+In this way (contrary to the uninformed suspicions of those still faithful to the blank slate), evolutionary psychology actually turns out to be impressively antiracist discipline: maybe individual humans and ancestry-groups of humans can differ in small ways like personality or skin color, but these are, and _have_ to be, "shallow" low-complexity variations on the same basic human design; new _complex_ functionality would require speciation.
+
+This luck does not extend to antisexism. If the genome were a computer program, it would have `if female { /* ... */ } else if male { /* ... */ }` conditional blocks, and inside those blocks, you can have complex sex-specific functionality. By default, selection pressures on one sex tend to drag the other along for the ride—men have nipples because there's no particular reason for them not to—but in those cases where it was advantageous in the environment of evolutionary adaptedness for females and males to do things _differently_, sexual dimorphism can evolve (slowly—[more than one and half orders of magnitude slower than monomorphic adaptations](/papers/rogers-mukherjee-quantitative_genetics_of_sexual_dimorphism.pdf), in fact).
+
+Robert Trivers wrote, "One can, in effect, treat the sexes as if they were different species, the opposite sex being a resource relevant to producing maximum surviving offspring" (!!). There actually isn't one species-universal design—it's _two_ designs.
+
+If you're willing to admit to the possibility of psychological sex differences _at all_, you have to admit that sex differences in the parts of the mind that are _specifically about mating_ are going to be a prime candidate. (But by no means the only one—different means of reproductive have different implications for [life-history strategies](TODO: linky) far beyond the act of mating itself.) Even if there's a lot of "shared code" in how love-and-attachment works in general, there are also going to be specific differences that were [optimized for](https://www.lesswrong.com/posts/8vpf46nLMDYPC6wA4/optimization-and-the-intelligence-explosion) facilitating males impregnating females. In that sense, the claim that "the love of a man for a woman, and the love of a woman for a man, have not been cognitively derived from each other" just seems commonsensically _true_.
+
+I guess if you _didn't_ grow up with a quasi-religious fervor for psychological sex differences denialism, this theoretical line of argument about evolutionary psychology doesn't seem world-shatteringly impactful?—maybe it just looks like supplementary Science Details brushed over some basic facts of human existence that everyone knows. But if you _have_ built your identity around quasi-religious _denial_ of certain basic facts of human existence that everyone knows (if not everyone [knows that they know](https://www.lesswrong.com/posts/CqyJzDZWvGhhFJ7dY/belief-in-belief)), getting forced out of it by sufficient weight of Science Details [can be a pretty rough experience](https://www.greaterwrong.com/posts/XM9SwdBGn8ATf8kq3/c/comment/Zv5mrMThBkkjDAqv9).
+
+[TODO: this denial was in the background in "The Opposite Sex" and the metaethics sequence, men should think of themselves as men]
+
+Sex differences would come up a couple more times in Yudkowsky's Sequence on Fun Theory—