You can have a stable/growing population with only 1 male per n>1 females. So, the evolutionarily optimal strategy is to crank up trait variance in males and have females select only the top 1/n males (hand-wavily speaking). Most modern human cultures suppressed this dynamic via socially enforced pair bonding. When you lose that social adaptation, you revert back to more atavistic matching dynamics.
You can have a stable/growing population with only 1 male per n>1 females. So, the evolutionarily optimal strategy is to crank up trait variance in males and have females select only the top 1/n males (hand-wavily speaking). Most modern human cultures suppressed this dynamic via socially enforced pair bonding. When you lose that social adaptation, you revert back to more atavistic matching dynamics.