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62 A. C. Ciani and C. Capiluppi
differences in the phenotype. Whenever the outflow of
particular alleles, due to emigration, is not replaced by a
corresponding inflow of the same alleles in the population,
we can expect a progressive reduction in the frequency of
that allele, generation after generation (Fisher, 1930). After a validity of our hypothesis, perhaps in very different
sufficient number of generations this frequency reduction
should be measurable in the phenotype expressed by those
alleles. The difference between outflow and inflow rates and
the number of generations that the gene flow process has
been active constitute critical factors.
Immigration to small islands, and other small confined
environments, in the past has been random personality-wise,
because it was determined by exogenous life events, which
were unrelated to personality. In our study’s case, immigrants
to the Egadi islands were not selected on the basis of
personality traits (Calleri, 2006). Only very recently has
tourism attracted a few individuals to a permanent and
voluntary settlement in the archipelago. We suggest that this
condition holds true for a majority of isolated populations. In
the past, before the advent of modern tourism, very few
people deliberately decided to resettle in a small remote
isolated community.
As an alternative to the Personality Gene Flow
hypothesis, Chen et al. (1999) suggest that selective
mortality on individuals who emigrate to new environments
favors extravert and open to experience individuals, while in
their native environment, it favors introverted and closed
individuals, who are more attached to the land (Chen et al.,
1999). However, in these Italian archipelagoes the change in
frequency of the personality traits happened quickly, in
relatively few generations and with no particular mortality
recorded (Gallitto, 2008; ISTAT, 2009). Hence, selective
mortality is unlikely to be the mechanism responsible for the
differences in personality traits observed.
Various explanations have been suggested to explain why
many alleles influencing personality are not selected against
and removed from large populations (Buss, 1991, 1999;
Dawkins, 1977; Mealey, 1995; Tooby & Cosmides, 1990).
We here suggest that the active human-environment
interaction explains why no measurable differences of
personality are found in wide-scale population surveys (such
as national ones). In large populations gene flow happens
within the same population, as people displace from one
environmental niche to the other within the same city, area or
country, hence large-scale personality investigations cannot
detect any group differences. On the contrary, significant
measurable differences can be found in a small isolated
environment, as is the case with the Egadi archipelago
studied here. In small isolated populations, where the socio-
environmental niches are limited and cannot fit each possible
personality profile, people that do not adapt, do not die but
they do migrate elsewhere. In this case, gene flow happens
between populations, then personality studies can detect
population personality differences between populations
because emigrants (and their descendents), after having
abandoned the island, are no longer present there and remove
their alleles from the isolated population.
In conclusion, we propose here that if the Personality
Gene Flow hypothesis holds true, then personality differ-
Copyright # 2010 John Wiley & Sons, Ltd.
ences in small relatively isolated populations should rapidly
appear over time wherever there is strong non-random
emigration paired with random and reduced immigration, as
is the case in most isolated small populations in the world,
such as small islands or isolated high mountains commun-
ities. Further research is necessary to increase the external
geographic locations with different historical backgrounds.
Our results are based on questionnaires and genetic factors
are estimated by demographic variables (ancestry, pedigree),
not by direct genetic tests, and we can only indirectly point to
possible underlying microevolutionary changes. A further
study based on genetic tests is needed to support our
arguments that assume the association between ancestry and
alleles. Our hypothesis predicts that future genetic investi-
gations will find significantly different allelic frequency
distributions between isolated small populations and
corresponding large ones, but only for genes, which
influence traits of Extraversion and Openness to experience.
This study further underlines the adaptable nature of our
species, which responds to environmental challenges not
only by selecting physical traits but also by selecting
behavioural and personality traits.
ACKNOWLEDGMENTS
The Ethics Committee of the Department of General
Psychology, University of Padova, approved the methods
and questionnaire used in this study. We are most grateful to
M. Gallitto and D. Ligresti for revealing to us historical
aspects of the islands and their population. We thank A.
Veronese, and all the 18 assistants who volunteered for this
project. We thank P. Castillo for her initial contribution to
this project. No public funds were used for this research, as it
is quite usual for Italian research nowadays, and it was solely
funded by the authors’ own interest in science.
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DOI: 10.1002/per