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Tuesday, October 31, 2006
Modern Humans, Neanderthals May Have Interbred:
"To me, what happened is that the Neanderthals were [genetically] absorbed into and overwhelmed by modern humans coming into Europe from Africa, and they disappeared through this absorption," Trinkaus said. The paper will be on the PNAS site sometime this week, apparently it is behind an 'embargo wall' right now and already in circulation amongst those with special access. This is a morphology story, it seems that individuals with a mosaic of African and Neandertal traits existed in Europe ~30,000 years ago. What does this tell us? If we didn't have the genetic evidence I think one would have to assume that the highest likelihood is that some interbreeding went on. But didn't we learn last week that humans and Neandertals were separate and distinct lineages, with the latter contributing nothing to the genome of the former? 1) Not all regions of the genome are created equal when it comes to a particular phenotype (e.g., if you looked at Y lineages Mexican Americans should be Spaniards, if you looked at mtDNA lineages they should be Amerindians, and yet they are a mix of both when it comes to the vast majority of their genome, the Y & mtDNA just happen to be convenient for genetic analysis). 2) Selection can operate on specific regions of a genome independently from others. This is why you see "selective sweeps" across lengths of sequence while neutrality seems to be operative elsewhere. 3) There nature of genomic sequences shaped by neutral evolution vs. those subject to selective forces can differ a great deal because of the alternative dynamics at work as a function of time. The former can be far more informative about ancestry than the latter because in the case of the latter not all ancestors are created equal. 4) There are always papers in the pipeline which can modulate your priors. One should credit Trinkaus et. al. because of other pieces of data which will come to light in the near future.
The dynamics of Machiavellian intelligence. Abstract:
The "Machiavellian intelligence" hypothesis (or the "social brain" hypothesis) posits that large brains and distinctive cognitive abilities of humans have evolved via intense social competition in which social competitors developed increasingly sophisticated "Machiavellian" strategies as a means to achieve higher social and reproductive success. Here we build a mathematical model aiming to explore this hypothesis. In the model, genes control brains which invent and learn strategies (memes) which are used by males to gain advantage in competition for mates. We show that the dynamics of intelligence has three distinct phases. During the dormant phase only newly invented memes are present in the population. During the cognitive explosion phase the population’s meme count and the learning ability, cerebral capacity (controlling the number of different memes that the brain can learn and use), and Machiavellian fitness of individuals increase in a runaway fashion. During the saturation phase natural selection resulting from the costs of having large brains checks further increases in cognitive abilities. Overall, our results suggest that the mechanisms underlying the "Machiavellian intelligence" hypothesis can indeed result in the evolution of significant cognitive abilities on the time scale of 10 to 20 thousand generations. We show that cerebral capacity evolves faster and to a larger degree than learning ability. Our model suggests that there may be a tendency toward a reduction in cognitive abilities (driven by the costs of having a large brain) as the reproductive advantage of having a large brain decreases and the exposure to memes increases in modern societies.
Below the fold is the full text of a paper circa 1993 that reports that freshmen college students tend to misattribute political beliefs to professors on the basis of merely factual material presented in class. The results obviously extend to other areas.
