PZ Myers outlines synteny. RPM says he's kind of wrong. Check out the definition in Wikipedia. Since RPM came down on me for confusion on this term I knew he would bring this up. I don't really care much about which definition is "correct," but I thought I'd point interested readers to the debate.....

Labels: Genetics

Remember that better time when college coeds frolicked on the quad lawn, safe from the eyes of older males, who were drawn instead to the allure of a mature woman? Indeed, doesn't it seem like nowadays, in our Girls Gone Wild culture, we shove females into the sexual spotlight at ever younger ages? That's what you'd conclude from the 50,000 alarmist results that a Google search for "+sexualizing +young" returns, in particular the recent panic over 15 year-old Miley Cyrus posing semi-topless for Vanity Fair. The cropped picture to the left is of Elizabeth Ann Roberts, who was 16 when she was photographed nude as Playboy Playmate of the Month -- of January 1958.

On an intuitive level, though, we know that the culture must be more hostile than before to sexualizing young females -- there would be no hysteria if it were acceptable. Plus, suburban housewives and city-dwelling cougars have never hogged so much of our attention. Still, let's turn to three datasets that show the trend is, if anything, toward sexualizing increasingly older females in popular culture. We will look at data across the decades on beauty pageant winners, girls featured in nude magazines, and hardcore porn actresses.

First, take the winners of the Miss America beauty pageant, a competition determined mostly by how closely the contestant fits the ideal look of the time. A writer for the website Seduction Labs has already done an extensive analysis, so I took the age data from his work. Here is how Miss America's age has changed over the decades:



It sure looks like Miss America is getting older -- the ones from before 1940 are quite young -- and this is true: Kendall's tau for the correlation between year and age is +0.50 (p = 3 x 10^(-10), two-tailed). Admittedly, estimating the youth-obsession of each year with only one data-point -- the winner from that year -- is less desirable than averaging all contestants' ages for that year, but the data are hard enough to come by that this is the best we can do.

Next, consider the Playboy Playmates of the Month, averaged for a given year. While the 1950s had fewer data, each year still had at least 7 data-points. Using 12 data-points to estimate each year should make us more confident in the results, shown here:



Again, the average Playboy Playmate is getting older: Kendall's tau for the correlation between year and age is +0.44 (p = 3 x 10^(-6), two-tailed). The trend is clearly not linear, though, since there was a decrease in age at least from the mid-1950s, when the data begin, throughout the 1960s.

In response to a criticism brought up in the comments to the post showing that the popularity of blonds is recent, I've also calculated Kendall's tau based on the raw month-by-month data-points, rather than yearly averages: it is +0.18 (p = 1 x 10^(-10), two-tailed). As I mentioned to the commenter, I think it's more instructive to look at the year's average since the Playboy people likely have a target girl in mind for the year's subscription, based on the perceived demand. That is, the Playmates within a given year are comparable to the Miss America contestants for a given year -- they are chosen to fill out a year's run, and Miss April could just as well have been Miss December. Still, even by this perhaps overly stringent standard, the trend is positive and significant.

Finally, we look at actresses in hardcore porn movies. Collecting a representative sample of active females in a given year would be incredibly arduous, so instead I took famous actresses and determined how old they were when they made their first movie, and entered this as a data-point for the year in which they started making movies.

The lists I used are the AVN Hall of Fame, the XRCO Hall of Fame (which barely added anyone else), and a list of female porn stars by decade drawn up by the porn geeks at Wikipedia. I required each year to have at least 5 data-points; if there were too few, I merged that year's data with an adjacent year (whichever had fewer data-points than the other choice), so that the data-sparse year is excluded and the beefed-up year is included. This mostly affects the 1970s and early 1980s. Here are the ages of first-time porn stars by year of their first movie:



There is no increase or decrease over time: Kendall's tau for the correlation between year and age is nowhere near significance. There are several apparent upward and downward trends, though. This might be the only example of the 1980s and early 1990s showing greater progress by the declinists' standards. I recently analyzed a large, representative sample of porn stars and found that their average age is 23, for what it's worth. Again, that's what we really want to see: the age of the typical actress for a given year.

