The genetic legacy of the expansion of Bantu-speaking peoples in Africa.

The expansion of people speaking Bantu languages is the most dramatic demographic event in Late Holocene Africa and fundamentally reshaped the linguistic, cultural and biological landscape of the continent1-7. With a comprehensive genomic dataset, including newly generated data of modern-day and ancient DNA from previously unsampled regions in Africa, we contribute insights into this expansion that started 6,000-4,000 years ago in western Africa. We genotyped 1,763 participants, including 1,526 Bantu speakers from 147 populations across 14 African countries, and generated whole-genome sequences from 12 Late Iron Age individuals8. We show that genetic diversity amongst Bantu-speaking populations declines with distance from western Africa, with current-day Zambia and the Democratic Republic of Congo as possible crossroads of interaction. Using spatially explicit methods9 and correlating genetic, linguistic and geographical data, we provide cross-disciplinary support for a serial-founder migration model. We further show that Bantu speakers received significant gene flow from local groups in regions they expanded into. Our genetic dataset provides an exhaustive modern-day African comparative dataset for ancient DNA studies10 and will be important to a wide range of disciplines from science and humanities, as well as to the medical sector studying human genetic variation and health in African and African-descendant populations.

Parents' perspectives on the use of children's facial images for research and diagnosis: a survey.

Computer-aided facial diagnostic tools are valuable emerging technologies for the early detection and initial diagnosis of congenital disorders. These tools require large datasets of facial photographs, especially of infants and children, to identify these disorders and improve classification accuracies. Researchers need to balance this need for larger datasets with patients' privacy rights, needs and preferences. This study aimed to investigate parents' views regarding the collection, storage, use and publication of their children's facial images for research and diagnostic purposes. A total of 151 parents of children with and without congenital disorders completed an online survey evaluating their views on the collection, storage, use and publication of children's facial images for research and diagnosis. Overall, 72.5% of parents would allow researchers to take facial photographs of their children, preferring the images to be stored in a secure database that is not available to the public. Parents of children with congenital disorders were more accepting of researchers taking facial photographs of their children, compared to parents of children without these conditions. Half of the respondents would allow facial photographs of their children to be published in academic journals, without their eyes covered, and this acceptance increased as the proportion of the child's face covered increased. Parents also indicated specific requirements to allow the use of these images in other similar research studies which need to be taken into consideration when planning studies that involve facial analysis research.

Male-biased migration from East Africa introduced pastoralism into southern Africa.

BACKGROUND: Hunter-gatherer lifestyles dominated the southern African landscape up to ~ 2000 years ago, when herding and farming groups started to arrive in the area. First, herding and livestock, likely of East African origin, appeared in southern Africa, preceding the arrival of the large-scale Bantu-speaking agro-pastoralist expansion that introduced West African-related genetic ancestry into the area. Present-day Khoekhoe-speaking Namaqua (or Nama in short) pastoralists show high proportions of East African admixture, linking the East African ancestry with Khoekhoe herders. Most other historical Khoekhoe populations have, however, disappeared over the last few centuries and their contribution to the genetic structure of present-day populations is not well understood. In our study, we analyzed genome-wide autosomal and full mitochondrial data from a population who trace their ancestry to the Khoekhoe-speaking Hessequa herders from the southern Cape region of what is now South Africa. RESULTS: We generated genome-wide data from 162 individuals and mitochondrial DNA data of a subset of 87 individuals, sampled in the Western Cape Province, South Africa, where the Hessequa population once lived. Using available comparative data from Khoe-speaking and related groups, we aligned genetic date estimates and admixture proportions to the archaeological proposed dates and routes for the arrival of the East African pastoralists in southern Africa. We identified several Afro-Asiatic-speaking pastoralist groups from Ethiopia and Tanzania who share high affinities with the East African ancestry present in southern Africa. We also found that the East African pastoralist expansion was heavily male-biased, akin to a pastoralist migration previously observed on the genetic level in ancient Europe, by which Pontic-Caspian Steppe pastoralist groups represented by the Yamnaya culture spread across the Eurasian continent during the late Neolithic/Bronze Age. CONCLUSION: We propose that pastoralism in southern Africa arrived through male-biased migration of an East African Afro-Asiatic-related group(s) who introduced new subsistence and livestock practices to local southern African hunter-gatherers. Our results add to the understanding of historical human migration and mobility in Africa, connected to the spread of food-producing and livestock practices.

