Weaning
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Weaning is the process of gradually introducing a mammal infant, either human or animal, to what will be its adult diet and withdrawing the supply of its mother's milk.
The process takes place only in mammals, as only mammals produce milk. The infant is considered to be fully weaned once it no longer receives any breast milk (or bottled substitute).
Normally, at the end of the weaning process, mammals experience reduced lactase production, becoming lactose intolerant. This is estimated to be the case with 70% of humans, with the rest being lactase persistent.[citation needed]
[edit] Weaning conflict
Weaning conflict occurs when the mother wishes to stop nursing but the infant wishes to continue.[1] At this point, the mother tries to force the infant to cease nursing, while the infant attempts to coerce the mother to continue. From an evolutionary perspective, weaning conflict may be considered the result of the cost of continued nursing to the mother, perhaps in terms of reduced ability to raise future offspring, exceeding the benefits to the mother in terms of increased survival of the current infant.[1] This can come about because future offspring will be equally related to the mother as the current infant, but will share less than 100% of the current infant's genes. So, from the perspective of the mother's evolutionary fitness, it makes sense for her to cease nursing the current infant as soon as the cost to future offspring exceeds the benefit to the current infant.[1] But, assuming the current infant shares 50% of the future offsprings' genes, from the perspective of the infant's own evolutionary fitness, it makes sense for the infant to continue nursing until the cost to future offspring exceeds twice the benefit to itself.[1][2] Weaning conflict has been studied for a variety of mammal species, including primates and canines.[3][4][5]
[edit] See also
[edit] References
- ^ a b c d Salmon, C. & Shackelford, T.K. (2008). Family Relationships: An Evolutionary Perspective. Oxford University Press. pp. 148-149. ISBN 9780195320510.
- ^ "Parent-offspring conflict". http://www-personal.umich.edu/~phyl/anthro/conflict.html. Retrieved 2009-09-23.
- ^ Trivers, R. (2002). Natural selection and social theory. Oxford University Press. pp. 124-126. ISBN 9780195130621.
- ^ "Gorilla". National Primate Research Center, University of Wisconsin - Madison. http://pin.primate.wisc.edu/factsheets/entry/gorilla/behav. Retrieved 2009-09-23.
- ^ Packard, J.M., Mech, L.D. & Ream, R.R.. "Weaning in an arctic wolf pack:behavior mechanisms". pp. 1269-1275. http://www.wolf.org/wolves/learn/wow/pdf/172weaningarcticwolf.pdf. Retrieved 2009-09-23.
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