Posts matching tags 'genetics'
2008/1/31
Scientists studying the genetics of eye colour have found that all people with blue eyes inherited them from a common ancestor, who lived about 6,000 to 10,000 years ago in the northwestern Black Sea region, and developed a very specific mutation which disrupted melanin production in the iris.
It is still not clear why the mutation was selected for and spread as widely, though possible explanations are that it conferred some advantage in northern latitudes, or else that it spread purely because, by some quirk of psychology, it was considered sexually attractive.
2007/12/11
New research shows that the human race is evolving faster than ever, and that, far from the accepted truth of the human race being biologically homogeneous, different populations have, over the past 10,000 years, been evolving apart, pushed by different selection pressures:
“Genes are evolving fast in Europe, Asia and Africa, but almost all of these are unique to their continent of origin. We are getting less alike, not merging into a single, mixed humanity.
“Our study denies the widely held assumption that modern humans appeared 40,000 years ago, have not changed since and that we are all pretty much the same. We aren’t the same as people even 1,000 or 2,000 years ago.”
The scientists said this reflected the great increase in human populations over that period, which has allowed more beneficial mutations to emerge. Changes in the human environment, particularly the rise of agriculture, also created new selective pressure to which humans adapted.Examples of evolutionary divergences include lactose tolerance among descendents of northern European populations (where the lack of sunlight would have made this mutation beneficial), differences in resistance to diseases such as malaria, smallpox and HIV between European and African populations, and more controversially, the hypothesis that above-average intelligence in Ashkenazi Jews is a result of selection pressures in mediaeval Europe (where they were confined to a small number of primarily cognitively demanding vocations). (And wasn't there a study a while ago that showed that the average IQ of a population was proportional to how many generations their ancestors had lived in urban environments?)
2007/12/10
Irony of the day: James Watson, the disgraced Nobel laureate who recently claimed that people of African descent are less intelligent than those of European descent, is found to have genes indicating recent African ancestry. More specifically, 16% of Watson's genome is likely to have come from a black ancestor of African descent, whereas with the average European, that figure is 1%:
"This level is what you would expect in someone who had a great-grandparent who was African," said Kari Stefansson of deCODE Genetics, whose company carried out the analysis. "It was very surprising to get this result for Jim."
2007/11/1
The cat genome has been sequenced. Well, most of it. The feline
Analysis of the cat genome sequence could also shed light on everything from evolution to the origins of feline domestication, they say.
"One thing I'd like to discover is the genes for good behaviour in the cats - the genes for domestication, the things that make them not want to kill our children but play with them," he added.If they do find the makes-a-good-pet gene, they could possibly use it to create transgenic pets which don't do the amount of ecological damage to non-native environments that cats do. (There would be a solid case for eliminating cats from, say, Australia, though because of their popularity, such a move would be impossible to implement in anything resembling a democracy.) An alternative would be to find the genes responsible for predatory instincts and knock them out, creating a cat that's, well, a pussycat. Oh, and if they find out how to encode bitmaps into the cat's coat patterns, designer kittens could be as much a possibility as laser-engraved iPods.
2006/8/23
Scientists have created a mouse that's permanently happy. The mouse lacks the TREK-1 gene, which affects the transmission serotonin in the brain, and as such doesn't suffer from depression (which, presumably, normal mice do):
Mice without the TREK-1 gene ('knock-out' mice) were created and bred in collaboration with Dr. Michel Lazdunski, co-author of the research, in his laboratory at the University of Nice, France. "These 'knock-out' mice were then tested using separate behavioral, electrophysiological and biochemical measures known to gauge 'depression' in animals," says Dr. Debonnel. "The results really surprised us; our 'knock-out' mice acted as if they had been treated with antidepressants for at least three weeks."
