Certain invertebrate species such
as ants, in which individuals subordinate their own needs to those of the
group, are said to be eusocial.
The term has also been applied more loosely to some vertebrate species,
particularly Homo sapiens. Unlike ants, though, humans act
selfishly for their own survival and reproductive benefit as well as
altruistically for the benefit of groups to which they belong.
Eusociality is the thought-provoking subject of my book club's
latest selection, The
Social Conquest of Earth by E. O. Wilson of Harvard
University. Wilson is one of the
world's leading biologists and probably its leading entomologist. His lifelong study of eusociality in
insect colonies led him to study it in humans, in order to explain how we came
to dominate the biosphere. In
describing the difference between eusociality in ants and humans, Wilson wryly
observed that "Karl Marx was right, socialism works, it is
just that he had the wrong species."
A warning before I proceed: Wilson is one of the originators
and a strong proponent of a controversial sociobiological theory which asserts
that eusociality is dependent on evolution of groups as groups, a level of evolution above that of
individuals. As did Darwin with
ant and bee colonies, he sees the group as a macro-organism, subject to forces
of natural selection. It is a
top-down theory, in which the group selectively chooses as members those who
express a set of innate altruistic traits favoring the group's success in
competition with other groups.
Wilson is an equally strong opponent of an alternative evolutionary
theory called kin selection, a bottom-up theory, which posits that altruistic
behavior in groups evolves only because individuals in the groups already share
family genes, and accordingly at times act selflessly to assure the
perpetuation of their genes in others if not in themselves.
The argument literally rages. Evolutionists Jerry Coyne of the University of Chicago and Richard
Dawkins of Oxford have unsparingly attacked Wilson [1,2]. In the remainder of this posting,
however, I'll summarize some key points of Wilson's book as well as I can—it is
not always easy for a layperson to follow.
****
The development of eusociality is quite rare. Of the many millions of invertebrate
species, only a score or so have independently achieved it, the remaining
species competing largely at the level of individuals rather than groups. (Think flies and ants.) Among vertebrates, eusociality is even
rarer, having occurred in just a handful of species, including Homo sapiens. Its
appearance in ants has led to their dominance over the insect world, in humans
to their dominance over the world at large.
What is amazing, Wilson maintains, is that eusociality has
occurred at all, for the evolutionary maze that leads to it is so extensive and
full of twists and dead ends, that for any species to wend its way through the
maze is something of a miracle.
After all, eusociality must get its rudimentary start in a species where
the rule is selfish natural selection at the individual level, and selflessness/altruism
the exception. Still, ants and
their precursors negotiated the maze successfully over many millions of years,
as did the line of hominins leading to Homo sapiens in a somewhat shorter time. Wilson describes the process as
involving a long sequence of small evolutionary pre-adaptations over hundreds
of thousands to millions of years, leading to a tipping point where the random
mutation of as little as a single gene in an individual could start the final
conversion to full eusociality.
Eusociality in humans is of course very far from the extreme
of the genetically homogeneous, fixed-caste behavior of ants, yet goes much
farther than the social behavior of other vertebrates. A critical competitive advantage of
humans vis-à-vis other vertebrates is that they build defensible,
multigenerational, task-allocating cooperatives to which members may have no
genetic kinship. Each community,
Wilson says, selects for inclusion individuals who express a desirable subset
of altruistic behaviors, most of which were already deeply ensconced in the
human genome at the time Homo sapiens
emigrated from Africa some 60,000 years ago. The chosen subset reflects the evolved culture of the group.
The
tension in mankind between the opposing forces of individual/selfish natural
selection and group/selfless selection is complex. Genetic evolution in the former arises from competition
between members of a group, in the latter from competition between groups. The
two types of competition point evolutionarily in opposite directions because
one requires selfishness and the other altruism. Homo sapiens
maintains a tenuous balance between the two because of what Wilson calls the
"iron rule": selfish individuals beat altruistic ones, yet groups of
altruists beat groups of selfish individuals.
The
relationship between genes and culture in eusocial groups is also a critical
element in group evolution, Wilson asserts, and equally complex. In building a culture, genes make
available not just one trait as opposed to another, but patterns of traits that
together define the culture. The
expression of multiple traits is plastic, allowing a society to choose an
ensemble from many available combinations, the choices differing among societies. Wilson contends that the degree of
plasticity itself is subject to evolution by natural selection. These concepts add another perspective
to the nature/nurture question, very different, e.g., from one presented in a
book by psychologist Bruce Hood that I discussed in my posting The Self.
A
final, quintessential point. For
Wilson, the indispensible requirement for the development of human
eusociality—without which group selection could not have proceeded—is the
primitively evolved instinct to form tribes. He says that people feel they must belong to tribes for their existential sense of
identity, security and well-being.
Eons ago they were small bands that hunted and gathered together, built
encampments, and defended each other and their young. Today, individuals join many interlocking tribes—city,
country, religion, even sports teams—each commanding loyalty, communal effort,
and competition with other tribes of the same genre. In this sense
group evolution is bilateral: groups select individuals based on group needs,
and individuals choose groups based on their own needs.
As
evidence that the tribal instinct is extremely deeply embedded in the species, Wilson
cites a recent experiment showing that, when pictures of out-group people are
flashed in front of experimental subjects, their amygdalas—their brains'
centers of fear and anger—activate so quickly and subtly that the conscious
centers of their brains are unaware of the response. Other experiments revealed that even when experimenters
created groups at random, inter-group prejudice quickly established itself,
subjects always ranking the out-group below the in-group.
****
Many of the ideas in Wilson's book are
indeed controversial, and at times I found them alternately too detailed or too
sketchy. Still, it is a feast
for thought, which has forced me to reconsider some previous musings in
this blog.
First,
the deep-seated need for tribal association undermines my conjecture in a recent posting,
where I discussed tribalism/clannishness and what I called their antithesis,
"anticlans." I suggested
that tribalism might be ready for obsolescence in our modern, globally
hyper-connected society. I was of
course out of my depth, and therefore took to wild speculation. I asked whether the modern obsessive
inclusiveness of social-networking activities could lead to a widespread
"we're all in it together" anticlan behavior, which over the long run
could evolutionarily trump the exclusionary, "we vs. them" behavior of
clans.
I think
Wilson would answer my question with a definitive "No." He spends just one paragraph of his
350-page book noting that the increasing interconnection of people worldwide
through the internet and globalization weakens the relevance of ethnicity,
locality, and nationhood as sources of identification. Tribes may wax and wane and sources of
tribal identification may shift, but Wilson would hold that tribalism itself
will survive, overwhelming anticlan behavior just as it has always defeated
less-tribal species. Bummer.
Second, the almost-impossibility of negotiating the
evolutionary labyrinth to yield a species like Homo sapiens sheds further light on my posting
on the search for extra-terrestrial intelligence (SETI). In a catalog of obstacles to the
success of SETI, I listed the rarity of a star having a planet capable of
hosting life at all, much less an advanced civilization that was existent at a
time when electromagnetic radiation from it might be detected by us now. If Wilson is correct about the very
remote possibility that Homo sapiens
could have evolved on Earth, the odds against there being a similar one
extraterrestrially are even larger than I thought. Could we therefore be alone in the Galaxy, dare I say in the
universe? We'll probably never
know. Bummer again.
I sometimes wish that newly developing scientific theories
didn't get in the way of one's fondest hopes.