Transcript Human mate choice

Variation in Human Mate
Choice: Simultaneously
Investigating Heritability,
Parental Influence, Sexual
Imprinting, and Assortative
Mating
By: Phillip Skaliy
Terms
 Assortative Mating – the frequency at which
individuals mate with persons of similar phenotype
(positive assortative mating) or different phenotype
(negative assortative mating)
 Sexual Imprinting - individuals acquire mate-choice
criteria during development by using their opposite-sex
parent as the template of a desirable mate
 MZ – monozygotic (identical twins)
 DZ – dizygotic (non-identical twins)
Overview
 Human mate choice is essential to evolution
 Basis of variation in mate choice is not well understood
 Look at twins, partners, parents
 Test for genetic and family environmental influences on
mate choice
 Different traits analyzed
 Test for sexual imprinting
Background
 Studies before this
 Romantic partners correlate positively on age, social
attitudes, and religiosity
 Believed that similarity between partners is due to initial
choice (assortative mating)
 Conflicting results – why do we choose a particular mate
over another
 Constraints of mating market
 Could be genetic or non-genetic
Background
 Possible non-genetic/environmental factor is the
influence of Parents on mate decision
 Ensure daughters marry successful men
 Sexual Imprinting
 Opposite sex parent as template for mate
 Traits looked at:
 Education, yearly income, Religiosity, Social attitudes,
Personality, Height and age, Body mass index (BMI), Length
of relationship
Experiment
 Non-genetic
 it should be revealed in a twin study as a family
environmental effect on females for mate choice regarding
investment-related traits.
 Genetic influences
 See if there is any similarity or correlations between the twin’s
spouses and see if there is a difference between the spouses of
MZ and DZ twins
 Sexual Imprinting
 Twin’s partner should be more similar to the twin’s oppositesex parent than to a co-twin or a same-sex parent
Table One
 22,861 individuals from 6,105 independent families
Table 2
In this table it is clear that twins’ partners were not more similar in any trait
to the twins’ opposite-sex parent than to the twins’ same-sex parent.
That’s a strike against the imprinting thesis.
Table 3

Table 3 shows that partners correlated very weakly on some traits (e.g., income and
personality) but strongly on others (e.g., religiosity and attitudes).
Table 4 - shows the correlations between twin pair partners on
each trait

Notice that there’s not a difference between MZ and DZ females for income.
From the tables
 Twin’s Partners correlated weakly on most traits but
positive on some
 Correlation between twin pair partners was not
significant for BMI, height, and all personality scales,
but there were small but significant correlations
between twin pair partners for education, income,
religiosity, attitudes, and age.
 Tested to see if there was a difference between MZ and DZ
partners, but there was none (correlation not higher in MZ)
 indicates no significant genetic influence on mate choice
From the tables
 Specifically for income and age, correlations between female
MZ and DZ twin pair partners were highly significant and
similar in size, indicating a genuine family environmental
influence on women’s mate choice for these traits even after
controlling for assortative mating
 There was no evidence for the sexual imprinting hypothesis.
 A twin's spouse was much more similar to the twin and co-twin
than the twin's opposite-sex parent.
 For the heritability of each trait, twin pair correlations were
significantly greater for MZ pairs than for DZ pairs
Discussion
 Overall, found that genetic variation accounts for very
little individual variation in human mate choice.
 Twin’s partners correlated very little
 Furthermore, there were no significant genetic effects on
mate choice in either males or females for any individual
trait.
 it is remarkable that a choice behavior so central to
individuals’ lives exhibits a near-zero genetic
component
 But choice of mate requires reciprocity
Discussion
 One positive finding in the results is an influence of
family environment on female mate choice in terms of
the income and age of a partner
 parental influence is expected to primarily involve pressure
on a daughter to mate with successful man
 There was little evidence for substantial familial effects on
other aspects of mate choice.
 Main conclusion: Despite being one of the most
important choices in human life, variation in partner
choice followed no apparent order aside from a small
family environmental influence on the age and income
of females’ mate choices and the similarity of partners
in some traits.
Improve Study
 Study different traits – pheromones, facial
characteristics
 Look at newlyweds and see if there is a difference
 Done in Australia – different environmental influences
References
 http://www.britannica.com/EBchecked/topic/39494/assortative
-mating
 http://blogs.discovermagazine.com/gnxp/2011/04/love-is-nota-hardwired-battlefield/
 http://www.jstor.org.pallas2.tcl.sc.edu/stable/10.1086/659629?
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