(via /.) ¶ [no comments]
2006/6/26
More evidence of neoteny being a characteristic of evolutionary advancement: as coping the modern world requires more flexibility, immaturity levels in adults are rising. Which sounds alarming, until you consider that "maturity" (and the nebulous "wisdom" that comes with it) is a sclerotic set-in-one's-ways inflexibility and resistance to change, which no longer cuts it:
"The psychological neoteny effect of formal education is an accidental by-product -- the main role of education is to increase general, abstract intelligence and prepare for economic activity," he explained. "But formal education requires a child-like stance of receptivity to new learning, and cognitive flexibility."
"When formal education continues into the early twenties," he continued, "it probably, to an extent, counteracts the attainment of psychological maturity, which would otherwise occur at about this age.
While the human mind responds to new information over the course of any individuals lifetime, Charlton argues that past physical environments were more stable and allowed for a state of psychological maturity. In hunter-gatherer societies, that maturity was probably achieved during a persons late teens or early twenties, he said.
By contrast, many modern adults fail to attain this maturity, and such failure is common and indeed characteristic of highly educated and, on the whole, effective and socially valuable people," he said.Some of the symptoms of neoteny include novelty-seeking, which ties in with the possibility of a "neophilia gene" previously mentioned here. In fact, if there was a genetic mutation that caused neophilia, the abovementioned article suggests that, in today's environment, it would be strongly selected for.
(via /.) ¶ [no comments]
2006/6/23
Researchers in Japan have found an enzyme correlated with novelty-seeking tendencies.
it seems that genetic differences mean that people produce different variations of a mitochondrial enzyme called monoamine oxidase A. That's according to research from the Yamagata University School of Medicine in Japan, which was recently published in the scientific journal Psychiatric Genetics and mentioned in the New Scientist magazine.
The researchers found that one form of this enzyme was "significantly associated with higher scores of novelty seeking." In other words, people who produce that form of the enzyme are more likely to have novelty-seeking traits in their personality than others.This suggests that there may be a genetic cause for neophilic tendencies. Though some are skeptical about whether a neophilia gene could work:
Colin Campbell, a professor of sociology at the University of York in the UK, has studied the nature of consumerism, and he believes that the existence of novelty seeking is a relatively new phenomenon. So it can't by definition be genetic.
"Pre-modern societies tend to be suspicious of the novel. It is a feature of modernity that we are addicted to novelty," says Campbell. Campbell dates the emergence of novelty seeking to the beginnings of the industrial revolution in the mid 18th century. As he explains, "Modern fashion evolved then."I'm not sure about that. For one, a neophilia gene would cause a predisposition to novelty, which could be indulged or otherwise by the society, culture and economy the individual is in; unless it proved maladaptive (i.e., by making the carriers less likely to pass their genes on), it wouldn't be selected out. And while it may be true that individuals in pre-modern societies would find less to gratify their neophilic tendencies than the white-earphoned, designer-label-wearing channel-surfers and BlackBerry addicts of today, it could also be said that our hunter-gatherer ancestors, being unable to walk into a Krispy-Kreme outlet, had less to satisfy their taste for fatty and sugary foods than today, though it is widely accepted that such a taste evolved back then, when small, expensively-obtained amounts of such food were more likely to ward off malnutrition than cause obesity. It could well be that a "neophilia gene", if one exists, evolved in similar circumstances.
(via Gizmodo) ¶ [no comments]
2006/5/26
Philosophers have solved one of the great conundra, the question of which came first: the chicken or the egg. The answer: the egg came first, even if you implicitly exclude non-chicken eggs:
Genetic material does not change during an animal's life. Therefore, the first bird that evolved into what we would call a chicken, probably in prehistoric times, must first have existed as an embryo inside an egg.
Professor John Brookfield, a specialist in evolutionary genetics at the University of Nottingham, who was put to work on the dilemma, said that the pecking order was perfectly clear: the living organism inside the eggshell would have the same DNA as the chicken that it would become.Of course, the conclusion is not entirely indisputable, especially in the non-reality-based community:
Creationists, for example, will argue that if God created Adam and Eve, he probably had a spare five minutes to knock up a chicken as well.
