1. Journal club at IEND presented by:
REHAB YOUSIF MOHAMED IDREES
Faculty of pharmacy
drrehab2008@yahoo.com
Khartoum university

4. was developed in the late 1970s
and early 1980s to explain how
human behavior is a product of two
different and interacting
evolutionary processes: genetic
evolution and cultural evolution.

5. DIT is a "middle-ground" between
much of social science, which views
culture as the primary cause of human
behavioral variation, and human
sociobiology and evolutionary psychology
which view culture as an insignificant by-
product of genetic selection . In DIT,
culture is defined as information in human
brains that got there by social learning

6. •Cultural evolution is considered a
Darwinian selection process that acts on
cultural information.
• Dual Inheritance Theorists often describe
this by analogy to genetic evolution, which is
a Darwinian selection process acting on
genetic information.

7. Culture can profoundly influence
gene frequencies in a population.
One of the best known examples is
the prevalence of the genotype for adult
lactose absorption in human
populations, such as Northern Europeans
and some African societies, with a long
history of raising cattle for milk.

8. Other societies such as East Asians
and Amerindians, retain the typical
mammalian genotype in which the
body shuts down lactase production
shortly after the normal age of
weaning.

9. This implies that the cultural practice of
raising cattle for milk led to a selection for
genetic traits for lactose digestion.
Recently, analysis of natural selection on
the human genome suggests that
civilization has accelerated genetic change
in humans over the past 10,000 years

11. Over the last 30 years, social
psychologists have documented an
impressive array of psycho cultural
differences. For example , in East
Asian cultures the self tends to be
defined in relationship to the group,
or collective

12. whereas in Western cultures (e.g.
Europe and the nations of the
former British Commonwealth)
there is a greater proclivity for the
self to be viewed as unique, stable
and independent of the social
group .

13. A critical question raised by
such findings is how do such
cultural differences arise? Why do
some groups tend towards
collectivism, while others tend
towards individualism

14. Answering this complex question will
require integrating many levels of
analysis . A helpful means of integrating
these diverse influences is to adopt a
cultural neuroscience perspective
, because the brain is the central part or
the hub where each of these influences
converge.

15. Accordingly, genes affecting
brain function are likely to influence
the adoption and formation of cultural
norms and, conversely, culture may
also shape the expression and
selection of genes.

16. Although the study of psychological
genetics is in its infancy and much is still
to be learned, data suggesting that
variation in several genes known to affect
brain function appear to influence the
degree to which one is emotionally
responsive to the social environment

17. Individualism emphasizes personal
freedom and achievement.
Individualist culture therefore awards
social status to personal
accomplishments such as important
discoveries, innovations or great
artistic achievements

19. Collectivism makes collective action
easier in the sense that individuals
internalize group interests to a
greater degree. However, it also
encourages conformity and
discourages individuals from standing
out..

26. The promoter region of the SLC6A4 gene
contains a polymorphism with "short" and
"long" repeats in a region: 5-HTT-linked
polymorphic region (5-HTTLPR or
SERTPR). The short variation has 14 repeats
of a sequence while the long variation has 16
repeats. The short variation leads to less
transcription for SLC6A4, and it has been
found that it can partly account for anxiety-
related personality traits

27. It reuptakes serotonin in the synaptic
cleft and terminates its function. It
allows neurons, and other cells to
accumulate the chemical
neurotransmitter serotonin, which
affects emotions and drives.

29. As a neurotransmitter, serotonin helps to
relay messages from one area of the brain to
another.
Of the approximately 40 million brain cells
, most are influenced either directly or
indirectly by serotonin. This includes brain
cells related to mood, appetite, memory and
learning, temperature regulation, and some
social behavior.

31. Joan Y. Chiao and Katherine D. Blizinsky

32. Culture-gene coevolution of individualism-collectivism and
the serotonin transporter gene
Joan Y. Chiao and Katherine D. Blizinsky
Supplementary data
tml
http://rspb.royalsocietypublishing.org/content/suppl/2009/10/27/rspb.2009.1650.DC1.h
"Data Supplement"
References
http://rspb.royalsocietypublishing.org/content/277/1681/529.full.html#related-urls
Article cited in:
http://rspb.royalsocietypublishing.org/content/277/1681/529.full.html#ref-list-1
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33. Here, we examined the association
between cultural values of individualism–
collectivism and allelic frequency of the
serotonin transporter functional
polymorphism (5-HTTLPR) as well as the
role this culture–gene association may play in
explaining global variability in prevalence of
pathogens and affective disorders.

