genetics
mikethemadbiologist | August 4, 2009Heritability: I do not think it means what you think it means.
There's been a spate of posts about obesity, started by a post by Megan McArdle. In these posts, a high heritability for obesity is bandied about (0.9!!! ZOMG!! TEH GENEZ R MAKIN U FAT!). But this demonstrates a lack of understanding of what heritability estimates mean--and, more importantly, what they do not mean.
A couple of years ago, the Three-Toed Sloth wrote a wonderful post about heritability, and I'll quote liberally from it here (instead of rephrasing it inelegantly) and add some additional commentary. I should…
edyong | August 3, 2009Swine flu has made the world all too aware of the possibility of diseases making the leap from animal hosts to human ones. Now, we know that another disease made a similar transition from chimpanzees to humans, several thousand years ago. This particular infection is caused by a parasite, and a very familiar and dangerous one - Plasmodium falciparum, the agent responsible for malaria.
Transmitted by the bite of mosquitoes, P.falciparum infects over 500 million people every year. Its closest relative is a related parasite, Plasmodium reichenowi, which infects chimpanzees. Leading an…
edyong | August 2, 2009This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science.
"Congratulations, it's a stunted, malformed, necrotic hybrid!" Those aren't really the words that new parents want to hear but thankfully, plants aren't in a position to be that upset.
In several species of plants, a surprising number of offspring turn out to be malformed hybrids that quickly wither and die. Now, Kirsten Bomblies and colleagues from the Max Planck Institute for Developmental Biology have found out why.
Two genes, one passed down by each parent, ignite an reaction in the hybrid…
razib | July 30, 2009Megan McArdle has a post, Thining Thin, a follow up to America's Moral Panic Over Obesity. She says:
1. Obesity is increasing in the population, so it can't be genetic.
Well, average height is also increasing in the population. Does that mean that you could be as tall as me, if you weren't too lazy to grow?
Twin studies and adoptive studies show that the overwhelming determinant of your weight is not your willpower; it's your genes. The heritability of weight is between .75 and .85. The heritability of height is between .9 and .95. And the older you are, the more heritable weight is.…
razib | July 30, 2009An ancestry informative marker set for determining continental origin: validation
and extension using human genome diversity panels:
Results
In this study, genotypes from Human Genome Diversity Panel populations were used to further evaluate a 93 SNP AIM panel, a subset of the 128 AIMS set, for distinguishing continental origins. Using both model-based and relatively model-independent methods, we here confirm the ability of this AIM set to distinguish diverse population groups that were not previously evaluated. This study included multiple population groups from Oceana, South Asia, East…
edyong | July 30, 2009This article is reposted from the old Wordpress incarnation of Not Exactly Rocket Science.
A humble species of fruit fly is the genetic equivalent of a Russian doll - peer inside its DNA and you will see the entire genome of a species of bacteria hidden within.
The bacteria in question is Wolbachia, the most successful parasite on earth and infects about 20% of the world's species of insects. It's a poster child for selfishness. To further its own dynasty, it has evolved a series of remarkable techniques for ensuring that it gets passed on from host to host. Sometimes it gives infected…
razib | July 27, 2009
Update: The author of the paper clears up confusions.
Update: Here's the paper. End Update
The British media is abuzz with another paper from Satoshi Kanazawa, the evolutionary psychologist who has great marketing savvy. I can't find the study online anyway, so here is the Times Online:
In a study released last week, Markus Jokela, a researcher at the University of Helsinki, found beautiful women had up to 16% more children than their plainer counterparts. He used data gathered in America, in which 1,244 women and 997 men were followed through four decades of life. Their attractiveness was…
razib | July 23, 2009Earlier today I linked to a Jonah Leher post on food that hooks into the role that dopamine plays in our decision making. Dopamine looms in the neuroscience angle of Jonah's book How We Decide because the chemical's role in cognition is established. Dopamine related genes are often fingered in behavior genetic studies as the causal root of some observed psychological variation. So a new paper in Nature Neuroscience is in perfect position to stand astride the literal slush pile of this research, Prefrontal and striatal dopaminergic genes predict individual differences in exploration and…
razib | July 22, 2009
BMC Evolutionary Biology has a new paper which will be up soon (not on site), Reconstructing Indian-Australian phylogenetic link. ScienceDaily has a preview:
Dr Raghavendra Rao worked with a team of researchers from the Anthropological Survey of India to sequence 966 complete mitochondrial DNA genomes from Indian 'relic populations'. He said, "Mitochondrial DNA is inherited only from the mother and so allows us to accurately trace ancestry. We found certain mutations in the DNA sequences of the Indian tribes we sampled that are specific to Australian Aborigines. This shared ancestry suggests…
grrlscientist | July 21, 2009tags: TEDTalks, medicine, Psychopathic Killers, epigenetics, brain damage, psychology, MAOA gene, serotonin, Jim Fallon, streaming video
Psychopathic killers are the basis for some must-watch TV, but what really makes them tick? Neuroscientist Jim Fallon talks about brain scans and genetic analysis that may uncover the rotten wiring in the nature (and nurture) of murderers. In a too-strange-for-fiction twist, he shares a fascinating family history that makes his work chillingly personal [4:42]
TEDTalks is a daily video podcast of the best talks and performances from the TED Conference,…
gregladen | July 20, 2009Mendel was born on July 20th, 1822. He is famous for his discovery of peas and genetics.