When Teaching is Evaluated on Political Grounds Stanley Coren Psychology University of British Columbia, Vancouver BC, CANADA V6T IZ4 Psychologists and other behavioral scientists who teach courses containing material on individual differences often find themselves presenting research findings that are politically unpopular in today's social climate. For example, segments of most introductory psychology courses deal with intelligence and mental abilities. An honest treatment of this material requires that evidence be presented indicating that both environmental and genetic factors determine intelligence. The evidence for heritable factors in intelligence is supported by data from selective breeding studies using animal subjects, from twin studies, and from family studies. In exploring the implications of this work the lecturer generally presents the evidence that different racial groups score differently on intelligence tests, and then analyzes the factors that contribute to this observed difference. Most researchers (and most textbooks) agree that although environmental factors are important, genetic contributions cannot be ignored, since they play a large role in determining group differences in mental abilities scores./1/ The case is quite similar in the discussion of sex differences in cognitive abilities. There are systematic differences in the pattern of abilities displayed by males and females on standardized tests. Although many of these differences may be environmental in origin or reflect differences in the socialization of males and females, some ability differences appear to be genetically determined. It appears that the disparity between male and female scores on certain abilities measures are the direct consequence of hormonal, neurological, and even brain structure differences between the sexes. The conscientious lecturer interested in presenting the full picture must discuss these physical differences as well as the environmental factors./2/ Potential Evaluation Problems Unfortunately, in the current political climate on college and university campuses, it appears that the teaching of research on ability differences among racial or sexual groups may have implications for the careers of faculty members. The potential problem arises in institutions that use teaching evaluations as part of the data upon which decisions about tenure, promotion, and merit pay increments are based. This became clear to me during the course of some committee deliberations at my institution, the University of British Columbia (UBC) in Vancouver, Canada. The UBC psychology department follows teaching evaluation procedures that are common in many universities. One important component in the evaluation process is the mandatory distribution of a questionnaire to every student at the end of each course. Traditionally, students are asked to comment on their perception of a number of aspects of the course and the instructor. Items addressed include the fairness of evaluation procedures, instructor preparation and interest in the material, clarity of delivery, availability during office hours, rapport with the class, and so forth. Comments are numerically coded and summarized. These summaries then become apart of the instructor's permanent file. Student evaluations have often played a pivotal role in tenure and promotion deliberations pertaining to particular faculty members. They are most likely to have a major impact when the candidate is borderline in some other respects, in which case the teaching evaluations may swing the decision in one direction or another. Probably as a response to social pressures within the university, the UBC teaching committee decided to "modernize" the current course evaluation questionnaire. This revision involved the deletion of several objective items, such as whether the course was organized logically, or whether the final grade was based upon several evaluations or tests rather than a single assessment. More disturbing was the introduction of several items involving issues of sex and race. Thus students were asked to assess whether the instructor used "examples or stories that were demeaning to members of certain racial or cultural groups" or demeaning either to women or to men. Additional items highlighting racial or sexual identity were also included. To some faculty members the inclusion of such potentially "political" items in the questionnaire seemed inappropriate, for terms like "demeaning" involve certain assumptions and interpretations in which the listeners' biases are as much a factor as the content of the lecture. A student who is told that one racial group does not do as well as another on certain mental abilities tests may well interpret those remarks as "demeaning" to that group. (As president Harry S. Truman once quipped, "I never did give anybody hell. I just told the truth and they thought it was hell.") The committee revising the questionnaire did not perceive any such risk. The chairman of the committee felt that students know the difference between opinion and scientific data and would not negatively evaluate an instructor for presentation of data, no matter the conclusion reached. Thus, despite objections, several items involving race and sex were included in the revised teaching evaluation questionnaire. Some Concerns I was quite concerned about the inclusion of such items. My major trepidation was that students would mistake the conclusions reached in presenting material dealing with race and sex as reflecting the attitudes of the instructor rather than objective reporting of scientific data. I was also concerned that such questionnaire items are based upon the presumption that we can ask students of eighteen and nineteen years of age, who are less than a year beyond high school, to answer difficult questions about what constitutes racist or sexist content in a course and whether their lecturer is guilty of purveying such content. Given that society as a whole and many academics and scholars have struggled with these issues for many years and still have not reached a consensus, the validity of this presumption seems dubious. If student