Objective: Our objective was to compare total body fat to lean mass ratio (F:LM) in Aboriginal, Chinese, European, and South Asian individuals with differences in insulin resistance.
...
Results: After adjustment for confounders and at a given body fat, South Asian men had less lean mass than Aboriginal [3.42 kg less; 95% confidence interval (CI) = 1.55-5.29], Chinese (3.01 kg less; 95% CI = 1.33-4.70), and European (3.57 kg less; 95% CI = 1.82-5.33) men, whereas South Asian women had less lean mass than Aboriginal (1.98 kg less; 95% CI = 0.45-3.50), Chinese (2.24 kg less; 95% CI = 0.81-3.68), and European (2.97 kg less; 95% CI = 1.67-4.27) women. In adjusted models, F:LM was higher in South Asian compared with Chinese and European men and higher in South Asian compared with Aboriginal, Chinese, and European women (P < 0.01 for all). Insulin and HOMA were greatest in South Asians after adjustment; however, these differences were no longer apparent when F:LM was considered.
Conclusions: South Asians have a phenotype of high fat mass and low lean mass, which may account for greater levels of insulin and HOMA compared with other ethnic groups.
HOMA = homeostatic model assessment, used to quantify insulin resistance and beta-cell function. The second bolded part is important, you can change your fat to lean mass ratio. Change what you eat, and exercise. I've seen data from England, where there are large numbers of Pakistanis and Bangladeshis, that the latter are in a higher risk category than the former when it comes to adult onset diabetes.
Update: A comment:
Minor quibble: Please be so kind as to use the term 'type 2 diabetes' in the future.
A large amount of type 1 diabetics get the disease in adulthood and these results have zero relevance for them or that disease.
It's incidentally (now that we are splitting hairs...) also incorrect to use the term IDDM (insulin dependent diabetes mellitus) as a shorthand for type 1 diabetes, which is something you often see people do without thinking. A recent Danish study found that half of all type 2 diabetes patients will need insulin treatment within 6 years of diagnosis, which probably means that a majority of all insulin-dependent diabetics are type 2 patients, considering that they make out the great majority of all diabetics (in DK, 80-90% of all diabetics have type 2 diabetes).
The cooling effects of historic volcanic eruptions on world climate are well known but the impacts of even bigger prehistoric eruptions are still shrouded in mystery. The eruption of Toba volcano in northern Sumatra some 73,000 years ago was the largest explosive eruption of the past two million years, with a Volcanic Explosivity Index of magnitude 8, but its impact on climate has been controversial. In order to resolve this issue, we have analysed pollen from a marine core in the Bay of Bengal with stratified Toba ash, and the carbon isotopic composition of soil carbonates directly above and below the ash in three sites on a 400 km transect across central India. Pollen evidence shows that the eruption was followed by initial cooling and prolonged desiccation, reflected in a decline in tree cover in India and the adjacent region. Carbon isotopes show that C3 forest was replaced by wooded to open C4 grassland in central India. Our results demonstrate that the Toba eruption caused climatic cooling and prolonged deforestation in South Asia, and challenge claims of minimal impact on tropical ecosystems and human populations.
Citation Martin A.J. Williamsa, Stanley H. Ambroseb, Sander van der Kaarsc, Carsten Ruehlemannd, Umesh Chattopadhyayae, Jagannath Pale and Parth R. Chauhanf, Environmental impact of the 73 ka Toba super-eruption in South Asia, doi:10.1016/j.palaeo.2009.10.009
Cannibalism 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 scurrilous insults hurled between ethnic groups which have antagonistic relationships. Since the arguments Gardner lays out were presented it seems that the skeptical case is looking weaker, though controversy remains in specific instances. In the domain of genetics, there is some evidence of natural selection on genetic loci which imply widespread prion diseases in the past. Diseases which are often the outcomes of cannibalism. These sorts of molecular genetic data should perhaps change our perspective as to the imaginative color which archaeologists and paleoanthropologists might add to their inferences from ancient or prehistoric human remains.
But the case of cannibalism among the Fore people of Papua New Guinea it is not speculation or a matter of historical or archaeological inference. They were engaging in the practice as late as the 1960s. So it is of interest that a new paper has come out reinforcing the finding that the kuru epidemics might have left a genetic imprint, A Novel Protective Prion Protein Variant that Colocalizes with Kuru Exposure:
Results Persons who were exposed to kuru and survived the epidemic in Papua New Guinea are predominantly heterozygotes at the known resistance factor at codon 129 of the prion protein gene (PRNP). We now report a novel PRNP variant -- G127V -- that was found exclusively in people who lived in the region in which kuru was prevalent and that was present in half of the otherwise susceptible women from the region of highest exposure who were homozygous for methionine at PRNP codon 129. Although this allele is common in the area with the highest incidence of kuru, it is not found in patients with kuru and in unexposed population groups worldwide. Genealogic analysis reveals a significantly lower incidence of kuru in pedigrees that harbor the protective allele than in geographically matched control families.