Maybe girls enter at earlier ages in recent times but don't reach their peak in popularity until they are in their early 20s. Another drawback of looking at age at first movie is that it ignores the recent popularity of "MILF" actresses -- maybe it's just that the variance in age is increasing. Admittedly, these pornstar data are not ideal.

Finally, we examine the popularity of beauty pageants specifically for teenage contestants. While I don't have datasets to analyze, such as the annual TV ratings, there is enough information on them to get a rough picture. First, there is Miss Teen USA, the adolescent version of Miss Universe. It was created in 1983, reached its peak for ratings in 1988, and has declined in popularity afterward, to the point where it may not even be televised anymore. And second, there is Miss Teenage America, which was created in 1962 and was last televised in 1977. Judging by its corporate sponsorship and celebrity hosts, it must have been somewhat popular. There are other beauty pageants for teenagers, but they are not even televised, and so do not count as evidence of an obsession with youth. Rather, we see a shift away from throwing young girls into the purely sexual spotlight.

Since there are no huge long-term swings up and down in these data, as opposed to the cases of sluttiness and violence, all generations can say that they've improved over previous generations, or at least done no worse. If any generation is to be accused of sexualizing younger girls in popular culture, though, it is surely the older ones. It is true that the current culture does not value women over 30, but that has never been the case -- just the opposite.

As with sluttiness, part of the declinists' misperception may be due to fashion trends, such as even prepubescent girls wearing adult-inspired clothing. That's hardly evidence of their being sexualized, though -- no guy is actually looking at them as a sex object, and dressing like an adult doesn't make you behave like one sexually. While it may be a bizarre fashion trend -- though more bizarre than when pre-pubescents started wearing two-piece bathing suits? -- it doesn't reflect a sexualization of the young.

What's causing this trend toward older sex symbols? Oh, I don't know, but I'm sure we'll get a bunch of half-baked ideas in the comments, so I'll get the goofball ball rolling. Women are having their first kid later, if at all, so there's a wider age range of females who haven't ruined their figure by giving birth. Still, according to the analysis of Miss America winners at Seduction Labs, there are other trends: starting around 1960, winners became taller, less buxom, and less hourglass in shape, in addition to older. In short, the feminine ideal in popular culture has been worn down by the march of the masculine minxes. It's a mistake to blame this on the women's movement of the 1970s, though, since most of these trends began in the early-to-mid-1960s. Radical feminists were just jumping on the bandwagon and trying to steal credit for it.

Though it's harder to measure, the manliness of these sex symbols' faces has surely increased -- go back and look at some of the Playboy Playmates from the late 1950s through the late 1960s. They look like girls, not butch transvestites (NSFW, obviously). I see this as a form of cultural decline, of course, but the declinists who decry our obsession with youth could not be more wrong.

Labels: babes and hunks, previous generations were more depraved

Doubling Of Sexually Transmitted Infections Among Over-45s In Under A Decade. Dare we say an "epidemic???" If you want to push the envelope of course, She was 82. He was 95. They had dementia. They fell in love. And then they started having sex. In any case:

While the numbers of infections identified in younger age groups rose 97% during the period of the study, those identified in the over 45s rose 127%.
...
"Indeed, it may be argued that older people are more susceptible [to sexually transmitted infections] as they are less likely to use condoms than younger people," they say, adding that as successive waves of people with more liberal sexual attitudes and behaviours age, the problem is likely to worsen.

I guess the "safe sex" message just isn't getting through to the less young.

Related: Your generation was sluttier.

Labels: sex

Long-time readers know that one of my beliefs that I'll stop at nothing to prove is that blond women are not sexier than brunettes, whatever other appeal they obviously have for many men. Point-estimates of the current popularity of blond hair neglect the fact that standards of beauty can change over time -- within boundaries, to be sure, but still. Perhaps we only live in a blond-obsessed world today, while brunettes may have ruled in the past. Indeed, I will show just that. Furthermore, the shift toward blonds parallels several other shifts toward a more masculine ideal of female beauty since the early / mid-1960s.

