>
>I was thunderstruck the first time someone said to me, "Of course, the
>basic family unit is mother and child."  How culture-bound we can be.  That
>the irreducible, fundamental family unit for any mammal is mother-child,
>not mother-father-child, had just never occurred me.  Duh!

Well . . . . in some species of mammals, the basic unit is
mother-father-offspring.  In other words, the adults are monogamous and
pair-bonded for life.  Among primates, for example, gibbons and siamangs
(lesser apes, the ones who hang below the tree branches and ricochet around
their enclosures at the zoo and make wild hooting calls) are monogamous and
pair-bonded for life, and the basic family unit is mother-father-offspring
until the offspring get old enough and are kicked out.  The mother and
father together defend a well-defined territory against all other gibbons or
siamangs, including their own grown children.  In those species of primates
that are monogamous and pair-bonded, the male and female are the same size
and shape.  We anthropology types say they have "no sexual dimorphism."  The
greater the sexual dimorphism between males and females, the more the basic
social unit tends towards one male and multiple females.  Humans have some
degree of sexual dimorphism -- males on average are taller, heavier, broader
shouldered, have facial and body hair, etc.  But the difference in size
between male and female humans isn't as great as the difference in size
between male and female gorillas, where the males are almost twice as big as
the females, have huge crests on their heads, and turn silver on their
backs.  Gorillas live in small groups with one "silver-back" male and 5-10
females.  So -- the basic family unit for humans is probably 2-3 women per
each adult male.
Katherine A. Dettwyler, Ph.D.
Associate Professor of Anthropology and Nutrition
Texas A&M University