Broad-faced men are more aggressive

From the New Scientist:

No matter how hard men try, they may not be able to hide their aggression. A study in male ice-hockey players suggests that to gauge a man's aggression levels, you just have to look at the proportions of his face.

Cheryl McCormick and Justin Carre from Brock University in Ontario, Canada, found that the larger the width-to-height ratio of a player’s face, the more aggressive they were.

They measured aggression by the number of penalty points each player accrued for potentially harmful behaviour, such as elbowing and fighting.

In general, men's faces tend to have a larger width-to-height ratio than women's. This physical characteristic has been linked to higher levels of testosterone, which in turn is linked to aggressive behaviour.

Interesting quote from the Physiognomonica attributed to Aristotle:

εν εκαστω γενει θηλυ αρρενος μικροκεφαλωτερον εστι και στενοπροσωποτερον και λεπτοτραχυλοτερον

in each genus, the female has a smaller head than the male, and a narrower face and a thinner neck

and the Physiognomonica attributed to Polemon:

τον ευφυην τοιουτον ειναι νοει ... επηρμενα προσωπα και σαρκωδη, ου μην λεπτα

consider the man of good nature to be such... raised and fleshy faces, but not narrow

and the Physiognomonica of Adamantius:

το θηλυ ως επι το πολυ εχει του αρρενος ... προσωπον στενωτερον

the female in most cases, compared to the male, has ... a narrower face

A reader asks in the comments whether men are indeed broader-faced than women. Looking at the data of Farkas et al. [International Anthropometric Study of
Facial Morphology in Various Ethnic Groups/Races], it appears that this is not the case. Out of the 25 groups where both male and female data exist, in 19 men have a higher facial index (narrower-faced) than women, and in 6 the opposite is true.

Here are the 6 groups where men have broader faces than women (greater difference first):

Slovaks [men's F.I. = 97.6% women's], Czechs, Germans, Hungarians, Vietnamese, Angolan [men's F.I. = 99.9% women's]

The median ratio of men/female F.I. is 101.9% (Slovenians); for Greeks it is 102%, very close to the median. For white Americans, the ratio is 102.3%.

I also looked at Howells' craniometric data, which includes a wider sampling of world populations, taking the ratio of Nasion-Prosthion/Bizygomatic. The ratio of the male to the female average is 99.5%, practically the same.

So, while men do have wider faces in the absolute sense (mean +7.6%, median +3.6% in the Howells set; mean +5.6%, median +6.3% in the Farkas set), they do not appear to have wider faces in terms of proportions compared to women.

[I will comment further when I read the article]

UPDATE (Aug 21)

I have posted the abstract below. They looked at the upper face, not the total face height, thus the data of Farkas et al. (which did not measure upper face height) are not relevant. But, the skull data of Howells is relevant, and do show the predicted sexual dimorphism, although not very noticeable on a global scale.

The authors cite Weston et al. (2007).

Young children possess shorter, broader faces relative to those of adults. However, a distinction between the sexes can also be observed that is linked to distinct male and female growth trajectories (Figure 1). Analysis of individual traits against age indicates that male and female growth trajectories diverge at puberty for BZW but not for FHT (Figures S2 and S3). This relationship of width-to-height of the upper face deviates from predictions based on ontogenetic scaling, as males (which are, on average, larger than females) have similar facial heights to females, whereas facial breadth is larger in the male

They used a South African collection to arrive at this conclusion.

I examined ZYB/NPH on either Europeans or Zulu, and list the mean and median values of the trait for men and women:

Europeans		Men	Women
Mean	ZYB/NPH	1.969	1.977
Median	ZYB/NPH	1.971	1.984
Zulu		Men	Women
Mean	ZYB/NPH	1.936	1.943
Median	ZYB/NPH	1.926	1.922

So, these don't look supportive of greater ZYB/NPH in males than in females. In this paper, the authors measured ZYB/NPH from photographs. It is very difficult to get an accurate estimate of the nasion, prosthion or zygomata using a photograph; the authors report high inter-rater reliability, but reliability means that different raters measure similarly, not that they measure correctly!