The data come from Playboy Playmates of the Month ("Playmates") from 1954 to 2007. We need to look at sources that pander to popular demand in sexual tastes, which excludes runway fashion magazines (not used by males for fantasy purposes) as well as data on high-ranking Hollywood actresses (who are esteemed only in part based on their looks). We also need comparable data that stretch over decades, and that provide us with many data-points for each year -- in a worst case scenario, we might look at something like Miss Universe winners, but estimating the value of blond-obsession for a given year with only a single data-point is hardly ideal. Playmates, though, yield 12 data-points per year.

In the name of scientific discovery, I looked at pictures of every Playmate [1], and coded her hair color as either 1 for blond or 0 for non-blond. Dark blonds counted as blond, light browns as non-blond. Redheads counted as blond if they had very fair, strawberry blond hair, and as non-blond otherwise. The point is not to measure the popularity of the full spectrum of hair colors -- just blondness. A small handful of Playmates had several hair colors within the single issue they appeared in. I coded these as 0.5 because their pictures were split pretty evenly between blond and non-blond hair -- maybe due to wigs, I don't know.

I then took the fraction of blonds in a given year and plotted these over time. Here is the raw scatter-plot, together with 3-year and 7-year moving averages that smooth it out:



The scatter-plot suggests an increasing trend, and this is true: Kendall's tau for the correlation between year and percent blond is +0.27 (p = 0.01, two-tailed). [2] However, because each year's value can only take on roughly 12 values (1 / 12, 2 / 12, etc.), there are a lot of tied years, which may underestimate the true correlation. Kendall's tau for the correlation between year and the 3-year moving average of percent blond is +0.47 (p = 2 x 10^(-6), two-tailed), and is +0.64 (p = 2 x 10^(-10), two-tailed) when the 7-year moving averages are used. Using a moving average gives us a better idea since they can take on far many more values, and so produce fewer ties.

Whichever one we choose, it is clear that blonds have increased quite a bit in popularity over the decades. At the same time, the trend is clearly not linear: there is a decrease in blond-obsession at least from the mid-1950s, when the data begin, to the early / mid-1960s. There follows an increase, and an apparent reversal since the turn of the millennium -- please god, let it be so. This looks periodic, like a fashion cycle.

In trying to account for this trend, we should try to be as general as possible. What other trends in female beauty show an increase after the early 1960s? I didn't look at other aspects of the Playmates, but someone else has tabulated data on Playmates of the Year from 1960 to 2006 -- again, estimating the popularity of some trait in a given year based on a single data-point is worst-case, but I'm relying on it here because I've already spent enough time collecting hair color data. The links in footnote 1 provide all the anthropometric data, though, so if you want to collect an analyze it, we will link to your analysis.

I calculated the Waist-to-Hip Ratio and BMI of Playmates of the Year from the above data, and Kendall's tau for the correlation between year and WHR is +0.53 (p = 4 x 10^(-7), two-tailed), while between year and BMI it is -0.24 (p = 0.02, two-tailed). So, these sex symbols are increasingly losing their feminine hourglass shape and fatty softness -- nearly all BMI points are below 20, so it's not like they used to be fat but are now healthy. They are also getting taller: Kendall's tau is +0.31 (p = 0.004); and smaller in the chest: Kendall's tau is -0.35 (p = 0.001).

Someone else has also done an analysis of Miss America winners, and the exact same trends emerge there as well (see his graphs).

The common factor of all these trends is that the ideal of female beauty has become increasingly masculinized. Recall that males are more likely to be blond, so the hair color trend is part of the larger masculinizing trend. I didn't look at eye color, but if it's part of the overall trend, the earlier Playmates should be less blue-eyed than later ones, as blue eyes are also more typical of males. Skin color would be tougher to analyze; if it's part of the same trend, it should get darker over time. Anecdotally, these two guesses seem to be true, but someone should look at the data to check.

