Binge-drinking in the European Union

The full report has more data.

Recent positive selection in humans

Yet another study on positive selection in modern humans; you can find many many more by searching for "recent selection" or "positive selection" via the site search on the right sidebar.

The findings are reported in PLoS Biology (free text). Nicholas Wade also covers the study in the New York Times:

Providing the strongest evidence yet that humans are still evolving, researchers have detected some 700 regions of the human genome where genes appear to have been reshaped by natural selection, a principal force of evolution, within the last 5,000 to 15,000 years.

The genes that show this evolutionary change include some responsible for the senses of taste and smell, digestion, bone structure, skin color and brain function.

Many of these instances of selection may reflect the pressures that came to bear as people abandoned their hunting and gathering way of life for settlement and agriculture, a transition well under way in Europe and East Asia some 5,000 years ago.

From the new paper:

A fully rigorous estimation of the ages of the candidate sweeps is difficult with the current data. However, making the simplistic assumption of a star-shaped genealogy for the favored haplotypes and assuming a generation time of 25 y, suggests average ages of ≍6,600 years and ≍10,800 years in the non-African, and African populations, respectively (Materials and Methods).

...

Some of the strongest signals of recent selection appear in various types of genes related to morphology. For example, four genes involved in skin pigmentation show clear evidence of selection in Europeans (OCA2, MYO5A, DTNBP1, TYRP1). All four genes are associated with Mendelian disorders that cause lighter pigmentation or albinism, and all are in different genomic locations, indicating the action of separate selective events. One of these genes, OCA2, is associated with the third longest haplotype on a high frequency SNP anywhere in the genome for Europeans. A fifth gene, SLC24A5, has recently been shown by another group to impact skin pigmentation and to have a derived, selected allele near fixation in Europeans [45]. Though iHS has reduced power for alleles near fixation, SNPs near this gene also show strong iHS signals in Europeans (Table S2).

Various genes involved in skeletal development have also been targets of recent selection. Three related proteins involved in bone morphogenesis show signals of selection in Europeans (BMP3 and BMPR2) and in East Asians (BMP5). In addition, GDF5, a gene in which mutations cause skeletal malformations, shows strong signals of selection in both Europeans and East Asians. Other morphological features also appear to be targets of selection, including hair formation and patterning in Yoruba (the keratin cluster near 17q12; and FZD6).

An important type of selective pressure that has confronted modern humans is the transition to novel food sources with the advent of agriculture and the colonization of new habitats [19,21]. As noted above, we see a strong signal of selection in the alcohol dehydrogenase (ADH) cluster in East Asians, including the third longest haplotype around a high frequency allele in East Asians. A variety of genes involved in carbohydrate metabolism have evidence for recent selection, including genes involved in metabolizing mannose (MAN2A1 in Yoruba and East Asians), sucrose (SI in East Asians), and lactose (LCT in Europeans). Processing of dietary fatty acids is another system with signals of strong selection, including uptake (SLC27A4 and PPARD in Europeans), oxidation (SLC25A20 in East Asians) and regulation (NCOA1 in Yoruba and LEPR in East Asians). The latter gene (LEPR) is the leptin receptor and plays an important role in regulating adipose tissue mass.

Recent articles have proposed that genes involved in brain development and function may have been important targets of selection in recent human evolution [8,9]. While we do not find evidence for selection in the two genes reported in those studies (MCPH1 and ASPM), we do find signals in two other microcephaly genes, namely, CDK5RAP2 in Yoruba, and CENPJ in Europeans and East Asians [46]. Though there is not an overall enrichment for neurological genes in our gene ontology analysis, several other important brain genes also have signals of selection, including the primary inhibitory neurotransmitter GABRA4, an Alzheimer's susceptibility gene PSEN1, and SYT1 in Yoruba; the serotonin transporter SLC6A4 in Europeans and East Asians; and the dystrophin binding gene SNTG1 in all populations.

PLoS Biology Volume 4 | Issue 3 | MARCH 2006

A Map of Recent Positive Selection in the Human Genome

Benjamin F. Voight1, Sridhar Kudaravalli1, Xiaoquan Wen1, Jonathan K. Pritchard1*

The identification of signals of very recent positive selection provides information about the adaptation of modern humans to local conditions. We report here on a genome-wide scan for signals of very recent positive selection in favor of variants that have not yet reached fixation. We describe a new analytical method for scanning single nucleotide polymorphism (SNP) data for signals of recent selection, and apply this to data from the International HapMap Project. In all three continental groups we find widespread signals of recent positive selection. Most signals are region-specific, though a significant excess are shared across groups. Contrary to some earlier low resolution studies that suggested a paucity of recent selection in sub-Saharan Africans, we find that by some measures our strongest signals of selection are from the Yoruba population. Finally, since these signals indicate the existence of genetic variants that have substantially different fitnesses, they must indicate loci that are the source of significant phenotypic variation. Though the relevant phenotypes are generally not known, such loci should be of particular interest in mapping studies of complex traits. For this purpose we have developed a set of SNPs that can be used to tag the strongest ∼250 signals of recent selection in each population.

