10k you mean? Although it sometimes feels like people have smaller brains just lately, too... It’s plausible that early humans broke into the “success through

10k you mean? Although it sometimes feels like people have smaller brains just lately, too... It’s plausible that early humans broke into the “success through smarts” niche by a sudden expanded brain mutation that left them with a horrendous birth mortality rate, and that since then selection for mutations for smaller heads (and thus better birth safety) has been very strong (though hopefully not as strong as overall selection for intelligence- essentially evolution finding ways to pack more into a smaller space.) Those huge Neanderthal brains were just the clunky and unstable Minimum Viable Product; ours are the more refined version.