When I first read this, I thought that it doesn't flow very well and that it might be better if the two parts were flipped around: "If the winning genes were playing negative sum games, a species could evolve to extinction". Know I'm not sure. I suppose it depends on how you say it.

Considered it, but I think the repetition of the word "genes" that this would create (in conjunction with the previous line) would be weirder.

But how would a preference for simpler propositions reuse "our Occam prior", instead of just being our Occam prior?

This actually did bother me slightly, considering how to rework it.

linguistically/verbally

this whole section may be getting revised, but I actually think some of the complex words are necessary to create some contrast between the naive, aspiring rationalist and the austere rationalist.

The word "even" doesn't make much sense to me here. "Just" seems to be what's needed here.

Agreed, changed.

You don't usually say that parents create their children, so I assume it's meant that they are designed by their parents, especially with the later line "there were intelligent beings who were not themselves intelligently designed", that suggest that the speaker is intelligently designed.

Huh. This is NOT how I saw it at all, but an interesting idea. You're not recommending a change, and I think that's correct - it's a neat thought that might occur to people but not central to the thesis, so I'll just let it occur to people naturally, if at all.

The title is "The Gift We Give Tomorrow" and so the end should, I think, emphasize the future and what we do with that gift, not where the gift ultimately comes from (natural means, instead of god).

Have you read Beyond the Reach of God? I think you may be interpreting the line based on a traditional understanding, rather than a specific context. (I'll be referencing BtRoG earlier in the presentation, so people who hadn't read that particular sequence-post will have some context) (http://lesswrong.com/lw/uk/beyond_the_reach_of_god/)