9 Family Matters
the pinnacle of unconditional love may be that between a mother and
her child. Still, even the most devoted nurturers among us must be impressed
by the Australian social spider. Soon after giving birth to about a
hundred hungry spiderlings, Moms body literally liquefies into
a pile of mushy flesh. The babies then munch on the flesh so they can
start their lives with full bellies.
being equal, the genes living in the mom would prefer to live for another
day. All things are not equal, however. The death of the mom, although
costly, is more than compensated for by the head start it gives the
many babies, each carrying copies of Moms genes.
built parents that "selflessly" give everything for their
offspring, but this isnt the only way to show family devotion.
Organisms share genes with cousins, aunts, siblings, uncles, and more,
too. We ought to see animals that also make sacrifices for these relatives,
and we doall the time.
Tasmanian hens, many females live with just one male, but there is also
a large number of polygamous females that keep a pair of males on hand
instead. This female literally rules the roost: she allows both males
to mate with her and requires both to provide food for her babies. This
is a pretty sweet arrangement for the females. One study found that
hens with two males had an average of 9.6 babies, while those with just
one guy managed only 6.6 babies.
males protest? To the contrary. Beyond merely tolerating it, they seem
completely unruffled by their Threes Company arrangement.
Even some of the biggest males welcome small competitors into their
nest with little objection. Why? ...