judgments lack validity or, worse, if they are biased by the conclusions reached by the research under discussion, this could prove quite disastrous for faculty members who teach about individual and group differences in behavior. My long-range concern was that the knowledge that such politically charged items are to be used in teaching evaluations would inevitably serve to "muzzle" faculty. The likeliest targets are young faculty who know that their teaching ratings will affect their chances for promotion and tenure. In effect, the inclusion of "sensitive" items could eventually cause faculty simply not to teach certain substantive areas. The fear motivating such behavior is that lectures that reach politically unpopular conclusions will lead some students to apply labels of "sexist" or "racist" to the lecturer. An Empirical Assessment As an experimental psychologist it seemed to me that the best way to address this issue would be to collect some data from the very students who would be called upon to evaluate faculty members. In this way I could either clarify the problems inherent in this form of teaching evaluation, or set my own misgivings to rest. My test sample consisted of 198 students enrolled in an introductory psychology class. There were 109 women and 89 men; the mean age was 18.7 years. Each received a questionnaire. Students were told not to put their names on the survey form, just as they are not required to sign the teaching evaluation questionnaires. The introduction to the survey reads: University Teaching Questionnaire Recently, the public and press have brought to light some issues that are important to the normal functioning of the university. Two, which have been mentioned many times, are: 1. In the minds of many people there are some topics that are appropriate and others that are inappropriate topics for university and college classes. 2. It has been occasionally suggested that some professors may let their own personal views enter into their teaching, and these views might be inappropriately presented as fact. Both of these issues are controversial and many individuals hold different viewpoints about them. We are interested in your opinions about these issues. Below you will find some sample descriptions of lectures that might be given in an introductory psychology course. Consider what you feel your own reactions would be to such lectures and briefly answer the questions below them. Four simple lecture summaries were presented in paragraph form: 1. Professor W gives a lecture about learning. In it he notes that simple repetition does not improve learning. He concludes that rereading the textbook several times will not result in good comprehension. He suggests several working techniques and activities that he feels will improve memory. 2. Professor X gives a lecture about intelligence. In it he describes some evidence for biological factors, such as genes, that affect intelligence. He suggests that although culture and experience are important in determining scores on intelligence tests, genetic factors can be used to explain some portion of the differences in IQ scores that are obtained when different races take intelligence tests. 3. Professor Y gives a lecture about aging. In it he notes evidence that older individuals have difficulty learning certain material and solving certain problems. He suggests that these differences may reflect a slowing in thinking processes in elderly people. 4. Professor Z gives a lecture about sex differences. In it he notes evidence that males consistently score better than females on spatial and mathematical tests. He suggests that while societal and environmental contributions should not be ignored, some portion of these sex differences in ability may be due to genetic factors or differences in the brain structure of males and females. After each lecture summary, several questions were asked. The first was simply, "Is this material appropriate for a psychology course?__Yes__No." The second and third questions were much more open-ended: "What are the professor's reasons or motives for presenting this subject matter?" and "What does this lecture tell you about Professor__ ?" The results of this survey supported my fears about how students would evaluate faculty members who present unpopular conclusions. The relevant lectures, of course, are 2 and 4. Although each lecture summary contains subject matter that is often taught in introductory psychology courses, lectures 2 and 4 also deal with the more politically sensitive issues of race and sex differences in intelligence and mental abilities. Before looking at the data, it is important to note that the viewpoints expressed by Professors X and Z in lectures 2 and 4 are quite consistent with data in the behavioral literature. They agree with the conclusions of many researchers and are in accord with several large literature reviews./3/ Many textbooks for introductory psychology courses also present material of a similar nature. Notice as well that these lecture summaries are clearly moderate in tone, and do not contain anything inflammatory or demeaning to any group. Nevertheless, the results suggest that these eighteen- and nineteen- year-old students saw the lectures as much more negative and problematic. Lecture 2: Evidence for a Genetic Contribution to Intelligence In lecture 2 Professor X suggests that there is a genetic contribution to intelligence. Although he acknowledges contributions from culture and environment, he concludes that the genetic contribution to intelligence might account for "some portion" of the differences observed in IQ scores between the races. An amazing 38 percent (76/198) of student evaluators felt that this was not an appropriate topic for a psychology course. Furthermore, in the question on the professor's motives for presenting this material and the question about what this lecture indicated about Professor X, 24 percent (48/198) specifically mentioned "racist," "racism," or notions of "racial superiority" as motivating the presentation of this material. Thus the very discussion of genetic and racial differences in intelligence, if