How unlikely is very unlikely?
I am poorly calibrated at assigning numbers to probabilities like this, so I don't think I can add more here.
I only need to change a few to drastically alter what one would expect.
My original claim was not that any noteworthy changes were impossible, but that any aliens that are social talking thinkers will be deeply similar to humans with high probability. (Implicitly attached is the claim that anything that isn't a social talking thinker we wouldn't consider intelligent and/or wouldn't reach HLI.)
It could be that some aspect of human psychology that was adaptive for us just fails to exist in some alien species. But I think the chances of that are amazingly small. It could be that something I think is an universal driven by practicality turns out to be a close competitor with something else (like sequential hermaphroditism vs. bisex, or whatever that's called), and on some planets things went the other way. If that's the case, I suspect deep similarities will still exist, and the change will be relatively minor. (For example, I suspect sequential hermaphroditism would be female->male, and the resulting social system would look a lot like pederasty.)
In the vast majority of species that have substantial mate competition, the competition is almost exclusively among the males and it frequently takes a visual component. In humans that's false. We're an exception in that regard.
Females don't compete in other species?
Human universals surround pregnancy and the related issues. Almost every society has associated rituals and taboos. And some gender issues come from the fact that females are stuck for months being very vulnerable.
So, there will be egg rituals and taboos instead, and I imagine some couples will trade off being 'pregnant'. The invention of incubators will be comparable to the (future) invention of artificial wombs.
I would guess for example that if HLI had arose from elephants rather than primates one would see much less overactive pattern seeking because of the lack of threats they face.
Alright, but that's an argument that elephants are less likely to reach HLI, as there's less selection pressure for pattern-matching / swiftness of thought.
Why wouldn't it? If I understand how minds work better that makes me more adept not less adept at manipulating others. There are arguments that this would not be the case, but they seem contingent on specifics of how humans function.
There are three factors in play: ability to know your motives, ability to lie convincingly, and ability to detect sincerity. The easiest one to drop is the ability to know your motives- when people promise to always be faithful, for example, they typically mean it, even though, beneath their consciousness, they don't.
Females don't compete in other species?
Note I made a comment about the vast majority of species. There's a conference devoted to such competition precisely because they are the exception not the rule.
Alright, but that's an argument that elephants are less likely to reach HLI, as there's less selection pressure for pattern-matching / swiftness of thought.
Speed of thought isn't necessarily related to overall intelligence. Note that elephants are one of the smarter species even though they aren't subject to much of the specific selection pressure that ...
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.