07 May 2011


HUMAN DIASPORA. The geographic origin and dispersal of our species is generally interpreted in one of two ways within paleoanthropology. The Recent African Origin is the most prevalent model, corroborated by the study of mitochondrial DNA (normally inherited from the mother), and by fossil evidence which indicate that "archaic Homo Sapiens evolved to anatomically modern humans solely in Africa, between 200,000 and 150,000 years ago, that members of one branch of Homo Sapiens left Africa between 125,000 and 60,000 years ago, and that over time these humans replaced earlier human populations such as Neandrathals and Homo erectus without interbreeding with them. (see map above, click to enlarge.)

"The major competing hypothesis is the multiregional origin of modern humans, which envisions a wave of Homo Sapiens migrating from Africa and interbreeding with local Neandrathal populations in multiple regions of the globe. Most multiregionalists still view Africa as a major wellspring of human genetic diversity, but allow a much greater role for hybridization."

Whichever theory one finds more credible, the question remains .... why migrate at all? It happens that around 70,000 years ago, human population had reached a bottleneck of approximately 1 million. Whether propelled by competition for increasingly scarce resources, by disease, by famine, or some other cause, during a population bottleneck survival odds are random, and may result in recovery or extinction. Migration to other, more fertile lands is one obvious response which would enhance survival. But how would our ancestors have begun to conceive of such a strategy?

It turns out that they may have had a little genetic assistance. A study published in the American Journal of Physical Anthropology proposes that Novelty-seeking DRD4 polymorphisms are associated with human migration distance out of Africa. The authors propose that "this rapid migration into new habitats selected for individuals with low reactivity to novel stressors. Certain dopamine receptor D4 (DRD4) polymorphisms are associated with exploratory behavior, novelty seeking, and risk taking." In short, a genetic predisposition to curiosity which overrides perceived dangers.

It's one thing to suggest that we are a curious species. It's another to discover the possible biological mechanism. When I was in high school, back during the Punic Wars, our science teacher told us that (at that time) human knowledge doubles every ten years. Given the quantum leaps in computer technology and our own resourcefulness, I have a hunch that our knowledge doubles much more frequently now. If only we could set aside our political and cultural differences (perhaps even celebrate them!), and focus instead on refining our understanding of the sciences, the arts, the planet, and how we ourselves function, wouldn't that make for a better world? I know, hopelessly naive and idealistic. Still.

In a small step toward that end, check out Nerd Flashcards -- 26 alphabet cards and 12 number cards, illustrated to describe an appropriate science or math concept. I suspect that the intended "all ages" might include a fair number of adults in our science-and-math-illiterate society. Just remember -- nerd is the new sexy.

NIGHT SKY. Once again my Chicago friend Bill has provided a breathtaking resource, this one a 360 degree panorama of the night sky created by a 28-year old, first-time astrophotographer from 37,000 images. "The genesis of this was to educate and enlighten people about the natural beauty that is hidden, but surrounds us." Who says that science and art, knowledge and beauty, must be mutually exclusive? Again, click on the image to enlarge.

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