the conclusion is that they exist, renders the lecturer a racist in the minds of nearly one-quarter of these students. Lecture 4: Evidence for Sex Differences in Cognitive Skills In this lecture Professor Z suggests that there are differences between males and females in spatial and mathematical ability. Although acknowledging the contribution of social and environmental factors, he concludes that "some portion" of these differences may be due to physiological or genetic differences between males and females. Again, the results are quite distressing. Thirty-one percent (62/198) of the class felt that this was a topic that was not appropriate for a psychology course. There was a strong difference between male and female respondents. Forty eight percent (52/109) of females, while only, 11 percent (10/89) of males, felt that the topic was inappropriate. In the discussion of motives, or what this lecture indicated about Professor Z, 26 percent (51/198) mentioned "sexist," "sexism," "anti-women," "putting women down," or the equivalent as the primary motivation for the presentation. Again, there was a strong difference between the sexes, with 94 percent (48/51) of the sexism charges coming from female students. Thus, in the minds of more than a quarter of all the students, and nearly one-half the female students, simple presentation of data and conclusions that are accepted in the experimental psychology literature makes the lecturer a sexist. Implications for Faculty Assessment The conclusions that can be reached based on these data should be obvious--and somewhat frightening. It is quite clear that many students, especially the freshmen tested here, cannot separate the scientific evidence presented by an instructor from the instructors own opinions. Also, they make one variety of the "fundamental attribution" error so well-known to social psychologists./4/ In this case, the error involves the belief that the conclusions reached by the lecturer are the conclusions desired by the lecturer. In other words, the observer (here the student) believes that the lecturer must be driven by internal motives consonant with the data he presents. Based on the data described above, what can we conclude about how students would describe Professor X if asked whether he "used examples that demeaned any racial or cultural group?" How would students evaluate Professor Z if they were asked whether he used any "examples that demeaned women?" Obviously, many students would describe Professor X as a racist and Professor Z as a sexist. These data, if they are a valid indicator of how students form opinions about instructors based upon the presentation of particular material in class, have dire implications for faculty members whose courses include the topic of individual differences. In light of teacher evaluation forms that require students to draw conclusions about the political and social attitudes of their professors based upon the content of lectures, this situation can have only one outcome. If faculty members are aware of or suspect there are student biases about such material, then a sizable proportion of junior faculty will refuse to teach this material. The same is probably true for senior faculty, who know that poor teaching ratings might adversely affect decisions about merit pay increases. Where up to a third of your students wilt negatively evaluate you simply for presenting data that reflect the dominant thinking and empirical results reported in the literature, perhaps it is better to select a book that reaches the "politically correct" conclusions. And in lectures, perhaps it is better to "tailor" the data to reach those same conclusions. Or perhaps it is better not to bring up the topic at all, and thus be absolutely sure that no charges of racism or sexism can be leveled at you. We must ask ourselves and our teaching evaluation committees: What are political questions doing on an instrument that is supposedly designed to evaluate teaching effectiveness? By allowing political interpretations to form a component in our teaching evaluations we effectively subvert the ideal of dispassionate research and teaching. Teacher assessments based on the student's political or social interpretation of the empirical data or on how well the conclusions accord with his preconceptions and social attitudes must lead to suppression of unpopular data. It seems that the academic establishment has not recognized what Adlai Stevenson knew about the public psyche. He observed, "You will find that the truth is often unpopular and the contest between agreeable fancy and disagreeable fact is unequal. For, in the vernacular, we are suckers for good news."/5/ If teaching evaluations use student opinions about the social or political implications of the material taught, then behavioral scientists will soon find themselves pressured to teach only the "good news" that there are no differences in the abilities of racial or sexual subgroups--even if this involves ignoring or suppressing the bulk of the research data. Thus the evaluation of teaching ability will become nothing more than the evaluation of how well a faculty member's lectures conform to the political norm. It is sad to think that humorist Josh Billings may have been correct when he said, "As scarce as the truth is, the supply has always been in excess of the demand." Notes 1. These issues have been covered extensively elsewhere, as in Robert Plomin, "Environment and Genes: Determinants of Behavior," American Psychologist 44.2 (1989), or the sprightly debate in H.J. Eysenck, The Intelligence Controversy (New York: Wiley, 1981). 2. For an excellent and remarkably balanced review, see Diane F. Halpern, Sex Differences in Cognitive Abilities (Hillsdale, N.J.: Erlbaum Associates, 1986). 3. See Robert Plomin, Nature and Nurture: An Introduction to Behavioral Genetics (Pacific Grove, Calif.: Brooks/Cole, 1990). 4. See L. Ross, "The Intuitive Psychologist and His Shortcomings: Distortions in the Attribution Process," in Advances in Experimental Social Psychology, ed. L. Berkowitz (New York: Academic Press, 1977). 5. Adlai Stevenson, New York Times, 9 June 1958.
