Slick, sanctimonious Dr. Robert Bellarmino at the National Institutes of Health touts future genetic cures he doubts will ever happen. Bellarmino knows that individual genes don't determine specific traits such as homosexuality, violence, high IQ, short stature or resistance to Alzheimer's disease; their interaction with other genes and with the environment is staggeringly complex. But it's good for the research business to pretend otherwise. When doctors bend the rules in long-odds attempts to provide the cures for inherited illnesses that the public demands, Bellarmino works to shield them from censure.
November 30, 2006
Michael Crichton's Next
Michael Crichton, author of popular books such as Jurassic Park has written a new novel about genetic engineering, titled Next. I didn't much like his previous book which expressed unwarranted reservations about the reality of global warming, but this bit from a review of his book seems to me to be right on the money:
Nature article on Antikythera mechanism
From the BBC:
The New York Times:
Jo Marchant writing in Nature:
François Charette in Nature:
From the paper:
Nature 444, 587-591 (30 November 2006)
T. Freeth et al.
The Antikythera Mechanism is a unique Greek geared device, constructed around the end of the second century bc. It is known1, 2, 3, 4, 5, 6, 7, 8, 9 that it calculated and displayed celestial information, particularly cycles such as the phases of the moon and a luni-solar calendar. Calendars were important to ancient societies10 for timing agricultural activity and fixing religious festivals. Eclipses and planetary motions were often interpreted as omens, while the calm regularity of the astronomical cycles must have been philosophically attractive in an uncertain and violent world. Named after its place of discovery in 1901 in a Roman shipwreck, the Antikythera Mechanism is technically more complex than any known device for at least a millennium afterwards. Its specific functions have remained controversial11, 12, 13, 14 because its gears and the inscriptions upon its faces are only fragmentary. Here we report surface imaging and high-resolution X-ray tomography of the surviving fragments, enabling us to reconstruct the gear function and double the number of deciphered inscriptions. The mechanism predicted lunar and solar eclipses on the basis of Babylonian arithmetic-progression cycles. The inscriptions support suggestions of mechanical display of planetary positions9, 14, 15, now lost. In the second century bc, Hipparchos developed a theory to explain the irregularities of the Moon's motion across the sky caused by its elliptic orbit. We find a mechanical realization of this theory in the gearing of the mechanism, revealing an unexpected degree of technical sophistication for the period.
Link
For example, the Moon sometimes moves slightly faster in the sky than at others because of the satellite's elliptic orbit.
To overcome this, the designer of the calculator used a "pin-and-slot" mechanism to connect two gear-wheels that introduced the necessary variations.
"When you see it your jaw just drops and you think: 'bloody hell, that's clever'. It's a brilliant technical design," said Professor Mike Edmunds.
The New York Times:
The mechanism, presumably used in preparing calendars for seasons of planting and harvesting and fixing religious festivals, had at least 30, possibly 37, hand-cut bronze gear-wheels, the researchers reported. An ingenious pin-and-slot device connecting two gear-wheels induced variations in the representation of lunar motions according to the Hipparchos model of the Moon’s elliptical orbit around Earth.
The functions of the mechanism were determined by the numbers of teeth in the gears. The 53-tooth count of certain gears, the researchers said, was “powerful confirmation of our proposed model of Hipparchos’ lunar theory.”
Jo Marchant writing in Nature:
The researchers realized that the ratios of the gear-wheels involved produce a motion that closely mimics the varying motion of the Moon around Earth, as described by Hipparchus. When the Moon is close to us it seems to move faster. And the closest part of the Moon's orbit itself makes a full rotation around the Earth about every nine years. Hipparchus was the first to describe this motion mathematically, working on the idea that the Moon's orbit, although circular, was centred on a point offset from the centre of Earth that described a nine-year circle. In the Antikythera Mechanism, this theory is beautifully translated into mechanical form. "It's an unbelievably sophisticated idea," says Tony Freeth, a mathematician who worked out most of the mechanics for Edmunds' team. "I don't know how they thought of it."
...
Charette also hopes the new Antikythera reconstruction will encourage scholars to take the device more seriously, and serve as a reminder of the messy nature of history. "It's still a popular notion among the public, and among scientists thinking about the history of their disciplines, that technological development is a simple progression," he says. "But history is full of surprises."
François Charette in Nature:
From the paper:
The Antikythera Mechanism shows great economy and ingenuity of design. It stands as a witness to the extraordinary technological potential of Ancient Greece, apparently lost within the Roman Empire.
