A short and interesting paper by Daniel Dennett. PDF attached. - Dallas
The Cultural Evolution of Words and Other Thinking Tools
The emergence of language and culture is one of the major transitions in evolution (Maynard Smith and Szathmary 1995), and the key to the cumulative nature of cultural transmission in Homo sapiens as contrasted with other species is the digital nature of language, which permits semi-understood designed entities to be preserved and transmitted. Phonemes are not the only systems of self-correcting (digitized) norms; other “alphabets” of practices also contribute to high-fidelity preservation of cultural products.
Anthropocentrism often distorts our vision of evolution, encouraging us to see our own case as special, but there are objective grounds for maintaining that the emergence of language and culture is one of the major transitions in evolution (Maynard Smith and Szathmary 1995). The key to the cumulative nature of cultural transmission in Homo sapiens, as contrasted with cultural transmission in other species, is the digital nature of language, which permits semi-understood designed entities to be preserved and transmitted. Phonemes and written letters are not the only systems of self-correcting (digitized) norms; other “alphabets” of practices also contribute to high-fidelity preservation of cultural products despite variable comprehension. The role of comprehension in human culture is often overestimated, and the best way to see the spectrum of possibilities is to adopt the perspective of memes (Dawkins 1976), cultural items that replicate with varying amounts of input from intelligent vectors. Words can be seen to be the foundational memes that permit the accumulation and transmission of ever more elaborate artifacts and practices.
CULTURE AS A MAJOR TRANSITION IN EVOLUTION
According to calculations by Paul MacCready (1999), at the dawn of human agriculture 10,000 years ago, the worldwide human population plus their livestock and pets was ~0.1% of the terrestrial vertebrate biomass. Today, he calculates, it is 98%! (Most of that is cattle.) His reflections on this amazing development are worth quoting:
Over billions of years, on a unique sphere, chance has painted a thin covering of life—complex, improbable, wonderful and fragile. Suddenly we humans . . . have grown in population, technology, and intelligence to a position of terrible power: we now wield the paintbrush. (MacCready 1999, p.19).
Some biologists are convinced that we are now living in the early days of a sixth great mass extinction event (the “Holocene”), to rival the Permian–Triassic extinction ~250 million years ago and the Cretacious–Tertiary extinction ~65 million years ago. And because, as MacCready puts it so vividly, we wield the paintbrush, this mass extinction, if it occurs, would go down in evolutionary history as the first to be triggered by the innovations in a single species. Compared to the biologically “sudden” Cambrian explosion, which occurred over several million years ~530 million years ago, what we may call the MacCready explosion has occurred in ~10,000 years, or ~500 human generations (of course, thousands of prior generations were required to set up many of the conditions that made this possible). There is really no doubt, then, that it has been the rapidly accumulating products of cultural evolution—technology and intelligence, as MacCready says—that account for these unprecedented transformations of the biosphere. So Maynard Smith and Szathmary (1995) are right to put language and culture as the most recent of the “major transitions of evolution”:
Read the rest in the attached PDF.
I wonder why MacCready uses terrestrial verebrate biomass as his indicator, and 98% does seem high. It conveniently ignores ants and termites.
So you're saying that culture, i.e. memes, are the factor behind human-controlled vertebrate biomass manipulation. In other words memes have basically taken control of vertebrate evolution. An interesting proposition, which puts things into rather surreal perspective.
I read and posted this back in February, so I'd have to reread it again I think in order to really address your questions. But as to the question about memes controling vertebrate evolution, Susan Blackmore brings that up in The Meme Machine, and she gives a definite yes (if I remember correctly). She claims that with memes comes a sort of value selection (we choose one meme over another), and by extension these value selections affect sexual selection, too. Which in turn effects evolution.
The link above will take you to my review of TMM, and there you'll find a scan of chapter 8 on meme-gene coevolution.