Monday, October 30, 2006
I just wasted 15 minutes exploring the Uncyclopedia after seeing a referral from the entry on Asian Nazis. A lot of the other stuff is pretty funny too. Check out this snip from the entry on Bangladesh:
Bangladesh holds the world record for the only country which has more people than mosquitos. Mosquitos are the second largest ethnic populace of Bangladesh. The human population is made up of 49% males, 43% females, 6% hermaphrodites and 2% George W. Bush look alikes. The current list of famous Bangladeshis include the pop band The Bangles, the lovable canine actor Benji, [redacted]. Bangladesh hopes to produce another famous person, of an equal calibre, by approximately 2025 AD.
A recent Perspective in Nature Reviews Neuroscience presents an alternative to the radial unit hypothesis of cortical expansion. As you may recall, one of the major alterations in gross brain structure as you move toward primates and those particular primates that we hold dear is the large increase in cortical surface area. The increase is not accompanied by a proportional increase in skull size because the increased amount of cortex is folded in on itself to form sulci (crevices) and gyri (hills). Smooth brains are called lyssencephalic. Wrinkly brains are gyrencephalic.
The radial unit hypothesis suggests that the increase in the size of the neocortex is due to an increase in the cells that both give birth to most cortical neurons and provide the scaffold for those newborn neurons to climb to their proper position in the cortex. These radial glia lie next to the ventricles (fluid filled cavities in the middle of your brain, one of the earliest neural structures to form) in an area called the ventricular zone (VZ) and are attached to the ventricles and to the outer surface of the developing cortex. Strangely enough, the area one layer further away from the ventricles is called the subventricular zone (SVZ). During cortical neurogenesis, neurons are created next to the radial glia and migrate up the scaffold. More cortex space can be created by producing more scaffolds. More scaffolds can be made by increasing the amount of time radial glia divide symmetrically to produce only more radial glia rather than neurons or reducing the number of radial glia that die after they are produced. A and B below.  But one potential issue with the radial unit hypothesis is that the ventricles should grow proportionally to the neocortical growth through evolution. This isn't the case. To circumvent this problem, the intermediate progenitor hypothesis suggests that the immediate product of asymmetric radial glia division is an intermediate progenitor rather than a neuron (C above). These intermediate progenitors migrate to the SVZ just above the radial glia and divide symmetrically some more to produce a crop of intermediate progenitors. Wherever you want more cortical neurons you let more intermediate progenitors be produced. Eventually these cells in a way that produces differentiated neurons and they migrate up to their proper position in the cortex. My favorite piece of evidence for this hypothesis is shown below. You can sort of predict where a cortical fold will be by measuring the thickness of the SVZ early in development. Thinner SVZs will be below sulci, and thicker ones will be below gyri.  Not knowing enough to really critique, my only obvious issue is that it doesn't seem like their criticism of the radial unit hypothesis has to be so. It seems possible to me for radial glia to proliferate without increasing the size of the ventricles that much. As far as I know, noone has shown that the ventricle surface is so jampacked with radial glia feet that it can't accomodate a few more. Also worth noting is that both hypotheses suggest that putting off neurogenesis to produce more progenitors might underlie cortical expansion in humans. So at this point, both hypotheses might lead to similar predictions about the particular genes involved.
