Consciousness Explained (D. Dennett): Part VIII; The Baldwin effect

We are the result of natural selection. Natural selction works by 1) allowing mistakes in the genome of an animal's offspring and 2) selecting the offsprings whose genome makes them better at survival/reproducing. If you are not familiar with this concept, go to buy "the selfish gene" from R. Dawkins (a live changing book).

The Baldwin effect is a mechanism that speeds up natural selection in a very peculiar way. It require you to have a plastic nervous system, in short: an ability to learn. If there is a "good trick" out there for an animal to learn, e.g. a behaviour that would greatly enhance an animal success at reproducing, any animal having this good trick hard-wired in its genome would be at an advantage. However, since having this "good trick" within it would be an all or nothing story, there maybe lacking a sufficiently progressive slope for natural selection to opearte swiftly. Hence, the time for this trick to be hard-wired in every animal within its species might be very long indeed. See left side of the figure below:

However, species not having this good trick hard-wired in their genome but having a plastic brain wired in such a way that they are capable to learn that trick during their livetime, are able to evolve the hard-wirering of this trick much faster. Here is how it works: Animal A has a brain slightly more able to learn the good trick than animal B. Animal A has therefore an advantage over animal B and will therefore probably leave more offsprings. Amongst said offsprings, animal A', due to a fortunate mutation, is still beter at learning the trick than its parent was, A' acquires it faster in his livetime than his siblings and therefore outcompete them and makes more offsprings. Amongst the kids of animal A', animal A'' is gifted with a further fortunate mutation that makes him particularly able to learn the good trick...and so on and so forth until the good trick (or at least the ability to learn the trick damned-easy) is practically hard-wired in the genome. What the Baldwin effect provides is a gentle slope for natural selection to operate on (see right side of the figure above). Any small improvement in the learning ability of the individual gives him a higher chance to hit on the good trick(s).

This makes clear the big advantage that a plastic brain provides to a species.