Link

IQ at age 18-20 predicts mortality 30 years later

This is probably due to the fact that IQ is a signal of good overall health, and that different occupational and social worlds are inhabited by people depending on their cognitive ability.

Int J Epidemiol. 2006 Jan 30; [Epub ahead of print]

The association between cognitive ability measured at ages 18-20 and mortality during 30 years of follow-up--a prospective observational study among Swedish males born 1949-51.

Hemmingsson T, Melin B, Allebeck P, Lundberg I.

OBJECTIVES: An association between childhood cognitive ability measured with IQ tests and mortality has been reported recently. It is not clear from those studies if the relative risk is increased only among those in the lower end of the IQ score scale or if there is graded increase in mortality from the lowest to the highest. This study aims to investigate the association between cognitive ability measured at age 18-20 and mortality during a 30 year period of follow-up. METHODS: Data on cognitive ability was collected from 49 323 men, born in 1949-51, who were conscripted for compulsory military training in 1969/70. Data on mortality were obtained from the Causes of Death register 1971-2000. RESULTS: Cognitive ability was a strong predictor of all-cause mortality, cardiovascular disease (CVD)-mortality, mortality from violent causes, and alcohol-related mortality. A striking finding was a pronounced gradient in mortality risk across all IQ score groups. Adjustment for adult socioeconomic position attenuated the increased risk somewhat [for all-cause mortality: crude hazard ratio (HR) 1.16 (1.13-1.19), adjusted HR 1.12 (1.09-1.15)]. CONCLUSION: IQ test score measured in late adolescence (only males) was a significant predictor of all-cause, as well as cause-specific (CVD and injuries), mortality during 30 years of follow-up. The risk increased from high to low IQ test score results for all outcomes.

Link

DNA Testing: In Our Blood.

Newsweek has an article titled "DNA Testing: In Our Blood", which offers layman's introduction to the world of population genetics and geneaological testing.

From the article:

The research led Skorecki's team to Africa, where they tested members of the Lemba tribe, a group that believed they were descended from the Biblical land of Judea. Some of their DNA matched the Cohan signature. "We share a common paternal ancestry," says Skorecki. In 2001, Father Bill Sanchez, a Roman Catholic priest in Albuquerque, N.M., discovered he closely matched the Cohan signature, too. Sanchez's Jewish roots go back to Spain (his mother's heritage is Native American). Today he keeps pictures of his Christian and Jewish ancestors on his wall; in November he traveled to Israel. Now his niece Jessica Gonzales, 24, wants to go. Raised Catholic, she wants to learn more about her family roots. "I've been reading a lot about Judaism," she says.

I don't know the specifics of Father Sanchez family origins, but I have to wonder when Skorecki et al. will finally decide to come clean about the significance of their "Cohen signature" and the little-known fact that it is neither a Jewish nor a Cohen-specific signature. I have a feeling that there are quite a lot of people out there who've been "reading about Judaism" based on false beliefs created by dubious science.

Also, from the article:

Last fall, Wells packed up 500 blood-collection tubes, needles, alcohol wipes and cheek swabs and headed off to Chad, one of the project's first testing sites, where he took 300 DNA samples from towns and villages around the country. Thirty-five to 40 came from members of the isolated Laal community, whose population, at fewer than 750, is declining. Wells fears that this community will die out within the next 10 to 30 years, taking with it valuable DNA and cultural traditions and an ancient language—information that could provide critical insights into the first people to live in Central Africa more than 40,000 years ago. "We can use DNA to figure out some of these great mysteries, to make sense of the past," says Wells.

I guess I was right about Dr. Wells' activities in my New Year's predictions... and their name is Laal. Now, let's hope that Dr. Wells and his team will find some time to devote to the other 6,000,000,000-750 of us.

The Uralic suicide phenomenon

Am J Med Genet C Semin Med Genet 15;133(1):43-7

History and geography of suicide: could genetic risk factors account for the variation in suicide rates?


Marusic A.