Conclusions The 127V polymorphism is an acquired prion disease resistance factor selected during the kuru epidemic, rather than a pathogenic mutation that could have triggered the kuru epidemic. Variants at codons 127 and 129 of PRNP demonstrate the population genetic response to an epidemic of prion disease and represent a powerful episode of recent selection in humans.
National Geographic has an interesting piece of ethnographic travel writing up on the Hadza of Tanzania. The Hadza are one of the few remaining hunter-gather populations in the world, and their language is an isolate which has clicks. There's a bit too much "noble savage" archetype loaded into the piece, but this portion is of note:
The chief reason the Hadza have been able to maintain their lifestyle so long is that their homeland has never been an inviting place. The soil is briny; fresh water is scarce; the bugs can be intolerable. For tens of thousands of years, it seems, no one else wanted to live here. So the Hadza were left alone. Recently, however, escalating population pressures have brought a flood of people into Hadza lands. The fact that the Hadza are such gentle stewards of the land has, in a way, hurt them--the region has generally been viewed by outsiders as empty and unused, a place sorely in need of development. The Hadza, who by nature are not a combative people, have almost always moved away rather than fight. But now there is nowhere to retreat.
Like all extant hunter-gatherer populations* the Hadza exist precisely because their territory is unappealing or unsuitable for agriculture. It follows that the simplicity of the Hadza may be a function of the spare and marginal nature of the ecology with they depend upon for their livelihood, not the style of their livelihood. I am willing to hazard that hunter-gatherers more fertile territory would still have less inequality and social complexity than equivalent agriculturalists, but the hard-scrabble hunter-gatherers who remain surely give us an extremely distorted view of that mode of life.
* Many which anthropologists were able to study in the 20th century are no longer hunter-gatherers, so the presently extant list is shrinking fast.
Perhaps because we only remember the good stuff? Or only the good suff & famous authors get reprinted. I'm prompted to offer this hypothesis in response to Chad Orzel's commentary that there was a lot of bad space opera even during the "Golden Age" of science fiction. I recall that Zadie Smith once noted that 99.99% (or something to that effect) of Victorian fiction is forgotten and out of print. All that remains read are the "classics," so contemporary audiences have a biased perspective as to the median quality of Victorian-era writers. Of course the insight can be generalized to the arts overall; only the good gets reproduced or remembered.
To be fair, some science fiction authors, such as George R. R Martin (who also writes other genres obviously), have claimed that the turn away from "hard" sf rooted in physics and engineering is reflective of a cultural shift. In the 1950s the "atomic age" was viewed positively, and the possibilities seemed unbounded. Today a lot of the fiction deeply influenced by science in constructing a story may take a more ambivalent, or even pessimistic, view of how science effects human happiness (e.g., dystopian futures where nanotech gets out of control).
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 differences of CNVs between Caucasians and Asians. Three thousand and nineteen CNVs, including 2381 CNVs in autosomes and 638 CNVs in X chromosome, from 985 Caucasian and 692 Asian individuals were identified, with a mean length of 296 kb. Among these CNVs, 190 had frequencies greater than 1% in at least one ethnic group, and 109 showed significant ethnic differences in frequencies (p<0.01). After merging overlapping CNVs, 1135 copy number variation regions (CNVRs), covering approximately 439 Mb (14.3%) of the human genome, were obtained. Our findings of ethnic differentiation of CNVs, along with the newly constructed CNV genomic map, extend our knowledge on the structural variation in the human genome and may furnish a basis for understanding the genomic differentiation of complex traits across ethnic groups.
Here's a figure which shows the distributions, CHI = Chinese and CAU = Caucasion.*
The big picture issue is CNVs may be important in gene expression, the paper cites a number that ~18% of the variance in this may be due to CNVs. An interesting recent case was CNV differences in regards to the gene which codes for amylase, with some researchers suggesting this is due to selection for the ability to digest starches for agriculturalists. In relation to the title, there might not be anything there:
A third example of ethnic variation is that the genomic coverage of CNVs in Asians is 1.6-fold higher than that in seen in Caucasians, indicating that genome variants were more common in Asians than in Caucasians. Further sensitivity analysis resulted in an only 1.2-fold elevated genomic coverage of Chinese CNVs compared to Caucasian CNVs. Considering different DNA extraction methods for Chinese and Caucasian samples, the ethnic differences seen in genomic coverage may be partially due to different binding affinities of diverse DNA extracts to the SNP chip array.