In particular they measured upper facial height from the brow to the lip. Their photograph indicates that they took this measurement from the lower point of the eyebrows. Since men are both hairier and don't remove eyebrow hair, it is quite possible that women's upper facial height was inflated. In any case, taking the upper facial height from the brow is not consistent with taking the nasion-prosthion height.

So, while the conclusion that broader-faced men are more aggressive is correct, the explanation that it is due to men having a higher breadth/upper face ratio seems suspect.

Proceedings of the Royal Society B doi: 10.1098/rspb.2008.0873

In your face: facial metrics predict aggressive behaviour in the laboratory and in varsity and professional hockey players

Justin M. Carré, Cheryl M. McCormick

Abstract

Facial characteristics are an important basis for judgements about gender, emotion, personality, motivational states and behavioural dispositions. Based on a recent finding of a sexual dimorphism in facial metrics that is independent of body size, we conducted three studies to examine the extent to which individual differences in the facial width-to-height ratio were associated with trait dominance (using a questionnaire) and aggression during a behavioural task and in a naturalistic setting (varsity and professional ice hockey). In study 1, men had a larger facial width-to-height ratio, higher scores of trait dominance, and were more reactively aggressive compared with women. Individual differences in the facial width-to-height ratio predicted reactive aggression in men, but not in women (predicted 15% of variance). In studies 2 (male varsity hockey players) and 3 (male professional hockey players), individual differences in the facial width-to-height ratio were positively related to aggressive behaviour as measured by the number of penalty minutes per game obtained over a season (predicted 29 and 9% of the variance, respectively). Together, these findings suggest that the sexually dimorphic facial width-to-height ratio may be an ‘honest signal’ of propensity for aggressive behaviour.

ESHG 2008 abstracts

The European Society of Human Genetics conference is coming up, and there are some very interesting abstracts.

Note: The ESHG site has updated with a notice that the abstracts are embargoed until their presentation time. Therefore, I have decided to remove the body of this post until then, although I think it is a bit weird to embargo something that one places on the public web. In any case, you can find the abstracts easily by going to the site above. (June 1): post restored.

The peopling of North Asia: Y and X perspectives

V. A. Stepanov, V. Kharkov, I. Khitrinskaya, O. Medvedeva, M. Spiridonova, A. Marusin, V. Puzyrev; Institute for Medical Genetics, Tomsk, Russian Federation.

Presentation Number: P07.056

To reconstruct the origin and evolution of human populations in North Asia we investigated the genetic diversity in 50 population samples (about 2000 individuals totally) using Y and X chromosome lineages. Y-chromosomal haplotypes were constructed with unique event polymorphisms (UEP) and STR markers according to Y Chromosome consortium (YCC) classification. SNP markers in a single 60 kb linkage disequilibrium region of ZFX gene was used to trace the X chromosomal population history. The genetic diversity of Y haplogroups was quite high (0.70 - 0.95) in most populations except few very isolated groups. The proportion of inter-population differences in the total genetic variability measured by Fst statistics is 17% for binary haplogroups and 19% for YSTR. Multidimensional scaling and principal component analysis revealed four major components in North Asian Y gene pool, reflecting the presence of Paleoasiatic (Q), Proto-Uralic (N3, N2), Eastern Asian (O, C), and Western Eurasian (R1, I, J) lineages. X-chromosomal haplotypes in North Asia are less divers (gene diversity within populations 0.65 - 0.80) and less differentiated (Fst = 4%) compared to Y lineages. The population clustering by X and Y gives, to a first approximation, a similar picture, and matrixes of genetic distances between populations for X and Y haplotypes significantly correlates. The age of genetic diversity generation and time of population differentiation demonstrates the Upper Paleolithic origin of major Y and X lineages and post-glacial population expansions. This work is supported by RFBR grants ##06-04-48274 and 07-04-01629.

