Re: Sociobiological Concepts

From: Alexandra Bilak (
Date: Mon Oct 06 1997 - 10:47:14 BST

In Tuesday's seminar, we started off by asking ourselves what evolution
was, and agreed on the simplified definition that evolution implies the
passing on, over the years, of "recipes" for a succesful survival of a
species. This process of Natural Selection is thus a causal one, since
succesful members of the species will be selected and "kept" throughout
history, whilst unsuccesful ones will simply vanish.

This was closely followed by the idea of an inevitable reproductive
scheme, a "competition" enabling species to be maintained throughout
the years. We pointed out that there were several ways in which
organisms reproduce themselves, either by cloning, or fission, or, by
far the most succesful, sexual reproduction. If we accept then that it
is the succesful genes that are passed on (and it is important to know
that genes control development, act as a type of "coding mechanism"
determining an individual's phenotype), one can say that an organism is
merely a vehicle used by a gene to embody its success. Indeed, Natural
Selection favours replicators that will be good at elaborating survival

We then went on to talk about the idea of an EEA, Environment of
Evolutionary Adaptiveness, ie that of a natural original environment
that has great implications for theories of evolution, simply because
it no longer exists. This EEA concept explains that certain human
traits were developed millions of years ago (in an original environment
different from our own) and were shaped by selection over a very long
time period. It is thus to these ancient conditions that human
behaviour is adapted. For example, in a time span of a million years,
99% of that period will have been characterised by an undomesticated
way of life, small population densities and small groups that will have
been genetically adapted to hunting and gathering. It has been argued
that human sexuality will have been molded by this selection (see
Symons: Precis of the evolution of human sexuality, in short loan), in
that males will be more prone to move around looking for as many
sexually appropriate partners as possible, whilst females will be more
prone to settling down to raise their offspring.

Over the time, however, novel environmental conditions have enabled
human behaviour to experience variability. Indeed, like we pointed out
in the seminar, human behaviour can be understood by looking at
proximal and distal causes; distal causes representing behaviour
originally shaped millions of years ago by conditions at that time, and
proximal causes representing novel adaptations to a more complex way of
life. The sweet tooth example explains this by postulating that our
sweet tooth was developed in a natural environment in which sugar
represented a necessity for survival. In the paper Stevan gave us in
the seminar, Symons explains this well: he says that the sweet tooth
mechanism was shaped in ancestral populations because for example a
fruit containing lots of sugar would be more nutritious than an
overripe or rotten one, hence individuals who can detect and eat the
high sugar fruit will be more succesful and produce more progeny than
individuals habing eaten the low sugar fruit.. Thus, selection favours
sweet tooth individuals. Over the years, it is interesting to see how
things remain fairly constant: in modern societies where sugar is very
easily accessible, our sweet tooth may be dysfunctional, but our
behaviour is still shaped by our will to experience sweetness. So human
behaviour is flexible and adaptive but its goal is the achievement and
experiencing of specific pleasures (eg sweetness, being warm...).

We also talked about ESSs, Evolutionarily Stable Strategies, that are
closely related to the concept of Natural Selection. Indeed, an ESS is
a strategy dominating a population simply because it is the most
succesful one. In more precise terms, "an ESS is a stategy, which, if
most members of a population adopt it, cannot be bettered by an
alternative stategy" (see Dawkins, The selfish gene). An ESS, then, if
adopted, will enable an individual to leave many genes behind him in
the gene pool. As a simplified example, like Dawkins explains in The
Selish Gene, if we take two different fighting strategies in a
population of a particular species-say, HAWK and DOVE-, it is
interesting to see how throughout time and different environmental
conditions, hawks and doves will both alternatively represent
evolutionarily stable atrategies. This will of course depend on which
genes will spread through the population. Depending on a diversity of
environmental conditions(variety of rituals, and so on...), hawk genes
will gain a majority and "sweep to ascendancy"; as a consequence of
this, dove genes will gain majority and thus increase their number
until hawks begin to ascend again, etc...It is the ratio of hawks to
doves that itself represents an evolutionarily stable strategy. It is
interesting to note what Dawkins points out, namely the distiction
between an Ess and a "conspiracy" of say, only doves, the latter being
prone to treachery. Indeed, in a population of doves and doves only, a
single hawk could do so well that nothing could stop the evolution of
hawks :"the conspiracy is therefore bound to be broken by treachery
from within". Dawkins then postulates that an ESS is stable simply
because it is immune to such treachery.

The ESS theory can also be applied to human pacts, for example in the
case of price-fixing. A price is set for petrol (for examle) at a high
value, being in the interests of all garage owners of a population, and
thus representing a stable strategy, because it corresponds to a
general conscious decision. If someone was to suddenly decide to lower
prices, everyone would be forced to follow, thus breaking the
"pact".Even in human affairs, then, stable stategies are prone to
collapse because of treachery from witin.

(I'm not sure I've quite understood this concept. Wouldn't
 mind having it explained to me in more detail perhaps on Tuesday?)

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