genetics
razib | October 14, 2009
A few days ago I pointed to a paper, Stature, Mortality, and Life History among Indigenous Populations of the Andaman Islands, 1871-1986. It looks at the specific case of the Andaman Islanders to explore the general phenomenon of "pygmy" populations, especially among "Negritos." The Andaman Islanders are an interesting test case, as the authors note, because the disparate groups have taken different stances toward interaction with the outside world. The Great Andaman Islanders have mixed for over a century with the British and Indian settlers. The Onge began to interact with the outside…
razib | October 14, 2009Reading the papers on Ardipithecus ramidus which just came out in Science one of the take-home points that jumps out at me is that extant apes may be very misleading analogs to extinct hominins. Here is Owen Lovejoy:
In retrospect, clues to this vast divide between the evolutionary trajectories of African apes and hominids have always been present. Apes are largely inept at walking upright. They exhibit reproductive behavior and anatomy profoundly unlike those of humans. African ape males have retained (or evolved, see below) a massive SCC and exhibit little or no direct investment in their…
sporte | October 14, 2009If you have a little time, the Dolan DNA Learning Center at Cold Spring Harbor will be presenting some really interesting workshops on neuroscience and genetics.
The dates are:
Nov. 5, 2009: Inside Cancer - workshop on teaching cancer; Raritan
Valley Community College, Somerville, NJ
Nov. 6, 2009: Genes To Cognition - workshop on teaching neuroscience;
Raritan Valley Community College, Somerville, NJ
Nov. 21, 2009: Inside Cancer - workshop on teaching cancer; Great Bay
Community College, Portsmouth, NH
Nov. 20, 2009: Genes To Cognition - workshop on teaching neuroscience;
Great Bay…
razib | October 13, 2009I'm talking about coeliac disease:
Coeliac disease is caused by a reaction to gliadin, a gluten protein found in wheat (and similar proteins of the tribe Triticeae, which includes other cultivars such as barley and rye). Upon exposure to gliadin, the enzyme tissue transglutaminase modifies the protein, and the immune system cross-reacts with the small-bowel tissue, causing an inflammatory reaction. That leads to a truncating of the villi lining the small intestine (called villous atrophy). This interferes with the absorption of nutrients, because the intestinal villi are responsible for…
razib | October 13, 2009A new paper adding some decimal places on Indian mtDNA phylogeography, Updating Phylogeny of Mitochondrial DNA Macrohaplogroup M in India: Dispersal of Modern Human in South Asian Corridor:
To construct maternal phylogeny and prehistoric dispersals of modern human being in the Indian sub continent, a diverse subset of 641 complete mitochondrial DNA (mtDNA) genomes belonging to macrohaplogroup M was chosen from a total collection of 2,783 control-region sequences, sampled from 26 selected tribal populations of India. On the basis of complete mtDNA sequencing, we identified 12 new haplogroups…
razib | October 12, 2009I've talked about menopause before. One question in evolutionary anthropology is whether it is an adaptation, a derived trait in our species which emerged due to the force of natural selection, or simply a physiological byproduct of some other phenomenon. The key point is the peculiar asymmetry in male and female reproductive potentials; males decline gradually over time, while the general suite of female reproductive function simply shuts down at during middle age. Eric Michael Johnson reviews a new paper by the redoubtable Virpi Lummaa, Fitness benefits of prolonged post-reproductive…
edyong | October 12, 2009If you've ever put a pair of headphones in your pocket, you'll know how difficult it is to keep a long cord in a bundle without getting it hopelessly tangled and knotted. You'll also start to appreciate the monumental challenge that our cells face when packaging our DNA. At 2 metres in length, the human genome is longer than the average human but it needs to be packaged inside the nucleus of every one of our cells, each just 6 millionths of a metre long. How does it do it?
One of the secrets behind this monumental feat of folding has just been revealed by research that reveal's the human…
razib | October 11, 2009About two weeks ago I pointed to the peculiar disjunction between what a paper on Indian genetics actually said, and how people, including some of the researchers who contributed to the paper, were spinning it. For instance, the finding that South Asians can be reasonably modeled as a two-way admixture between "Ancestral North Indians" (ANI) and "Ancestral South Indians" which varies in ratio between between 7:3 and 2:3 across regions & caste groups was translated into "the genetic unity of India." And now I notice in The Guardian another Indian has an article titled Tracing the fissures…
razib | October 10, 2009Dienekes points to a new paper which attempts to quantify the genetic ancestry of South Asian Muslims into indigenous and exogenous components:
Islam is the second most practiced religion in India, next to Hinduism. It is still unclear whether the spread of Islam in India has been only a cultural transformation or is associated with detectable levels of gene flow. To estimate the contribution of West Asian and Arabian admixture to Indian Muslims, we assessed genetic variation in mtDNA, Y-chromosomal and LCT/MCM6 markers in 472, 431 and 476 samples, respectively, representing six Muslim…
grrlscientist | October 5, 2009tags: Tree of Life, conservation, biodiversity, ecology, evolution, biology, statistics, teaching, streaming video
This video presents a very brief glimpse into what I do as a professional researcher studying "my birds" -- the parrots of the South Pacific Ocean (during those rare and beautiful times when I actually have a job!!). To say the least, it fills me with intense longing to reclaim my long lost life.
grrlscientist | October 4, 2009tags: Tree of Life, conservation, biodiversity, ecology, evolution, biology, statistics, teaching, streaming video
This video presents a very brief glimpse into what I do as a professional researcher studying "my birds" -- the parrots of the South Pacific Ocean (during those rare and beautiful times when I actually have a job!!). It features interviews with one of the scientists whom I worked with when I was in grad school at the University of Washington: Scott Edwards, who now is at Harvard University. To say the least, this video fills me with intense longing to reclaim my long lost life…
edyong | October 3, 2009This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.