2005/12/13
Two scientists speculate on a genetic cause for why America is full of loud, energetic go-getters. Their hypothesis is that "American hypomania" results from the American gene pool containing many genes from immigrants, a group which, by its nature, would self-select for genes encouraging curiosity, risk-taking, neophilia and boldness:
Peter C. Whybrow of U.C.L.A. and John D. Gartner of Johns Hopkins University Medical School make their cases for an immigrant-specific genotype in their respective books, "American Mania" and "The Hypomanic Edge." Even when times are hard, Whybrow points out, most people don't leave their homelands. The 2 percent or so who do are a self-selecting group. What distinguishes them, he suggests, might be the genetic makeup of their dopamine-receptor system - the pathway in the brain that figures centrally in boldness and novelty seeking.
Why aren't Canada and Australia, where many immigrants and their descendants also live, as hypomanic as the United States? Whybrow answers that behavior is always a function of genetics and environment - nature with an overlay of nurture. "Here you have the genes and the completely unrestricted marketplace," he says - with the anything-goes rules of American capitalism also reflecting immigrant genetics. "That's what gives us our peculiar edge."Of course, the fact that a lot of the descendents of Australians did not choose to emigrate could also have something to do with it.
By coincidence, I was thinking about American hypomania recently, in the context of American culture having a propensity for maximality in various areas (the biggest cars, the fastest roller-coasters, the most exciting movies, the loudest, most attention-grabbingly garish TV); it came up in the context of the ongoing popularity of the death penalty in America, and the recent execution of Stanley "Tookie" Williams. Other than the ancient imperative for vengeance ("an eye for an eye and a tooth for a tooth", as it says in the Hammurabi codex the Bible), it is arguable that humanely euthanasing a convicted criminal is not a greater punishment than leaving them to contemplate their wrongdoing for some decades from within a cell with no hope of release. However, from an observer's point of view, the ritual of executing an evildoer is a grander statement of symbolic redressing of wrongs than the boringly administrative option of merely locking them up.
(via mindhacks) ¶ [no comments]
2005/6/8
A paper recently published by the University of Utah makes several controversial statements: that Ashkenazi Jews have genetic mutations which enhance their cognitive abilities, making them more intelligent than average, that this originated from selection pressures in mediæval Europe (where Jews could only make a living in various cognitively-demanding niches, many of which Christians were barred from), and that the same mutations cause many of the degenerative diseases common among the Ashkenazi population, as well as high incidences of depression (could it be no coincidence that cities with high Jewish populations (such as New York and Buenos Aires) have the most psychiatrists?):
Greg has referred to this hypothesis as "overclocking". The analogy is to overclocking computer processors (computer processing units or CPUs). Some hobbyists turn up the clocks on their desktop PCs to them run faster than they were designed to run. This can cause system instability and other problems. In the case of the Ashkenazis in Europe the hypothesis proposes that selective pressures for higher Ashkenazi intelligence were so high that it caused the propagation of mutations that pushed their intelligence up so quickly (evolutonarily speaking) that the selective pressure overrode the reduction in reproductive fitness caused by the deleterious side effects on some of those who received those mutations. The problem with overclocking is that "Sometimes you get away with it, sometimes you don't."