It therefore appears that a preference for blonds should also correlate with a preference for taller and less curvy women. Again, someone else can look that up in the psychology literature and post in the comments. But the words "tall," "thin," and "blond" usually co-occur, don't they? Whatever appeal such women have, raw sex appeal is unlikely to be among the top reasons. Blond hair correlates with something like introversion, and that makes sense since men on average are more introverted than women. So, maybe guys start digging blonds when they become more marriage-minded, or if they are inveterate monogamists. A blond will be less likely to be bouncing off the walls and being constantly out and about in search of social stimulation.

Bang a brunette, bank on a blond? It would fit with the trend toward lower sluttiness in recent times, which we expect to weed out the sex kitten types from popular culture. This suggests that dark hair is part of that highly sexualized image -- something that was always obvious to everyone but the blond-lovers.

[1] For years 1954 to 1992, I used this source that contains the full shoot for each Playmate, and for 1993 to 2007, Playboy's official website (if the single picture available on the Playboy site was ambiguous, I did a Google image search to get a better idea).

[2] You can easily calculate Kendall's tau with this website, which I used here.

Labels: babes and hunks

Genetic Variation in Political Participation:

The decision to vote has puzzled scholars for decades...The results show that a significant proportion of the variation in voting turnout can be accounted for by genes. We also replicate these results with data from the National Longitudinal Study of Adolescent Health and show that they extend to a broad class of acts of political participation. These are the first findings to suggest that humans exhibit genetic variation in their tendency to participate in political activities.

Additive genetic variance ~ 0.50. You can read the whole paper, though I've blogged it elsewhere.

Labels: Behavior Genetics

Something new in my RSS over the past few weeks, PhDiva. Feel free to mention blogs of note or that you find interesting (or your own blog) in the comments....

On this week's In Our Time they're talking about the Islamic conquests. The author of When Baghdad Ruled and The Great Arab Conquests is one of the guests, so if you meant to read the books but never got around to it for whatever reason, might be worth a listen. As I told a friend the first few centuries of the emergence of what we know as the Islamic World (650-850) are interesting, but after that point you hit a somewhat stationary state (most of the sects and schools of Islamic law emerged during this period, even if their identity only full crystallized between 850 and 1150). Details such as how Iran was transformed into a Shia state by the Safavids in the 16th century are not trivial, but they pale in contrast to the implications for world history of a new ideology & empire which stretched from the Atlantic to the Indus.

Labels: History

There have been a number of posts on this site regarding EDAR--in summary, a non-synonymous SNP has swept up to high frequency in East Asian populations via positive selection, and appears to account for some variation in hair form. The evidence for function in hair form comes largely from an association study on hair thickness. Now add a mouse model to the evidence:

We show that elevation of Edar activity in transgenic mice converts their hair phenotype to the typical East Asian morphology. The coat texture becomes coarse, with straightening and thickening of individual hairs and conversion of fiber cross-sectional profile to a circular form. These thick hair fibers are produced by enlarged hair follicles, which in turn develop from enlarged embryonic organ primordia. This work shows that the multiple differences in hair form between East Asian and other human populations can be explained by the simplest of genetic alterations.

On the right is a wild-type mouse, contrasted with the "Asian" mouse. The mechanism by which this works is kind of intriguing--apparently the substitution in EDAR leads to increased signaling via NFkB, but it's an open question (both in this case and more generally) how the modification of the activity of a transcription factor leads to phenotypic changes at the level of an organism.

Labels: Genetics

Previously we found that your generation was sluttier, so we turn now to another great threat to civilization -- violence (between individuals). As before, our concern is with whether violent crime rates are increasing or decreasing, and not so much with the absolute level: it is easier to screw up civilization than it is to improve on it, so a decline can quickly snowball, while it may take much longer to restore things to their previous levels.