Every month, at the full moon, tourists and students gather on the beach at Koh Phangan, Thailand for a night of booze, dancing, and debauchery. But the moon-themed antics of these party-goers look positively tepid when compared to those of the Great Barrier Reef's corals. With the help of two genes and a spot of moonlight, the corals synchronise one of the greatest spectacles of the natural world - a mass annual…
razib | September 28, 2009The past 10 years have seen a lot of ups & downs in the Cohen Modal Haplotype (CMH) hypothesis, which suggests some veracity to the Biblical narrative whereby the priestly caste status of the Jewish people is passed down patrilineally from Aaron, the brother of Moses. But could there be multiple Aarons? Possibly. Extended Y chromosome haplotypes resolve multiple and unique lineages of the Jewish priesthood:
It has been known for over a decade that a majority of men who self report as members of the Jewish priesthood (Cohanim) carry a characteristic Y chromosome haplotype termed the Cohen…
razib | September 27, 2009A geologist, Suvrat Kher, has a very good post on the recent paper on Indian genetics. He concludes:
The Indian Press has made a hash of the finding. For example they have only reported those parts of the study that deal with the kinship among Indians and have stressed that castes and tribes cannot be differentiated or that there is no divide between the Aryans (roughly north Indians) and Dravidians (south Indians). That is all true for average relatedness. But the study also clearly points out that there are genetic differences between north and south Indians and between upper and lower…
razib | September 24, 2009A reader pointed me to an article, Aryan-Dravidian divide a myth: Study. Some of the authors of the paper I reviewed today (actually, I wrote the post yesterday and put it in schedule) had some interesting things to say:
The great Indian divide along north-south lines now stands blurred. A pathbreaking study by Harvard and indigenous researchers on ancestral Indian populations says there is a genetic relationship between all Indians and more importantly, the hitherto believed ''fact'' that Aryans and Dravidians signify the ancestry of north and south Indians might after all, be a myth.
''…
razib | September 24, 2009A few weeks ago I posted on a paper, Genetic Discontinuity Between Local Hunter-Gatherers and Central Europe's First Farmers.Another one is out in the same vein, Ancient DNA Reveals Lack of Continuity between Neolithic Hunter-Gatherers and Contemporary Scandinavians:
The driving force behind the transition from a foraging to a farming lifestyle in prehistoric Europe (Neolithization) has been debated for more than a century...Of particular interest is whether population replacement or cultural exchange was responsible...Scandinavia holds a unique place in this debate, for it maintained one of…
razib | September 24, 2009A few months ago a friend tipped me off to the fact that David Reich was going to publish a paper about the genetics of Indians which he ascertained was going to model these populations as hybrids between "Europeans and Andaman Islanders." The paper is out, and my friend was roughly right. Reconstructing Indian population history:
India has been underrepresented in genome-wide surveys of human variation. We analyse 25 diverse groups in India to provide strong evidence for two ancient populations, genetically divergent, that are ancestral to most Indians today. One, the 'Ancestral North…
razib | September 23, 2009Being raised in a single-parent household, especially when a woman is head of household, puts you at higher risk for all sorts of negative personal outcomes, right? If that data is all you know, yes. But as they say, correlation does not equal causation. But the assumptions of causation come out in the responses of people to these social statistics; conservatives often want to maintain stability in the home, put the father there because the father is critical. Many liberals will focus on the economic outcomes of single motherhood, and argue that buffering the family against fiscal stress…
edyong | September 22, 2009This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science. The blog is on holiday until the start of October, when I'll return with fresh material.
As a species, we value fair play. We're like it so much that we're willing to eschew material gains in order to punish cheaters who behave unjustly. Psychological games have set these maxims in stone, but new research shows us that this sense of justice is, to a large extent, influenced by our genes.
When it comes to demonstating our innate preference for fair play, psychologists turn to the 'Ultimatum Game',…
razib | September 22, 2009Sometimes I wonder if the period between the publication of The History and Geography of Human Genes and The Journey of Man, roughly from the mid-90s to the early 2000s, will be seen as a golden age for historical population genetics in hindsight. A few weeks ago I pointed to new data based on DNA extraction which really confuses the picture of how Europe was populated over the past 25,000 years. It seems the more data we get, the more interesting things get. In the late 1990s the emergence of powerful technologies to extract and amplify genetic material and sequence it shed light on several…