The "Wisteria Vine" view of human evolution and diversification
This pencil sketch illustrates our general model of "branching" and "anastomosing"
within each region of the world. The expansion out of Africa, however,
sampled only part of the African gene pool with additional genetic drift
accumulating before non-African populations diverged, thereby establishing
a pattern of variation common to all non-Africans. As humans migrated farther
from Africa and then expanded locally to occupy all of Eurasia even more
drift accumulated because the subsets of the local gene pools carried forward
by migrants became successively more homogeneous. The result is a general
clinal pattern of decreasing heterozygosity and increasing linkage disequilibrium
with increasing distance from Africa but with a marked founder effect associated
with the expansion out of Africa.
© 1999 Kenneth K Kidd, Yale University. All rights reserved. This
material may be reproduced for classroom use only.