Why did “живот” once mean “life” in Russian?

Today живот is simply “belly” or “stomach”: у меня болит живот, “my stomach hurts.” But in Old Russian живот meant life, from the same root as жить, “to live,” and живой, “alive.” The old sense survives in fixed phrases: не жалеть живота is “to not spare one’s life,” to give everything for a cause.

Another fossil is биться не на живот, а на смерть, “to fight to the death,” literally “not for life but for death.” Medieval texts like Vladimir Monomakh’s Instruction use живот for “life,” and the meaning later narrowed to the body part. The teacher here uses it every way she can: втягиваем живот, “we suck in our stomachs,” урчит в животе, “my stomach is rumbling.”