Nature 444, 587-591 (30 November 2006)
T. Freeth et al.
The Antikythera Mechanism is a unique Greek geared device, constructed around the end of the second century bc. It is known1, 2, 3, 4, 5, 6, 7, 8, 9 that it calculated and displayed celestial information, particularly cycles such as the phases of the moon and a luni-solar calendar. Calendars were important to ancient societies10 for timing agricultural activity and fixing religious festivals. Eclipses and planetary motions were often interpreted as omens, while the calm regularity of the astronomical cycles must have been philosophically attractive in an uncertain and violent world. Named after its place of discovery in 1901 in a Roman shipwreck, the Antikythera Mechanism is technically more complex than any known device for at least a millennium afterwards. Its specific functions have remained controversial11, 12, 13, 14 because its gears and the inscriptions upon its faces are only fragmentary. Here we report surface imaging and high-resolution X-ray tomography of the surviving fragments, enabling us to reconstruct the gear function and double the number of deciphered inscriptions. The mechanism predicted lunar and solar eclipses on the basis of Babylonian arithmetic-progression cycles. The inscriptions support suggestions of mechanical display of planetary positions9, 14, 15, now lost. In the second century bc, Hipparchos developed a theory to explain the irregularities of the Moon's motion across the sky caused by its elliptic orbit. We find a mechanical realization of this theory in the gearing of the mechanism, revealing an unexpected degree of technical sophistication for the period.
Link
November 29, 2006
The Gagauz of Moldova
Annals of Human Genetics (Online Early)
The Gagauz, a Linguistic Enclave, are not a Genetic Isolate
Ivan Nasidze et al.
Summary
The Gagauz are a Turkic-speaking group that migrated from Turkey to their present location in the southern part of the Republic of Moldova about 150 years ago. Surrounded by Indo-European-speaking populations, they thus form a linguistic enclave, which raises the following question: to what extent have they remained in genetic isolation from their geographic neighbours? Analyses of mtDNA and Y chromosome variation indicate that despite their linguistic differences, the Gagauz have admixed extensively with neighbouring groups. Our data suggest that there has been more mtDNA than Y chromosome admixture, in keeping with the patrilocal nature of these groups. Moreover, when compared with another linguistic enclave, the Kalmyks there appears to be a correlation between the amount of genetic admixture and the amount of linguistic influence that these two linguistic enclaves have experienced from neighbouring groups.
Link
The Gagauz, a Linguistic Enclave, are not a Genetic Isolate
Ivan Nasidze et al.
Summary
The Gagauz are a Turkic-speaking group that migrated from Turkey to their present location in the southern part of the Republic of Moldova about 150 years ago. Surrounded by Indo-European-speaking populations, they thus form a linguistic enclave, which raises the following question: to what extent have they remained in genetic isolation from their geographic neighbours? Analyses of mtDNA and Y chromosome variation indicate that despite their linguistic differences, the Gagauz have admixed extensively with neighbouring groups. Our data suggest that there has been more mtDNA than Y chromosome admixture, in keeping with the patrilocal nature of these groups. Moreover, when compared with another linguistic enclave, the Kalmyks there appears to be a correlation between the amount of genetic admixture and the amount of linguistic influence that these two linguistic enclaves have experienced from neighbouring groups.
Link
November 23, 2006
Copy number variation in humans
From the paper:We obtained the optimal clustering with the assumption of three ancestral populations, with the African, European and Asian populations clearly differentiated
Nature 444, 444-454 (23 November 2006)
Global variation in copy number in the human genome
Richard Redon et al.
Copy number variation (CNV) of DNA sequences is functionally significant but has yet to be fully ascertained. We have constructed a first-generation CNV map of the human genome through the study of 270 individuals from four populations with ancestry in Europe, Africa or Asia (the HapMap collection). DNA from these individuals was screened for CNV using two complementary technologies: single-nucleotide polymorphism (SNP) genotyping arrays, and clone-based comparative genomic hybridization. A total of 1,447 copy number variable regions (CNVRs), which can encompass overlapping or adjacent gains or losses, covering 360 megabases (12% of the genome) were identified in these populations. These CNVRs contained hundreds of genes, disease loci, functional elements and segmental duplications. Notably, the CNVRs encompassed more nucleotide content per genome than SNPs, underscoring the importance of CNV in genetic diversity and evolution. The data obtained delineate linkage disequilibrium patterns for many CNVs, and reveal marked variation in copy number among populations. We also demonstrate the utility of this resource for genetic disease studies.
Link (Free access)
November 17, 2006
Phylogeography of mtDNA haplogroup L1c
Mol Phylogenet Evol. 2006 Oct 5; [Epub ahead of print]
Phylogeography of the human mitochondrial L1c haplogroup: Genetic signatures of the prehistory of Central Africa.
Batini C, Coia V, Battaggia C, Rocha J, Pilkington MM, Spedini G, Comas D, Destro-Bisol G, Calafell F.
Abstract
Interindividual variation of human mitochondrial DNA has been extensively studied over the last two decades, and its usefulness for reconstructing evolutionary relationships of extant populations has been proved. However, some mitochondrial lineages still need to be studied using a combination of larger and tailored datasets and increased level of resolution in order to shed light on their origin and on the processes underlying their present distribution. In this study, we analyze the phylogeny of the L1c haplogroup of human mitochondrial DNA using sequence data from hypervariable regions 1 and 2 obtained from 455 individuals (extracted from a total sampling of 2542 individuals) belonging to sub-Saharan African and African-American populations. We propose a substantial revision of L1c phylogeny, by introducing one new sub-haplogroup (L1c4), two new L1c1 clades (L1c1b and L1c1c), and by reassigning the previous L1c1a1 sequences to a clade which we termed L1c5. The new phylogeny encompasses distinct lineages with different evolutionary histories. In fact, based on population frequency, internal variation and mismatch distribution, we propose that L1c1b, L1c1c and L1c2 originated in Bantu ancestors, whereas L1c1a, L1c4 and L1c5 evolved among Western Pygmies. The population structure of L1c is not comparable to any known mitochondrial or, even, Y-chromosomal haplogroup, and challenges the current view that most of mtDNA variation in Pygmies might reflect admixture with Bantu or a persistence of plesiomorphic characters. In fact, the unique feature of the L1c is that it retains a signature of a phase common to the ancestors of the Bantu and Western Pygmies, while encompassing some specific sub-clades which can indicate their divergence. This allowed us to attempt a phylogenetically based assessment of the evolutionary relationships between the two groups. Taking into consideration estimates of the time to the most recent common ancestor of L1c and its clades together with archaeological and paleoclimatological evidence, we propose that the ancestors of Bantu and Western Pygmies separated between 60 and 30kya.
Link
Phylogeography of the human mitochondrial L1c haplogroup: Genetic signatures of the prehistory of Central Africa.
Batini C, Coia V, Battaggia C, Rocha J, Pilkington MM, Spedini G, Comas D, Destro-Bisol G, Calafell F.
Abstract
Interindividual variation of human mitochondrial DNA has been extensively studied over the last two decades, and its usefulness for reconstructing evolutionary relationships of extant populations has been proved. However, some mitochondrial lineages still need to be studied using a combination of larger and tailored datasets and increased level of resolution in order to shed light on their origin and on the processes underlying their present distribution. In this study, we analyze the phylogeny of the L1c haplogroup of human mitochondrial DNA using sequence data from hypervariable regions 1 and 2 obtained from 455 individuals (extracted from a total sampling of 2542 individuals) belonging to sub-Saharan African and African-American populations. We propose a substantial revision of L1c phylogeny, by introducing one new sub-haplogroup (L1c4), two new L1c1 clades (L1c1b and L1c1c), and by reassigning the previous L1c1a1 sequences to a clade which we termed L1c5. The new phylogeny encompasses distinct lineages with different evolutionary histories. In fact, based on population frequency, internal variation and mismatch distribution, we propose that L1c1b, L1c1c and L1c2 originated in Bantu ancestors, whereas L1c1a, L1c4 and L1c5 evolved among Western Pygmies. The population structure of L1c is not comparable to any known mitochondrial or, even, Y-chromosomal haplogroup, and challenges the current view that most of mtDNA variation in Pygmies might reflect admixture with Bantu or a persistence of plesiomorphic characters. In fact, the unique feature of the L1c is that it retains a signature of a phase common to the ancestors of the Bantu and Western Pygmies, while encompassing some specific sub-clades which can indicate their divergence. This allowed us to attempt a phylogenetically based assessment of the evolutionary relationships between the two groups. Taking into consideration estimates of the time to the most recent common ancestor of L1c and its clades together with archaeological and paleoclimatological evidence, we propose that the ancestors of Bantu and Western Pygmies separated between 60 and 30kya.
Link
Human eye color explained by a three-SNP haplotype
A very exciting new preprint in AJHG describes how a haplotype defined by three SNPs, i.e., single-letter changes in the genetic code, describes most variation in human eye color. I am sure that this paper will make the news once its edited version appears, but this is very exciting development for many different reasons.
American Journal of Human Genetics (preprint)
A three-SNP haplotype in the first intron of OCA2 explains most human eye color variation
David L. Duffy, Grant W. Montgomery, Wei Chen, Zhen Zhen Zhao, Lien Le, Michael R. James, Nicholas K. Hayward, Nicholas G. Martin, Richard A. Sturm
Abstract
We have previously shown that a QTL linked to the OCA2 region of 15q accounts for 74% of variation in human eye color. We conducted additional genotyping to clarify the role of the OCA2 locus in the inheritance of eye color and other pigmentary traits associated with skin cancer risk in white populations. Fifty eight synonymous and non-synonymous exonic SNPs and tagging SNPs were typed in a collection of 3839 adolescent twins, their sibs, and parents. The highest association for blue:non-blue eye color was found with three OCA2 SNPs; rs7495174 T/C, rs6497268 G/T and rs11855019 T/C (P-values of 1.02x10-61, 1.57x10-96, and 4.45x10-54 respectively) in intron 1. These three SNPs are in one major haplotype block with TGT representing 78.4% of alleles. The TGT/TGT diplotype found in 62.2% of samples was the major genotype seen to modify eye color, with a frequency of 0.905 in blue or green compared with only 0.095 in brown eye color. This genotype was also at highest frequency in subjects with light brown hair and was more frequent in fair and medium skin types, consistent with the TGT haplotype acting as a recessive modifier of lighter pigmentary phenotypes. Homozygotes for rs11855019 C/C were predominantly without freckles and had decreased mole counts. The minor population impact of the nonsynonymous coding region polymorphisms Arg305Trp and Arg419Gln associated with non-blue eyes, and the tight linkage of the major TGT haplotype within the first intron of OCA2 with blue eye color and lighter hair and skin tones, suggest that differences within the 5’ proximal regulatory control region of OCA2 gene alter expression or mRNA transcript levels and may be responsible for these associations.