34. Individuals carrying the S allele of the
5-HTTLPR produce significantly less5-
HTT mRNA and protein, resulting in
higher concentrations of serotonin in the
synaptic cleft relative to individuals
carrying the L allele Evidence from
behavioral genetics indicates that the S
allele of the serotonin transporter gene (5-
HTTLPR) is associated with increased
negative emotion.

35. In a typical East Asian sample, 70–80%
of individuals are S carriers compared with
a typical European sample where 40–45%
of individuals are S carriers of the 5-HTT
genotype .
It remains unclear why there exists
genetic selection for S relative to L allele
carriers in East Asian regions ,but not
other geographical regions of the world.

36. One possible explanation for greater
prevalence of S allele carriers in East Asia is that
geographical variability in environmental
pressures has led to cultural variability in
individualism–collectivism via genetic selection.
Recent research has shown that
geographical variability in historical and
contemporary pathogen prevalence predicts
variability in individualistic and collectivistic
cultural norms .

37. That is, nations with greater historical
and contemporary prevalence of disease-
causing pathogens or infectious diseases(e.g.
malaria, typhus and leprosy) are more likely
to endorse collectivistic cultural
norms, likely due to the anti-pathogen
defense function that collectivistic norms
may serve.

40. Geographical coincidence between serotonin
transporter gene diversity and cultural traits of
individualism-collectivism across countries. Gray
areas indicate geographical regions where no
published data are available.
( a ) Map of frequency distribution of Individualism-
Collectivism. ( b ) Map of frequency distribution of S
alleles of 5-HTTLPR. ( c ) Map of frequency of
global prevalence of anxiety. ( d ) Map of frequency
of global prevalence of mood disorders. Yellow to red
colour bar indicates low to high prevalence.

41. We found evidence that collectivistic
cultures were significantly more likely to
comprise individuals carrying the short(S)
allele of the 5-HTTLPR across 29 nations.

42. Results further show that historical
pathogen prevalence predicts cultural
variability in individualism–collectivism
owing to genetic selection of the S allele.
Additionally, cultural values and
frequency of S allele carriers negatively
predict global prevalence of anxiety and
mood disorder.

43. Finally, mediation analyses further
indicate that increased frequency of S
allele carriers predicted decreased
anxiety and mood disorder
prevalence owing to increased
collectivistic cultural values.

44. Taken together, our findings suggest
culture–gene co evolution between allelic
frequency of 5-HTTLPR and cultural
values of individualism–collectivism and
support the notion that cultural values
buffer genetically susceptible populations
from increased prevalence of affective
disorders

45. Importantly ,we also reveal a novel and
surprising negative association between
individualism–collectivism, frequency of S
allele carriers of the serotonin transporter
gene and global prevalence of anxiety and
mood disorder.

47. Proc. R. Soc. B published online 22 September 2010
Dan T. A. Eisenberg and M. Geoffrey Hayes

48. While it is a pleasure to see Chiao
and Blizinsky test hypotheses relating
to the evolutionary origins of
behaviorally implicated genes, there are
a number of flaws in their
methodology which call their findings
into question.

49. Upon examination of the original sources cited
by Chiao and Blizinsky from which 5-HTTLPR
frequencies were derived, the above non-Eurasian
locales exhibit considerable European cultural
and genetic influence. The sampled South
Africans Brazilians Australians and
Argentineans were of Caucasian/European
descent. Additionally, the New Zealand sample is
predominantly of European descent

50. We then proceeded to examine the association
between
individualism–collectivism and 5-HTTLPR
allele frequency in Eurasia inside Europe and
Asia separately.
No association between 5-HTTLPR and
individualism–collectivism in the sample of
14 European countries is
evident r(14) 0.32, p 0.26

51. Since this lack of association could be
due to reduced sample sizes, we took
10 000 different random samples of 14
countries from the original dataset of
29 and examined the distribution of
correlation coefficients

52. Correlations0.32 or less were found less than
3 per cent of the time, suggesting that the small
correlation in the European only analysis was
not due to the limited sample size in Europe. In
fact, if Turkey is dropped from the analysis,the
relationship switches to the opposite direction of
predicted (r(13) _.18, p 0.55

53. While Chiao and Blizinsky
hypothesis is compelling and
deserves further examination, we feel
that it is not supported by the
current data in light of these
analyses.

54. Further study would benefit from a
larger number of independent samples
and controls for underlying population
structure

55. In addition, since selection probably
works on multiple loci in related
pathways simultaneously expanding to
other loci that are correlated with
similar phenotypes would further
strengthen the case.

56. Through more careful cross-
population analysis, we predict that
cases of gene culture co evolution
will be found to be prevalent .

58. Thank you