More generally, if this is what I think it is, all these Ashkenazi neurological diseases are hints of ways in which one could supercharge intelligence. One, by increasing dendrite growth: two, by fooling with myelin: three, something else, whatever is happening in torsion dystonia. In some cases the difference is probably an aspect of development, not something you can turn on and off. In other cases, the effect might exist when the chemical influence is acting and disappear when the influence does. In either case, it seems likely that we could - if we wanted to - developed pharmaceutical agents that had similar effects. The first kind, those affecting development, would be something that might have to be administered early in life, maybe before birth. while the second kind would be 'smart pills' that one could pop as desired or as needed. Of course, we have to hope that we can find ways of improving safety. Would you take a pill that increased your IQ by 10 or 15 points that also had a 10% chance of putting you in a wheel chair?The article goes on to suggest that mediæval laws on Christian and Jewish occupations were ultimately responsible for the founding of the state of Israel. Meanwhile, there's a New York Times piece on the paper here, which has a quote from evolutionary psychologist Steven Pinker:
"It would be hard to overstate how politically incorrect this paper is," said Steven Pinker, a cognitive scientist at Harvard, noting that it argues for an inherited difference in intelligence between groups. Still, he said, "it's certainly a thorough and well-argued paper, not one that can easily be dismissed outright."Anyway, back to selection pressures in medieval Europe; I imagine that the fact that the brightest Christians were put into monasteries and sworn to celibacy could also have had an effect on inherited intelligence among that group. Could it also be that Europeans of Christian descent are (inadvertently) bred for low cognitive ability?
(via /.) ¶ [no comments]
2005/2/13
A new study has found that men with feminine faces are attractive to more women. Square-jawed he-men are preferred by women who consider themselves highly attractive (and, according to an earlier study, are healthier), though their more androgynous brethren are preferred by a greater number and variety of women.
"Those women who prefer masculine men are selecting genetic benefits for their children, despite the fact that high testosterone levels can also increase the likelihood that the male will have an affair.
Which makes sense; the women selecting he-men consider themselves to be highly attractive, which suggests a calculation that they could prevail in competition.
Meanwhile, another study by the same group has shown that women seen with a dominant male were considered more attractive by other men.
2004/10/21
Scientists may have discovered an evolutionary basis for (male) homosexuality, previously considered a paradox of evolutionary biology. It appears that the same genetic factors that are responsible for homosexuality in men cause higher fecundity in women; i.e., whilst (most) gay men don't have children, their female relatives (who share the genetic factors) make up for this. (via FmH)
"This is a novel finding," says Simon LeVay, a neuroscientist and commentator on sexuality at Stanford University in California. "We think of it as genes for 'male homosexuality', but it might really be genes for sexual attraction to men. These could predispose men towards homosexuality and women towards 'hyper-heterosexuality', causing women to have more sex with men and thus have more offspring."
2004/7/19
Databases of genetic research data, it has emerged, have been irreversibly corrupted by Microsoft Excel's autocorrection feature. Excel, in its infinite wisdom, assumed that some gene identifiers (such as SEPT2) were really dates (i.e., 2-Sep), and corrected the "mistake"; meanwhile, Excel's floating-point conversions wreaked their own havoc elsewhere. (via bOING bOING)
2004/6/18
Scientists find monogamy gene in voles, successfully making a promiscuous variety of the rodents monogamous by changing one gene (commonly found in a different, more monogamous, variety). The article suggests that the research could have implications for humans with autism or Asperger's Syndrome, which impair social bonding. Though, putting this assertion together with the commonly cited piece of folklore about autism being a concentrated form of a condition which, in its weaker form, is common among "geek" subcultures, is intriguing. For one, it suggests a genetic basis for the prevalence of polyamory among "geek" subcultures. Though perhaps that's stretching things a bit too far. (via MeFi)
2003/11/16
A mother of three recently found out that she was not the biological parent of her children, all of whom were naturally conceived. As if that wasn't weird enough, it turns out that her DNA isn't her own either. "Jane", 52, is a tetragametic chimera, someone whose body is made up of two genetically different lines of cells. She is one of only 30 such individuals ever discovered. (via Lt. Wilkes)
2003/10/15
Chinese scientists create foetus with three parents (two female and one male). However, polyamorist group marriages in the West will have to wait a bit longer as such research is banned in the US and UK. Also, the foetus only contained genetic material from two of the parents; the third merely donated an egg. (Though perhaps some master-slave threesomes may not have a problem with such inequalities.)
2003/2/13
Are one in every 200 people on Earth today descended from Genghis Khan? A new population genetics study suggests that may be the case; or perhaps it's some other Mongolian?