Here is his stuff translated into English.
razib | July 20, 2009Genotyping of five single nucleotide polymorphisms in the OCA2 and HERC2 genes associated with blue-brown eye color in the Japanese population:
Human eye color is a polymorphic phenotype influenced by multiple genes. It has recently been reported that three single nucleotide polymorphisms (SNPs) within intron 1 of the OCA2 gene (rs7495174, rs4778241, rs4778138) and two SNPs in intron 86 (rs12913832) and the 3 UTR region (rs1129038) of the HERC2 gene - located in the upstream of the OCA2 locus - have a high statistical association with human eye color. The present study is the first to…
razib | July 20, 2009Perceptual variation in umami taste and polymorphisms in TAS1R taste receptor genes:
A subset of subjects displays extremes of sensitivity, and a battery of different psychophysical tests validated this observation. Statistical analysis showed that the rare T allele of single nucleotide polymorphism (SNP) R757C in TAS1R3 led to a doubling of umami ratings of 25 mmol MPG/L. Other suggestive SNPs of TAS1R3 include the A allele of A5T and the A allele of R247H, which both resulted in an approximate doubling of umami ratings of 200 mmol MPG/L. We confirmed the potential role of the human TAS1R1-…
razib | July 18, 2009Alex Tabarrok points me to a new paper on the effects of Toxoplasma gondii, Increased incidence of traffic accidents in Toxoplasma-infected military drivers and protective effect RhD molecule revealed by a large-scale prospective cohort study:
We confirmed, using for the first time a prospective cohort study design, increased risk of traffic accidents in Toxoplasma-infected subjects and demonstrated a strong protective effect of RhD positivity against the risk of traffic accidents posed by latent toxoplasmosis. Our results show that RhD-negative subjects with high titers of anti-Toxoplasma…
razib | July 17, 2009There's a new paper on ancient DNA out, Targeted Retrieval and Analysis of Five Neandertal mtDNA Genomes:
Analysis of Neandertal DNA holds great potential for investigating the population history of this group of hominins, but progress has been limited due to the rarity of samples and damaged state of the DNA. We present a method of targeted ancient DNA sequence retrieval that greatly reduces sample destruction and sequencing demands and use this method to reconstruct the complete mitochondrial DNA (mtDNA) genomes of five Neandertals from across their geographic range. We find that mtDNA…
emjohnson | July 17, 2009How genes for altruism can benefit strangers as well as kin
The generosity of adoption has long been considered a unique human hallmark.
Image: Shadows of Forgotten Ancestors
For decades it was conventional dogma that humans were the only species that used tools. "Man the Toolmaker" was our celebrated designation. The hominin fossil Homo habilis (or "handy" man) was even defined within our genera primarily because the skeleton was associated with stone implements. However, when Jane Goodall discovered chimpanzees using modified sticks at Gombe to "fish" for termites, Louis Leakey famously…
edyong | July 16, 2009Compare the elegant grace of a running wolf with the comical shuffle of a waddling dachshund, and you begin to understand what millennia of domestication and artificial selection can do to an animal. As dachshunds develop, the growing tips of their limb bones harden early, stunting their growth and leading to a type of dwarfism called chondrodysplasia. The same applies to at least 19 modern breeds including corgis, Pekingese and basset hounds, all of which have very short, curved legs.
These breeds highlight the domestic dog's status as the most physically diverse of mammals. Now, a team of…
pharyngula | July 15, 2009
No, not really — my title is a bit of a sensationalistic exploitation of the thesis of a paper by Peterson, Dietrich, and McPeek, but I can buy into their idea that microRNAs (miRNAs) may have contributed to the pattern of metazoan phylogenies we see now. It's actually a thought-provoking concept, especially to someone who favors the evo-devo view of animal evolution. And actually, the question it answers is why we haven't had thousands of Cambrian explosions.
In case you haven't been keeping up, miRNAs are a hot topic in molecular genetics: they are short (21-23 nucleotides) pieces of…
razib | July 14, 2009Steve points me to a new genetic genealogical study on a super-male lineage, 7 Million People Direct Descendants:
"This is one of the largest diasporas known to have descended from a single progenitor," said head researcher Lawrence Ghilcrest, adding that DNA evidence now corroborates stories about the Welshman that historians once dismissed as myth. "To have propagated his genetic material so effectively, and across so much territory, we can only infer Gwilym was quite the charmer."
ddobbs | July 8, 2009I must keep my nose on the not-beta, hidden-till-last-minute, writing-Not-For-FREE grindstone, where it's getting shredded to bits -- but in the meantime, wanted to pass on these worthy web distractions, worthy of full engagement if you've the time:
Vaughan Bell peeks at The long dark nightie of the soul and wonders "why mentally distressed women are always portrayed in their nighties." Separately, he considers some strange security concerns raised by the growing use of brain implants.
Much interesting attention to schizophrenia this week: A big study parsing the genetics of schizophrenia,…