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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RACookPE1978 says:
December 27, 2012 at 2:44 pm
““Evolution” – as it is accepted in today’s “science” – cannot predict, adapt,defend, change, nor prevent changes in any single generations Only an Intelligent Designer can act deliberately and with forethought.”
You can direct an evolution by designing the evaluation function. I’m not very good at that. A creator god would probably be more capable.
The author Michael Crichton proposed that development occurs best in the border region between stability and chaos.
Too much stability and there is no impetus for growth, too much chaos and there is no stable ground on which to build growth.
“This is not exactly ‘new’ research …”
I’m not even sure if it was exactly ‘new’ research twenty years ago when I first remember reading about it as an undergrad. Then again, this was in a class where the prof was fond of saying that the discovery of new species was often more closely correlated to researchers’ needs for funding than the appearance of new information. No reason the same doesn’t apply to new theories as well?
RACookPE1978
December 27, 2012 at 2:44 pm
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Yes, prey variability has been an important result of climate variability that has driven Carnivore evolution, but habitat variability has also played a significant role. Without going into much detail, carnivores can be classed as hyper-carnivores, meso-carnivores, or hypo-carnivores. Hyper-carnivory tends to be more vulnerable to changes in prey. But one of the best examples of a hyper-carnivore extinction, the Dire Wolf, not only succumbed to reduction of its prey, but to the elimination of its habitat. It was a grassland animal, ill suited for life in the forest that replaced the grasslands. The Grey Wolf, who has its own climate change story, was well suited to life in the forest and more importantly to life on the prairie as well. As a side note, it is also less hyper-carnivorous, so far less dependent on prey variability then poor C. dirus.
BTW, one carnivore line that has not changed much, a dedicated meso, is the one that is currently represented by my namesake, the coyote, and the golden jackal. But in general, the evolution of meso-carnivores is tightly linked to climate effects not related to prey directly.
One of the big drivers has been the opening and closing of the land route between Asia and North America. The ancestor to the large wolf-like canines probably first showed up in India, spread about Asia, when the last glaciation stranded a population in the Bearingia refugia. This population became old C.lupus. Another land bridge story is the Leopard, who’s ancestors are from North America. This lineage also led to the Jaguar before it extended its range to South America. It is sill found in Arizona.
As for the rest of your comment, I’ll start with a disclaimer. I am a Christian who believes in a G*D Who has a Plan, a G*D Who uses Processes. Evolution is a process. I am also an amateur mathematician who loves playing with chaotic system. I see no contradiction, and never have.
First, I see evolution in terms of trajectories. I hate using the term superior. I read an interesting statement once. “Every organism is perfectly adapted to its environment.” It’s true that evolution tends toward the more complex, but examples of the opposite are abundant. Is an placoderm inferior to a teleost? Who can judge? Not I. As for trajectories, carnivore evolution is filled with examples of lineages headed to a hyper-carnivorous condition, then back to a meso. Trajectory changes.
Second, evolution is not really about survival of the fittest, as much as it is about the ability of a population to produce offspring who live long enough to reproduce. Individuals don’t evolve, populations do. I hope you understand the significance of that. The simple random mutation model sort of falls a little flat.
In addition to enhancement to the ability to adapt, like C. latrans. one of classes of traits that organisms have evolved, are enhancements to the ability to evolve. I have kept aquarium fish for close to 40 years. I notice a very strange phenomena while breeding cichlids (which, for the record are superior!). The spawn from a pair that had just reached maturity would exhibit a great deal of variability. Subsequent breeding would produce successively less variability until the parents fourth or fifth spawning. In the wild, cichlids don’t normally successfully breed until they are a few years old.
Boy, I have written too much already. Its hard to serialize out the thoughts I am trying to express. I’ll try to sum things up. The process of evolution is far more complicated then the simple story that is taught in school more as a vehicle to slam Christianity, then to teach actual science. Its more then just chance random events, ore else the same forms would not keep showing up in different lineages.
Those interested in the subject will like Nassim Taleb’s book “Antifragile: Things That Gain from Disorder”.
For an introduction, read his recent article in the WSJ: Learning to Love Volatility.