The current state of knowledge of genetic predisposition towards the suicidal behavior allows for a question whether genetic risk factors account for the variation in suicide rates through time and space. Accordingly, the presented paper will attempt to tackle the genetics behind suicidal behavior from the perspective of the populational genetics. First, the variability of suicide rates across Europe is discussed. This is followed by a brief discussion of the J curve (on a map of Europe, the countries with a higher suicide rate form a so-called J curve, which starts in Finland and extends down to Slovenia), which maps on to the second principal component identified for European gene distribution, representing the ancestral adaptation to cold climates and the Uralic language dispersion. Furthermore, we will discuss whether the group of people living within the J-curve could share genes, which may not tolerate excessive amounts alcohol, the combination of which is more likely to end in suicidal behavior. Further along we list possible ways in which suicidal behaviour could have been selected for genetically in populations and identify those specific populations in which it may have appeared. Finally, we point at other locations in the world where a similar interplay of genes and environment has probably occurred, Greenland being the best example of the malignant interaction of alcohol consumption and the trait-like characteristics, which might constitute the vulnerability to suicidal behaviour.


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Slovenia is a good example to illustrate that such prediction would not be valid. According to environmental predictors, Slovenia should share the same low rate with its Mediterranean neighbours such as Italy. Also about 70 per cent of its population are Roman Catholic; a religion where suicide is strictly forbidden. However, Slovenia has a suicide rate above 30 per 100,000 per year. Also, the annual suicide rate in Slovenia has remained remarkably stable, despite recent profound political and social change. Moreover, high rates of suicide in the native rather than the immigrant population of Slovenia also contradicts the theory that social and ecological risk factors are the major influence on suicide statistics [Marusic and Farmer, [2001]]. Finally, Slovenia does differ from other suicide-prone nations in some environmental predictors. This suggests that factors other than environmental predictors may be implicit in determining national suicide rates in Europe. Such factors could include some shared genetic vulnerability to suicidal behaviour among some European nations.

An example of similar genetic origins could be the Hungarians of central Europe (living in Hungary, Transylvania in Romania and Vojvodina in Serbia) and the Finns and Karelians in the North, who belong to the same (Finno-Ugrian) ethno-lingual group. Among all these groups, suicide is widespread, and we find even higher suicide rates among individuals in the original territory of both ethnic groups, which is in the Urals, specifically between Mari and Udmurts with the suicide rates three times higher than those in Hungary and Finland. Kondrichin [[1995]] was the first to suggest that the high rates, which we see among individuals of Finno-Ugrian ethnicity, extend to the early development of ethnic groups in whom a collection of shared genes contributed to an elevated susceptibility to suicide. It is interesting that in their genetic inheritance, both Finns and Hungarians have approximately the same ratio of European (90 %) and Uralic genes (10 %) [Cavalli-Sforza et al., [1994]]. Mogyorosi [[1996]] claimed that there is no evidence that so-called Finno-Ugrian nations are genetically closer to each other than to their geographical neighbors. Melhus [[1996]] pointed at recent analyses of mitochondrial lineages in European population, which show that the Finnish population belongs to a gene pool common to most other European groups [Sajantila and Paabo, [1995]]. The mitochondrial DNA will, however, only show maternal DNA. Hence, it remains possible that it is the male DNA that discriminates between the Finnu-Ugrians and other Europeans. For example, according to some theories, Hungary was occupied by 100.000-500.000 Magyar invaders, herders who spoke a Uralic language in 862. They formed a fraction of 10-50% of the total population after the invasion; subsequent gene flow from neighbors is likely to have decreased this initial proportion. The current estimate of admixture is 13%. Other Finnu-Ugrians are Finns and Lapps. The Finns have a proportion of 90% European genes and 10% Uralic [Guglielmino et al., [1990]].

...

A historical review of the traditions associated with wine in Slovenia and the discerning of inheritance and environmental factors can shed some light on this question. Wine-growing, which the Romans first introduced to the area now encompassing Slovenia, nearly died out when the Slavs and Magyars conquered the area. The production of wine was very limited until the 12th century. A theory exists that the members of these tribes, whose inheritance or genetic structure was not compatible with the consumption of alcohol, are the primary ancestors of those whose present suicide rate is among the highest in Europe. Once religious (environmental) factors had led to the re-establishment of vine growing, the region's inhabitants who were genetically unsuited to alcohol consumption, soon developed the highest rates of alcohol related mental disorders. This adverse combination of genetic propensity and high alcohol consumption led to the high rates of suicide noted in the region today. It is worth noting that current suicide rate in the north-east of Slovenia is the same as the Hungarian rates, and about twice as high as those in more western regions of Slovenia [Marusic and Farmer, [2001]].