MHC Class II Heterozygosity Associated With Attractiveness of Men and Women.

The genes of the Major Histocompatibility Complex (MHC), which plays a fundamental role in the immune system, are some of the most diverse genes in vertebrates and have been connected to mate choice in several species, including humans. While studies suggest a positive relationship between MHC diversity and male facial attractiveness, the connection of MHC diversity to other visual traits and female attractiveness is still unclear. The purpose of this study was to investigate further whether MHC heterozygosity, indicating genetic quality, is associated with visual traits affecting mate preferences in humans. In total 74 Latvian men and 49 women were genotyped for several MHC loci and rated for facial and, in men, also body attractiveness. The results indicate a preference for MHC heterozygous female and male faces. However, the initially positive relationship between MHC heterozygosity and facial attractiveness becomes non-significant in females, when controlling for multiple testing, and in males, when age and fat content is taken into account, referring to the importance of adiposity in immune function and thus also attractiveness. Thus overall the effect of MHC heterozygosity on attractiveness seems weak. When considering separate loci, we show that the main gene related to facial attractiveness is the MHC class II DQB1; a gene important also in viral infections and autoimmune diseases. Indeed, in our study, heterozygous individuals are rated significantly more attractive than their homozygous counterparts, only in relation to gene DQB1. This study is the first to indicate a link between DQB1 and attractiveness in humans.

Dysbiosis Signatures of Fecal Microbiota in South African Infants with Respiratory, Gastrointestinal, and Other Diseases.

OBJECTIVE: To determine the association between the fecal microbiota diversity of the infants with different disease conditions, and vitamin A supplementation, antibiotic, and deworming therapies. STUDY DESIGN: In this case-control study, the bacterial community variations and the potential pathogens were identified through 16S ribosomal RNA gene-based amplicon sequencing and quantitative insights into microbial ecology pipeline in fecal samples. The participants were South African infants (mean age, 16 ± 8 months; 17 male and 17 female) hospitalized and diagnosed with gastrointestinal, respiratory, and other diseases. RESULTS: The top phyla of the infants with respiratory disease were Proteobacteria, followed by Firmicutes, which were equally abundant in gastrointestinal disease. A significant difference in Shannon (alpha) diversity index (95% CI, 2.6-4.4; P = .008), among the microbiota of the fecal samples categorized by disease conditions, was observed. In beta diversity analysis of fecal microbiota, remarkable variations were found within the groups of deworming therapy (95% CI, 0.40-0.90; P = .033), disease conditions (95% CI, 0.44-0.86; P < .012) through unweighted and antibiotic therapy (95% CI, 0.20-0.75; P = .007), vitamin A intake (95% CI, 0.10-0.80; P < .033) and disease conditions (95% CI, 0.10-0.79; P = .006) through weighted UniFrac distances. The candidate pathogen associated with the disease groups were identified through analysis of the composition of microbiomes analysis. CONCLUSIONS: This study provides preliminary evidence for the fecal microbiome-derived dysbiosis signature and pathobiome concept that may be observed in young children during illness.

Effects of Varying the Color, Aroma, Bitter, and Sweet Levels of a Grapefruit-Like Model Beverage on the Sensory Properties and Liking of the Consumer.

Color, aroma, sweet, and bitter tastes contribute to the sensory perception of grapefruit juice. Consumers differ about liking grapefruit. A reason is the bitter taste that characterize the fruit. The objective was to determine the effect of varying the color (red or yellow), aroma (two levels), bitterness (three levels), and sweetness (three levels) of a grapefruit-like model beverage, on consumers' liking and perception of its sensory properties. The sensory profiles of thirty-six grapefruit-like beverages, created on the basis of a factorial design, has been described. Consumers rated their liking of color, aroma, and flavor of the twelve most diverse beverages. Bitter and sweet levels of the beverages had a significant effect on the flavor and aftertaste attributes. Aroma concentration had a significant effect on the majority of the sensory attributes. Color had a significant effect on perception of some of the aroma attributes, as well as the grapefruit's flavor intensity. Consumers liked the red beverages more than the yellow ones, and those with low aroma over the high aroma intensity. Consumers preferred the low bitter/high sweet beverages. Pungent and grapefruit aroma were found to be negative drivers for liking of the aroma. Sweet and citrus flavors were found to be positive drivers and sour and bitter flavors were found to be negative drivers of flavor-preferences (or liking) of the tested beverages.

