First, humans aren’t at equilibrium; as you point out, our environment has shifted much more quickly than evolution has time to catch up with. So we should expect that many analyses that make sense at equilibrium aren’t correctly describing what’s happening now.
Second, while it seems like “humans are very different yet mice are all the same,” this is often because it’s easy to track the differences in humans but difficult to track the differences in mice. What fraction of mice become parents (a decent proxy for the primary measure of success, according to evolution)? Would it look like the core skills of being a mouse (finding food, evading predators, sociability, or so on) have variance comparable to the human variation in intelligence? What fraction of humans become parents?
Third, while we have some evidence that humans are selected for intelligence (like the whole skull/birth canal business), intelligence is just one of many traits that are useful for humans, and we don’t have reason to believe this is the equilibrium that would result if intelligence were the only determinant of fitness. Consider Cochran et al on evidence for selection for intelligence for Ashkenazi Jews; they estimate that parents had perhaps a 1 IQ point edge over non-parents for the last ~500 years (with lower estimates on the heritability of intelligence having to only slightly increase that number).
Fourth, rapid population growth generally amplifies variance along dimensions that aren’t heavily selected for if the population growth is accomplished in part by increasing the number of parents.
Four factors of some relevance:
First, humans aren’t at equilibrium; as you point out, our environment has shifted much more quickly than evolution has time to catch up with. So we should expect that many analyses that make sense at equilibrium aren’t correctly describing what’s happening now.
Second, while it seems like “humans are very different yet mice are all the same,” this is often because it’s easy to track the differences in humans but difficult to track the differences in mice. What fraction of mice become parents (a decent proxy for the primary measure of success, according to evolution)? Would it look like the core skills of being a mouse (finding food, evading predators, sociability, or so on) have variance comparable to the human variation in intelligence? What fraction of humans become parents?
Third, while we have some evidence that humans are selected for intelligence (like the whole skull/birth canal business), intelligence is just one of many traits that are useful for humans, and we don’t have reason to believe this is the equilibrium that would result if intelligence were the only determinant of fitness. Consider Cochran et al on evidence for selection for intelligence for Ashkenazi Jews; they estimate that parents had perhaps a 1 IQ point edge over non-parents for the last ~500 years (with lower estimates on the heritability of intelligence having to only slightly increase that number).
Fourth, rapid population growth generally amplifies variance along dimensions that aren’t heavily selected for if the population growth is accomplished in part by increasing the number of parents.