PSYC 3350 Chapter Notes - Chapter 11: Lactase, Lactose Intolerance, Cultural Practice

67 views8 pages
Published on 19 Apr 2013
School
York University
Department
Psychology
Course
PSYC 3350
Cultural psyc chapter 11 Physical Health
Early humans feet: less bipedal than modern humans, wider, with larger gap between first 2
toes and higher arch
Difference due to not wearing shoes: people who habitually wear shoes tend to have narrower
feet, 2 first toes closer together and lower arch.
Shape of feet can be seen as a cultural product: wearing shoes changes shape of feet, and way
we run
Running has been central enough to human history that some researchers proposed humans
have evolved to be endurance runners, enabling them to outrun prey
Running in barefeet: more likely to land on fore-feet or midfeet
Running in shoes: tend to land rear feet
Anecdotal reports indicate that barefooted running leads to reduced injury rates; also children
take longer steps when wearing shoes
BIOLOGICAL VARIABILITY OF HUMANS
Two categories of explanation for human biology variation
1. Humans in different parts of the world were subject to different selection pressures
over many generations, and this resulted in the human genome diverging across
different populations (innate biological differences)
2. People living in different cultures have experiences within their own lifetimes that have
an impact on their biology (acquired biological differences)
Genetic Variation Across Populations
Selection pressures vary across different geographical and cultural environments, so humans
have been evolving some particular traits that differ across regions of the world
Humans all first lived in Africa
Small population of humans quickly expanded in Africa before some left, and as a result of this
quick expansion, there’s far less genetic variability across the difference races of humans than in
populations of chimpanzees
Most obvious genetic variability of humans across populations is skin color.
o Difference due to body’s ability to synthesize vitamin D
o Skin must allow UVR to penetrate skin layer to synthesize, but too much can cause a
breakdown of folic acid
o Humans first emerged in Africa, where UVR is high, they evolved to have enough
melanin(darker color) in their skin to allow enough UVR, but not enough to break down
folic acid
o When humans moved to places with less UVR, they needed to absorb more; evolved to
have less melanin(whiter)
Skin color is an adaptive response to climate differences among populations
Strong selective forces:
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 8 pages and 3 million more documents.

Already have an account? Log in
o Climate: ex. individuals who better adapt to local climate will have more surviving
offspring, different genetic variations associated with heat stress
o Presence of certain kinds of local pathogens: those more genetically resistant to
pathogens, more likely to survive/reproduce
Genetic adaptation to local climate and pathogens are were geographical factors have shaped
the genotype
Cultural factors also can shape genotype: ex. Most adults who drink milk will develop symptoms
of lactose intolerance because they do not have the lactase enzyme
o Lactase nonpersistence has been seen in ancestral population before they left Africa
o Some populations(particularly northern Europe) then developed a mutation for lactase
persistence: developed in areas where cows have been domesticated for the longest
period
o Cultural practice of dairy farming led to the selection of lactase persistence among cattle
raising populations
Culture has strong selective role on human genome: commonly seen in cultural differences in
dietary practices
o Humans vary in amount of starch they eat and people whose cultures consume a lot of
starch likely to have a mutation that increases the amount of amylase protein in their
saliva, which helps digest starch
o Asians less likely than Euro to have an enzyme which sufficiently detoxifies alcohol; half
Asians react to alcohol with a rapid increase in heart rate and temperature (causes Asian
flush)
Probably because of cultural difference in how they solved contaminated water
supply: Euro solved problem by creating a cultural practice of drinking more
wine/beer, whereas Asians boiled their water and drank tea.
Ways culture can influence genome sometimes indirect
o Cultural practice of yam farming led to more pools of water, which led to more malaria
carrying mosquitoes
o Malaria spread to these regions and lead to evolution of genetic variant for hemoglobin
that is associated with sickle cell anemia, which has the benefit of making one more
resistant to developing malaria
Number of international research projects have identified several gene variants associated with
psychological variables that differ in their frequencies around the world
o Alleles associated with at least 3 different genes predict enhanced social sensitivity, and
each one is more common in Asian samples than in euro. (collectivism may have genetic
foundation)
Some studies which explore the relations between genes and psychological variables across
cultures commonly find opposite effects of western data
o Ex. Genetic variant that is associated with increased emotional support seeking in times
of distress for euro-Americans is associated with decreased emotional support seeking
among Koreans
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 8 pages and 3 million more documents.

Already have an account? Log in
o Variant associated with increased attention to foreground objects among Euro-AM
shows the opposite effect among Koreans
o Variant that leads to better responses to antidepressants among Caucasians leads to
worse responses among jp and kr
Studies which included a sample of kr Americans, who were genetically more similar to krs but
culturally more similar to euro, showed results that were more similar to euro, demonstrating
that cultural experiences can actually shape how genes are expressed in body
o Shows that even if gene frequencies may vary across cultures, it does not mean
associated psychological traits will also vary
Controversial whether psychological differences across cultures might be related to population
level genetic differences
Acquired Physical Variation across cultures
There is evidence which suggests physical variation of people that exists independently of
genetics
Moken children (tribe of sea nomads who spend 6-8 months on small boats) have more than
twice the underwater visual acuity of euro children through controlled accommodation. This
ability is not a genetic adaptation; acquired through practice and euro children can also be
trained
Obesity and diet
o People from diff cultures differ from each other in weight
o Variability in obesity rates; rates have increased esp in US and UK (not explained by
genetics, more on cultural changes)
o French paradox: diet rich in fats yet lower rates of heart rates in France (US obesity rates
5x more than France)
One explanation is that fr drink more wine than Americans which serves to
inhibit platelet reactivity, and thereby reducing risk of coronary heart disease
Another explanation is that fr eat less calories per day than Americans, and they
do so because they live in different cultural environments that affect the sizes of
their portions and their attitudes toward food
Study: yogurt containers in US are 80% bigger than in France and a variety of
food sold in individual servings are larger; fruit also larger
More fries in US McDonalds than in France
o Larger portions in US and elsewhere are the product of a recent cultural evolution
o Ex. Starbucks coffee sizes keep getting larger
o There is also differences in fr and amer attitudes toward food
Fr view eating more as a leisurely and enjoyable activity than Americans.
Fr spend more time eating their food
Americans have conflicted attitudes toward food, esp women
Unlock document

This preview shows pages 1-3 of the document.
Unlock all 8 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Early humans feet: less bipedal than modern humans, wider, with larger gap between first 2 toes and higher arch. Difference due to not wearing shoes: people who habitually wear shoes tend to have narrower feet, 2 first toes closer together and lower arch. Shape of feet can be seen as a cultural product: wearing shoes changes shape of feet, and way we run. Running has been central enough to human history that some researchers proposed humans have evolved to be endurance runners, enabling them to outrun prey. Running in barefeet: more likely to land on fore-feet or midfeet. Running in shoes: tend to land rear feet. Anecdotal reports indicate that barefooted running leads to reduced injury rates; also children take longer steps when wearing shoes. Selection pressures vary across different geographical and cultural environments, so humans have been evolving some particular traits that differ across regions of the world.

Get OneClass Grade+

Unlimited access to all notes and study guides.

YearlyMost Popular
75% OFF
$9.98/m
Monthly
$39.98/m
Single doc
$39.98

or

You will be charged $119.76 upfront and auto renewed at the end of each cycle. You may cancel anytime under Payment Settings. For more information, see our Terms and Privacy.
Payments are encrypted using 256-bit SSL. Powered by Stripe.