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A few years ago, a new paper, SLC24A5, a putative cation exchanger, affects pigmentation in zebrafish and humans, made some waves. It used zebrafish to elucidate the genetics of a locus, SLC24A5, which is responsible for 1/3 of the between population difference between Europeans and Africans in skin color. In short, Europeans are fixed for […]
One of the secondary issues which cropped up with Nina Davuluri winning Miss America is that it seems implausible that someone with her complexion would be able to win any Indian beauty contest. A quick skim of Google images “Miss India” will make clear the reality that I’m alluding to. The Indian beauty ideal, especially […]
Pigmentation is one of the few complex traits in the post-genomic era which has been amenable to nearly total characterization. The reason for this is clear in hindsight. As far back as the 1950s (see The Genetics of Human Populations) there were inferences made using human pedigrees which suggested that normal human variation on this […]
One of the pitfalls about talking about genetics, especially human genetics, is that the public wants a specific gene for a specific trait. Ergo, the “God gene” or the “language gene.” In some cases science has been able to pull a rabbit out of the hat, and offer up a gene for a trait. But […]
The Pith: the evolution of lighter skin is complex, and seems to have occurred in stages. The current European phenotype may date to the end of the last Ice Age. A new paper in Molecular Biology and Evolution, The timing of pigmentation lightening in Europeans, is rather interesting. It’s important because skin pigmentation has been […]
A comment below: Does the higher genetic diversity in sub-Saharan Africans explain why mixed children of blacks + other couples usually look more black than anything? As in, the higher number of genetic characteristics overwhelms those of the other parent and allows them to be present in the child. But this makes you ask: is […]
I was pointed today to a piece in the BBC titled What makes a mixed race twin white or black?. The British media seems to revisit this topic repeatedly. There are perhaps three reasons I can offer for this. First, it tends toward sensationalism. Even though the BBC is relatively staid, when it comes to […]
A story in The Los Angeles Times seems to point medical implications of being a sickle cell carrier, Sickle cell trait: The silent killer: At least 17 high school and college athletes’ deaths have been tied to sickle cell trait during the past 11 years. The group includes Olivier Louis, a player at Wekiva High […]
In science, like most things, one prefers simple over complex whenever possible. You keep adding variables until the explanatory juice starts hitting diminishing marginal returns. So cystic fibrosis is due to a mutation at one gene, and the disease expresses recessively at that locus. The reality is that one mutation accounts for ~65-70% of cystic […]
Recently I was looking for images of the alpine biomes of the New Guinea highlands* and stumbled onto some intriguing, though not entirely surprising, set of photographs of individuals from Papua New Guinea. They were noteworthy because they manifested the conventional Melanesian physical type, but their hair had a blonde cast to it. For example, […]
One of the most successful achievements of the “post-genomic era” has been the elucidation of the genetic architecture which undergird the variation in human pigmentation. I like to point out that in 2005 the geneticist Armand Leroi observed in his book Mutants that we didn’t know the genetics of normal variation in relation to the […]
Over the history of this weblog I have blogged about pigmentation a fair amount. The major reason is that that’s where the money is; unlike height, let alone intelligence, the genetic architecture and evolutionary history of pigmentation has been elucidated with relative clarity. That is, we know roughly the number and nature of the genes […]
In the aughts the elucidation of human pigmentation genetics was of one the major successes of ‘omic’ techniques. The fact that humans exhibit some continuous variation in complexion was strongly suggestive that more than one gene was at work to generate the range of the phenotype. On the other hand pedigree based studies going back […]
Two interesting papers, one which relates KITLG and cancer, and another which connects ABCC11 and cancer. These are familiar genes. KITLG has been implicated in depigmentation, both of skin and hair. ABCC11 in earwax form and body odor. If you knock around a gene there is a high probability that you’ll perturb multiple traits. Somethings […]
Richard Sturm in Human Molecular Genetics has a really good review of the current state of pigmentation genetics, with a human centric focus: The genetic basis underlying normal variation in the pigmentary traits of skin, hair and eye colour has been the subject of intense research directed at understanding the diversity seen both between and […]
You know what the Human Genome Diversity Project (HGDP) is implicitly, they’re the list of populations you’ve seen in many human genetics papers already. Now the Pritchard lab has put up a nice browser to query the data in a manner analogous to Haplotter. One of the major improvements, aside from the fact that you’re […]
Genetic Future points me to a Nature News story, Making babies: the next 30 years. He highlights this section: There’s speculation that people will have designer babies, but I don’t think the data are there to support that. The spectre of people wanting the perfect child is based on a false premise. No single gene […]
Sandy pointed me to letter to Nature by a group which has done some earlier pigmentation work, Two newly identified genetic determinants of pigmentation in Europeans: We present results from a genome-wide association study for variants associated with human pigmentation characteristics among 5,130 Icelanders, with follow-up analyses in 2,116 Icelanders and 1,214 Dutch individuals. Two […]
One of the main facts about American life is hypodescent, “the practice of determining the lineage of a child of mixed-race ancestry by assigning the child the race of his or her more socially subordinate parent.” Barack Obama & the Kenyan politician Raila Odinga (who, probably falsely, claims to be Obama’s first cousin) are both […]
No, this should not be in the “Physical Science” category. By hypersphere I’m thinking of the model that R.A. Fisher popularized as opposed to Sewall Wright’s conception of the adaptive landscape, a multidimensional sphere within which was located a position which was the adaptive optimum. While Wright’s landscapes were rugged, and so opened up the […]