Citation: Li J, Yang T, Wang L, Yan H, Zhang Y, et al. 2009, Whole Genome Distribution and Ethnic Differentiation of Copy Number Variation in Caucasian and Asian Populations. PLoS ONE 4(11): e7958. doi:10.1371/journal.pone.0007958
* If they use "Caucasian" for European origin people, why not "Mongoloid" for Chinese?
Although the North American megafaunal extinctions and the formation of novel plant communities are well-known features of the last deglaciation, the causal relationships between these phenomena are unclear. Using the dung fungus Sporormiella and other paleoecological proxies from Appleman Lake, Indiana, and several New York sites, we established that the megafaunal decline closely preceded enhanced fire regimes and the development of plant communities that have no modern analogs. The loss of keystone megaherbivores may thus have altered ecosystem structure and function by the release of palatable hardwoods from herbivory pressure and by fuel accumulation. Megafaunal populations collapsed from 14,800 to 13,700 years ago, well before the final extinctions and during the Bølling-Allerød warm period. Human impacts remain plausible, but the decline predates Younger Dryas cooling and the extraterrestrial impact event proposed to have occurred 12,900 years ago.
What about humans, those pesky slayers of animals? Some scientists believed that North America's Clovis people specialised in hunting big mammals, causing a "blitzkrieg" of spear-throwing that drove many species to extinction. But these hunters only arrive in North America between 13,300 and 12,900 years ago, around a thousand years after the population crashes had begun.
If people were responsible, they must have been pre-Clovis settlers. There's growing evidence that such humans were around, but they weren't common or specialised. They may have contributed to the beasts' downfall, while Clovis hunting technology delivered a coup de grace to already faltering populati0ons.
By analysing the sediment at Appleman lake - spores, pollen, charcoal and all - Gill has replayed the history of the site, spanning the last 17,000 years. Her data rule out a few theories, but as she says, they "[do] not conclusively resolve the debate" about climate causes versus human ones. It's possible that similar studies at different sites and other continents will help to provide more clues.
A complex story like this is perhaps more common than an event such as the extinction of the passenger pigeons. Populations of organisms often go through cycles in census size, whether due to environmental variation or coevolutionary dynamics with parasites. Consider the example of the Tasmania devil, the disease which it is susceptible to is not the doing of humans, but the introduction of dingos (probably by humans) mean that the species is restricted to Tasmania. Additionally, humans have laid claim to much of the habitat of the devil (or what was the habitat of the devil). When a virulent disease hits, the devil has a much smaller margin of error than it had before. It could be that recent megafaunal extinctions are ultimately due to humans, even if they are not always proximately due to humans.
During the first few years of ScienceBlogs there was a lot of talk about religion. Yes, there's talk about religion now, but it's toned down in the wake of the ebbing of the publicity around The God Delusion. Naturally in the wake of the New Atheism a raft of conventional apologetics have been published, The Dawkins' Delusion being a typical example. More recently more nuanced books which wend the middle ground between militant atheism and conventional apologetics have taken center strage. Karen Armstrong's The Case for God approaches this from a philo-theistic angle, while Robert Wright's The Evolution of God is predicated on materialist presuppositions.
...We synthesize mitochondrial phylogenetic information from 263 subfossil moa specimens from across NZ with morphological, ecological, and new geological data to create the first comprehensive phylogeny, taxonomy, and evolutionary timeframe for all of the species of an extinct order. We also present an important new geological/paleogeographical model of late Cenozoic NZ, which suggests that terrestrial biota on the North and South Island landmasses were isolated for most of the past 20-30 Ma. The data reveal that the patterns of genetic diversity within and between different moa clades reflect a complex history following a major marine transgression in the Oligocene, affected by marine barriers, tectonic activity, and glacial cycles. Surprisingly, the remarkable morphological radiation of moa appears to have occurred much more recently than previous early Miocene (ca. 15 Ma) estimates, and was coincident with the accelerated uplift of the Southern Alps just ca. 5-8.5 Ma. Together with recent fossil evidence, these data suggest that the recent evolutionary history of nearly all of the iconic NZ terrestrial biota occurred principally on just the South Island.
"Subfossil" means that it hasn't totally fossilized and one can extract organic material from the remains.
It's hard to say exactly how much support the theory of evolution enjoys in the world's Muslim countries, but it's definitely not very much. In one 2006 study by American political scientists, people in 34 industrial nations were asked whether they agreed or disagreed with the idea that human beings evolved from earlier life forms. Turkey, the only Muslim country in the survey, showed the lowest levels of support - barely a quarter of Turks said they agreed. By comparison, at least 80 percent of those surveyed in Iceland, Denmark, Sweden, and France agreed. (The United States ranked second lowest, after Turkey, at 40 percent.) Turkey is widely seen as the most culturally liberal Muslim nation, and on attitudes about evolution, other polling has borne this out: A recent study of religious attitudes found that only 16 percent of Indonesians, 14 percent of Pakistanis, and 8 percent of Egyptians believed in evolution.
