"If whole populations are adaptive, it seems possible
that adaptations producing beneficial death of an
individual -- death for the benefit of the population might
evolve . . . It may be concluded from these data that . . .
natural selection operates upon the whole interspecies
system, resulting in the slow evolution of adaptive
integration and balance. Division of labor, integration,
and homeostasis characterize the organism and the
supraorganismic interspecies population. The
interspecies system has also evolved these
characteristics of the organism and may thus be called
an ecological supraorganism." (Allee et al., 1949)
“Benefits to groups can arise as statistical summations of
the effects of individual adaptations. When a deer
successfully escapes from a bear by running away, we
can attribute is success to a long ancestral period of
selection for fleetness. Its fleetness is responsible for its
having a low probability of death from bear attack. The
same factor repeated again and again in the herd means
not only that it is a herd of fleet deer, but also that it is a
fleet herd. (Williams, 1966)
"No matter how functionally dependent a gene may be,
and no matter how complicated its interactions with other
genes and environmental factors, it must always be true
that a given gene substitution will have an arithmetic mean
effect on fitness in any population. One allele can always
be regarded as having a certain selection coefficient
relative to another at the same locus at any given point in
time. Such coefficients are numbers that can be treated
algebraically, and conclusions inferred for one locus can
be iterated over all loci. Adaptation can thus be attributed
to the effect of selection acting independently at each
locus. (Williams, 1966)
"Selection simply cannot see genes and pick among them
directly. It must use bodies as an intermediary. A gene is
a bit of DNA hidden within a cell. Selection views bodies .
. . There is not gene "for" such unambiguous bit of
morphology as your left kneecap or your fingernail.
Bodies cannot be atomized into parts, each constructed
by an individual gene. Hundreds of genes contribute to
the building of most body parts and their action is
channeled through a kaleidoscopic series of
environmental influences: embryonic and postnatal,
internal and external. Parts are not translated genes, and
selection doesn't even work directly on parts. It accepts
or rejects entire organisms because suites of parts,
interacting in complex ways, confer advantages. (Gould,
1980)
Fig. 8.3
Coefficients of relatedness
Coefficients of relatedness
Frequency of cooperation in
defense against intruders in
Belding’s ground squirrels
(Sherman 1981)
Probability of helping by non-breeding whitefronted beeeaters (Emlen and Wrege , 1988)
Probability of helping by non-breeding white-fronted
beeeaters (Emlen and Wrege (1988)
Bee-eaters
Fig. 8.16
Aggression in naked mole rat queens (Reeve and Sherman 1991)
Blood sharing in vampire bats (Wilkinson 1984)
Blood sharing in vampire bats (Wilkinson 1984)
Fig. 8.12
Fig. 8.14 top
Fig. 8.14 middle
Fig. 8.14 bottom
Fig. 8.20 top
Fig. 8.20 bottom
“Let us now consider the individualistic claim that ‘virtually
adaptations evolve by individual selection.’ If by individual
selection we mean within-group selection, we are saying that
A-types virtually never evolve in nature, that we should
observe only S-types. This is a meaningful statement,
because it identifies a set of traits that conceivably could
evolve, but does not, because between-group selection is
invariably weak compared to within-group selection. Let us
call this valid individualism. . . . If by individual selection we
mean the fitness of individuals averaged across all groups,
we have said nothing at all. Since this definition includes
both within- and between-group selection, it makes
‘individual selection’ synonymous with ‘whatever evolves’
including either S- or A-types. It does not identify any set of
traits that conceivably could evolve but does not. Let us
therefore call it cheap individualism.” (D.S. Wilson, 1989)