...

In the mid-13th century, Genghis Khan's Mongol hordes swept across the Russian plain, seizing Moscow and imposing their rule over much of the country for the next 250 years. Almost eight centuries later, it seems that genetic traces the Mongols left behind are partly to blame for Russia's traditional weakness for alcohol. The gene, known as ADH2-2, is common in Asian countries but almost non-existent among Europeans. Carriers of the gene are more susceptible to the effects of drinking and more likely to become alcoholics. Since alcohol consumption was rare among Asiatic tribes, they evolved differently from Europeans, who have a long tradition of producing and consuming alcohol. The culture of drinking has existed for centuries in Europe, dating back to before the Roman Empire, so Europeans have built up a natural resistance. Scientists have long known that the ADH2-2 gene is common among Russians, but Ogurtsov et al. [[2001]] were the first to test how it affects alcohol consumption. There is a negative correlation between the ADH2-2 allele and alcohol misuse (both alcoholic dependence and alcoholic cirrhosis). This correlation is expressed more in alcoholic dependence. Among many other negative characteristics, it has also been found that those with the gene were more likely to have negative emotional responses (like aggression and depression) and more likely to suffer withdrawal symptoms [Mainville, [2004]].

Further north-east, in Alaska, an average of 130 suicides occurred annually in the last decade [Anonymous, [2003]]. The most recent suicide rate was above 21 per 100.000 per year, which is the highest in the United States and twice the national average. Most striking is the data among Alaskan Natives whose rate of suicide (42.7) is four times the national rate. Furthermore, among Native American males the rate (68.5) is six times the national average [Anonymous, [2003]].

Another population of the Inuit have been faced with high suicide rates, namely the Inuit of Greenland [Bjerregaard and Curtis, [2002]]. This is however a much clearer example of the malignant interaction of alcohol consumption and the trait-like characteristics, which might constitute the vulnerability to suicidal behavior. The majority of the population of Greenland are Inuit, the ancestors of whom migrated from Asia about 20-30 000 years ago. In Greenland, alcohol consumption has recently increased dramatically. In 1950, the estimated average consumption among adults, expressed as litres of alcohol, was 7 litres per year. By 1987 this had increased to a maximum of 22 litres. Accordingly, suicides were uncommon in the 1950s with an estimated rate of 4.6 per 100.000 per year. During the following years, suicides increased dramatically and in the early nineties the suicide rate was 107 per 100.000 per year [Bjerregaard and Curtis, [2002]].

Link

Benefits of Mediterranean Diet

A new study from Europe in this morning's Journal of the American Medical Association shows just how powerful the effect of following healthy lifestyle advice can be over the years, reports The Early Show's Dr. Emily Senay.

Researchers looked at people aged 70 to 90 for more than a decade, and found those who adhered to a healthy low-fat Mediterranean-style diet lowered their risk of death by 23 percent. People who drank alcohol moderately lowered their risk by 22 percent. Physical activity lowered the risk by 37 percent. Nonsmoking lowered the death risk by 22 percent. And people who had all four of these healthy lifestyle factors lowered their risk of death from any cause by 65 percent.

It's powerful proof that a healthy lifestyle can work wonders.

The Mediterranean diet comes from countries like Italy and Greece. It's high in foods that provide health benefits like whole grains, fruits, vegetables, legumes, nuts, fish and olive oil.

It also includes low amounts of meat, dairy and saturated fats, and moderate alcohol consumption. Another new study showed that the Mediterranean diet reduced metabolic syndrome, a cluster of symptoms that puts people at a much higher risk for heart disease and Type 2 diabetes later in life like obesity, fat buildup in the arteries, high blood pressure, and glucose or blood sugar intolerance.

People on the Mediterranean diet had significant decreases in metabolic syndrome symptoms and risk factors and improvements in good cholesterol compared to those who weren't on the diet. There was also evidence that the healthier eaters suffered less from the inflammation of cells that may contribute to the risk of disease.

Two additional studies in the journal reinforce the importance of exercise in the health equation, even low-intensity exercise like walking. Physical activity was associated with better mental functioning in older women. Women aged 70 and older who participated in higher levels of physical activity scored better on cognitive performance tests and showed less cognitive decline than women who were less active.

A different study showed that even walking is associated with reduced risk of Alzheimer's in older men. Older men who walked the least had nearly twice the risk for diseases like Alzheimer's, compared to men who walked the most. This is the first time that a low-intensity exercise has been proven to keep the mind sharp.

Link (CBS)