Facial Adiposity, Attractiveness, and Health: A Review.

The relationship between facial cues and perceptions of health and attractiveness in others plays an influential role in our social interactions and mating behaviors. Several facial cues have historically been investigated in this regard, with facial adiposity being the newest addition. Evidence is mounting that a robust link exists between facial adiposity and attractiveness, as well as perceived health. Facial adiposity has also been linked to various health outcomes such as cardiovascular disease, respiratory disease, blood pressure, immune function, diabetes, arthritis, oxidative stress, hormones, and mental health. Though recent advances in the analysis of facial morphology has led to significant strides in the description and quantification of facial cues, it is becoming increasingly clear that there is a great deal of nuance in the way that humans use and integrate facial cues to form coherent social or health judgments of others. This paper serves as a review of the current literature on the relationship between facial adiposity, attractiveness, and health. A key component in utilizing facial adiposity as a cue to health and attractiveness perceptions is that people need to be able to estimate body mass from facial cues. To estimate the strength of the relationship between perceived facial adiposity and body mass, a meta-analysis was conducted on studies that quantified the relationship between perceived facial adiposity and BMI/percentage body fat. Summary effect size estimates indicate that participants could reliably estimate BMI from facial cues alone (r = 0.71, n = 458).

Facial Shape Analysis Identifies Valid Cues to Aspects of Physiological Health in Caucasian, Asian, and African Populations.

Facial cues contribute to attractiveness, including shape cues such as symmetry, averageness, and sexual dimorphism. These cues may represent cues to objective aspects of physiological health, thereby conferring an evolutionary advantage to individuals who find them attractive. The link between facial cues and aspects of physiological health is therefore central to evolutionary explanations of attractiveness. Previously, studies linking facial cues to aspects of physiological health have been infrequent, have had mixed results, and have tended to focus on individual facial cues in isolation. Geometric morphometric methodology (GMM) allows a bottom-up approach to identifying shape correlates of aspects of physiological health. Here, we apply GMM to facial shape data, producing models that successfully predict aspects of physiological health in 272 Asian, African, and Caucasian faces - percentage body fat (21.0% of variance explained), body mass index (BMI; 31.9%) and blood pressure (BP; 21.3%). Models successfully predict percentage body fat and blood pressure even when controlling for BMI, suggesting that they are not simply measuring body size. Predicted values of BMI and BP, but not percentage body fat, correlate with health ratings. When asked to manipulate the shape of faces along the physiological health variable axes (as determined by the models), participants reduced predicted BMI, body fat and (marginally) BP, suggesting that facial shape provides a valid cue to aspects of physiological health.

Facial appearance reveals immunity in African men.

Facial appearance is thought to indicate immunity in humans, but very few studies have tested this relationship directly. The aim of this study was to test the relationship between direct measures of immunity, perceived facial health and attractiveness, and facial cues in African men. We show that men with a stronger cytokine response are considered significantly more attractive and healthy. Men with more masculine, heavier facial features (i.e. muscular appearance) have a significantly higher cytokine response and appear significantly healthier and more attractive, while men with a yellower, lighter, "carotenoid" skin colour, have a marginally higher immune response and are also considered significantly more healthy and attractive. In contrast, more symmetrical, skinnier looking men appeared more attractive and healthier, but did not have a stronger cytokine response. These findings also shed new light on the "androgen-mediated" traits proposed by the immunocompetence handicap hypothesis (ICHH) and we propose that facial muscularity serves as a better estimate of an "androgen-mediated" trait than facial masculinity. Finally, we build on previous evidence to show that men's facial features do indeed reveal aspects of immunity, even better than more traditional measures of health, such as body mass index (BMI).

Cross-cultural agreement in facial attractiveness preferences: the role of ethnicity and gender.

