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Human Evolution (Book of the Week) 14 June 2006

Posted by Todd in Academia & Education, Evolution.
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I didn't make it all the way through Theory and Reality yet, but will be picking it back up in a few days. I find the philosophies and arguments in scientific method to be stimulating, to say the least, but the reading is challenging me to rethink a lot of my treasured assumptions about research and science. So I needed to take a break. Here's the next book on my list:


“Human Evolution : An Illustrated Introduction” (Roger Lewin)

Roger Lewin has written a lot about the development of evolutionary theory and especially about the rapidly progressing field of human evolution. I just finished the first “unit” in this textbook this morning, and I'm really excited. I feel I finally get the relationship between macro-evolution and micro-evolution, and also finally understand the relationship between natural selection (gradualism) and punctuated equilibrium.

One of the things that really stood out to me in my emerging thoughts about the relationship between evolutionary theory and social theory, is the development of the theory of broad adaptation and distribution to avoid extinction. Although it sounds obvious, it took a while for scientists to build up the mathematical models and the evidence to support it. Basically, over the past 25 years or so, biologists and paleontologists have demonstrated that species that are broadly adapted (versatile) and can move from one ecosystem to another are less likely to go extinct; further, species with a broad geographical distribution are most likely to survive extinction events. Combine this with the notion that sometimes adaptations aren't the cause of speciation, but rather the effect of geographical separation and external pressures on a species. Scientists have also found that the related homonin species (radiated adaptation) were all increasing their brain size (encephalyzation) at the same time.

Which brings me to the no-shit conclusion that hominins' and eventually the genus Homo's brain size increased (timing appears to be after bipedalism) in a punctuated equilibrium mechanism that gave rise (quickly) to homo sapiens, with their big brains, producing an incredibly diverse species, capable of surviving in nearly any environment.

For me this is significant because it links human culture (knowledge, language, symbol systems, meaning) to humanity's nature: it is an adaptation. Culture, as powerful and amazing as it is, must not be seen as an ultimate cause (as it is often assumed to be in the humanities and social sciences); rather it must be seen as a kind of adaptive tool. This would explain, in evolutionary terms, how the findings of cognitive science (and the evolution of mind) overlap with social and cultural theory. Now what this all means, I'll have to figure out later.

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