The following seems to be a very important study; in particular the notion that particular Y chromosome/mtDNA haplogroups may be associated with higher or lower fertility may have implications about their distribution.

UPDATE (May 21): I did a quick and dirty analysis of the Y-haplogroup and mtDNA-haplogroup data from Bosch et al. (2006) (Ann Hum Genet. 2006 Jul;70(Pt 4):459-87.), and there is a -0.43 correlation between Y-haplogroup I and mtDNA-haplogroup H and a +0.46 correlation between Y-haplogroup R1 and mtDNA-haplogroup H. While not significant (with only 10 populations), this is definitely in the right direction for a selection effect for/against specific Y-DNA/mtDNA combinations.

... on the other hand, another quick and dirty analysis of 23 populations from Rootsi's survey on Y-haplogroup I and mtDNA frequencies from AJHG Volume 80, Issue 4, April 2007, Pages 759-768 didn't turn up any correlation. Perhaps, someone can look at possible correlations between Y-chromosome and mtDNA haplogroups in Europe to see if anything interesting turns up.

Male infertility induced by mtDNA/Y unfavorable combination? An association study on human mitochondrial DNA

S. C. Gomes1, S. Fernandes2, R. Gonçalves1, A. T. Fernandes1, A. Barros3, H. Geada4, A. Brehm1; 1Human Genetics Laboratory, University of Madeira, Funchal, Portugal, 2Genetics Department, Faculty of Medicine, University of Porto, Porto, Portugal, 3Centre of Reproductive Genetics A Barros, Porto, Portugal, 4Faculty of Medicine, University of Lisbon, Lisboa, Portugal.

Presentation Number: P07.084

There is growing evidence that certain mtDNA haplogroups determine a genetic susceptibility to various disorders bringing out the interest in the possible role of mtDNA background on the phenotype expression of mitochondrial genetic disorders. An association between haplogroup T and asthenospermia has been reported and several sublineages of haplogroup U were associated with differences in sperm motility and vitality. The deletion of some DAZ copies gene in 10-15% of azoospermic and oligospermic patients has been reported but also present in fertile men belonging to certain Y-haplogroups. The findings of one study have rarely been replicated by studies in other populations and conflicting associations have been reported. Our focus in this case-control study is to investigate the existence of other influences, besides a weak mtDNA background, promoting male infertility. The occurrence of a specific mtDNA variant associated to a certain Y-chromosome haplogroup could represent a vital link that will compromise the sperm function and be responsible for male infertility. A group of 99 infertile men and other one composed by 90 subjects with proven fertility were selected and analysed. The frequency of the combination mtDNA-haplogroup H (especially with the CRS sequence) and Y-haplogroup R was higher in fertile than in infertile men seemingly to be favorable to fertility. On the other hand, a considerable number of infertile men belonging to mtDNA-haplogroup H (CRS) and to Y-haplogroup I, associated to a specific DAZ gene deletion pattern- 2+4d, suggests a non favorable combination to male fertility.

The Bayash Roma: phylogenetic dissection of Eurasian paternal genetic elements

I. Martinovic Klaric, M. Pericic Salihovic, L. Barac Lauc, B. Janicijevic; Institute for Anthropological Research, Zagreb, Croatia.