For the die-hards. I taped the Buzsaki and Wilson lectures at the Visualizing and Recording Large-Scale Ensembles short course at SFN. Quality isn't really great and a lot of it doesn't make sense without the slides, but, hey, it's there if you want it:
Buzsaki Intro and Lecture (mostly about multi-unit recording and unit isolation) Wilson Lecture (more about the same, but focus on tetrodes and some data) Buzsaki vs. Wilson (Breakout group with some questions, interesting to hear them converse and joke. Best sound quality I think.)
The paper describing the sequence and analysis of the dog genome ends thusly:
For millennia, dogs have accompanied humans on their travels. It is only fitting that the dog should also be a valued companion on our journeys of scientific discovery.The lamest line in a scientific paper ever?
Derb has a long article up where he answers all the "religion questions" he's had to deal with and chronicles his drift away from Anglican theism. Not quite Rod Dreher level of personal anguish, but Ponurru isn't pleased....
See What You Want to See: Motivational Influences on Visual Perception:
People's motivational states-their wishes and preferences-influence their processing of visual stimuli. In 5 studies, participants shown an ambiguous figure (e.g., one that could be seen either as the letter B or the number 13) tended to report seeing the interpretation that assigned them to outcomes they favored. This finding was affirmed by unobtrusive and implicit measures of perception (e.g., eye tracking, lexical decision tasks) and by experimental procedures demonstrating that participants were aware only of the single (usually favored) interpretation they saw at the time they viewed the stimulus. These studies suggest that the impact of motivation on information processing extends down into preconscious processing of stimuli in the visual environment and thus guides what the visual system presents to conscious awareness. (via Chris) Why does this matter? People see what they want to see, and their logic leads them to what they want them to see. Thank god natural science has reality!
Sunday, October 29, 2006
Steve's newest column tackles the next election (and the likely shift toward the Democrats) and its relevance to immigration. Meanwhile, Derb has been talking up Lou Dobbs Democrats. I don't know what to think about this. I haven't talked about immigration much because I've been rather pessimistic of late...but now I'm not sure sure. Perhaps I won't have to make sure that I'm part of the 21st century oligarchy.
Saturday, October 28, 2006
The New York Times Magazine has a piece on the Iranian bomb and Islamic attitudes toward use of extreme measures in battle. In Infidels: A History of the Conflict Between Christendom and Islam Andrew Wheatcroft suggests that the Islamic attitude toward battle and war lagged the West in regards to a transition to rational and utilitarian paradigm in theory and practice. In other words, medieval values of valor and courage as opposed to victory at all costs persisted longer in the world of Islam than in Christendom, to the disadvantage of Muslim powers after 1500. So it is interesting to see how some Muslim scholars are now rationalizing barbarities, and how most Muslims now accept suicide bombers as martyrs. I bring this up, because as an unbeliever
1) I am always struck by the enthusiasm that followers of "higher religion" have toward assailing or battling those with whom their disagreemants are on the smallest matters of creed or ritual interpretation (to the point where one wonders if the foot soldiers who die for the sake of the creed can even genuinely discern the differences for which they lay their lives down!). 2) ...and yet, there is such slippery ease with which the clerics and intellectuals of said "higher religion" can re-interpret the propositions entailed by their beliefs when the situation warrants. When I was a child in the 1980s many of the more traditionalist Muslims would not accept the taking of pictures because it was idolatry, and yet now the most radical of the ghazis videotape themselves, and it seems clear that this media serves as a focal point of devotion and adoration! I suppose from the perspective of the unbeliever the question is this: what is the structure and nature of religious beliefs which allows such plasticity which masks itself as rigidity? Consider that Islamic radicals kill ostensibly in the name of a traditional society, but in the process they sanction the usage of non-traditional tactics such as female suicide bombers! To me, the heart of the piece above is that Islamic scholars will expend a great deal of time rationalizing whatever suits their own ultimate needs, so the background implication that there is some true axiomatic logic which demands that a group of believers espouse a particular set of beliefs down a chain of propositions seems ultimately implausible. Though killing will continue in the name of small differences, those differences are themselves subject to the contingencies of the age. Addendum: Of course, remember that there is a difference between what people believe and what they believe they believe, and what they say motivates and what truly motivates them. Such considerations need to move past the simple analyses of the past such as Freudianism or Marxist materialism, but there various vectors can I think eventually help in constructing a model of the mind as it moves through the social and physical universe.
