Calcium isotopic patterns in enamel reflect different nursing behaviors among South African early hominins.

Nursing is pivotal in the social and biological evolution of hominins, but to date, early-life behavior among hominin lineages is a matter of debate. The calcium isotopic compositions (δCa) of tooth enamel can provide dietary information on this period. Here, we measure the δCa values in spatially located microsized regions in tooth enamel of 37 South African hominins to reconstruct early-life dietary-specific variability in , , and early Very low δCa values (<-1.4‰), indicative of milk consumption, are measured in early but not in and . In these latter taxa, transitional or adult nonmilk foods must have been provided in substantial quantities relative to breast milk rapidly after birth. The results suggest that early have continued a predominantly breast milk-based nursing period for longer than and and have consequently more prolonged interbirth interval.