Transcript Kinship is only one way in which this can occur (albeit the most

“Selfishness beats altruism
within groups. Altruistic groups
beat selfish groups. Everything
else is commentary.”
or is it?
• Darwin was a “group-selectionist”…
“How the workers have been rendered sterile
is a difficulty; but not much greater than that
of any other striking modification of structure;
for it can be shown that some insects and
other articulate animals in a state of nature
occasionally become sterile; and if such insects
had been social, and it had been profitable to
the community that a number should have
been annually born capable of work, but
incapable of procreation, I can see no very
great difficulty in this being effected by natural
selection”
Page 236
…or at least did not bother to discuss kinship
• Darwin was a “group-selectionist”…
“It must not be forgotten that although a high
standard of morality gives but a slight or no
advantage to each individual man and his children
over the other men of the same tribe . . . an
increase in the number of well-endowed men and
an advancement in the standard of morality will
certainly give an immense advantage to one tribe
over another.”
Here he recognizes the problem but still doesn’t
think much of it:
Within groups nice guys tend to lose out, but it
provides an advantage to their groups. Two
opposing forces of selection
Page 236
A
B
Selection
A
B
Selection
A altruistic
B selfish
• Following Darwin there wasn’t much critical
discussion of individual and group selection as
alternatives
• Until Wynne-Edwards marshaled the idea of
population regulation via processes that he
thought was evidence for adaptation at the
group level
– Prudent use of resources, territoriality etc..
– W-E was operating from a population perspective,
whereas Lack was operating from an individualcentric view
vs
The Demise of Group Selection
• The argument against group selection:
– Selective forces at the group level, if they oppose selective forces
at the individual level, will tend to lose out except in very limiting
circumstances (Maynard Smith)
– GS still theoretically possible and required to explain if the
adaptations that W-E proposed really exist (Williams), but no
evidence for such adaptations that require a special explanation
beyond individual competition (Lack)
– Apparent behaviors of helping can be explained by alternative
hypotheses such as kin selection, reciprocity etc…
“Enormous credit would accrue to anyone
who could pull off the seemingly impossible
and rehabilitate group selection. . . But
actually, such rehabilitation can’t be achieved,
because the great heresy really is wrong.”
Genic selection (selfish genes): what gets
selected are genes not even individuals.
Individuals are merely vehicles, lumbering robots carrying the
real thing, the gene (well, technically, a whole group of them)
Not so fast…
W2: The return of group selection
• Empirical evidence:
– Evolution of restraint in hostparasite systems
Kerr et al. Nature, 2006
W2: The return of group selection
• Empirical evidence:
– Evolution of sex ratios
Aviles, 1986, Am Nat
W2: The return of group selection
• Empirical evidence:
– Humans
http://edge.org/conversation/the-false-allure-of-group-selection
W2: The return of group selection
• Empirical evidence:
– Eusociality (Thursday)
Wilson and Hölldobler, 2005, PNAS
W2: The return of group selection
• Are alternatives really all
that different?
– W2 Argue that they are not,
kin selection, reciprocity etc
do not change basic vector
calculus of multi-level
selection. They are simply
alternative ways of defining
what a “group” is…
Bill Hamilton
1963-64: Hamilton is very skeptical of
group selection and proposes inclusive
fitness as an alternative
1975: Hamilton still criticizes the “recent
trend in evolutionary thought” of group
selection, however, extends the concept of
inclusive fitness to cover group selection
(George Price’s influence)
1981: “group selection results from a
misreading of evolutionary theory
Inclusive fitness (or what?)
Multi-level
Inclusiveselection:
fitness:
Trait groups etc.
Non-related
group selection:
group
selection:
discrete
groups
discrete
groups
of non-relatives
of non-relatives
individuals in
continuous
populations
Kin selection: relatives
Kin selection: relatives
interacting in continuous
interacting in continuous
populations
populations
Sober and Wilson
Hamilton, 1975
Discrete groups of relatives
“It is generally assumed that inclusive fitness is merely kin selection.
However, as Hamilton pointed out, inclusive fitness theory is much
more general than kin selection. Specifically, when considering the
evolution of altruism, inclusive fitness theory states that what is
necessary is a statistical association of (altruistic) genotypes (or
partners). Kinship is only one way in which this can occur (albeit the
most obvious). Alternatives include altruists recognizing fellow
altruists as such and repeatedly interacting with them (e.g. through tit
for- tat type strategies in prisoner’s dilemma games or green beard
genes), patterns of dispersal leading to altruists settling together, and
selection creating positive correlations between altruistic individuals”
(p.19)
• Griffin and West, 2002, “Kin selection: fact and fiction” TREE, vol. 17
“There are three different ways of partitioning social
selection: (i) the inclusive fitness extension of individual
selection; (ii) the direct fitness model of individual selection;
(iii) and the within and- between group selection model.
Fletcher et al. spend most of their time advocating the second
(a form of kin selection theory) but then conclude that group
selection is best. In reality, all three models are important and
useful tools for investigating and modeling social evolution
and, if applied carefully, will give the same answers.” (p. 601)
Foster, K. R., Wenseleers, T., et al. 2006. There is nothing
wrong with inclusive fitness. TREE, Vol. 21
Modern group selection theory is as
mathematically rigorous as individual selection
or inclusive fitness theory. I say this despite
being someone who favors the inclusive fitness
approach and whose entire career has been
based on it. I think of these less as alternative
theories that make different predictions than
as two different languages describing the same
world.…. Pinker is therefore correct that
multilevel selection results can usually be seen
as restating things we already knew in a
different language . But I am loath to say that
just because I speak English, others cannot
speak in (as homage to Peter Kropotkin)
Russian.
Dave Queller
So why can’t we get along?
http://edge.org/conversation/the-false-allure-of-group-selection
Take home message questions
• Are W2 right about the theoretical disarray in
sociobiology?
• How useful is group selection perspective to
your research?
• Are there “group-level adaptations”?
Pyotr Kropotkin:
Geographer, Naturalist, Anarchist
George Price:
Chemist, theoretical biologist, altruist
A false statement, backed by great prestige, propagates exponentially at second and
third hand.
Sewall Wright, Genic and Organismic Selection, Evolution, 1980
Nowak et al.
• Where the ….. did
that come from?