Previous work showed high agreement in facial attractiveness preferences within and across cultures. The aims of the current study were twofold. First, we tested cross-cultural agreement in the attractiveness judgements of White Scottish and Black South African students for own- and other-ethnicity faces. Results showed significant agreement between White Scottish and Black South African observers' attractiveness judgements, providing further evidence of strong cross-cultural agreement in facial attractiveness preferences. Second, we tested whether cross-cultural agreement is influenced by the ethnicity and/or the gender of the target group. White Scottish and Black South African observers showed significantly higher agreement for Scottish than for African faces, presumably because both groups are familiar with White European facial features, but the Scottish group are less familiar with Black African facial features. Further work investigating this discordance in cross-cultural attractiveness preferences for African faces show that Black South African observers rely more heavily on colour cues when judging African female faces for attractiveness, while White Scottish observers rely more heavily on shape cues. Results also show higher cross-cultural agreement for female, compared to male faces, albeit not significantly higher. The findings shed new light on the factors that influence cross-cultural agreement in attractiveness preferences.

Effect of beta-carotene supplementation on African skin.

The quantification of skin carotenoid levels has a range of applications in Caucasian populations, from serving as a versatile and noninvasive biomarker (e.g., of systemic carotenoid levels, carotenoid consumption, the antioxidative capacity of skin, and oxidative stress) to being used in appearance-based interventions. Yet, no study has investigated the quantitative effect of carotenoid supplementation on African skin. The aim of this study was to determine if beta-carotene supplementation produces a significant color change in three different regions of African skin. To do so we supplemented the diet of African participants with beta-carotene over an eight-week period. Reflectance spectrophotometry measurements were taken on a weekly basis for the duration of the supplementation study. Results show a significant increase in the carotenoid coloration of lightly pigmented skin (palm of the hand) and highly pigmented skin with low sun exposure (inner arm) after supplementation. The latter was no longer significant after Bonferroni correction. The carotenoid coloration of highly pigmented skin areas with high sun exposure did not increase significantly. Skin carotenoid measurements of the palm of the hand might, therefore, serve as a potential biomarker for systemic carotenoid concentrations in people of African descent.

Looking like a leader-facial shape predicts perceived height and leadership ability.

Judgments of leadership ability from face images predict the outcomes of actual political elections and are correlated with leadership success in the corporate world. The specific facial cues that people use to judge leadership remain unclear, however. Physical height is also associated with political and organizational success, raising the possibility that facial cues of height contribute to leadership perceptions. Consequently, we assessed whether cues to height exist in the face and, if so, whether they are associated with perception of leadership ability. We found that facial cues to perceived height had a strong relationship with perceived leadership ability. Furthermore, when allowed to manually manipulate faces, participants increased facial cues associated with perceived height in order to maximize leadership perception. A morphometric analysis of face shape revealed that structural facial masculinity was not responsible for the relationship between perceived height and perceived leadership ability. Given the prominence of facial appearance in making social judgments, facial cues to perceived height may have a significant influence on leadership selection.

Facial attractiveness is related to women's cortisol and body fat, but not with immune responsiveness.

Recent studies suggest that facial attractiveness indicates immune responsiveness in men and that this relationship is moderated by stress hormones which interact with testosterone levels. However, studies testing whether facial attractiveness in women signals their immune responsiveness are lacking. Here, we photographed young Latvian women, vaccinated them against hepatitis B and measured the amount of specific antibodies produced, cortisol levels and percentage body fat. Latvian men rated the attractiveness of the women's faces. Interestingly, in women, immune responsiveness (amount of antibodies produced) did not predict facial attractiveness. Instead, plasma cortisol level was negatively associated with attractiveness, indicating that stressed women look less attractive. Fat percentage was curvilinearly associated with facial attractiveness, indicating that being too thin or too fat reduces attractiveness. Our study suggests that in contrast to men, facial attractiveness in women does not indicate immune responsiveness against hepatitis B, but is associated with two other aspects of long-term health and fertility: circulating levels of the stress hormone cortisol and percentage body fat.

Adiposity, compared with masculinity, serves as a more valid cue to immunocompetence in human mate choice.

According to the 'good genes' hypothesis, females choose males based on traits that indicate the male's genetic quality in terms of disease resistance. The 'immunocompetence handicap hypothesis' proposed that secondary sexual traits serve as indicators of male genetic quality, because they indicate that males can contend with the immunosuppressive effects of testosterone. Masculinity is commonly assumed to serve as such a secondary sexual trait. Yet, women do not consistently prefer masculine looking men, nor is masculinity consistently related to health across studies. Here, we show that adiposity, but not masculinity, significantly mediates the relationship between a direct measure of immune response (hepatitis B antibody response) and attractiveness for both body and facial measurements. In addition, we show that circulating testosterone is more closely associated with adiposity than masculinity. These findings indicate that adiposity, compared with masculinity, serves as a more important cue to immunocompetence in female mate choice.

African perceptions of female attractiveness.

Little is known about mate choice preferences outside Western, educated, industrialised, rich and democratic societies, even though these Western populations may be particularly unrepresentative of human populations. To our knowledge, this is the first study to test which facial cues contribute to African perceptions of African female attractiveness and also the first study to test the combined role of facial adiposity, skin colour (lightness, yellowness and redness), skin homogeneity and youthfulness in the facial attractiveness preferences of any population. Results show that youthfulness, skin colour, skin homogeneity and facial adiposity significantly and independently predict attractiveness in female African faces. Younger, thinner women with a lighter, yellower skin colour and a more homogenous skin tone are considered more attractive. These findings provide a more global perspective on human mate choice and point to a universal role for these four facial cues in female facial attractiveness.

Judging the health and attractiveness of female faces: is the most attractive level of facial adiposity also considered the healthiest?

Perceived facial adiposity plays an important role in perceptions of both facial attractiveness and health, but people might differentiate between the level of adiposity they find most attractive and healthy. The aim of this study was therefore to test whether or not similar levels of adiposity in faces were preferred for judgments of health and attractiveness. Fifty-three Caucasian university students were asked to make three-dimensional female faces appear as healthy and attractive as possible by changing faces along a continuum that portrays the facial adiposity change associated with a change in body mass index. Results showed that women preferred a significantly lower level of facial adiposity when judging attractiveness than when judging health, while men did not differentiate between the 'most attractive' and 'most healthy' looking level of facial adiposity. These findings are discussed in terms of the sociocultural portrayal of female body ideals and the preference for healthy individuals.

African and Caucasian body ideals in South Africa and the United States.

African women are often thought to be protected from developing eating disorder pathology because they experience less cultural pressure to be thin. Yet, to our knowledge, no previous study has quantified the African body ideals portrayed by the media. We determined the African and Caucasian body ideals portrayed by the media in the United States (US) and South Africa (RSA), by calculating the average body mass index of male and female fashion models in the respective countries. The African female body ideal was significantly heavier than the Caucasian body ideal in the US, but significantly thinner than the Caucasian body ideal in RSA. The African male body ideal was significantly thinner than the Caucasian body ideal in both countries. Findings indicate that the body ideals portrayed by the media parallel the previously reported eating disorder pathology for both sexes, and in both countries.

Deciphering faces: quantifiable visual cues to weight.

Body weight plays a crucial role in mate choice, as weight is related to both attractiveness and health. People are quite accurate at judging weight in faces, but the cues used to make these judgments have not been defined. This study consisted of two parts. First, we wanted to identify quantifiable facial cues that are related to body weight, as defined by body mass index (BMI). Second, we wanted to test whether people use these cues to judge weight. In study 1, we recruited two groups of Caucasian and two groups of African participants, determined their BMI and measured their 2-D facial images for: width-to-height ratio, perimeter-to-area ratio, and cheek-to-jaw-width ratio. All three measures were significantly related to BMI in males, while the width-to-height and cheek-to-jaw-width ratios were significantly related to BMI in females. In study 2, these images were rated for perceived weight by Caucasian observers. We showed that these observers use all three cues to judge weight in African and Caucasian faces of both sexes. These three facial cues, width-to-height ratio, perimeter-to-area ratio, and cheek-to-jaw-width ratio, are therefore not only related to actual weight but provide a basis for perceptual attributes as well.