Re: LBI Broods and Social Sharing

Paul Crowley (
Sat, 05 Oct 96 16:12:11 GMT

In article <01bbae4e$a5de1de0$> "John Waters" writes:

> It was the increase in the hominid infantile stage which led to
> the development of the LBI brood characteristic. At some point
> in time, the hominid mother gave birth to a new baby, while her
> previous born infant was still in its infantile stage. The
> mother concerned may have been overindulgent, perhaps even
> abnormal. But if there was a super abundance of food, she would
> be able to feed the previous born infant on adult foods, while
> breastfeeding her new-born baby.

It's not a matter of the mother's choice; there has to be some
mechanism in which prevents a harmful number of pregnancies. (A
chimp mother would not want two small infants at the same time as
both would have reduced chances of growing up strong enough to
leave descendants.) In apes it seems that lactation inhibits
ovulation. Conception is delayed until the infant has weaned.

I wonder if there is an allied mechanism. Chimps appear to need
a significant proportion (10%?) of animal protein in their diet.
Males hunt small monkeys, and females fish for termites and ants.
Older infants get most of their sustenance from fruit, but perhaps
they get their protein from mother's milk. By weaning age at four
or five, can they termite-fish? Or beg meat from adults? Or rob
bird's nests?

So I suggest that SBI (short birth interval) would not be possible
unless the mother had a good supply of protein to feed direct to
her infant(s).

Is there anything in this? While chimps are the most relevant,
has anyone done work on the protein content of gorilla, orang
and gibbon diets?

BTW, I have replied to your other points but a lot of my posts
seem to be going astray. (Don't cheer). I'll re-post if they
don't appear soon.