Link
- First, it shows that a very striking observable difference among humans can be explained by minute differences in the genetic code. This should be a reminder to those who engage in grocery-style genetics. Quantity matters not.
- Second, eye color is an important phenotypical character that people actually care about. Genetics becomes exciting when it's about stuff that people are interested in (intelligence, eye color, the chance of getting cancer before 40, etc.).
- Third, we are finally getting to the point where genetics can be used to infer characteristics of organisms that are not preserved in bones. This will doubtlessly lead to applications in ancient DNA research (see also here).
American Journal of Human Genetics (preprint)
A three-SNP haplotype in the first intron of OCA2 explains most human eye color variation
David L. Duffy, Grant W. Montgomery, Wei Chen, Zhen Zhen Zhao, Lien Le, Michael R. James, Nicholas K. Hayward, Nicholas G. Martin, Richard A. Sturm
Abstract
We have previously shown that a QTL linked to the OCA2 region of 15q accounts for 74% of variation in human eye color. We conducted additional genotyping to clarify the role of the OCA2 locus in the inheritance of eye color and other pigmentary traits associated with skin cancer risk in white populations. Fifty eight synonymous and non-synonymous exonic SNPs and tagging SNPs were typed in a collection of 3839 adolescent twins, their sibs, and parents. The highest association for blue:non-blue eye color was found with three OCA2 SNPs; rs7495174 T/C, rs6497268 G/T and rs11855019 T/C (P-values of 1.02x10-61, 1.57x10-96, and 4.45x10-54 respectively) in intron 1. These three SNPs are in one major haplotype block with TGT representing 78.4% of alleles. The TGT/TGT diplotype found in 62.2% of samples was the major genotype seen to modify eye color, with a frequency of 0.905 in blue or green compared with only 0.095 in brown eye color. This genotype was also at highest frequency in subjects with light brown hair and was more frequent in fair and medium skin types, consistent with the TGT haplotype acting as a recessive modifier of lighter pigmentary phenotypes. Homozygotes for rs11855019 C/C were predominantly without freckles and had decreased mole counts. The minor population impact of the nonsynonymous coding region polymorphisms Arg305Trp and Arg419Gln associated with non-blue eyes, and the tight linkage of the major TGT haplotype within the first intron of OCA2 with blue eye color and lighter hair and skin tones, suggest that differences within the 5’ proximal regulatory control region of OCA2 gene alter expression or mRNA transcript levels and may be responsible for these associations.
Link
November 16, 2006
Personality traits of voters for US presidential elections
Personality and Individual Differences (Article in Press)
Voters’ personality traits in presidential elections
Claudio Barbaranelli et al.
Abstract
Personality measures of more than 6000 US electors on the Big Five Factors have been collected on the Web through a Web site designed to assess their personality. By means of structural equation modeling the impact of personality factors as well as of demographic variables, such as age and sex, on voting intentions on the forthcoming US presidential elections was investigated. Personality variables accounted for 16% of variance of voting intentions, while gender and age accounted for no more than 3%. High Agreeableness and Openness were predictive of intention to vote for Kerry, while all high Energy, Conscientiousness and Emotional Stability were predictive of intention to vote for Bush. Results are consistent with previous research conducted in a different country, using a different language.
Link
Voters’ personality traits in presidential elections
Claudio Barbaranelli et al.
Abstract
Personality measures of more than 6000 US electors on the Big Five Factors have been collected on the Web through a Web site designed to assess their personality. By means of structural equation modeling the impact of personality factors as well as of demographic variables, such as age and sex, on voting intentions on the forthcoming US presidential elections was investigated. Personality variables accounted for 16% of variance of voting intentions, while gender and age accounted for no more than 3%. High Agreeableness and Openness were predictive of intention to vote for Kerry, while all high Energy, Conscientiousness and Emotional Stability were predictive of intention to vote for Bush. Results are consistent with previous research conducted in a different country, using a different language.
Link
Being rich lowers mens' attractiveness to women
Personality and Individual Differences (Article in Press)
Too good to be ‘true’? The handicap of high socio-economic status in attractive males
Simon Chu et al.
