Contents - Konrad Lorenz Institute

Steven M. Platek
Figure 1: Graph depicting the additive and deception predictions from this model. If there is no actual resemblance and no one
ascribes resemblance of the child to the dad then male parental investment should be low, if present. If the actual resemblance is
present, but social mirror-mediated resemblance is not or actual resemblance is not present, but social mirror-mediated resemblance
is present than male parental investment should be somewhere in the middle probably with much between male variance;
corresponds to a coefficient of abuse score of 1. The optimal condition for male parental investment would be a situation in which
both actual and social mirror-mediated resemblance is present. Females would be predicted to invest equally among all conditions
since maternal resemblance in this model is not predicted to affect female behavior towards children. Filled circles represent female
reactions towards children. Open circles represent male reactions under the additive model; X-filled circles represent male reactions
under the deception model.
netic non-relatedness, G. It is important again to
keep in mind that probability of cuckoldry probably
varies dramatically from 50% and is probably on the
order of 1–20% (CERDA-FORES et al. 1999; SASSE,
MULLER, CHAKRABORTY/OTT 1994; SYKES/IRVEN 2000).
Therefore, if G is multiplied by an estimate of the
cuckoldry rate (C k ) we can obtain an estimate of a
male’s relative certainty of paternity as a function of
an estimate of the population estimates of EPP that
will be referred to as C:
Therefore, G · C k = C (2)
The model equation for paternal investment
(PatI) can be reduced to:
PatI = P/C (3)
The equation might be viewed as a coefficient of
paternal investment, given that as paternal certainty
decreases as a function of decreased perceived or actual
paternal resemblance, the likelihood that the
male would be motivated to engage in offspring
abuse would be expected to increase and investment
would be expected to decrease. Furthermore,
holding P constant and changing the relative rate of
EPP will affect male investment in a manner consistent
with contemporary evolutionary meta-theory.
P is the product of P rt and P rs , which are proportions,
and thus must be less than 1, with 1 being representative
of the highest degree of actual paternal resemblance
and the highest degree of social affirmation
of resemblance (both abstract and difficult to measure).
If we substitute modern estimates of EPP
(range 1–20%), we find that an optimal paternal investment
score (P rt = 1, P rs = 1, C k = 0.5, and
G = 0.01) would equal 400 and decrease logarithmically
to the lowest possible degree of paternal investment
(or depending upon the interpretation paternal
abuse) to 0.1 (P rt = 0.1, P rs = 0.1, C k = 0.5,
G = 0.2).
My colleagues and I have collected data pertaining
to the paternal resemblance portion of this model.
We have found that males bias their reactions to children’s
faces, and hypothetically invest more in children
that share more facial characteristics with them
(PLATEK et al. 2002, 2003, under review; PLATEK 2002).
We have also begun to test how actual or social mirror-mediated
resemblance accounts for the variance
in the way a male reacts towards the faces of children.
The model predicts that when both actual and social
mirror-mediated resemblance are present, a man’s reactions
toward that child should be overwhelmingly
positive, whereas when neither are present his reac-
Evolution and Cognition ❘ 194 ❘ 2003, Vol. 9, No. 2