I've been doing some reading on the grandmother effect as part of a 
paper I'm writing on grandmothers breastfeeding, and I came up with a 
rather odd thought I thought to share with you all. Here goes:

The grandmother effect addresses the question "why do women live past 
their childbearing years?" Most animals do not live past their 
offspring bearing years and from an evolutionary perspective( survival 
of the species mostly through reproduction) that makes sense. If they 
can't reproduce, it's not good for the species if they live on and use 
resources that could be better used by younger reproducing members of 
the species or group. Humans are almost unique in that the females live 
well past their childbearing years, and this has been true for a long 
time. Why? The grandmother effect theory says essentially that 
grandmothers help their children so that they start reproducing 
earlier, have more babies, and more of their babies live to adulthood 
(so they too can reproduce). so the genes of the grandmothers live on 
to another generation.
There is also medical and anthropological literature indicating that 
grandmothers nursing their grandchildren on an occasional or part time 
basis is not uncommon in many parts of the world. They can and do 
relactate. They do so so that their daughters can engage in other 
productive work like growing or gathering food.
Here's my question: I wonder if part of the grandmother effect is that 
grandmothers nurse their grandchildren enough so that the contraceptive 
effect of bfing is lost for the mothers and that is one reason the 
mothers have more babies. As far as I can tell there is no research out 
there on this specific question. The research on grandmothers nursing 
is largely anecdotal or very small samples. Evolutionary research 
requires large samples to be able to say anything meaningful. I don't 
think we even really know how widespread the phenomenon of cross 
nursing or grandmothers nursing is.

Just some thoughts. Any comments from the evolutionary biologists or 
anthropologists in the group?

Naomi Bar-Yam


--------------------------------
Naomi Bar-Yam Ph.D.
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Researcher, Writer, Educator
in Maternal and Child Health
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