Presentation Number: P07.110

The Bayash consist of numerous and small Romani groups speaking different dialects of the Romanian language and living dispersedly in Croatia, Hungary, Bosnia and Herzegovina, Serbia, Romania, Bulgaria, and to the lesser extent in Macedonia, Greece, Ukraine, Slovakia and Slovenia. Larger Bayash groups migrated to Croatia most likely during the 19th century, after abolition of slavery in Romania. Molecular architecture and the origin of the Croatian Bayash paternal gene pool was addressed by analysing 151 Bayash Y chromosomes from two Croatian regions, 332 Y chromosomes from Romani populations across Europe, 814 Y-chromosomes from non-Romani host populations living in Southeastern, Southern and Eastern Europe as well as with 1680 Y-chromosomes from South Asian populations. The Bayash in Croatia represent one population of largely shared paternal genetic history characterized by substantial percentage (44%) of common H1-M82 and E3b1-M78 lineages. Relatively ancient expansion signals and limited diversity of Indian specific H1-M82 lineages imply descent from closely related paternal ancestors who could have been settled in the Indian subcontinent between 7th and 9th centuries AD. Minimal time divergence of the Bayash subpopulations is consistent with their putative migratory split within Romania towards Wallachia and Transilvania. Substantial percentage of E3b1 lineages and high associated microsatellite variance in the Bayash men is a reflection of significant admixture with majority populations from the Vardar-Morava-Danube catchment basin - possibly a common paternal signature of Romani populations in Southeastern Europe. Additional traces of admixture are evident in the modest presence of typical European haplogroups.

Are the Moravian Valachs of Czech Republic the Aromuns of Central Europe? Model population for isolation and admixture

E. Ehler1,2, V. Vančata2; 1Department of Anthropology and Human Genetics, Charles University in Prague, Faculty of Science, Prague, Czech Republic, 2Department of Biology and Ecological Education, Charles University in Prague, Faculty of Education, Prague, Czech Republic.

Presentation Number: P07.129

Moravian Valachs of Czech Republic are one of the most distinct ethnic groups from Central Europe. Related to similar populations in Poland and Slovakia, they emerge at the end of 15th century, as the north-westernmost prominence of migration that started 250 years earlier in northern Romania. Being predominately highland sheep herders and of putative Romanian origin, they represent a Central European analogue of Balkan Aromanian populations. We have gathered Y-chromosomal, linguistic, ethnographic and historical data for this population and compared them with surrounding as well as with east European populations. Linguistic data show specific parts of shared vocabulary of Romanian origin between several pastoral groups in Central and Eastern Europe. Comparing genetic and linguistic pairwise distance matrices (Mantel test) in these populations did not revealed any significant correlation. Thus we confirmed that plain geographical distance still plays the major role in genetic distances between populations in Europe. From our further analysis it is clear, that the Moravian Valachs, after at least five centuries of admixture, are not overly genetically different from surrounding populations. On the other hand, from the point of view of intra-population diversity, they are much more similar to isolated Balkan populations (e.g. Aromuns) than to Central European populations.

Phylogeography of the human Y chromosome haplogroup E3a

F. Cruciani1, B. Trombetta1, D. Sellitto2, C. Nodale1, R. Scozzari1; 1Sapienza Università di Roma, Rome, Italy, 2Consiglio Nazionale delle Ricerche, Rome, Italy.

Presentation Number: P07.134

The Y chromosome specific biallelic marker DYS271 defines the most common haplogroup (E3a) currently found in sub-Saharan Africa. A sister clade, E3b (E-M215), is rare in sub-Saharan Africa, but very common in northern and eastern Africa. On the whole, these two clades represent more than 70% of the Y chromosomes of the African continent. A third clade belonging to E3 (E3c or E-M329) has been recently reported to be present only in eastern Africa, at low frequencies. In this study we analyzed more than 1,600 Y chromosomes from 55 African populations, using both new and previously described biallelic markers, in order to refine the phylogeny and the geographic distribution of the E3a haplogroup. The most common E-DYS271 sub-clades (E-DYS271*, E-M191, E-U209) showed a non uniform distribution across sub-Saharan Africa. Most of the E-DYS271 chromosomes found in northern and western Africa belong to the paragroup E-DYS271*, which is rare in central and southern Africa. In these latter regions, haplogroups E-M191 and E-U209 show similar frequency distributions and coalescence ages (13 and 11 kyr, respectively), suggesting their involvement in the same migratory event/s. By the use of two new phylogenetically equivalent markers (V38 and V89), the earlier tripartite structure of E3 haplogroup was resolved in favor of a common ancestor for haplogroups E-DYS271 (formerly E3a) and E-M329 (formerly E3c). The new topology of the E3 haplogroup is suggestive of a relatively recent eastern African origin for the majority of the chromosomes presently found in sub-Saharan Africa.

