Biology 5C ~ Lecture 25 ~ Evolution and Notions of Human Race

LINNAEUS AND ESSENTIALIST THINKING

-invented the binomial nomenclature system used for classifying organisms

-believed that all living organisms were created by God with unique “essences” (an unchanging Earth created by God and things classified by 'closeness' to God)

-"stability of type and hierarchy"

race definiton:

a worldview and social classification that divides humans into groups based on their appearance and assumed ancestry, and that has been used to establish social hierarchies

race as a socially defined category is very real

-it provided an early scientific cover to justify colonization and slavery

Race as a biologically defined category does not exist

-all known social classifications of race fail to map onto observed genetic variation across groups

* human beings are not divisible into unambiguous "biological races" based on genetics or ancestry

race:

even though race is not a biological category...

dividing individuals into racial categories has very real biological effects!

-social constructions make out reality--> all knowledge is socially constructed

race as we use it is a flexible category because:

-how "races" are categorized differs across cultures and time (who fits into what race is fluid and poorly defined)

-these categories change to fit different social and political environments (different countries have varying racial categories)

MEASURING GENETIC DIFFERENCES BETWEEN POPULATIONS

-measures the difference between genomes (organisms complete set of DNA)

-about 99.99% of the genomes of living humans are identical (differ by ~3.3mbp)

POPULATION SUBDIVISION STATISTIC(FST)

-a mutation in coding regions are often observed with lower freq.

-mutations with non-coding regions are where most genetic variation is observed

-ranges from 0 to 1.00

-quantifies the difference in the frequencies of alleles in a population compared with the allele frequency of the entire species (variation within population divided by total variation)

THERE IS MORE VARIATION WITHIN HUMAN POPULATIONS THAN BETWEEN THEM

-greatest diversity in sub-saharan Africa

-other groups "bottlenecked as they migrated out of Africa

-some specific genes are strongly differentiated between pops. (particular genes do show geographically-based variation)

Variation

-an FST value of 0.25 or greater may indicate “biological races”

-particular genes do show geographically-based variation

LOCAL ADAPTATION AND ISOLATION BY DISTANCE

-migration started abt 100k YA
-in Africa for 200,000 years

*humans vary continuously across geographic areas

defining racism

-systematic discrimination by a powerful individual or institution against individuals based on their perceived membership in a socially defined racial group

defining racism pt.2

-only governments, corporations, social groups, and individuals who have collective political and social power can implement racism

racist ideology dictates what race means

-official racial classifications are unstable and bend to meet the needs of those in power

racism consequences for medicine

-faulty assumption that human genetic variation is patterned along socially defined race or color lines

-this can be problematic for diagnosing illnesses based on perceived skin color differences in humans

review 1:

“race” may be defined either biologically or socially but biologically-defined race does not exist in human species

review 2:

genetic comparisons of human populations show that within- population variation is greater than between-population variation for many traits

review 3:

even though biologically-defined race does not exist in human species, racial categories still produce real biological effects!

review 4:

faulty assumptions about biological race have real implications for healthcare and the treatment of disease