slow-twitch

Advocates suggest subsequent millennia spent chasing down prey shaped many unique human features, including our springy arched feet, slow-twitch muscle fibers optimized for efficiency, heat-shedding bare skin, and prodigious ability to sweat.

These included a shift in slow-twitch muscle fibres to express genes characteristic of the lost fast-twitch subtype, and increased regeneration of remaining fast-twitch fibre subtypes.

More research is needed, but there are suggestions the point where women overtake comes when their greater distribution of slow-twitch muscle fibres - providing more resistance to fatigue - becomes an advantage.

Females have more type I, or “slow-twitch,” muscle fibers than males do.

According to Bohannon, this may be because women have more so-called slow-twitch muscle fibers than men, whose bodies favor fast-twitch muscles.