Dienekes and Maju have both commented on a new paper which looked at the likelihood of lactase persistence in Neolithic remains from Spain, but I thought I would comment on it as well. The paper is: Low prevalence of lactase persistence in Neolithic South-West Europe. The location is on the fringes of the modern Basque country, while the time frame is ~3000 BC. Table 3 shows the major result:
Lactase persistence is a dominant trait. That means any individual with at least one copy of the T allele is persistent. As Maju noted a peculiarity here is that the genotypes are not in Hardy-Weinberg Equilibrium. Specifically, there are an excess of homozygotes. Using the SJAPL location as a potentially random mating scenario you should expect ~7 T/C genotypes, not 2. Interestingly the persistent individual in the Longar location also a homozygote.
President William Howard Taft
It is the best of times, it is the worse of times. On the one hand the medical consequences of human genomics have been underwhelming. This is important because this is the ultimate reason that much of the basic research is funded. And yet we’ve learned so much. The genetic architecture of skin color has been elucidated, and we’ve seen a clarification of patterns of natural selection in the human genome. The finding last spring of Neandertal admixture in modern human populations is perhaps the most awesome pure science finding of late, coming close to resolving a decades old debate in anthropology. This doesn’t cure cancer, but it does connect the dots about the human past, and that’s not trivial. We are species haunted by our memories, so we might as well get them right!
But all hope is not lost. Research continues. And one area which general surveys of genomic variation have usually shown to be targets of natural selection, and, also have clear and immediate biomedical relevance, is that of metabolism. How we eat, and how we process and integrate the food we eat, is of obvious fitness relevance in the evolutionary and medical senses. It turns out that there is even variation in our saliva which is probably due to natural selection. The combination of diversity in human cuisine and susceptibility to the diseases of modern life indicate possibilities as to the relationship between past selection pressures and contemporary patterns of genetic variation. Of course one has to tread softly in this area, there are the inevitable confounds of environment, as well the unfortunate probability of any given locus being of small effect size in its influence on any given trait.
A new paper in Genome Research reports a SNP which seems to have been subject to natural selection in Eurasians within the last 10,000 years. This variant is located within an exon on a gene, GIP, which produces peptides critical in the regulation of various metabolic pathways, in particular insulin response. A possible biomedical relevance to risk susceptibility is then explored subsequent to the evolutionary genomic preliminaries. Adaptive selection of an incretin gene in Eurasian populations: