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.Publisher PDFPeer reviewe

Pollinating fig wasps’ simple solutions to complex sex ratio problems : a review

Local mate competition (LMC) favours female biased clutch sex ratios because it reduces competition between brothers and provides extra mating opportunities for sons. Fig wasps seem to ft LMC model assumptions and lay femalebiased sex ratios as predicted. These female biased sex ratios increase ftness greatly. In line with predictions, their sex ratios become less female-biased as the number of mothers laying in the same fg increases. However, this variation results in comparatively small ftness benefts compared to just biased ratios and data suggest substantial mismatches with LMC theory. The mismatches are due to several factors. (1) Multiple foundresses typically lay too many daughters. (2) Single foundress sex ratios are explained by sequential oviposition and ladies-last models. (3) Mortality that typically exceeds 10% may decouple the link between primary sex ratios, the focus of model predictions, and secondary sex ratios of adult wasps that are counted by researchers. (4) Model assumptions are frequently violated: (a) clutch sizes are unequal, (b) oviposition may not be simultaneous (c) cryptic/multiple wasp species inhabit the same host, (d) foundress numbers are systematically undercounted, (e) inbreeding coefcient calculations are inaccurate, and (f ) male wasps sometimes disperse. These data and calculations suggest that alternative explanations must be considered seriously. Substantial data show that wasps typically lay most of their male eggs frst followed by mostly female eggs require a new approach. These “slope” strategies result in more accurate sex ratios that are automatically adjusted to foundress number, own and relative clutch sizes and to sequential clutches. This efect will alter sex ratios in all species once the egg capacity of a fg is crossed or when interference reduces clutch sizes. In addition to this passive response, the females of about half the studied species have a conditional response that reduces female bias under higher foundress numbers by laying more sons. Therefore, wasps seem to use a very simple strategy that increases their ftness. Natural selection could have optimized parameters of the slope strategy and possibly the existence of the slope strategy itself. Variation in the slope strategy that is the result of natural selection is adaptive. Research should therefore focus on quantifying variables of this slope strategy. Currently, it is unclear how much of the variation is adaptive as opposed to being coincidental by-products.SUPPLEMENTARY INFORMATION: ADDITIONAL FILE 1. Supplementary text and figures. Explanation of methods, derivation of ESS sex ratio, analysis of wasp size and supplementary figures. ADDITIONAL FILE 2. Figure 4 data. Observed (± 95% CI) and expected sex ratios in 36 studies of 25 species. ADDITIONAL FILE 3. Figures 8 and 9 data. Clutch composition in 33 studies on 25 species. ADDITIONAL FILE 4. Figure 10 data. Single Foundress sex ratios, fraction of single foundress figs and clutch size of 39 species.https://frontiersinzoology.biomedcentral.com/dm2022BiochemistryGeneticsMicrobiology and Plant Patholog

Few figs for frugivores : riparian fig trees in Zimbabwe may not be a dry season keystone resource

Most plants flower and fruit at times of year when probabilities of pollination and seedling establishment are high. Fig trees (Ficus spp.) are often considered as keystone resources for vertebrate frugivores, in part because of year-round fig production. This unusual fruiting phenology results in the maintenance of fig wasp populations, but in seasonal environments this means fruiting occurs during periods when the chances of seedling establishment are low. Under these circumstances, selection is expected to favour any individuals that reduce or eliminate fruiting at these times. Here, we describe a large-scale survey of the extent of dry season fruiting by three riparian Ficus species in Gonarezhou National Park, Zimbabwe. Few trees of two monoecious species, F. sycomorus and F. abutilifolia, had figs, and most crops of F. sycomorus were far smaller than the trees were capable of producing. Large stands of the dioecious F. capreifolia were present, but fig densities were low and no mature female (seed containing) figs were recorded. Even though fig trees may have been the only species bearing fruit, the consequences of the low investment in reproduction by the three Ficus species were clear—there were too few figs for a landscape-scale keystone role.La plupart des plantes fleurissent et fructifient à des moments de l'année où les probabilités de pollinisation et d'établissement des semis sont élevées. Les figuiers (Ficus spp.) sont souvent considérés comme des ressources clés pour les frugivores vertébrés, en partie grâce à la production de figues toute l'année. Cette phénologie de fructification inhabituelle entraîne le maintien des populations de guêpes des figuiers, mais dans les environnements saisonniers, cela signifie que la fructification se produit pendant les périodes où les chances d'établissement des semis sont faibles. Dans ces circonstances, la sélection devrait favoriser tous les individus qui réduisent ou éliminent la fructification à ces moments. Nous décrivons ici une étude à grande échelle portant sur l'étendue de la fructification en saison sèche par trois espèces riveraines de Ficus dans le parc national de Gonarezhou, au Zimbabwe. Peu d'arbres de deux espèces monoïques, F. sycomorus et F. abutilifolia, avaient des figues et la plupart des fruit du F. sycomorus étaient beaucoup plus petits que ceux que les arbres étaient capables de produire. D’importants peuplements de F. capreifolia dioïque étaient présents, mais les densités de figues étaient faibles et aucune figue femelle mature (contenant des graines) n'a été enregistrée. Même si les figuiers étaient peutêtre la seule espèce à produire des fruits, les conséquences du faible investissement dans la reproduction par les trois espèces de Ficus étaient claires - il y avait trop peu de figues pour qu’elles jouent un rôle clé à l'échelle du paysage.https://wileyonlinelibrary.com/journal/ajeam2020BiochemistryGeneticsMicrobiology and Plant Patholog