Y-chromosome lineages in Xhosa and Zulu Bantu speaking populations

R. P. A. Gonçalves, H. Spínola, A. Brehm; Human Genetics Laboratory, Funchal, Portugal.

Presentation Number: P07.137

Y-chromosome Single Nucleotide Polymorphisms have been analysed in Zulu and Xhosa, two southern Africa Bantu speaking populations. These two ethnic groups have their origin on the farmer’s Bantu expansion from Niger-Congo border towards sub-Sahel regions on the southern tip of the continent, during the past 3000 years. Seven different Y-chromosome haplogroups were found in Zulu contrasting with only two in Xhosa. E3a, a common haplogroup among West sub-Saharans associated to Bantu migration was the most prevalent in both populations (56.9% in Zulu and 90% in Xhosa). The second most common haplogroup was E2 (29.3% in Zulu and 10% in Xhosa), present both in West and East African populations. The present-day Zulu and Xhosa paternal legacy is essentially of West sub-Saharan origin. Zulu population shows a most diverse genetic influence comparing to Xhosa, revealing some pre-Bantu expansion markers and East African influences. Zulu presents 8.6% Y-chromosome haplogroups (A, B, J1) of non-Bantu influence that could indicate gene flow from other populations, particularly Khoisan.

Human genetic population structure: Patterns and underlying processes

Presentation Time: Tuesday, 9:15 a.m. - 9:45 a.m.

G. Barbujani; University of Ferrara, Department of Biology and Evolution, Ferrara, Italy.

Presentation Number: S15.2

Classical studies of genetic diversity in humans consistently showed that the largest proportion of human diversity occurs among members of the same population. On average, differences among different populations in the same continent represent 5% of the global human variance, and differences among continents another 10%. Genetic variation is largely discordant across the genome, meaning that different loci show different spatial patterns, and implying that a good description of population structure can only be based on the analysis of multiple loci. Studies of single loci are also unlikely to reasonably identify an individual’s place of origin. A general decline of genetic of genetic diversity with distance from Africa, and a parallel increase in linkage disequilibrium, can be accounted for by the effects of a series of founder effects accompanying the spread of anatomically-modern humans from Africa. Recent DNA analyses at the global level show that most allelic variants are cosmopolitan and only a small percentage are continent-specific, whereas a clearer continental structure emerges when considering composite haplotypes. This suggests that, at the global level, gene flow has had a strong impact on genetic diversity, through both directional dispersal and successive short-range migratory exchanges. At the local level, several factors have contributed to genetic differentiation, and, in particular, language barriers have been shown to be associated with small but non-negligible increases of the genetic differences between neighboring populations.

Hierarchical analysis of 28 Y-chromosome SNP’s in the population of the Republic of Macedonia

P. Noveski, S. Trivodalieva, G. D. Efremov, D. Plaseska-Karanfilska;
Macedonian Academy of Sciences and Arts, Research Centre for Genetic Engineering and Biotechnology, Skopje, Macedonia, The Former Yugoslav Republic of.

