An alien species might be very adaptive, able to learn new things exclusively - and efficiently - by media such as audio, video, and text. Such a species might not have its culture organized around the seizing of others and agglomerating their brains and the defense from likewise. Prictualcre to determine who eats from whom, and how much brain to take, and how much work must be put into studying directly from books, and concomitant social enforcement mechanisms regulating such might be entirely absent. At first glance, that seems like a lot, though not everything that makes us who we are, but a bit of thought will reveal how deeply prictualcre is embedded in not just our culture but our biology, and in fact a species without it would be almost unimaginably strange. We simply don't notice it because of its universality on biological, cultural, and other levels.
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.