I asked the reporter for a citation, and I received one, On being religious : patterns of religious commitment in muslim societies. You can download the PDF at that link (bottom of the page). It has a nice breakdown of religious beliefs, including attitudes toward evolution. But the sample is non-representative:
As you can see the sample is strongly skewed toward the more educated segments of society. On the other hand, they did try and include religious professionals as well, though I'm unclear as to the proportion within the samples. The N's are large, so probably only a few percent. But keep in mind the biases in the sample above when looking at the data below.
There was recently a conference on evolution in Egypt. Some interesting numbers:
Dr Guessoum, who is a Sunni Muslim, said that in countries such as Tunisia, Egypt, Turkey, Pakistan and Malaysia, only 15 per cent of those surveyed believed Darwin's theory to be "true" or "probably true". This stand was equally prevalent among students and teachers, from high school to university. Most alarmingly, he claimed, science teachers were misrepresenting the facts and theories of evolution by mixing it with religious ideologies.
A survey of 100 academics and 100 students that he conducted at his own university showed that 62 per cent of Muslim professors and students believed evolution to be an "unproven theory", compared with 10 per cent of non-Muslim professors. "The rate of acceptance of evolution and of the idea of teaching evolution was extremely low," he said. "I wondered, who are all these educated people rejecting evolution? They are even rejecting the fact that it should be taught as scientific knowledge."
I put more stock in the second paragraph since he did that survey himself, though I wouldn't be surprised if the numbers for the first checked out. I did find this Boston Globe article with more concrete numbers:
The relationship between language families and historical population genetics has a long history. In the 19th and early 20th centuries anthropologists were wont to substitute and synthesize the connections discerned in linguistic relationships with those of presumed biological affinities. This resulted in great hilarity. Older works sometimes labeled the Finns a "Mongoloid" people because of their Uralic language. But once the physical substrate of genetic inheritance (DNA) was ascertained some correspondences did emerge.
The figure to the left is from an L. L. Cavalli-Sforza paper, Genes, peoples, and languages. The correspondence between gene families and language families is clear. From the paper:
Most patterns found in the analysis of human living populations are likely to be consequences of demographic expansions, determined by technological developments affecting food availability, transportation, or military power. During such expansions, both genes and languages are spread to potentially vast areas. In principle, this tends to create a correlation between the respective evolutionary trees. The correlation is usually positive and often remarkably high. It can be decreased or hidden by phenomena of language replacement and also of gene replacement, usually partial, due to gene flow.
Genetic variation and languages are both characteristics of individuals & populations. One might imagine that gene flow between groups might be modulated by linguistic affinity between groups, or, linguistic affinity between groups might be modulated by gene flow between the groups. Cavalli-Sforza's colleague Marcus Feldman has asserted that the correlation does indeed emerge out of biases in mating patterns more explicitly of late.
Language and genes are passed from parents to offspring. But, there are clearly differences in terms of the specific constraints on inheritance. When it comes to genes we have both the Mendelian abstraction as well as DNA as a concrete substrate. Parent-offspring transmission is symmetrical (from both parents), subject to mutation, segregation, recombination, etc. Though there are attempts to model language, to my knowledge there is not such robust theoretical understanding of the inheritance of language from parents to offspring, in particular the biological substrate which acquires language (I do not class the arguments about deep structure in linguistics in the same class as Mendelian and DNA models of genetics).
Of course there is the reality of great differences in transmission of language and genes. In the domain of language horizontal transmission is critical to understanding its distribution & evolution (I am aware that horizontal gene transfer is important in biological evolution, but not so much in the scope and species we're talking about). One's parents may speak a different language because language acquisition and fluency is also dependent on peers in a way that genetic variation is not. Additionally, language transmission from parents need not be symmetrical, one may acquire the language of one parent but not the other. One may speak the same language as one's parents, but with a different accent (that one of one's peer group). Interestingly, the exception to this rule of accents are individuals with some socialization dysfunction, such as autism.
There are also similarities between languages and genes. The molecular clock has its analogy in the lexical clock. There is also lexical admixture between languages, for example the heavy load of French-derived terms in modern English, the influence of Slavic upon the Baltic languages. A new paper in PLoS Biology leans on these last similarities to utilize the Structure framework to flesh out the relationships of the language of New Guinea & Australia, what was once "Sahul" during the last Ice Age. The author's summary from Explaining the Linguistic Diversity of Sahul Using Population Models:
In medical news which won't be surprising to anyone, Ethnic Variation in Fat and Lean Body Mass and the Association with Insulin Resistance:
