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60 A. C. Ciani and C. Capiluppi

Figure 5. Emigrant Islanders versus Sedentary Islanders.

consistent with the genetic predictions than the environ- unlikely that this is the result of multiple and similar founder
mental ones (Table 3). Indeed, immigrants did not change effects.
their personality profile after immigrating to the insular
environment and remained different from islanders. Genetic versus environmental hypotheses

Founder effect hypothesis The adapted immigrants, after living in the island
environment for 20 years or more, still preserve most of
We have additional evidence against the alternative their original mainlander personality (Table 3); also the
hypothesis suggested by Van Oers (2007) that the personality native immigrants, despite having been born on the islands,
of the founding populations of the islands previously studied differ neither from mainlanders nor from adapted immi-
was different from the mainlanders right from the beginning, grants on any personality trait; the native immigrants, in
as per the founder effect (Fisher, 1930). Already Camperio contrast, differ from the native original islanders (with
Ciani et al. (2007) observed the same pattern of personality whom they have shared the same environment since birth) on
differences in three different archipelagos, and in this study extraversion, openness to experience and conscientiousness.
we again observed almost exactly the same pattern of These results are not consistent with an environmental
differences in another one, with a rather different historical influence on these personality traits, and suggest genetic
background. We here show in a comparative table (Table 4) implications.
between this study and the previous one that except minor
difference in effect size Extraversion, and Openness to In particular, the Early Experiences hypothesis (Costa &
experience show always the same pattern of differences, McCrae, 1992; Forgas & Van Heck, 1992; McCrae & Costa,
conscentiousness has only a minor difference when 1999) is not supported by the present findings as far as
comparing emigrants and sedentary islanders, and the other extraversion is concerned. The whole set of comparisons
two traits never show any significant differences. Hence, at presented in Table 3 is consistently significant for all the
present, after about 25 generations, we have observed four comparisons which lend support to the genetic hypothesis,
independent archipelagos (including the ones considered in while extraversion does not confirm any of the environ-
the previous study), composed of 15 inhabited islands in mental predictions. This suggests that extraversion is a
total, showing a convergent personality pattern (Table 4). It is fairly stable, endogenous trait, and is neither significantly
influenced by the environment, nor by early experiences

Table 4. Comparison between the studies of Camperio Ciani et al. (2007), and present one

Emotional Openness to
Extraversion Agreeableness Conscientiousness stability experience

Islanders vs. mainlanders Camperio Ciani et al. (2007) À þÀ
Islanders vs. immigrates Present study ÀÀ þ ÀÀ
Emigrates vs. islanders Camperio Ciani et al. (2007)
Present study À ÀÀ
Camperio Ciani et al. (2007) ÀÀ ÀÀ
Present study þþ À þþ
þþ þþ

Camperio Ciani et al. (2007) study includes three archipelagos with a total of ten inhabited islands and the present one includes one archipelago with three
inhabited islands.
Traits higher, less (þ) or more (þþ), than three standardized T-scores difference. Traits lower, less (S) or more (S S), than three standardized T-scores
difference. Only significant differences are shown in the table.

Copyright # 2010 John Wiley & Sons, Ltd. Eur. J. Pers. 25: 53–64 (2011)
DOI: 10.1002/per