Dividing is non-reciprocal sharing of time and of objects among kin and non-kin. It is the sharing of what get's less for individual use when we divide it up. Whenever there is an expectation of getting back not just "whatever something" but an equivalent, the underlying rationality is closer to trading (i.e. economic equivalent exchange) than to sharing or dividing.
Some authors limit unconditional sharing, dividing and helping/cooperating to kin. Doing so, according to Widlock "already contains reciprocity in the evolutionary framework of inclusive fitness (i.e. I help my kin because they help me reproducing a good proportion of my genes)"
# See also reciprocity, mutuality, Decouple Giving & Taking