The tiny volcanic island of Tristan da Cunha is the most remote inhabited place on Earth. It lies in the South Atlantic, 1,700 miles and a week’s journey by boat from Cape Town, South Africa. The island’s population of 300 is descended from a handful of founders, mostly shipwreck survivors, who settled there in the 19th century. The small number of founders is reflected in the fact that only se...

A number of studies indicates that there is a high sharing of HLA antigens in couples having recurrent spontaneous abortions. The genetic hypothesis to explain this phenomenon suggests that this fetal loss results from homozygosity of recessive lethal or deleterious alleles in gametic disequilibrium with HLA antigens. Theory predicting the lethality rate is derived when antigens are shared at o...

The theory of evolution at a selectively neutral locus that controls the recombination between two major loci that are under selection is studied. If the major loci are at a stable equilibrium in linkage disequilibrium under selection and recombination, then a mutation at the modifier locus will increase in frequency when rare if and only if it decreases the recombination fraction. If the major...