Abstract
Empirical evidence concerning human mate-choice preferences suggests that females should select partners on the basis of cues to genetic quality and/or ability to contribute resources to childcare. Paradoxically, while high levels of both factors should be an attractive combination to females, they might also dissuade females from entering into a relationship with such males since, by definition, they are likely to be highly attractive to other females, and therefore might increase the likelihood that such a male may cheat or desert the relationship. If so, females should be wary of entering into long-term relationships with physically attractive, high status males as compared with males of lower physical attractiveness or status. We asked females to rate a number of different males in terms of attractiveness as a long-term partner. Females were presented with attractive, average and unattractive male faces paired with lonely-hearts advertisements implying high, medium or low socio-economic status. Highest ratings were consistently given to attractive males of medium status rather than high status. We suggest that females see physically attractive, high status males as being more likely to pursue a mating strategy rather than parenting strategy. Under particular circumstances, high socio-economic status in males can be subtly counter-productive in terms of attractiveness as a long-term partner.
Link
Too good to be ‘true’? The handicap of high socio-economic status in attractive males
Simon Chu et al.
Abstract
Empirical evidence concerning human mate-choice preferences suggests that females should select partners on the basis of cues to genetic quality and/or ability to contribute resources to childcare. Paradoxically, while high levels of both factors should be an attractive combination to females, they might also dissuade females from entering into a relationship with such males since, by definition, they are likely to be highly attractive to other females, and therefore might increase the likelihood that such a male may cheat or desert the relationship. If so, females should be wary of entering into long-term relationships with physically attractive, high status males as compared with males of lower physical attractiveness or status. We asked females to rate a number of different males in terms of attractiveness as a long-term partner. Females were presented with attractive, average and unattractive male faces paired with lonely-hearts advertisements implying high, medium or low socio-economic status. Highest ratings were consistently given to attractive males of medium status rather than high status. We suggest that females see physically attractive, high status males as being more likely to pursue a mating strategy rather than parenting strategy. Under particular circumstances, high socio-economic status in males can be subtly counter-productive in terms of attractiveness as a long-term partner.
Link
November 13, 2006
Culture and ratings of attractiveness of different body shapes
Evolution and Human Behavior
Volume 27, Issue 6 , November 2006, Pages 443-456
Changing perceptions of attractiveness as observers are exposed to a different culture
Martin J. Tovée et al.
Abstract
It has been suggested that certain physical cues can be used to predict mate quality and that sensitivity to these cues would therefore be adaptive. From this, it follows that in environments where the optimal values for these features differ, the attractiveness preferences should also be different. In this study, we show that there are striking differences in attractiveness preferences for female bodies between United Kingdom (UK) Caucasian and South African Zulu observers. These differences can be explained by different local optima for survival and reproduction in the two environments. In the UK, a high body mass is correlated with low health and low fertility, and the converse is true in rural South Africa. We also report significant changes in the attractiveness preferences of Zulus who have moved to the UK. This suggests that these preferences are malleable and can change with exposure to different environments and conditions. Additionally, we show that Britons of African origin, who were born and who grew up in the UK, have exactly the same preferences as our UK Caucasian observers. These results suggest that humans have mechanisms for acquiring norms of attractiveness that are highly plastic, which allow them to track different ecological conditions through learning.
Link
Volume 27, Issue 6 , November 2006, Pages 443-456
Changing perceptions of attractiveness as observers are exposed to a different culture
Martin J. Tovée et al.
Abstract
It has been suggested that certain physical cues can be used to predict mate quality and that sensitivity to these cues would therefore be adaptive. From this, it follows that in environments where the optimal values for these features differ, the attractiveness preferences should also be different. In this study, we show that there are striking differences in attractiveness preferences for female bodies between United Kingdom (UK) Caucasian and South African Zulu observers. These differences can be explained by different local optima for survival and reproduction in the two environments. In the UK, a high body mass is correlated with low health and low fertility, and the converse is true in rural South Africa. We also report significant changes in the attractiveness preferences of Zulus who have moved to the UK. This suggests that these preferences are malleable and can change with exposure to different environments and conditions. Additionally, we show that Britons of African origin, who were born and who grew up in the UK, have exactly the same preferences as our UK Caucasian observers. These results suggest that humans have mechanisms for acquiring norms of attractiveness that are highly plastic, which allow them to track different ecological conditions through learning.
Link
Even facial color is attractive in women
The study I had posted about earlier.
Evolution and Human Behavior
Volume 27, Issue 6 , November 2006, Pages 433-442
Visible skin color distribution plays a role in the perception of age, attractiveness, and health in female faces
Bernhard Fink et al.