I haven't had regular access to cable television since July of 2004. I haven't had regular access to a television since March of 2005. Overall this has been a good thing, I've read more, I've thought more, and oh yes, I've blogged more, than I would have. Nevertheless over the past few months I have started to notice that my "pop culture lexicon" is getting out of date...I am simply cut off from the cultural touchstones of my peers. This isn't all a bad thing, the animal mutterings which pass for speech from most humans are inputs I only marginally process (just enough to respond as if I am actually listening to the vapid stream). Nevertheless, the rise of YOUTUBE and internet video enabled by broadband allows me to "sample" the Zeitgeist of popular culture now and then. So that was how I stumbled upon this Nelly Furtado video, Maneater. I have three immediate responses
1) Jesus fucking Christ!!! (and I don't even believe in that stuff) 2) Watching a video like that makes it clear just how un-sexy most internet porn is. Internet porn, with its anatomical focus is like a super-value meal, a lot of calories for the buck, but fundamentally unsatisfying once the aftertaste kicks in. 3) Southern European women sure do clean up after a good shaving, huh? The contrast of dark hair and light skin is their bane when it comes to the mustache tendency, but it can be quite striking when the lack of hair means they no longer look like a small men.... Addendum: I believe that for best data gathering you should simply start viewing about 60% of the way through. TangoMan Adds:To add another data point to the analysis see Georgian beauty Katie Melua. Her style tends to emphasis the range of her voice rather than relying on studio gimmickry. This video has a nifty Hannibal Lechter theme and some great video compositing. I particularly liked the intellectual controversy that surrounded Katie's song Nine Million Bicycles where her lyrics "We are 12 billion light-years from the edge. That's a guess - no-one can ever say it's true" came under public fire from cosmologist Simon Singh for their inaccuracy. In a one time performance Katie reworked her lyrics - "We are 13.7 billion light-years from the edge of the observable universe; that's a good estimate with well-defined error bars/and with the available information, I predict that I will always be with you". Most agreed that they had lost a little zip in translation. See also this video for a closer examination of what Georgia has to offer the world.
In case the newspaper photos weren't enough, here is a video clip of the pelican-pigeon encounter.
I doubt if the whole incident took anything like the 20 minutes claimed by some witnesses. Eye witnesses are notoriously bad at estimating the duration of events. Based on the video clip, I guess it may have taken up to 5 minutes.
I just received a review copy of Saxons, Vikings and Celts: The Genetic Roots of Britain and Ireland. I won't be talking about it until January as I've agreed to hold it until it starts being marketed after it's published here in the states. But, I do think it is kosher if I report the data which Bryan Sykes repeats from the 19th century work The Races of Britain.
