Love and hate on the Tree of Life

the last lesson ended with the image
of a lovers' triangle
portrayed geometrically
with the colors of its sides changing
between love-color (green, say)
and hate-color (red)

(realistically, we'd need a more complex way
to show asymmetrical feelings
but we'll postpone that step for now)

these simplified triangles can have three green sides
three red sides
two green and one red
or two red and one green

and the simplified-lovers' relationships
can shift between these variations




on the full Tree of Life the most-common pattern
is probably a small green cluster
connected to a neighboring green cluster by
unneighborly red lines

and for most of human prehistory these clusters
were tribes, about 30 members in size
who wandered within a limited territorial range
and had no relations, friendly or unfriendly
with tribes beyond their nearest neighbors

but with those near neighbors sometimes competing
sometimes providing new husbands or wives

and as we travel down the Tree
past apes to simpler mammals
the tribes probably become less-well-defined

until we reach creatures
who barely recognise their own family-members
with love and hate lasting only as long as
they're within each other's sight