Contents - Konrad Lorenz Institute

Steven M. Platek
genes in relatives two-steps removed (e.g., nieces,
nephews, and grandchildren), which provides indirect
support for the notion that, during human evolution
investment decisions not only in a male’s
own children, but also in his kin’s children and
grandchildren, may have been dependent upon a
resemblance perception mechanism/module.
Some other hypotheses about how our ancestors
might have assessed resemblance include the water
reflection hypothesis; i.e., our ancestors might have
been able to see themselves in reflections on the water’s
surface (Gallup, personal communication)—in
fact chimpanzees have been observed investigating
their images in pools of water and urine (KEENAN,
GALLUP/FALK 2003). This hypothesis, although intriguing,
is highly unlikely for three reasons: first,
rarely is water so still that one can stare at it and
gather accurate information from one’s reflection
and, moreover, the probability of still waters occurring
on a regular basis was probably also rare. Second,
a reflection of water is skewed by any motion
in the water and by the distortion due to murkiness.
Third, an adequate account of the reasoning for
why our ancestors would have benefited from contemplating
their existence while staring in the water
has yet to be developed. Further, it has been postulated
the possibility that the water reflection hypothesis
was a driving force behind the selection
against mirror self-recognition among gorillas, stating
that gorillas who stayed by the water side long
enough to contemplate their own existence were at
greater risk of predation by water-dwelling predators
such as crocodilians and reptiles.
Another hypothesis has to deal with proprioceptive
responses and suggests that an individual might
get information about the way he or she looks by 1)
touching his or her own face and 2) by internal visceral
proprioceptive responses from the underside
of the face. Both seem plausible in light of the fact
that the somatosensory system is highly connected
to the visual cortex and that the human brain creates
visual maps associated with tactile information
(e.g., MACALUSO/FRITH/DRIVER 2000; see also
HAUBER/SHERMAN 2001) for discussions of self-referent
phenotype matching). Although these alternative
hypotheses are tenable, recent neuroimaging
(fMRI) data suggests the presence of fundamental
neurocognitive sex differences in reactions to children’s
faces as a function of resemblance (PLATEK et
al., under review). It is likely that resemblance was
assessed via a number of sensory channels in the ancestral
environment and may incorporate a number
of the hypotheses that have been generated. Additionally
however, PLATEK, et al. (under review) have
recently demonstrated sex differences in neural activity
as a function of children’s faces based on resemblance.
Unlike females, who showed activation
typical of mental state attribution, males demonstrated
activity in the left frontal lobes in areas associated
with inhibition on negative responding.
These findings suggest that males may posses a generalized
skepticism about children that is alleviated
when they detect resemblance.
Paternal investment is likely affected by variables
other than resemblance as well. For example, birth
order has also been suggested as being related to the
degree and amount of abusive acts by the father
(DALY/WILSON 1984). An individual born early in
the birth order is less likely to incur abuse at the
hand of the father. This phenomenon should be
predictable to the extent that each additional child
represents 1) an instance of male ambiguity regarding
the paternity of that particular child, 2) the effects
that ambiguity about paternity has on his confidence
of the paternity of his other children, and 3)
an increased draw on his economic resources. Every
time a male’s mate gives birth to a child, the likelihood
that the child shares genes in common with
him is approximately 50% (i.e., the child is either
his or not, but males are probably more certainty because
the rate of EPP is estimated at 1–20% the likelihood
that a child shares genes in common with
him might be more like 80–99%). For example, each
additional child means increased psychological
strain for the male in the form of mate guarding,
suspicion of infidelity, physiological and behavioral
energy in the form of sperm competition and semen
displacement, allocation of resources and also having
to assess resemblance again. Furthermore, if the
male determines that subsequent children do not
share genes in common with him, he may begin to
question the paternity of his other children and engage
in abusive behaviors or ultimately abandon the
family in order to pursue alternative reproductive
opportunities.
Finally, resource allocation as a function of number
of offspring may related to offspring viability.
The more resources a parent invests in a child, the
higher the probability of that child reaching sexual
maturity. BECKER (1991) and DALY/WILSON (1984)
theorize that parents can maximize their investment
benefits by discriminate investment according
to age of offspring and quality of offspring. They
suggest that, under situations of environmental depravity
it would be most beneficial to invest in older
offspring because they have the highest probability
Evolution and Cognition ❘ 192 ❘ 2003, Vol. 9, No. 2