Abstract
Evolutionary psychologists have proposed that preferences for facial characteristics, such as symmetry, averageness, and sexual dimorphism, may reflect adaptations for mate choice because they signal aspects of mate quality. Here, we show that facial skin color distribution significantly influences the perception of age and attractiveness of female faces, independent of facial form and skin surface topography. A set of three-dimensional shape-standardized stimulus faces—varying only in terms of skin color distribution due to variation in biological age and cumulative photodamage—was rated by a panel of naive judges for a variety of perceptual endpoints relating to age, health, and beauty. Shape- and topography-standardized stimulus faces with the homogeneous skin color distribution of young people were perceived as younger and received significantly higher ratings for attractiveness and health than analogous stimuli with the relatively inhomogeneous skin color distribution of more elderly people. Thus, skin color distribution, independent of facial form and skin surface topography, seems to have a major influence on the perception of female facial age and judgments of attractiveness and health as they may signal aspects of underlying physiological condition of an individual relevant for mate choice. We suggest that studies on human physical attractiveness and its perception need to consider the influence of visible skin condition driven by color distribution and differentiate between such effects and beauty-related traits due to facial shape and skin topography.
Link
Evolution and Human Behavior
Volume 27, Issue 6 , November 2006, Pages 433-442
Visible skin color distribution plays a role in the perception of age, attractiveness, and health in female faces
Bernhard Fink et al.
Abstract
Evolutionary psychologists have proposed that preferences for facial characteristics, such as symmetry, averageness, and sexual dimorphism, may reflect adaptations for mate choice because they signal aspects of mate quality. Here, we show that facial skin color distribution significantly influences the perception of age and attractiveness of female faces, independent of facial form and skin surface topography. A set of three-dimensional shape-standardized stimulus faces—varying only in terms of skin color distribution due to variation in biological age and cumulative photodamage—was rated by a panel of naive judges for a variety of perceptual endpoints relating to age, health, and beauty. Shape- and topography-standardized stimulus faces with the homogeneous skin color distribution of young people were perceived as younger and received significantly higher ratings for attractiveness and health than analogous stimuli with the relatively inhomogeneous skin color distribution of more elderly people. Thus, skin color distribution, independent of facial form and skin surface topography, seems to have a major influence on the perception of female facial age and judgments of attractiveness and health as they may signal aspects of underlying physiological condition of an individual relevant for mate choice. We suggest that studies on human physical attractiveness and its perception need to consider the influence of visible skin condition driven by color distribution and differentiate between such effects and beauty-related traits due to facial shape and skin topography.
Link
Female advantage in recognizing emotional facial expressions
Evolution and Human Behavior
Volume 27, Issue 6 , November 2006, Pages 401-416
A female advantage in the recognition of emotional facial expressions: test of an evolutionary hypothesis
Elizabeth Hampson et al.
Abstract
A set of computerized tasks was used to investigate sex differences in the speed and accuracy of emotion recognition in 62 men and women of reproductive age. Evolutionary theories have posited that female superiority in the perception of emotion might arise from women's near-universal responsibility for child-rearing. Two variants of the child-rearing hypothesis predict either across-the-board female superiority in the discrimination of emotional expressions (“attachment promotion” hypothesis) or a female superiority that is restricted to expressions of negative emotion (“fitness threat” hypothesis). Therefore, we sought to evaluate whether the expression of the sex difference is influenced by the valence of the emotional signal (Positive or Negative). The results showed that women were faster than men at recognizing both positive and negative emotions from facial cues, supporting the attachment promotion hypothesis. Support for the fitness threat hypothesis also was found, in that the sex difference was accentuated for negative emotions. There was no evidence that the female superiority was learned through previous childcare experience or that it was derived from a sex difference in simple perceptual speed. The results suggest that evolved mechanisms, not domain-general learning, underlie the sex difference in recognition of facial emotions.
Link
Volume 27, Issue 6 , November 2006, Pages 401-416
A female advantage in the recognition of emotional facial expressions: test of an evolutionary hypothesis
Elizabeth Hampson et al.
Abstract
A set of computerized tasks was used to investigate sex differences in the speed and accuracy of emotion recognition in 62 men and women of reproductive age. Evolutionary theories have posited that female superiority in the perception of emotion might arise from women's near-universal responsibility for child-rearing. Two variants of the child-rearing hypothesis predict either across-the-board female superiority in the discrimination of emotional expressions (“attachment promotion” hypothesis) or a female superiority that is restricted to expressions of negative emotion (“fitness threat” hypothesis). Therefore, we sought to evaluate whether the expression of the sex difference is influenced by the valence of the emotional signal (Positive or Negative). The results showed that women were faster than men at recognizing both positive and negative emotions from facial cues, supporting the attachment promotion hypothesis. Support for the fitness threat hypothesis also was found, in that the sex difference was accentuated for negative emotions. There was no evidence that the female superiority was learned through previous childcare experience or that it was derived from a sex difference in simple perceptual speed. The results suggest that evolved mechanisms, not domain-general learning, underlie the sex difference in recognition of facial emotions.
