November 30, 2007

Objective beauty in the classical canon

From the paper:
The main question we addressed in the present study was whether there is an objective beauty, i.e., if objective parameters intrinsic to works of art are able to elicit a specific neural pattern underlying the sense of beauty in the observer. Our results gave a positive answer to this question. The presence of a specific parameter (the golden ratio) in the stimuli we presented determined brain activations different to those where this parameter was violated. The spark that changed the perception of a sculpture from “ugly” to beautiful appears to be the joint activation of specific populations of cortical neurons responding to the physical properties of the stimuli and of neurons located in the anterior insula.
PLoS One

The Golden Beauty: Brain Response to Classical and Renaissance Sculptures

Cinzia Di Dio et al.


Is there an objective, biological basis for the experience of beauty in art? Or is aesthetic experience entirely subjective? Using fMRI technique, we addressed this question by presenting viewers, naïve to art criticism, with images of masterpieces of Classical and Renaissance sculpture. Employing proportion as the independent variable, we produced two sets of stimuli: one composed of images of original sculptures; the other of a modified version of the same images. The stimuli were presented in three conditions: observation, aesthetic judgment, and proportion judgment. In the observation condition, the viewers were required to observe the images with the same mind-set as if they were in a museum. In the other two conditions they were required to give an aesthetic or proportion judgment on the same images. Two types of analyses were carried out: one which contrasted brain response to the canonical and the modified sculptures, and one which contrasted beautiful vs. ugly sculptures as judged by each volunteer. The most striking result was that the observation of original sculptures, relative to the modified ones, produced activation of the right insula as well as of some lateral and medial cortical areas (lateral occipital gyrus, precuneus and prefrontal areas). The activation of the insula was particularly strong during the observation condition. Most interestingly, when volunteers were required to give an overt aesthetic judgment, the images judged as beautiful selectively activated the right amygdala, relative to those judged as ugly. We conclude that, in observers naïve to art criticism, the sense of beauty is mediated by two non-mutually exclusive processes: one based on a joint activation of sets of cortical neurons, triggered by parameters intrinsic to the stimuli, and the insula (objective beauty); the other based on the activation of the amygdala, driven by one's own emotional experiences (subjective beauty).


November 27, 2007

Genetic variation in Native Americans

See Figure 7 for evidence of the substructure within the Native American race.

PLoS Genetics Vol. 3, No. 11, e185 doi:10.1371/journal.pgen.0030185

Genetic Variation and Population Structure in Native Americans

Sijia Wang et al.

We examined genetic diversity and population structure in the American landmass using 678 autosomal microsatellite markers genotyped in 422 individuals representing 24 Native American populations sampled from North, Central, and South America. These data were analyzed jointly with similar data available in 54 other indigenous populations worldwide, including an additional five Native American groups. The Native American populations have lower genetic diversity and greater differentiation than populations from other continental regions. We observe gradients both of decreasing genetic diversity as a function of geographic distance from the Bering Strait and of decreasing genetic similarity to Siberians—signals of the southward dispersal of human populations from the northwestern tip of the Americas. We also observe evidence of: (1) a higher level of diversity and lower level of population structure in western South America compared to eastern South America, (2) a relative lack of differentiation between Mesoamerican and Andean populations, (3) a scenario in which coastal routes were easier for migrating peoples to traverse in comparison with inland routes, and (4) a partial agreement on a local scale between genetic similarity and the linguistic classification of populations. These findings offer new insights into the process of population dispersal and differentiation during the peopling of the Americas.


November 21, 2007

Genetic structure of European Americans

NOTE: I inadvertetdly posted a draft of this post. Here is the final post; I will leave the draft online since some people already commented on it, before I noticed it.

A previous study on Europeans discovered that Caucasoid Europeans, who form a genetic cluster on a global scale can be further distinguished into subclusters that are correlated with ancestry and geography. Now, a new study on European Americans (hat tip gnxp) appearing in the free online journal PLoS Genetics has carried out a similar analysis of the genetic structure of American "Caucasians".

What I find fascinating about this new study is that an ethnic subgroup within American Caucasoids, namely Ashkenazi Jewish Americans can be distinguished at this point from other Caucasoids. Here is the clustering based on the validated set of markers from the paper:

The distinctiveness of Jewish Americans is probably due to their having a portion of Middle Eastern ancestry. We can only say that Jewish Americans are clearly genetically distinct from the other ethnic groups presented in the study, although it is unclear whether they are distinct from other groups of Middle Eastern background.

As biologically-averse intellectuals continue to question the very existence of race, pragmatic scientists are moving into an era when not only race, but ethnicity may become genetically identifiable.

Unlike race which by definition refers to an identifiable biological cluster, ethnicity may (or may not) refer to such a cluster.