There are very good and very clear data on violent crime, so this post will be much more direct than the one on sluttiness. Let's begin with homicide. The Bureau of Justice Statistics, part of the US Department of Justice, has taken homicide data from the CDC's National Center for Health Statistics and put it into a straightforward graph. I see five trends in the graph: an increase from 1900 to the mid-1930s, a decrease from the mid-1930s to about 1960, an increase from 1960 to the late 1970s, a fairly steady high level (with oscillations) throughout the 1980s, and a decrease from 1992 to the present.

To be generous to older generations, let's say that much of this homicide is committed by 15 year-olds. That means that the cohort born in 1945 is responsible for the increase that began in 1960. I figure you have to be about 73 years old in order to decry how violent the younger generations have been -- certainly the Boomers and Gen X-ers cannot complain, while Generation Y should be thankful they've lived through such peaceful times.

The homicide data also caution against viewing the past with rosy spectacles -- there was nothing peaceful at all about the first third of the 20th century. Declinists who long for better times in the past seem to latch onto a fleeting period of rest and prosperity. That's fine, as far as worshipping one period over another goes. However, we should not think that we can easily maintain that level, whether through individual choice or institutional incentives, as oscillations and limit cycles appear to be the rule rather than the exception. We should aim instead to have a somewhat low level of Bad Things, with low-amplitude fluctuations, and not let the mere existence of waxing and waning cause us hysteria.

What about the intersection of sex and violence -- how have forcible rape rates changed over time? Again we turn to BJS data, although they do not go back nearly as far as homicide data, the earliest year being 1960. After retrieving data from this page, looking at the entire United States, forcible rape rate, from 1960 to 2006, I put them into a simple graph:



There are only two trends here: an increase from 1963 to 1992, and a decrease afterward. In fact, the two trends look pretty linear on first glance. The slope of the increasing trend is about +1.11, and the slope of the decreasing trend is about -0.85, confirming the hunch that the decline of civilization snowballs more quickly than its restoration proceeds. As with homicide, Boomers and Gen X-ers cannot complain about rape epidemics in recent generations. This is particularly true for the Boomers and Gen X-ers who manufactured and continue to prop up the myth of the campus rape crisis.

The BJS also has an index of "violent crime" that includes murder and non-negligent manslaughter, forcible rape, robbery, and aggravated assault. I used the same search function as for the rape rate graph, and the trends for this general violent crime rate look the same as the rape rate trends, so I won't include the graph. In brief, there's an increase from 1962 to 1991, and a decrease afterward.

As in the case of sluttiness, using popular culture as a means of taking civilization's pulse is highly unreliable. Before, we saw that slutty behavior has been decreasing even as perceived slutty appearances have been increasing. Here, we see that violent crime has been decreasing even as video games, movies, and TV shows have become increasingly violent. To pick just one example, gangsta rap was invisible during the 1980s and only became popular when Dr. Dre's album The Chronic came out in 1992, drawing ever larger audiences throughout the 1990s -- at the very time when violent crime was falling.

I don't believe that trends in real behavior and in popular culture are causally related in an inverse way either -- just that they are independent of each other. Cycles of fashion in the cultural realm are self-contained, and oscillations and limit cycles in real behavior are also self-contained, at least to a first approximation. I've read posts at Cognitive Daily that exposure to violent video games (and perhaps TV shows?) desensitizes people to violence within controlled, experimental laboratory settings, and that is an interesting finding. However, in examining the world outside of the lab, violent media cannot hope to account for even a trivial share of the variance across time in violent behavior.

Labels: civilization, crime, previous generations were more depraved

The Pew US Religious Landscape Survey has come out with its second week of survey results, now focusing in more detail on the beliefs of various groups. Nice way to compare across groups. I've collected and reformatted a selection of responses and their frequencies for four groups, Evangelicals (excluding Historically Black Churches), Mainline Protestants, Catholics and Muslims. I havd argued before that the median religious beliefs of American Muslims are closer to Evangelical Christians than to the religious as a whole. Therefore, one has to be careful when comparing "moderate Christians" to "moderate Muslims," since the former is likely to have far more liberal religious and social beliefs than the latter, though they might be appropriately termed so in the spectrum of their tradition. The results seem to suggest that I was mostly right; though American Muslims are somewhat less conservative than Evangelicals. Interestingly, note that Roman Catholics and Mainline Protestants are hard to distinguish.

