distilled : environmental factors are more significant than social factors in determining brain size/activity in important brain areas (number of conspecifics is considered an environmental and not a social factor). Complexity of environment is most significant.
Monogamous species have more advanced brains.
Size of rocks is in some way which I don't understand important.
that's about as much sense as I can make of it :grinyes:
If there's a relevance to the home aquarist here, I would say it is that your rift lake cichlids in particular are happier in complicated and stimulating environments...which we all pretty much knew anyway.
That's not to say you should expect them to do Algebra.