Ethnic distinctiveness is due to both culture and biology, and the relative proportions of the two factors are specific to a particular ethnic group.

When ethnic groups have split recently, co-inhabit a geographical space, frequently intermarry, etc., then it is likely that they will have small biological differences, whereas other ethnic groups may be biologically as well as culturally distinct.

We should be careful to note that there are two levels of ethnic biological distinctiveness: group distinctiveness and individual distinctiveness:

Group distinctiveness means: if you are given the photographs of ten Englishmen on one side and ten Russians on the other, you would be able to decide with a very high level of success which group represented the Russians and which one the Englishmen.

Individual distinctiveness means: if you are given the photographs of ten Englishmen and ten Russians in random order, you would still be able to sort out the Russians from the Englishmen; whether this is possible, and with what level of success is less obvious than in the previous case.

We must wait for more studies with larger samples and more markers to study the biological component of human ethnicity. At present, some groups do seem to have individual distinctiveness in a particular societal context and with a particular set of markers (e.g., Jewish vs. non-Jewish Americans), while others are less distinct (e.g., Greek vs. Italian Americans).

November 20, 2007

Genetic structure of European Americans

UPDATE (Nov 21)See also some discussion here.

PLoS Genetics (early release)

Discerning the ancestry of European Americans in genetic association studies

Alkes Price et al.

European Americans are often treated as a homogeneous group, but in fact form a structured population due to historical immigration of diverse source populations. Discerning the ancestry of European Americans genotyped in association studies is important in order to prevent false positive or negative associations due to population stratification and to identify genetic variants whose contribution to disease risk differs across European ancestries. Here, we investigate empirical patterns of population structure in European Americans, analyzing 4,198 samples from four genome-wide association studies to show that components roughly corresponding to northwest European, southeast European and Ashkenazi Jewish ancestry are the main sources of European American population structure. Building on this insight, we constructed a panel of 300 validated markers that are highly informative for distinguishing these ancestries. We demonstrate that this panel of markers can be used to correct for stratification in association studies that do not generate dense genotype data.


November 19, 2007

Sea level rise and the beginning of the Neolithic

From a EurekAlert release about this paper:
The researchers created reconstructions of the Mediterranean and Black Sea shoreline before and after the rise in sea levels. They estimated that nearly 73,000 square km of land was lost to the sea over a period of 34 years. Based on our knowledge of historical population levels, this could have led to the displacement of 145,000 people. Archaeological evidence shows that communities in southeast Europe were already practising early farming techniques and pottery production before the Flood. With the catastrophic rise in water levels it appears they moved west, taking their culture into areas inhabited by hunter-gatherer communities.

Catastrophic early Holocene sea level rise, human migration and the Neolithic transition in Europe

Chris S.M. Turney et al.


The collapse of the Laurentidenext term Ice Sheet and release of freshwater 8740–8160 years ago abruptly raised global sea levels by up to 1.4 m. The effect on human populations is largely unknown. Here we constrain the time of the main sea level rise and investigate its effect on the onset of the Neolithic across Europe. An analysis of radiocarbon ages and palaeoshoreline reconstruction supports the hypothesis that flooding of coastal areas led to the sudden loss of land favoured by early farmers and initiated an abrupt expansion of activity across Europe, driven by migrating Neolithic peoples.


November 11, 2007

Anthropological Research Page status

Just a quick note to readers of the Anthropological Research Page (ARP), which used to be hosted at Due to a problem with the host (supposed hacker attack), the ARP will no longer to be hosted in Angeltowns.

All the content of the ARP can be found in the Internet Archive, with the latest version being here. The formatting is a bit off, but otherwise all the content is preserved. I will re-upload the ARP to a suitable server once I find the time.

Waist-hip-ratio of mothers and children's intelligence

There is a related story in the New Scientist about the following article.

Evolution and Human Behavior (in press)

Waist-hip ratio and cognitive ability: is gluteofemoral fat a privileged store of neurodevelopmental resources?

William D. Lassek, Steven J.C. Gaulin


Upper-body fat has negative effects and lower-body fat has positive effects on the supply of long-chain polyunsaturated fatty acids that are essential for neurodevelopment. Thus, waist-hip ratio (WHR), a useful proxy for the ratio of upper-body fat to lower-body fat, should predict cognitive ability in women and their offspring. Moreover, because teenage mothers and their children compete for these resources, their cognitive development should be compromised, but less so for mothers with lower WHRs. These predictions are supported by data from the Third National Health and Nutrition Examination Survey. Controlling for other correlates of cognitive ability, women with lower WHRs and their children have significantly higher cognitive test scores, and teenage mothers with lower WHRs and their children are protected from cognitive decrements associated with teen births. These findings support the idea that WHR reflects the availability of neurodevelopmental resources and thus offer a new explanation for men's preference for low WHR.