One of the main findings here is the north-south gradient within
England in the frequency of the lactase persistence allele. But
they also examine relationships between this genotype and health
measures in order to uncover the mechanism by which lactase
persistence may have been selected for. For example, did lactase
persistence arise due to the benefits (sugar, protein, fat) or
because it enabled one to avoid the ill effects of lactose non-
persitence (adverse health reactions)? In this paper, they test
for associations between the LCT genotype and various health-
related measures. They also have a good discussion about the
selection pressures that may have led to the lactase persistence
trait being favored. Among the hypotheses, many of which I had
never heard of, as outlined in the paper: 1) "nutritional (and
survival) advantage of milk consumption in populations that have
milk availability" 2) "the calcium absorption hypothesis which
considers the ability to use milk as of particular importance
for high lat