The absence of significant isotopic variation by sex or burial location at Yuzhniy Oleniy Ostrov indicates a uniform dietary regime across the population during the site’s 100–300 year use, reflecting shared food practices and limited dietary stratification.

People ate mostly fish, which are rich in protein but low in fat. Their bodies broke down the protein for energy and building tissues. Because the fish came from the same lake, everyone got the same type of protein with the same chemical signature. The body kept the carbon and nitrogen patterns from the fish unchanged in their bones, and flushed out excess nitrogen in a way that made the remaining nitrogen in bones even more similar across all people. This made everyone’s bones show nearly identical chemical fingerprints, no matter their gender or where they were buried.