Presentation Number: P05.211

Analysis of Y-chromosome haplogroups, defined by single nucleotide polymorphisms (SNP’s), has become a standard approach for studying the origin of human populations and measuring the variability among them. Furthermore, Y-SNP’s represent a new forensic tool, because their population specificity may allow to determine the origin of any male sample of interest for forensic purposes. The aim of this study was to develop a strategy for rapid, simple and inexpensive Y-chromosome SNP’s typing in the population of R. Macedonia. We have studied a total of 343 DNA male samples; 211 Macedonians, 111 Albanians and 21 of other ethnic origin (Roma, Serbs and Turks). Methodology included multiplex PCR and single nucleotide extension reaction by SNaPshot multiplex kit. The set of 28 markers has been grouped in 5 multiplexes in order to determine the most frequent haplogroups using only 1 or 2 multiplexes. Twenty different Y haplogroups were determined among 343 male DNA samples. The finding that five haplogroups (E3b1, I1b1, J2b1a, R1a and R1b) comprise more than 70% of the Y chromosomes is consistent with the typical European Y chromosome gene pool. The distribution of the Y-haplogroups differs between Macedonians and Albanians. The most common Y haplogroup among Macedonians is I1b1 (27.5%), followed by three haplogroups present with similar frequencies E3b1 (15.6%), R1a (14.2%) and R1b (11.4%). Among Albanians the most frequent Y haplogroup is E3b1 (28.8%), followed by R1b (18.0%), J2b1a (13.5%) and R1a (12.6%).

The following paper (probably) refers to a recent study, according to which:

One of the most elevated values of 35delG prevalence corresponds to Greece (1/28); the pattern of various 35delG prevalences is interpretated in the present meta-analysis as the result of Ancient Greek colonizations of the "Magna Grecia" in historical times.

Strong linkage disequilibrium for the frequent GJB2 35delG mutation in the Greek population
H. Kokotas¹, L. Van Laer², M. Grigoriadou¹, V. Iliadou³, J. Economides⁴, S. Pomoni¹, A. Pampanos¹, N. Eleftheriades⁵, E. Ferekidou⁶, S. Korres⁶, A. Giannoulia-Karantana⁷, G. Van Camp², M. B. Petersen¹;
¹Institute of Child Health, Athens, Greece, ²University of Antwerp, Antwerp, Belgium, ³AHEPA Hospital, Thessaloniki, Greece, ⁴‘Aghia Sophia’ Children’s Hospital, Athens, Greece, ⁵St. Loukas Hospital, Thessaloniki, Greece, ⁶Athens University, Athens, Greece, ⁷Athens University Medical School, Athens, Greece.

Presentation Number: P06.080

Approximately one in 1,000 children is affected by severe or profound hearing loss at birth or during early childhood (prelingual deafness). Up to forty percent of autosomal recessive, congenital, severe to profound hearing impairment cases result from mutations in a single gene, GJB2. The 35delG mutation accounts for the majority of GJB2 mutations detected in Caucasian populations and represents one of the most frequent disease mutations identified so far. Some previous studies have assumed that the high frequency of the 35delG mutation reflects the presence of a mutational hot spot, whilst other studies support the theory of a common founder. Greece is amongst the countries presenting high frequency of the 35delG mutation (3.5%), and a recent study raised the hypothesis of the origin of this mutation in ancient Greece. We genotyped 60 Greek deafness patients homozygous for the 35delG mutation for six single nucleotide polymorphisms (SNPs) and two microsatellite markers, mapping within or flanking the GJB2 gene, as compared to 60 Greek hearing controls. A strong linkage disequilibrium was found between the 35delG mutation and markers inside or flanking the GJB2 gene, at distances of 34 kb on the centromeric and 90 kb on the telomeric side of the gene, respectively. Our study supports the hypothesis of a founder effect and we further propose that ethnic groups of Greek ancestry could have propagated the 35delG mutation, as evidenced by historical data beginning from the 15^th century BC.

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

Affinities of Early Upper Paleolithic Europeans

Some interesting information about the affinities of Early Upper Paleolithic (EUP) European crania. EUP Europeans were generalized Caucasoids, and are remarkably similar to modern Europeans despite the tens of thousands of years that have intervened and the substantial replacement of the original EUP population by later migrations evidenced in European mtDNA.