DesertYote says:
December 27, 2012 at 11:14 pm
“I am a Christian who believes in a G*D Who has a Plan, a G*D Who uses Processes. Evolution is a process. I am also an amateur mathematician who loves playing with chaotic system. I see no contradiction, and never have.”
Very logical. See also universe as an evolutionary process (Big Bang theory was first introduced by a cleric and rejected by mainstream cosmologists – now the mainstream cosmologists themselves try to create theories that explain an evolution of particles and the natural laws that we observe now from a quite different starting condition; and see also the Brahma Egg creation myth of the Hindus)
The rabid atheism of Dakins looks more and more like a pretty ignorant position to me; a “lifeist” (Life-ism – an ideology that holds that life is special and superior to non-life… Dawkins can only explain what happened AFTER life suddenly came into existence – not HOW it came into existence or what happened before that moment. My non-living individuals in my genetic algorithms would object.)
Terrible piece of speculation, it even implies that we humans can adapt to a changing climate, a thing which is unprecedented in human history, according to climatology.
sarc off.
I agree the biggest obstacle to clear reasoning is our conceit. We control the weather, really we do, I insist its true. May storms strike if you doubt……..
Seriously I keep wondering if climatology is a mental disorder spawned by urban living and lack of physical experience with weather.
Will it go away when the sufferers are evicted from their parents basements? Released from their govt offices?
Kasuha says: December 27, 2012 at 1:47 am
That’s why climate change (or whatever you want to call it) is seen as such a threat.
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What climate change, pray tell?
@John: It seems likely climate change belief is a form of memory loss. The sufferer cannot remember what the weather was like over 10 minutes ago and thus believes any made up data he is presented with. Every storm seems the biggest and most damaging because they cannot remember any other storms. It’s sad.
The main question here is – why did genus Homo (Habilus say) evolve from the Australopithecus genus? The “climate” answer hardly satisfies this question. If the periodic ice ages, which started about 3 million years ago, caused such rapidly changing environments that higher intelligence was required to adapt, then why did not other animals evolve similarly?
Of course the answer involves other factors. These hominids apparently discovered how to use stone tools to access the meat in carcasses, which allowed them to scavenge, hunt, or steal meat off other predators. My favourite theory is the “stealing” strategy, as other predators and scavengers already abounded. Its unlikely that an Australopithicene could ambush prey, or run them down, or beat a hyena to left-over scraps. Stealing meat off predators obviously encourages higher intelligence, cooperative behaviour, and language.
Climate, which always changed slowly when measured against the lifespans of individual hominids, would simply have gradually moved ranges backwards and forwards, at a rate that the hominids could easily adapt to.
“May you live in interesting times.” Frequent severe bottlenecks are indeed the ideal stimulus to rapid evolution. Long boring periods of salubrious climate, not so much. Punk Eek ain’t fun to experience.
DirkH says:
December 27, 2012 at 1:15 pm
phlogiston says:
December 27, 2012 at 11:31 am
“@DirkH, reality check
Indeed the greens in question would do well to read some Steven J Gould (punctuated equilibrium).”
It can be observed in genetic algorithms. I often have weeks with no process, then a cluster of days with successive improvements. I observed this in logic optimization evolutions as well as in trading strategy optimizations. In both cases, I use analogons to s3xual reproduction (crossovers, introns).
Interesting result, it makes sense. Genetic evolution can only work on what is there – people sometimes ascribe (wrongly) a kind of omnipotence to genetic evolution, i.e. “anything that can be an advantage will evolve”. This is not the case – evolution is only possible from what is already there and by pathways that are possible. No organism (excluding the bacterial flagellum) has ever evolved a wheel, for example, despite the major advantages for travel that it provides. The requirements for blood supply and innervation, and the absence of any biological equivalent of “bluetooth”, make it impossible, despite its advantages.
Its worth noting that even in periods of apparent evolutionary quiescence (i.e. absence of major extinction events) if you look closely you find genetic evolution is still very busy. For instance the large cold-water king crabs, weighing up to 20 pounds (9 kg), evolved quite recently and very fast from hermit crabs – thats why they are still a little lopsided (asymmetric) even though they dont need to be since they no longer have to squeeze into a snail shell. Old habits die hard. Its an example of “carcination”, i.e. that “crab”-like animals have evolved 5-6 times from several starting points (in the sea, everyone wants to be a crab).