Um, the referenced The Psychological Unity of Humankind article isn't right. Humans vary considerably - from total vegetables up to Einstein. There are many ways for the human brain to malfunction as a result of developmental problems or pathologies.

Similarly, humans have many different goals - from catholic priests to suicide bombers. That is partly as a result of the influence of memetic brain infections. Humans may share similar genes, but their memes vary considerably - and both contribute a lot to the adult phenotype.

That brings me to a LessWrong problem. Sure, this is Eliezer's blog - but there seems to be much more uncritical parroting of his views among the commentators than is healthy.