Some of the discordance Van Vark et al. see between genetic and morphometric results may be attributable to their methodological choices. It is clear that the affiliation expressed by a given skull is not independent of the number of measurements taken from it. From their Table 3, it is evident that those skulls expressing Norse affinity are the most complete and have the highest number of measurements ( = 50.8), while those expressing affinity to African populations (Bushman or Zulu) are the most incomplete, averaging just 16.8 measurements per skull. Use of highly incomplete or reconstructed crania may not yield a good estimate of their morphometric affinities. When one considers only those crania with 40 or more measurements, a majority express European affinity.

To examine this idea further, we use the eight Upper Paleolithic crania available from the test series of Howells ([1995]), all of which are complete. Our analysis of these eight, based on 55 measurements, is presented in Table 1. Using raw measurements, 6 of 8 express an affinity to Norse, and with the shape variables of Darroch and Mosimann ([1985]), 5 of 8 express a similarity to Norse. Using shape variables reduces the Mahalanobis distance, substantially in some cases. Typicality probabilities (Wilson, [1981]), particularly for the shape variables, show the crania to be fairly typical of recent populations. The results presented in Table 1 are consistent with the idea that Upper Paleolithic crania are, for the most part, larger and more generalized versions of recent Europeans. Howells ([1995]) reached a similar conclusion with respect to European Mesolithic crania.



...

Next, let us examine the issue of whether the EUP situation can be regarded as parallel to the Native American one. There are some obvious differences, principal among them the time frame. The European crania used by Van Vark et al. span 26,000 years, as against our North American sample that spans about 2,400 years. Their EUP series dates from 37,000 BP to about 9,000 BP, as against a maximum time frame for our North American sample of 9,400-7,000 BP (Jantz and Owsley, [2001]). The Upper Paleolithic time span is significantly older and more than 10 times longer than the American one, yet the EUP crania are not correspondingly further removed from the contemporary population. Given that European fossil crania are separated from their supposed descendants by greater temporal distance than is the case in America, one could easily accept that European fossil crania might be more loosely connected to the modern population. Yet, we observe just the opposite. The data in Van Vark et al. demonstrate a higher degree of affiliation with the supposed descendent modern population (16/35 = 46%) than we found in the American situation (1/11 = 9%).

American Journal of Physical Anthropology
Volume 121, Issue 2, Pages 185-188

Reply to Van Vark et al.: Is European Upper Paleolithic cranial morphology a useful analogy for early Americans?

Richard L. Jantz, Douglas W. Owsley

No abstract

Link

Sexual dimorphism in 26 populations

Using the same data as before, I calculate the sexual dimorphism in 26 craniometric samples from around the world.

There are many ways to express sexual dimorphism, i.e., differences between men and women, which extend to both size and shape. I will limit myself to the simple measure of the average (over all traits) ratio of the male to the female mean (over all individuals).

Zulu 1.06
Egypt 1.06
Atayal 1.06
Zalavar 1.06
San 1.07
Hainan 1.07
Tasmanian 1.07
Moriori 1.07
Norse 1.07
Lake Alexandrina 1.07
Tolai 1.07
Dogon 1.08
Berg 1.08
Philippine 1.08
Yauyos 1.08
Teita 1.08
Buriat 1.08
Santa Cruz Island 1.08
North Kyushu 1.08
Ainu 1.09
Andaman Islands 1.09
Arikara 1.09
Hokkaido 1.09
Mokapu 1.09
Easter Island 1.09
Guam 1.09

So, it appears that these populations do not differ by much from each other in terms of sexual dimorphism. But, if we look at individual traits, the situation is much different. Men and women are most dimorphic (in decreasing order) in terms of their glabella projection (1.52), supraorbital projection (1.25), simotic subtense (1.2), mastoid breadth (1.18), mastoid height (1.16). So, it turns out that men and women can be quite different in terms of some traits, but not in terms of others.

Who is the most diverse of them all?

Here is the diversity ranking of Howells' 28 human populations based on 45 cranial measurements. The numbers are the average population standard deviation (for each population over all 45 measurements) as a percentage of the average human standard deviation (for all groups over all 45 measurements). In parentheses, the racial cluster of each population according to my previous analysis.

