we interpret the data. I’ve worked on carbon isotopes my whole career, and I’ve never seen anything like this before.”
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The research team’s statistical and mathematical models link the changes they see with other events at the time, such as alterations in the planet’s movement.
“The orbit of the Earth around the sun slowly changes with time,” Freeman said in statement. “These changes were tied to the local climate at Olduvai Gorge through changes in the monsoon system in Africa.”
Earth’s orbit around the sun can vary over time in a number of ways — for instance, Earth’s orbit around the sun can grow more or less circular over time, and Earth’s axis of spin relative to the sun’s equatorial plane can also tilt back and forth. This alters the amount of sunlight Earth receives, energy that drives Earth’s atmosphere. “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.”
The team also found links between changes at Olduvai Gorge and sea-surface temperatures in the tropics.
Here’s the paper abstract
The role of savannas during the course of early human evolution has been debated for nearly a century, in part because of difficulties in characterizing local ecosystems from fossil and sediment records. Here, we present high-resolution lipid biomarker and isotopic signatures for organic matter preserved in lake sediments at Olduvai Gorge during a key juncture in human evolution about 2.0 Ma—the emergence and dispersal of Homo erectus (sensu lato). Using published data for modern plants and soils, we construct a framework for ecological interpretations of stable carbon-isotope compositions (expressed as δ13C values) of lipid biomarkers from ancient plants. Within this framework, δ13C values for sedimentary leaf lipids and total organic carbon from Olduvai Gorge indicate recurrent ecosystem variations, where open C4 grasslands abruptly transitioned to closed C3 forests within several hundreds to thousands of years. Carbon-isotopic signatures correlate most strongly with Earth’s orbital geometry (precession), and tropical sea-surface temperatures are significant secondary predictors in partial regression analyses. The scale and pace of repeated ecosystem variations at Olduvai Gorge contrast with long-held views of directional or stepwise aridification and grassland expansion in eastern Africa during the early Pleistocene and provide a local perspective on environmental hypotheses of human evolution.
Also, here’s the Supporting Information Appendix and an AGU ePoster from the same authors.
So research finds that climate change influences human development versus the inverse, Live Science appears to be an objective and informative information source, and Penn St. has honest and credible researchers, amazing stuff. I can end 2012 with a smile, I hope you all do so as well. 🙂 Just The Facts
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So if the unstable climate in the distant past spurred human development, maybe the benign climate of the last 14,000 years has been the cause of the rapidly shrinking human brain. http://discovermagazine.com/2010/sep/25-modern-humans-smart-why-brain-shrinking
If we don’t get some real climate chaneg soon, like the next ice age, we may all turn into muddle headed climate scientists and won’t have the common sense left to squeak through the next ice age like we did 140,000 years ago. http://www.scientificamerican.com/article.cfm?id=when-the-sea-saved-humanity
“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 know the paper is fake just from this. The IPCC is clear. The sun has no effect on the planet and when it does its only from major changes like if it goes super nova.
So even extreme, variable weather can be a positive thing from an evolutionary point of view. Too bad there’s no real evidence that CO2 actually causes extreme changes in the climate.
“…Earth’s orbit around the sun can vary over time in a number of ways — for instance, Earth’s orbit around the sun can grow more or less circular over time, and Earth’s axis of spin relative to the sun’s equatorial plane can also tilt back and forth. This alters the amount of sunlight Earth receives, energy that drives Earth’s atmosphere. “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.”…”
How could the AGW Warmists allow this heresy to pass through the editors of the Live Science?
they said the word models
Kinda makes me wonder what we’d all look like now if for the last ~90,000 years we had always had central HVAC, mechanized food production, clean hot and cold water, TV, modern medicine, etc.? (Maybe like that movie about the future where everybody is just really really stupid?)
This is not exactly ‘new’ research as far as I kknow. Neither does it explain why other creatures stayed relatively unchanged. Too little information, too much speculation.
Do supercomputers navel gaze more robustly and with greater precision vis a vis the assumptive models fed into them than the lone scientists brain navel gazing over such matters?
