Does sharing become increasingly "rational" in the second year of life?

Forty-eight 1- and 48 2-year-olds were observed in groups of 3, with either a female or a male majority, on 2 consecutive days, 1 day with scarce resources and the other day with ample resources in counterbalanced order. Particular toys were available in duplicate for half the groups on both days. All the experimental variables together influenced spontaneous sharing, but sharing under pressure from peers was affected by age (1-year-olds sharing more often than 2-year-olds) and the relative loss of gain of resources across days