>>76640147
Here’s a clean comparison across the four main great apes, including humans:


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Mating System vs. Genital Traits

Species Typical Mating System Penis Size (erect) Testes Size (relative to body) Why This Pattern Exists

Gorilla Harem (1 male, many females) ~3 in (7.5 cm) Very small One dominant male monopolizes mates no sperm competition evolution favors strength, not genital size.
Chimpanzee Promiscuous (many males, many females) ~5 in (13 cm) Very large Intense sperm competition bigger testes to produce more sperm. Penis also relatively large despite small body size.
Bonobo Highly promiscuous, social-sexual bonding ~4.5 in (11–12 cm) Large Sex used for social cohesion frequent mating sperm competition still important.
Human Mixed (pair-bonding + some multi-male/female overlap historically) ~5–6 in (13–15 cm) Medium Humans aren’t strictly monogamous or promiscuous moderate sperm competition penis relatively long/thick compared to apes, testes mid-sized.
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Key pattern:

Harem system (gorillas): No sperm wars tiny testes + small penis.

Promiscuous system (chimps/bonobos): Lots of sperm wars large testes, relatively bigger penis.

Humans: Somewhere in between moderate testes, relatively large penis (especially in girth compared to other apes).


>>76640148
You ready for the sperm wars?