Plate tectonics? Would Africa have moved enough to effect climate?
“An examination of the fossil record indicates that the key junctures in hominin evolution reported nowadays at 2.6, 1.8 and 1 Ma coincide with 400 kyr eccentricity maxima, which suggests that periods with enhanced speciation and extinction events coincided with periods of maximum climate variability on high moisture levels.”
Trends, rhythms and events in Plio-Pleistocene African climate
Quaternary Science Reviews 28 (2009) 399–411
Not that many times in that short of a period. 200K years is basically two glacial/interglacial cycles.
I don’t think people fully appreciate exactly how these evolutions occur. Many seem to believe, in my conversations with them, that changes in the environment result in behavioral changes as the primary adaptation mechanism. While that is true to some extent, I don’t believe that is the primary mode. I believe that in any given large geographic region there are several practices among the people there. At any given moment, the local environment either favors or disfavors certain practices. So lets say there are two tribes and one tribe has a traditional practice that works best with woodland environments and another works best with savannah environments or maybe it isn’t even that clear cut, say one practice is less impacted by change than the other even if only to a small degree. As climate and the surrounding environmental conditions change, the impact is unequal between these two populations. Maybe they both suffer but one suffers disproportionately more than the other or maybe. Eventually one comes to dominate the other and maybe the other completely disappears.
We can see examples of this in our current situation. We have conditions that allow many different traditions to flourish. Veganism is one, in my opinion. That lifestyle requires year round access to a various vegetables that are not in season locally. It requires a huge infrastructure firing on all cylinders to support. In the case of a rapid change in climate to warming, that lifestyle thrives. In the opposite case, it would disappear. It takes a lot of energy to transport southern hemisphere veggies to Manitoba in winter.
So we have a period when a lot of different traditions can flourish and then we have a period of rapid climate change that causes a selection of the ones best able to handle the new conditions. This provides periods of experimentation and diversity where new experiments in human traditions are tried followed by periods of stress where those traditions that are most fragile are weeded out. This line of thought is one of the reasons why I oppose such things as maintaining river flows at “average” levels even in times of drought. Those species that live there have evolved under conditions of optimum followed by stress. This causes as selection of adaptations that are best suited to the entire range of conditions. By maintaining flows at “average” conditions, we are preventing the selecting out of the weaker lines and the results could be catastrophic when conditions get so bad that we can not maintain them by artificial means any longer. We NEED to have these periods of renaissance and “dark ages” to allow new ideas to spring forth and then a period of stress to test them and allow those who have an advantage to survive. In humans, it means a period of comfort where all sorts of new ideas can be tried followed by a period of hardship where the ideas best suited to harsh conditions out-perform those less suited to conditions. People don’t necessarily “change” their behaviors over time so much as groups of people with different ideas might triumph in the next period of hardship and people with other behaviors tend to diminish.
Toba (74kybp and similar pyroclastic events) punctuated things from time to time and contributed to basic point of the article.
crosspatch says:
December 26, 2012 at 11:27 pm
That pretty much defines where we just might be. Then again, since this is an eccentricity minima, ~200ky from the next eccentricity maxima, we may just have to engineer our way around Sirocko, et al’s, (2005) assessment:
““Investigating the pro¬cesses that led to the end of the last interglacial period is relevant for understanding how our ongoing interglacial will end, which has been a matter of much debate…..”
“The onset of the LEAP occurred within less than two decades, demonstrating the existence of a sharp threshold, which must be near 416 Wm2, which is the 65oN July insolation for 118 kyr BP (ref. 9). This value is only slightly below today’s value of 428 Wm2. Insolation will remain at this level slightly above the inception for the next 4,000 years before it then increases again.”
Given the latencies for atmospheric heat retention by CO2 literally littering the literature, can you think of anything we might do to make it through the next 4,000 years “before it (insolation) then increases again”?
Hmmmm, decisions decisions.….….….……
From the paper…..
The researchers discovered that Olduvai Gorge abruptly and routinely fluctuated between dry grasslands and damp forests about five or six times during a period of 200,000 years.