(Caution: don't read that much into the percentages on the margins. 6% of atheists and 14% of agnostics believe in a Personal God according to the survey! Also, readers will probably be interested in the detailed tables which breakdown by denominations)

	Evangelical	Muslim	Catholic	Mainline Protestant
Abortion legal in all cases	9	13	16	20
Homosexuality should be accepted by society	26	27	58	56
Receives answers to prayer once a week	29	31	15	14
Attend religion service more than once a week	30	17	9	8
Own religion is one true faith leading to eternal life	36	33	16	12
Only one true way to interpret religion	41	33	19	14
Gov. should do more to protect morality	50	59	43	33
Scripture literally true word of god	59	50	23	22
Frequency of prayer	78	71	58	53
Religion very important	79	72	56	52
Belief in God: absolutely certain	90	82	72	73

Labels: Religion

Recommendations?

Shyness drug could boost confidence; life might get a lot less fun for normals if this pans out.... H/T Marginal Revolution.

Dan at Genetic Future, a great guy, has another DRD4 post up. He has reproduced a chart from an article in The Economist which shows a trend where a higher frequency of the 7R (ADHD correlated variant) is found in groups which have migrated a greater distance. He asks whether "the "novelty-seeking" behavior associated with ADD may have extended into a desire to explore new territories." My first thought was this: perhaps people with the 7R variant were more likely to be kicked out of the tribe or village because they couldn't/wouldn't conform. Certainly the chart seems to imply that stable populations hovering around the Malthusian limit probably aren't too congenial for nonconformists. This is the argument at the heart of books such as The Moral Consequences of Economic Growth and Age of Abundance, though obviously there wasn't a genetic perspective there.

In any case, I think there's going to be some interesting stuff coming out of this area correlating lifestyle with personality profiles. You might recall that in Farewell to Alms Greg Clark repeated the old truism that farmers tended not to be more affluent than hunter-gatherers, and in fact the balance of the data implies most hunter-gatherer and nomadic groups have a median physiological fitness that is greater than that among farmers as measured by size and nutrition as evidenced by enamel growth. The genius of farming is that it obviously increased the productivity per unit area in terms of calories and so supported larger populations (physiological fitness obviously does not translate into reproductive fitness always), but it seems to me that the less violent and risky nature of this lifestyle (famines notwithstanding) meant that there was also less room for the nonconformists on the margins. I've argued in the past in some ways theat modern individualistic Westerners have more in common with hunter-gatherers than with peasants in "traditional" societies in regards to their mores. I wonder if the need and necessity for straight-jacket social control in village life induced a powerful bout of purifying selection against 7R across much of Eurasia, a pressure that is only now being relaxed.

Addendum: The expulsion of male misfits is one of the accounts given of the founding of Greek colonies. Of course, it could simply be that the annalists used the argument that these men were misfits to get rid of them and they were actually economical marginals who were a burden upon the citizenry.

Update: I want to be clear here to note that I don't expect that all H & G societies would favor 7R more than farmers. Just that I think that the constraints of an agrarian lifestyle around the Malthusian limit would result in less tolerance of variance of behavior on the margins. The marginal slack for H & G groups I assume would be due to more frequent tribe-level extinctions, war and interpersonal violence, as well as localized ecological parameters which have a more direct impact on H & G peoples.

Related: DRD4 posts.

Labels: Behavior Genetics

43% of young men who never go to church have a record, according to the Inductivist:

The same kind of pattern holds here. For men, 43% of those who never go to church have been arrested, while only 13% of the most frequent attenders have. The corresponding percentages for females is 14% and 8%.