1) Blonde hair is most common in East Anglia and Lincolnshire, with high values in Yorkshire, Cumbria, the north of Scotland and the Hebrides. It is least common in Ireland and Cornwall. Intermediate values can be found in most of England and Wales. 2) When it comes to eye color the cline is different. Brown eyes are common in the south and the east, where they exceed 40% in East Anglia and Cornwall. In Ireland, Yorkshire and Cumbria the frequency of blue or grey eyes rises to 75%. If you want a genetic moral from all this it is that eye color and hair color are not closely linked. There does seem to be some correlation between areas with a high frequency of red hair and light eyes (e.g., Scotland), but that is likely because the former trait is derived from a serial loss off function for melanin production on several loci, and light eyes are a natural byproduct of this genetic architecture. There are implied modal combinations, such as many dark eyed blondes in East Anglia, and the dominance of dark haired but blue eyed folk in Ireland, and the dark eyed and dark haired Cornish. Since I have British readers I will leave it to them to judge the accuracy of these ascertainments, though keep in mind that the data was collected in the late 1800s, so population movement might have homogenized the distribution of traits a bit.
Friday, October 27, 2006
 We've received a lot of search engine traffic over the past few days because of the phenomenon of "black" and "white" fraternal twins (two cases within the last week). Aside from the original post on this blog, I've commented on it a few times at my other blog, here, here and here. Also, some of you might find this 20/20 segment on the original British twins interesting, click on the video. I can't but help wonder if Brazilian readers don't find the commotion a bit amusing...
There's another article in Science about women and science.
It appears to consist predominately of (1) rebuttals to straw-men arguments and (2) Lewontin-like claims that we're all the same despite our differences. A great deal of the text deals with describing (without much detail) male-female differences on a variety of criteria. The magnitude of each gender difference was measured using the d statistic (6), d = (MM - MF)/sw,where MM is the mean score for males, MF is the mean score for females, and sw is the pooled within-sex standard deviation. The d statistic measures the distance between male and female means, in standard deviation units. They list a variety of metrics on which the sex-difference (measured in d) is small. They fail to mention the male advantage in spatial ability, but do mention the male advantage(?) in aggression. While focusing on differences in measures of ability among children, they relegate discussion of tail effects to the supplemental online text. There they mention tail effects as an effect of differences in variance, but ignore the fact that mean differences also cause tail effects. Rather than dig any deeper into this paper, I will present what they chose to ignore: the theoretical effects of small differences in mean and variance between males and females will produce large differences at the tails of a normally distributed trait. This table presents the percentage of females above a +3 SD threshold as various differences in mean (pink) and SD (orange) in standardized units units. Thus, if the mean and SD are equal (0,0) then women make up 50% of the population above 3 SD on this imaginary trait. But if d=0.3 and males have a variance that is 0.06 SD units greater than women, then the female percentage above 3 SD will be 17.1%. A d of 0.3 is labeled "small", and an SD difference of 0.06 (women SD = 0.97, men SD = 1.03) would be hard to establish in small samples. Nonetheless, it would produce exactly the kind of large differences in male:female ratios among the most talented individuals that we observe in math-heavy disciplines.
Afarensis points me to this new story in National Geographic about the Neandertal sequencing effort:
A new study by geneticist James Noonan at Lawrence Berkeley National Laboratory, however, reveals that modern humans and Neandertals' most recent common ancestor probably perished about 400,000 years ago. What could Paabo mean??? Stay tuned over the next few weeks....
H. Allen Orr shares three salient qualities with his hero Richard Lewontin: (1) the status of a leading theoretical geneticist of his time, (2) a range of intellectual interests encompassing more than his own discipline, and (3) an unseemly eagerness to trumpet PC pieties. In this light, his recent review of Nicholas Wade's book Before the Dawn is quite interesting. The review is mixed, containing both praise and criticism. Yet one gets the sense that Orr's critical faculties do not permit him to raise the temperature of his disparagement to the blistering degree that that he would like. A flavor of his restraint can be found in his footnote on the Cochran et al. (2006) hypothesis regarding the high mean IQ of the Ashkenazi Jews:
The GNXP faithful will find Orr's closing words quite provocative:
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