Why do you say that?
Because natural selection leads to convergence. Yes, mindspace is (probably) infinite- but the space of minds reachable by natural selection is a pretty small subset. I can confidently predict that creating progeny will be important to them, that they'll form pair bonds, that there will be sexual jealousy, that the sex with larger gametes will have a history of being seen as secondary, that status will motivate them, and so on. Solitary intelligences are astoundingly unlikely compared to social intelligences, and I'm counting hiveminds as solitary rather t...
One of the most important points raised by the sequences is that not all minds are like humans. In quite a few places, people have discussed minds with slight changes from human minds, which seem altogether different. However, a lot of this discussion has been related to AI, as opposed to minds created by evolution. I'm trying to think of ways that minds which evolved, and are effective enough to start a civilization, could differ from humans'.
Three Worlds Collide would seem like an excellent starting point, but isn't actually very useful. As far as I recall, the Babyeaters might have learned their baby eating habits as a result of societal pressure. The main difference in their society seemed to be the assumption that people who disagreed with you were simply mistaken: this contrasts to humans' tendency to form rival groups, and assume everyone in the rival groups is evil. The Super-Happies had self modified, and so don't provide an example of an evolved mind.
So here are my ideas so far.