genetics
razib | December 5, 2009About six months ago I had a post up on the Cape Coloureds of South Africa. As a reminder, the Cape Coloureds are a mixed-race population who are the plural majority in the southwestern Cape region of South Africa. Like the white Boers they are a mostly Afrikaans speaking population who are adherents of Reformed Christianity. After the collapse of white racial supremacy many white Afrikaners have argued that it is natural and logical to form a cultural alliance with the Cape Coloureds because of the affinity of language and faith (Afrikaans speaking Coloureds outnumber Afrikaans speaking…
razib | December 1, 2009We May Be Born With an Urge to Help:
What is the essence of human nature? Flawed, say many theologians. Vicious and addicted to warfare, wrote Hobbes. Selfish and in need of considerable improvement, think many parents.
But biologists are beginning to form a generally sunnier view of humankind. Their conclusions are derived in part from testing very young children, and partly from comparing human children with those of chimpanzees, hoping that the differences will point to what is distinctively human.
The somewhat surprising answer at which some biologists have arrived is that babies are…
razib | November 30, 2009This article pointed me to this interesting paper, Rapid adaptive evolution of northeastern coyotes via hybridization with wolves:
The dramatic expansion of the geographical range of coyotes over the last 90 years is partly explained by changes to the landscape and local extinctions of wolves, but hybridization may also have facilitated their movement. We present mtDNA sequence data from 686 eastern coyotes and measurements of 196 skulls related to their two-front colonization pattern. We find evidence for hybridization with Great Lakes wolves only along the northern front, which is…
razib | November 25, 2009The New York Times has an article on cousin marriage that's up. Here's some important bits:
Shane Winters, 37, whom she now playfully refers to as her "cusband," proposed to her at a surprise birthday party in front of family and friends, and the two are now trying to have a baby. They are not concerned about genetic defects, Ms. Spring-Winters said, and their fertility doctor told them he saw no problem with having children.
The couple -- she is a second-grade teacher and he builds furniture -- held their wedding last summer on a lake near this tiny town in central Pennsylvania. But their…
razib | November 25, 2009The state of China has 1/5 of humanity within its borders, so it's genetic structure is of interest. It is obviously important for medical reasons to clarify issues of population structure so that disease susceptibility among the Han is well characterized, in particular with the heightened medical needs of an aging population in the coming generation. And of course, there are the nationalistic concerns. About 20 years ago L. L. Cavalli-Sforza reported that his South Chinese samples were genetically closer to Southeast Asians than North Chinese in The History and Geography of Human Genes.…
milhayser | November 25, 2009
Charles Darwin's Origin of Species was published 150 years ago today, and it continues to inform, illuminate, and stir up controversy. Of course, some tortoises live longer than that, but Darwin's lasting legacy seems assured. On Gene Expression, Razib Khan tackles a study on the Fore, a cannibalistic people who ate their dead up until 1960. This diet left an imprint on their genes: a deadly prion-caused illness called Kuru led to selection against homozygosity in key alleles. Elsewhere, ERV explores invasive species and their fitness versus native species when both are infected with the…
razib | November 24, 2009A new paper in PLoS ONE, Evaluation of Group Genetic Ancestry of Populations from Philadelphia and Dakar in the Context of Sex-Biased Admixture in the Americas, doesn't add much to what we know. They looked at a several hundred individuals who are self-identified as African American and European American, as well as 49 Senegalese from Dakar. Additionally, they reanalyzed data from Latin America from whites and blacks in Brazil, as well as a group of mixed Cubans. They found what you might expect to find, African and Native ancestry shows a female bias, European ancestry shows a male bias.