Link
November 10, 2006
Origin of mtDNA haplogroup H
Molecular Biology and Evolution (Advance Access published online on November 10, 2006)
Origin and Expansion of Haplogroup H, the Dominant Human Mitochondrial DNA Lineage in West Eurasia: the Near Eastern and Caucasian Perspective
U. Roostalu et al.
Abstract
More than a third of the European pool of human mitochondrial DNA (mtDNA) is fragmented into a number of subclades of haplogroup (hg) H, the most frequent hg throughout western Eurasia. While there has been considerable recent progress in studying mitochondrial genome variation in Europe at the complete sequence resolution, little data of comparable resolution is so far available for regions like the Caucasus and the Near and Middle East - areas where most of European genetic lineages, including hg H, have likely emerged. This gap in our knowledge causes a serious hindrance for progress in understanding the demographic pre-history of Europe and western Eurasia in general. Here we describe the phylogeography of hg H in the populations of the Near East and the Caucasus. We have analyzed 545 samples of hg H at high resolution, including 15 novel complete mtDNA sequences. As in Europe, most of the present-day Near Eastern - Caucasus area variants of hg H started to expand after the Last Glacial Maximum (LGM) and presumably before the Holocene. Yet importantly, several hg H sub-clades in Near East and Southern Caucasus region coalesce to the pre-LGM period. Furthermore, irrespective of their common origin, significant differences between the distribution of hg H sub-hgs in Europe and in the Near East and South Caucasus imply limited post-LGM maternal gene flow between these regions. In a contrast, the North Caucasus mitochondrial gene pool has received an influx of hg H variants, arriving from the Pontocaspian/East European area.
Link
Origin and Expansion of Haplogroup H, the Dominant Human Mitochondrial DNA Lineage in West Eurasia: the Near Eastern and Caucasian Perspective
U. Roostalu et al.
Abstract
More than a third of the European pool of human mitochondrial DNA (mtDNA) is fragmented into a number of subclades of haplogroup (hg) H, the most frequent hg throughout western Eurasia. While there has been considerable recent progress in studying mitochondrial genome variation in Europe at the complete sequence resolution, little data of comparable resolution is so far available for regions like the Caucasus and the Near and Middle East - areas where most of European genetic lineages, including hg H, have likely emerged. This gap in our knowledge causes a serious hindrance for progress in understanding the demographic pre-history of Europe and western Eurasia in general. Here we describe the phylogeography of hg H in the populations of the Near East and the Caucasus. We have analyzed 545 samples of hg H at high resolution, including 15 novel complete mtDNA sequences. As in Europe, most of the present-day Near Eastern - Caucasus area variants of hg H started to expand after the Last Glacial Maximum (LGM) and presumably before the Holocene. Yet importantly, several hg H sub-clades in Near East and Southern Caucasus region coalesce to the pre-LGM period. Furthermore, irrespective of their common origin, significant differences between the distribution of hg H sub-hgs in Europe and in the Near East and South Caucasus imply limited post-LGM maternal gene flow between these regions. In a contrast, the North Caucasus mitochondrial gene pool has received an influx of hg H variants, arriving from the Pontocaspian/East European area.
Link
The Perfect comedy face
Anthony Little has created a facial composite of comedians. From the BBC:Scientists have used computer software to come up with what they say is the perfect comedy face.
The University of Stirling team blended together 179 different facial aspects of 20 top comedians.
They said soft and feminine features, typified by Ricky Gervais, were more likely to make people laugh.
The researchers also concluded that Conservative leader David Cameron, unlike Tony Blair or Gordon Brown, has features prone to make people laugh.
However, they said it was questionable whether a funny face was an electoral asset.
Researcher Dr Anthony Little, a psychologist, whose work was commissioned by Jongleurs comedy clubs, showed faces with a range of different features to volunteers, and asked them to rate how funny they thought the person was.
He said: "The features most likely to mark male comedians out for success are predominantly soft and feminine.
"The face is a strong indication of character, and today's study appears to explain why comedians of a certain appearance would have been drawn to their career.
"The characteristics of a feminine face imply that the person may be agreeable and co-operative, which can be causal in our first impressions of comedians as being friendly and funny."
Dr Little said Mr Cameron's round and wide facial shape, large eyes and soft features meant he had the right natural physical attributes for comedy.
November 08, 2006
Switch to Blogger beta
I have switched the blog to Google's blogger beta. Everything seems to work fine so far, but the site feed has a new address. You might want to update it in your news reader, since I'm not sure whether the old feed will continue to be updated (I will know after posting this).
UPDATE: Yep, the old feed still works.
UPDATE: The gmail-like system of search+label rocks! I just labeled all 911 posts of the blog in a few minutes right from the dashboard. Another great feature: no more waiting on the "publishing 34%" whenever you change your template or republish a post.
UPDATE: Yep, the old feed still works.
UPDATE: The gmail-like system of search+label rocks! I just labeled all 911 posts of the blog in a few minutes right from the dashboard. Another great feature: no more waiting on the "publishing 34%" whenever you change your template or republish a post.
