More thoughts on the modular mind

Another short thought on the nature of the modular mind. When I first started doing a lot of reading on psycholinguistics at the start of my PhD, I made a few brief notes of interesting facts and observations that I thought I might like to be able to easily reference later on. One of those notes is this:

No more than 20,000 - 25,000 genes have to account for the entire human body and brain - the vast majority of these genes are shared with other apes and even other mammals. There are apparently only a few kilobytes of new genetic information in our genome since our last common ancestor with chimps.

This note is annotated as being sourced from Sverker Johansson's 2005 "Origins of Language: Constraints on hypotheses", which I recall being excellent. I don't remember if the note above is a direct quote from Johansson or if I condensed a paragraph down into a few sentences.

Anyway, this is interesting from the point of view of thinking about the extent to which our mental modules rely on a shared toolbox. Considering that the differences in cognitive capacity between humans and chimps are significant, the fact that this difference represents only a few kilobytes of information suggests (although I am admittedly unsure as to how much our intuition about the difference a few KB of DNA can make to an organism's mind should be allowed to be guided by our intuition as to the difference a few KB of source code can make to a computer program) that our higher cognitive abilities are coded for very efficiently, which argues more in favour of the common toolbox approach than the specialised tools.

In fact, moving into highly speculative territory that I'm not really qualified to talk about, maybe the difference between chimps and humans today corresponds directly to taking these two paths away from our common ancestor: humans spent their few "bonus kilobytes" investing in a rich toolbox of reusable, domain-general processing methods, whereas the other primates coming from the same starting point spent theirs on expanding and refining their kit of specialist, "one-trick pony" algorithms. My concern in my previous entry that general purpose methods were harder to evolve (that q was significantly lower than p) then becomes in fact an explanation as to why humans alone amongst the primates have progressed to the extent we have. Maybe we are the one roll of the evolutionary dice where the unlikely outcome with probability qⁿ actually happened, and our fellow primates all followed the more likely path of getting stuck in local optima. I don't know enough about the learning abilities displayed by other primates in fields other than language (where, incidentally, they typically perform much more poorly than laypeople and sensationalist media outlets give them credit for) to have a good idea of how plausible this hypothesis is, but it seems plausible enough on the surface. I wish I knew more people knowledgeable about this sort of thing.