The results are from the GSS. The main question I would have are the affects of the background environment; in many socially conservative environments the expectation of involvement in a church is very strong and unchurched status could be a signal for anti-social tendencies. I know whereof I speak, I grew up for a while in a 3/4 Republican 99% white region of the Mountain West and those who were unchurched were often those who were "up to no good" (a small minority were secular liberals, but only a very small minority). My own prediction would be that this would be a more common phenomenon in a very religious country like the United States.

A post at my other weblog on a survey that came out last year. Nothing too surprising except for the disciplinary breakdowns....

Labels: Religion

Bad guys really do get the most girls:

But being just slightly evil could have an upside: a prolific sex life, says Peter Jonason at New Mexico State University in Las Cruces. "We have some evidence that the three traits are really the same thing and may represent a successful evolutionary strategy."
...
This observation seems to hold across cultures. David Schmitt of Bradley University in Peoria, Illinois, presented preliminary results at the same meeting from a survey of more than 35,000 people in 57 countries. He found a similar link between the dark triad and reproductive success in men. "It is universal across cultures for high dark triad scorers to be more active in short-term mating," Schmitt says. "They are more likely to try and poach other people's partners for a brief affair."
...
"They still have to explain why it hasn't spread to everyone," says Matthew Keller of the University of Colorado in Boulder. "There must be some cost of the traits." One possibility, both Keller and Jonason suggest, is that the strategy is most successful when dark triad personalities are rare. Otherwise, others would become more wary and guarded.

Frequency dependence. Control for environment and one might assume that personality morphs will hit an equilibrium in terms of relative proportion; but of course one assumes that any normal environment will be subject to exogenous shocks which jar the equilibrium on a regular basis. I wish popular science articles would bring up Hawk vs. Dove dynamics more often to introduce the general concept of variant strategies in populations. The relevance of this sort of result to recent posts should be pretty obvious, and is also one reason many people were always less than enthusiastic about Evolutionary Psychology's monomaniacal focus on human universals.

Labels: Behavior Genetics

One mechanism for the generation of new genes in the retrotransposition of mRNA back into the genome, creating a new, intronless copy of the parental gene. The majority of these copies, lacking proper promoters, end up as "processed pseudgenes". A neat paper recently published in PLoS Biology, however, demonstrates that a new gene generated by this mechanism in the primate lineage has actually rapidly evolved under positive selection. Strikingly, they're able to precisely track the function of the protein over time by recreating ancestral variants. From the abstract:

A microtubular CDC14B variant spawned CDC14Bretro through retroposition in the hominoid ancestor 18–25 million years ago (Mya). CDC14Bretro evolved brain-/testis-specific expression after the duplication event and experienced a short period of intense positive selection in the African ape ancestor 7-12 Mya. Using resurrected ancestral protein variants, we demonstrate that by virtue of amino acid substitutions in distinct protein regions during this time, the subcellular localization of CDC14Bretro progressively shifted from the association with microtubules (stabilizing them) to an association with the endoplasmic reticulum. CDC14Bretro evolution represents a paradigm example of rapid, selectively driven subcellular relocalization, thus revealing a novel mode for the emergence of new gene function.

Pretty cool stuff.

Labels: Genetics

A reader pointed me to this paper, Single-Nucleotide-Polymorphism-Based Association Mapping of Dog Stereotypes:

...Analysis of other morphological stereotypes, also under extreme selection, identified many additional significant loci. Less well-documented data for behavioral stereotypes tentatively identified loci for herding, pointing, boldness, and trainability. Four significant loci were identified for longevity, a breed characteristic not under direct selection, but inversely correlated with breed size. The strengths and limitations of the approach are discussed as well as its potential to identify loci regulating the within-breed incidence of specific polygenic diseases.

I've placed an important table below the fold.

Labels: Genomics

Made in America? The New World, the Old, and the Industrial Revolution. Greg Clark is one of the authors. Robin Hanson has the summary up.

Labels: Economics