But…
razib | November 24, 2009
Since The Origin of Species was published 150 years ago many articles on evolution are seeing the light of day today. Normally I'm all in favor of this, I ♥ evolution. But it also means that woolly thinking is put out there as conventional wisdom as journalists simply act as stenographers for any scientist who's in their rolodex. Some of the quotes in this National Geographic article make me want to tear my hair out. Ian Tattersall, a paleoanthropologist, decides to offer up his opinions as a population geneticist:
"Everything we know about evolutionary change suggests that genetic…
gregladen | November 24, 2009Perhaps we are all subject to falling into the trap of what I call the Hydraulic Theory of Everything. If you eat more you will be bigger, if you eat less you will be smaller. Emotional states are the continuously varying outcome of different levels of a set of hormones, forming "happy" or "stressy" or "angry" cocktails. Your brain is a vessel into which life pours various elixirs. Too much of one thing, and there will not be enough room for something else. Even political arguments are hydraulic. The 'balanced' middle view between two arguments is like the mixture of contrasting primary…
razib | November 23, 2009Cannibalism is a controversial topic. It is routine for particular societies to accuse "barbarians", enemies, or evil mythological figures, of cannibalism. When it comes to the archaeological record some skeptics have claimed that like "sacred objects" too often human remains found in peculiar circumstances are ascribed to human sacrifice or cannibalism. In Did Adam and Eve Have Navels? Martin Gardner lays out the skeptical case for why cannibalism is rare to non-existent, and rather something which emerges from the imaginations of ethnographers and archaeologists, or is rooted in…
razib | November 21, 2009No, this isn't about intellectual property issues and piracy. Whole Genome Distribution and Ethnic Differentiation of Copy Number Variation in Caucasian and Asian Populations:
Although copy number variation (CNV) has recently received much attention as a form of structure variation within the human genome, knowledge is still inadequate on fundamental CNV characteristics such as occurrence rate, genomic distribution and ethnic differentiation. In the present study, we used the Affymetrix GeneChip® Mapping 500K Array to discover and characterize CNVs in the human genome and to study ethnic…
milhayser | November 20, 2009
The pitched battle between evolutionary theory and Intelligent Design has become one of the signature conflicts of the decade. On Pharyngula, PZ Myers picks up the pieces after his debate with Jerry Bergman on whether ID should be taught in schools. Unambiguously he writes, "creationists are not the heralds of a coming paradigm shift; they are the rotting detritus of the old regime of unreason." Elsewhere, on Gene Expression, Razib Khan crunches some numbers which show that 10-20% of people in certain Muslim countries believe in evolution, versus 80% in certain European countries. The…
pharyngula | November 19, 2009Grrr. I was sent a link to these lying, sleazebag scammers at mygeneprofile.com, and it's the kind of thing that pisses me off. What you'll find there is a long video where the lowlife in a suit talks about how your children have in-built genetic biases ("from God", no less), and how if you want them to be truly happy and successful, you should tailor their upbringing to maximize their genetic potential. And he blathers on about how they will do a genetic test to determine whether your child has genes for science or art.
It's a complete lie. There is no such test. There can be no such test.…
milhayser | November 19, 2009
Forget fashion; when it comes to expressing yourself, it's your genes that wear you! On Not Exactly Rocket Science, Ed Yong discusses the explosive evolution of AEM genes in humans and elephants—two long-lived, social animals with "very, very large brains." Big brains need more juice to function, and AEM genes, which govern how mitochondria metabolize food energy, may be a key to evolving intelligence. On Gene Expression, Razib Khan explores the links between gene transmission and language transmission, writing that "linguistic affinity" could modulate gene flow, and vice versa. On Mike…
mikethemadbiologist | November 17, 2009I've finished reading Richard Nisbett's
Intelligence and How to Get It: Why Schools and Cultures Count, which is a wonderful counterargument to Charles Murray's (and others') genetic conservatism (my phrase, not Nisbett's): intelligence, typically ascertain using IQ, is highly heritable, so there's little point in spending excessively (whatever that means) on educating most people, since it won't make a difference.
Nisbett demolishes this argument in detail (I've also touched on some of these issues in the context of obesity), so I won't rehash the book here, except to note that when one…
razib | November 16, 2009Changes in the world of personal genomics. Dan MacArthur has the details on 23andMe changing up its offerings, perhaps signalling that the money gush is long over. And deCode is finally dead. Of course, just because the .com bubble burst doesn't mean that the internet is no longer a part of our lives. New players will likely emerge in the wake of this creative destruction, and old players will adapt to survive.
edyong | November 16, 2009At first glance, the African elephant doesn't look like it has much in common with us humans. We support around 70-80 kg of weight on two legs, while it carries around four to six tonnes on four. We grasp objects with opposable thumbs, while it uses its trunk. We need axes and chainsaws to knock down a tree, but it can just use its head. Yet among these differences, there is common ground. We're both long-lived animals with rich social lives. And we have very, very large brains (well, mostly).
But all that intelligence doesn't come cheaply. Large brains are gas-guzzling organs and they need…
razib | November 11, 2009There are many ways one can model population genetic dynamics. A simple avenue is to imagine a deme, a group of breeding individuals, subject to a few major parameters which are modulating genetic variation. Mutation, migration, random drift and selection. A model being what a model is, one's goal is to simplify, utilize approximations, and still manage to extract insight as to the relevant aspects of the dynamics one is focusing on (unless you're Stephen Wolfram). One of the major upsides of the Price Equation is that it makes no compromises, rather, it starts from first principles and…
razib | November 11, 2009In the post below on the Price Equation I stayed true to George Price's original notation in his 1970 paper where he introduced his formalism. But here is a more conventional form, the "Full Price Equation," which introduces a second element on the right-side.
Δz = Cov(w, z) / w
One can specifically reformulate this verbally for a biological context:
Change in trait = Change due to selection on individuals + Change due to individual transmission
The first element on the right-side is explicable as selection upon a heritable trait. w is the conventional letter used for "fitness," so w is…
edyong | November 11, 2009Today, a new paper published in Nature adds another chapter to the story of FOXP2, a gene with important roles in speech and language. The FOXP2 story is a fascinating tale that I covered in New Scientist last year. It's one of the pieces I'm proudest of so I'm reprinting it here with kind permission from Roger Highfield, and with edits incorporating new discoveries since the time of writing.
The FOXP2 Story (2009 edition)
Imagine an orchestra full of eager musicians which, thanks to an incompetent conductor, produces nothing more than an unrelieved cacophony. You're starting to…