……
Lends credence to Charles Hapgood’s theory of the poles wandering backwards and forwards over a short period every 35,000 years?
It’s accepted that grasses evolved fire ( the spreading of naturally occuring fire) to help them compete with trees. This study (the rapid transitions from savanah to forest) indicates plants have evolved to manipulate the climate, e;g; through albedo, transpiration and rainfall runoff.
I don’t completely disagree with this but events that cause significant dramatic changes are more frequent than Toba and other super volcanoes. For example, I think one of the things that greatly slowed the habitation of Western Europe (and possibly hastened the demise of the Neanderthal) by modern man was likely the eruption of Campi Flegrei about 40kya. The ash from this eruption seems to coincide with the transition from the middle to upper Paleolithic. Human habitation below the level of ash shows mostly Neanderthal technology. Habitation above, mostly modern. But this eruption practically sterilized a large swath of land that would have gone right across the migratory path of most of the herd animals of the time. It would have prevented human migration for a considerable time, too, until enough life returned to the region to sustain a trek on foot across it. In other words, this eruption would have cut off the path of animals migrating southward for the winter and they would have died attempting it. This would cut off or greatly diminished most of the food supply for the Neanderthal in what is now Central and Western Europe who relied on herds of animals that migrated considerable distances during the glacial. The Neanderthal in Eastern Europe would have been buried. A second smaller eruption about 12K years ago probably didn’t help matters much but much depends on which way the winds were blowing at the time. We know that ash from the first eruption can be found all the way to the outskirts of Moscow.
crosspatch says:
December 27, 2012 at 12:19 am
I quite enjoyed this perspective
It is long known fact that to enforce evolution on population, you need to split it up into many parts, apply stress, eliminate those parts of the population which failed to adapt, then repeat the process. That’s exactly what they discovered in Africa where many places were switching between habitable and unhabitable for human predecessors.
Also, large portions of pre-human population getting eliminated by then was not such a big deal, they just silently died and left room for better adapted.
Today humans won’t allow nature to perform any such inhumane experiments on them. That’s why climate change (or whatever you want to call it) is seen as such a threat.
Why didn’t people move with the monsoon belt. The animals did. It seems to me that the movement of the monsoon belt is the fall back position when scientists are confronted with rapidly changing climate. How quickly did the monsoon belt change? It seemed to move fairly rapidly during the Holocene, on a number of occasions. In these kind of papers I always try and look at what is missing rather than what is said. Lots of stuff is left unsaid.
Steven Mosher says:
December 26, 2012 at 10:35 pm
“they said the word models”
Steven, Climate models are great tools to illustrate the past but lousy tools for prediction, can we agree on that? In the hands of a computer operator they can make for really realistically looking planets.
Philip Bradley says:
December 27, 2012 at 12:16 am
“It’s accepted that grasses evolved fire ( the spreading of naturally occuring fire) to help them compete with trees. This study (the rapid transitions from savanah to forest) indicates plants have evolved to manipulate the climate, e;g; through albedo, transpiration and rainfall runoff.”
Very logical! Co-evolution! Of course!
Had biological niches not evolved, we’d still be crawling out of the sea.
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It is really just common sense. After all, you only have to consider how much wars have done to spur technological advances, back to the dawn of civilisation.
Mike M says:
December 26, 2012 at 10:41 pm
Kinda makes me wonder what we’d all look like now if for the last ~90,000 years we had always had central HVAC, mechanized food production, clean hot and cold water, TV, modern medicine, etc.? (Maybe like that movie about the future where everybody is just really really stupid?)
Think “Wall-E”…
mogamboguru says:
December 27, 2012 at 5:09 am
Mike M says:
December 26, 2012 at 10:41 pm
Kinda makes me wonder what we’d all look like now if for the last ~90,000 years we had always had central HVAC, mechanized food production, clean hot and cold water, TV, modern medicine, etc.? (Maybe like that movie about the future where everybody is just really really stupid?)
Think “Wall-E”…
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Less like “Wall-E”, more like Kent Dorfman
http://youtu.be/u1hnwvWhbJw