> IMHO, if children are nursed until they are several years old or older, then
> it is probably easy to find other ways to provide the nutrients they need
> from sources other than "milk" (of whatever species).

Kathy Dettwyler is correct, IMO. I recall Derek Jelliffe's intriguing
and brilliant observations on this, that humans are all born "too early"
(in order to fit our craniums through the pelvis) before fully
completing gestation. One way to define a fetus is one who is fully
dependent on the mother's body for survival (whether placenta or
breast). This led him to view many mammalian infants, definitely
including humans, as "post-gestate fetuses" until they could find (reach
and grab and put in own mouth) their own food *in addition to their own
mother's milk*.

Based on trends in the mammal kingdom then, Dr. Jelliffe maintained that
humans are minimally "gestational" until our first teeth come in around
9-12 months; the breasts substitute exclusively for the placenta's role
in feeding the "post-gestate fetus". Thus, we should be exclusive
nursers *at least* until then, at which point, breastmilk gradually (key
word: gradually) becomes supplemented by food from the "family pot." The
young of any species -including ourselves! - enjoy "foraging" for food
in mom's "plate"! (Moms model "how to eat" and "what to eat" in all
species at this opportune time of development. Eating is a *learned*
*social* behavior - ask anyone who has run programs to wean children
from long-term gastrotomy tubes just how difficult it is to "teach" a
desire to eat in children who have missed out on this!)

And, we should be frequent nursers until deciduous (baby) *molars*
arrive, placing weaning no earlier than 22-26 months. After that? Well,
looking at the ability to manage (chew/digest) adult food, our young
should still be supplemented nurslings until the first adult molars
arrive at age 6-7 years. At this age, the youngster has an excellent
chance to survive apart from mom - able to find food on their own, chew
it properly, digest it well with all the right enzymes produced directly
in their own bodies, and with a fully functioning immune system
(finally) to handle any disease that may enter the body via foodstuffs.
Amazing coincidence how breastfeeding is supportive until several
developmental steps (some unrelated to food per se) are attained, thus
assuring survival of the young.

If we were to hold weaning until these first adult teeth were in, then
this indicates complete weaning should not occur before the age of 6 or
7, ideally, as Kathy Dettwyler and others have long noted.

Katharine West, RN, MPH, IBCLC(exp)
Sherman Oaks, CA