A review of polygenic inheritance

Global Patterns of Human Variation Can be examined genetically Can be examined phenotypically Are phenotypic differences concordant with genetic differences?

Eight classes of genetic similarity enzyme & blood group loci Arrayed by increasing difference Distribution of eight classes of skin pigmentation intensity Concordance or discordance?

However, there IS geographic structuring of allele frequencies. Genetic distance map 42 native human populations Frequencies of 120 different alleles Closer proximity in graph = greater genetic similarity Related to geographic distances among the groups. PPPPPopu Population differences

Average genetic differences Distance curtails gene flow among groups

Populational differences among human groups Today, human races are distinguished by ethnic differences – NOT by biological differences. – Differences in culture nationality language religion – Biologically, there is no Jewish race, no African race, no African-American race, etc. – But, biological differences may still be emphasized, even in sociology; e.g., people of color.

Effects of gene flow on populations e.g., microevolution in Ireland Data set: anthropometric (skull) measurements Collected in 1930s >7000 men from 30 of 31 counties Phenotypic measurements converted into similarity measurements: genetic distances Plot of distances between samples from 30 counties. Graphical pattern reveals the pattern of variation.

Prediction: because of location, the four centrally located counties should be genetically similar to all of the other counties In a central position re of past migration routes and gene flow

H 1 : resulted from gene flow from Danish and Norwegian Viking invaders. One incursion Into; central Ireland involved 12,000 men. M counties displaced away from the other counties

Testing the hypothesis