Guam 76.8 (Mongoloid)
Andaman Islands 76.8 (Andamanese)
Santa Cruz Island 76.9 (Americanoid)
Zalavar 77.0 (Caucasoid)
Yauyos 77.8 (Americanoid)
Easter Island 77.9 (Polynesoid)
Arikara 78.2 (Americanoid)
Moriori 78.2 (Polynesoid)
Tolai 78.3 (Australoid)
Lake Alexandrina 78.3 (Australoid)
Atayal 78.8 (Mongoloid)
Hainan 79.2 (Mongoloid)
Anyang 79.9 (Mongoloid)
Norse 80.1 (Caucasoid)
North Kyushu 80.6 (Mongoloid)
Mokapu 80.9 (Polynesoid)
Ainu 81.3 (Ainu)
Eskimo 81.6 (Eskimo)
Egypt 82.8 (Caucasoid)
Phillipine 84.2 (Mongoloid)
Dogon 84.5 (Negroid)
Teita 84.8 (Negroid)
Zulu 85.1 (Negroid)
Berg 85.3 (Caucasoid)
Tasmanian 85.3 (Australoid)
Hokkaido 85.5 (Mongoloid)
Buriat 87.0 (Mongoloid)
San 89.0 (Capoid)

Caucasoid vs. Negroid phenotypic variation

It is well known that the populations of Africa have an excess of neutral genetic variation. This observation, in addition to paleoanthropological data has led to the conclusion that mankind has originated in Africa.

Neutral variation is just one type of human variation. It is the type of variation that doesn't seem to be doing anything, thus making it useful to assess the relationships between populations. On the other hand, genes that actually do something may be under selection, and hence their patterns of variation may reflect environmental selective pressure and not genetic relationship.

We can't at present quantify the amount of genetic variation for most human traits of interest, because we don't have a clue about which genes are responsible for these traits. Therefore, we have to turn to the study of human phenotypes thought to be under genetic control.

I have carried a simple experiment using Howells' craniometric data to measure the level of phenotypic diversity for 45 different measurements.

I limit myself to the three medieval European populations (Norse, Berg and Zalavar) and the three Sub-Saharan African populations (Dogon, Teita, Zulu). It's interesting that the European populations are spatially closer to each other than the African populations. Therefore, we should expect them to be more similar to each other than the Africans are. In addition, if African neutral genetic diversity extends also to the functional diversity underlying human cranial development, we would expect the Africans to be even more diverse.

I limit myself to the male samples and compute the standard deviation for each trait separately for the Europeans, the Africans, and the entire human sample.

First, we can compute what the average standard deviation is, i.e., averaged over all 45 traits. It turns out that this is (normalized so that humans have SD=100):

Humans (100) : Africans (88) : Europeans (85)

Predictably, humans in total are most diverse, followed by Africans, and then Europeans. It is however surprising that Europeans are almost as diverse as Africans, given that they are drawn from three medieval locations of Central-Northern Europe compared to the three widely separated African populations. It would be interesting to see how these numbers look if we sample from the entire range of the Caucasoid and the Negroid race, rather than just these convenient publically available populations.

Of course, the above ratio is averaged over all 45 traits. What about individual traits? I list the three traits in which Africans are most diverse compared to Europeans and vice versa. Here we set the African standard deviation to be 100:

Simotic chord (least nasal breadth): Europeans (73)
Bregma-subtense fraction: Europeans (77)
Orbit breadth (left): Europeans (77)
Interorbital breadth: Europeans (116)
Nasio-occipital length: Europeans (118)
Biauricular breadth: Europeans (140)

It is obvious that for some traits Africans are more diverse compared to Europeans and for others Europeans are more diverse than Africans.

In conclusion, it turns out that we should not generalize from neutral genetic variation to functional genetic variation, as the latter may show a different pattern of variation than the former. Moreover, each group may be more diverse in terms of some traits but not in terms of others.