Intelligence and socioeconomic success
Intelligence (in press)
Intelligence and socioeconomic success: A meta-analytic review of longitudinal research
Tarmo Strenze
Abstract
The relationship between intelligence and socioeconomic success has been the source of numerous controversies. The present paper conducted a meta-analysis of the longitudinal studies that have investigated intelligence as a predictor of success (as measured by education, occupation, and income). In order to better evaluate the predictive power of intelligence, the paper also includes meta-analyses of parental socioeconomic status (SES) and academic performance (school grades) as predictors of success. The results demonstrate that intelligence is a powerful predictor of success but, on the whole, not an overwhelmingly better predictor than parental SES or grades. Moderator analyses showed that the relationship between intelligence and success is dependent on the age of the sample but there is little evidence of any historical trend in the relationship.
Link
Intelligence and socioeconomic success: A meta-analytic review of longitudinal research
Tarmo Strenze
Abstract
The relationship between intelligence and socioeconomic success has been the source of numerous controversies. The present paper conducted a meta-analysis of the longitudinal studies that have investigated intelligence as a predictor of success (as measured by education, occupation, and income). In order to better evaluate the predictive power of intelligence, the paper also includes meta-analyses of parental socioeconomic status (SES) and academic performance (school grades) as predictors of success. The results demonstrate that intelligence is a powerful predictor of success but, on the whole, not an overwhelmingly better predictor than parental SES or grades. Moderator analyses showed that the relationship between intelligence and success is dependent on the age of the sample but there is little evidence of any historical trend in the relationship.
Link
Microcephalin haplotype from Neanderthals
Bruce Lahn continues his work on the Microcephalin haplogroup D. In a new paper in PNAS he and his team suggest that this brain gene may have introgressed into the modern human gene pool ~37kya from a separate Homo lineage, possibly the Neanderthals. Note that this is an open access article.
UPDATE (May 15, 2010): Neandertals had ancestral MCPH1 allele; hence this paper's inference is essentially falsified.
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0606966103
Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage
Patrick D. Evans et al.
At the center of the debate on the emergence of modern humans and their spread throughout the globe is the question of whether archaic Homo lineages contributed to the modern human gene pool, and more importantly, whether such contributions impacted the evolutionary adaptation of our species. A major obstacle to answering this question is that low levels of admixture with archaic lineages are not expected to leave extensive traces in the modern human gene pool because of genetic drift. Loci that have undergone strong positive selection, however, offer a unique opportunity to identify low-level admixture with archaic lineages, provided that the introgressed archaic allele has risen to high frequency under positive selection. The gene microcephalin (MCPH1) regulates brain size during development and has experienced positive selection in the lineage leading to Homo sapiens. Within modern humans, a group of closely related haplotypes at this locus, known as haplogroup D, rose from a single copy {approx}37,000 years ago and swept to exceptionally high frequency ({approx}70% worldwide today) because of positive selection. Here, we examine the origin of haplogroup D. By using the interhaplogroup divergence test, we show that haplogroup D likely originated from a lineage separated from modern humans {approx}1.1 million years ago and introgressed into humans by {approx}37,000 years ago. This finding supports the possibility of admixture between modern humans and archaic Homo populations (Neanderthals being one possibility). Furthermore, it buttresses the important notion that, through such adminture, our species has benefited evolutionarily by gaining new advantageous alleles. The interhaplogroup divergence test developed here may be broadly applicable to the detection of introgression at other loci in the human genome or in genomes of other species.
Link
Proc. Natl. Acad. Sci. USA, 10.1073/pnas.0606966103
Evidence that the adaptive allele of the brain size gene microcephalin introgressed into Homo sapiens from an archaic Homo lineage
Patrick D. Evans et al.
At the center of the debate on the emergence of modern humans and their spread throughout the globe is the question of whether archaic Homo lineages contributed to the modern human gene pool, and more importantly, whether such contributions impacted the evolutionary adaptation of our species. A major obstacle to answering this question is that low levels of admixture with archaic lineages are not expected to leave extensive traces in the modern human gene pool because of genetic drift. Loci that have undergone strong positive selection, however, offer a unique opportunity to identify low-level admixture with archaic lineages, provided that the introgressed archaic allele has risen to high frequency under positive selection. The gene microcephalin (MCPH1) regulates brain size during development and has experienced positive selection in the lineage leading to Homo sapiens. Within modern humans, a group of closely related haplotypes at this locus, known as haplogroup D, rose from a single copy {approx}37,000 years ago and swept to exceptionally high frequency ({approx}70% worldwide today) because of positive selection. Here, we examine the origin of haplogroup D. By using the interhaplogroup divergence test, we show that haplogroup D likely originated from a lineage separated from modern humans {approx}1.1 million years ago and introgressed into humans by {approx}37,000 years ago. This finding supports the possibility of admixture between modern humans and archaic Homo populations (Neanderthals being one possibility). Furthermore, it buttresses the important notion that, through such adminture, our species has benefited evolutionarily by gaining new advantageous alleles. The interhaplogroup divergence test developed here may be broadly applicable to the detection of introgression at other loci in the human genome or in genomes of other species.
Link
Subscribe to:
Posts (Atom)