Cochran speculated, "You'd need several factors to contend for the record. You'd need to conquer a big empire. You'd need a place where harems are common. So, forget Europe. Charlemagne couldn't have had the same impact. You'd have to be able to organize a big, long-lasting state, so medieval Africa is an unlikely setting. Maybe the founder of a long-lived Chinese dynasty would be in the running. Or the founder of a polygamous religion."
2002/9/30
A German study claims that blond-haired people will die out in 200 years. Blond hair is caused by a recessive gene, and is thus genetically disadvantaged. This was compensated for by blond people being widely seen as more attractive (*ahem*), but modern artificial blond colourings exploit this bias much more effectively than natural blond hair.
Or will blondes die out? Professor Jonathan Rees (who previously proved that redheads are sexier) claims that the blonde gene will become less common but never completely disappear, as it does not carry any disadvantage. (Except in jokes, that is.) (via FmH)
2002/8/15
Autism linked to "geek genes". Dramatic increases in incidents of autism among children born in places like Silicon Valley and Cambridge, are evidence for the hypothesis that the skills associated with high-technology industries such as programming and engineering may be genetically related to autism:
Some doctors now think that workers who have the complex analytical skills needed to succeed in high-tech industry, and who are perhaps slightly awkward socially - the classic profile of the "computer geek" - may, while not fully autistic themselves, at least be carrying at least a few of the genes that contribute to it.
(I once heard it claimed that 70% of programmers/engineers/high-tech workers have Asperger's Syndrome. Then again, 86.7% of statistics are made up.)
2002/8/13
Alba the glowing rabbit, genetically engineered at the commission of conceptual artist Eduardo Kac, is dead. Though there is some dispute over just how brightly the rabbit really glowed.
2002/5/28
A study by German geneticists supports the controversial theory that human intelligence is the product of sexual selection, or evolved primarily as a courtship device (much as the peacock's tail). Furthermore, the study argues that women are responsible for the evolution of intelligence by selecting intelligent mates (though some might well argue that they are responsible for stupidity by selecting dumb, brawny meatheads over the scrawny, brainy geek types).
2002/5/18
Interesting: DNA explained in computer science terms, with analogies to everything from program comments to makefiles. (via bOING bOING)
2001/8/10
Australian euthanasia advocate Dr. Philip Nitschke (he of the Laptop of Death and the floating euthanasia clinic) has come under attack from religious-right group Right To Life for his eminently Darwinian idea of making suicide pills available to angst-ridden teenagers. (The Darwinian implications of allowing depression-prone people to easily kill themselves, though, bear some thinking about; imagine a planet of Shiny Happy People, the descendents of those genetically predisposed towards contented apathy.)
2000/9/23
Eduardo Kac, the Brazilian conceptual artist who proposed creating a transgenic glowing dog with gene-splicing, has partly realised his idea with a glowing rabbit. The rabbit, named Alba, is an albino rabbit whose genes have been modified to incorporate Green Fluorescent Protein (GFP). (via bOING bOING)
2000/4/21
According to Oxford professor Brian Sykes, 99% of Europe's population is descended from one of seven women who lived in the past 45,000 years. (BBC News)
1999/10/21
Brazilian artist discusses the artistic promises of genetic engineering, proposes creating a transgenic glowing dog:
Transgenic art, I propose, is a new art form based on the use of genetic engineering techniques to transfer synthetic genes to an organism or to transfer natural genetic material from one species into another, to create unique living beings. Molecular genetics allows the artist to engineer the plant and animal genome and create new life forms...
Hence, my current work: GFP K-9. GFP stands for Green Fluorescent Protein, which is isolated from Pacific Northwest jellyfish (Aequorea Victoria) and which emits bright green light when exposed to UV or blue light... The use of the Green Fluorescent Protein in a dog is absolutely harmless, since GFP is species independent and requires no additional proteins or substrates for green light emission.