Sex ratio dependent dispersal when sex ratios vary between patches

Female biased sex ratios reduce competition between brothers when mating takes place within local patches. Male dispersal proir to mating is another strategy that reduces competition between brothers. One may thus expect these two traits to co-evolve and this is partially met in that sex ratios becomes less female baised as dispersal increases. However, the evolutionary stable degree of dispersal is unaffected by the sex ratio. The analytical models developed to reach these conslusions ignored variance in sex ratios, since this increases the structural complexity of models. For similar reasons finite clutch size are also routinely ignored. To overcome these shortfalls, we developed individual besed simulations that allowed us to incorporate ralistic clutch sizes and binomial variance in sex ratios between patches. We show that under variable sex ratios, males evolve to more readily disperse away from pathces with higher sex ratios that lower sex ratios. We show that, while the dispersal rate is insensitive tot the sex ratio when sex ratios are precise, it is affected by the number of males with dispersal decreasing as the number of males decreases.The National Research Foundationhttp://www.elsevier.com/locate/yjtbinf201

Appel Botha Cornelitz : the abc of a three hundred year old divorce case

In 1683 Maria Kickers and Jan Cornelitz got married in Cape Town. Today, 330 years later, the living patrilineal descendants of Maria’s four sons, number in excess of 76,000 people. Curiously, none of them carry the surname Cornelitz – in fact, they are all called Botha and include former President P.W. Botha, general Louis Botha and Minister Pik Botha. The reason for this anomaly is also the reason why Jan got divorced from Maria in 1700. According to Maria’s testimonies she did indeed have a long term relationship with Frederik Botha, but in her defence she claimed that her husband was impotent and that he actually encouraged her. Other witnesses, presumably prompted by Jan, gave testimonies that implied that Maria was in fact licentious. We combined haplotyping with the AmpF‘STR1 YfilerTM kit with deep-rooting genealogies to show that Maria’s first son was actually fathered by Ferdinandus Appel and that roughly half the living Bothas (38,000 people) actually descend from Ferdinandus Appel while the remaining three sons all stem from the same father, presumably Frederik Botha, and this implies that Maria’s husband did not father any of her sons.This work was supported by Grant 77256 from the National Research Foundation to JMG.http://www .elsevier.com /locate/fsighb201

Low nonpaternity rate in an old Afrikaner family

Extrapair paternity is a crucial parameter for evolutionary explanations of reproductive behavior. Early studies and human testis size suggest that human males secure/suffer frequent extrapair paternity. If these high rates are indeed true, it brings into question studies that use genealogies to infer human life history and the history of diseases since the recorded genealogies do not reflect paths of genetic inheritance. We measure the rate of nonpaternity in an old Afrikaner family in South Africa by comparing Y-chromosome short tandem repeats to the genealogy of males. In this population, the nonpaternity rate was 0.73%. This low rate is observed in other studies that matched genealogies to genetic markers and more recent studies that also find estimates below 1%. It may be that imposed religious morals have led to reduced extrapair activities in some historic populations. We also found that the mutation rate is high for this family, but is unrelated to age at conception.http://www.ehbonline.orghb2016Genetic

Facial-based ethnic recognition: insights from two closely related by ethnically distinct groups

Sherpa Romeo blue journal; open accessPrevious studies on facial recognition have considered widely separated populations, both geographically and culturally, making it hard to disentangle effects of familiarity with an ability to identify ethnic groups per se.We used data from a highly intermixed population of African peoples from South Africa to test whether individuals from nine different ethnic groups could correctly differentiate between facial images of two of these, the Tswana and Pedi. Individuals could not assign ethnicity better than expected by chance, and there was no significant difference between genders in accuracy of assignment. Interestingly, we observed a trend that individuals of mixed ethnic origin were better at assigning ethnicity to Pedi and Tswanas, than individuals from less mixed backgrounds. This result supports the hypothesis that ethnic recognition is based on the visual expertise gained with exposure to different ethnic groups

Three hundred years of low non-paternity in a human population

When cuckoldry is frequent we can expect fathers to withhold investment in offspring that may not be theirs. Human paternal investment can be substantial and is in line with observations from tens of thousands of conceptions that suggest that cuckoldry is rare in humans. The generality of this claim seems to be in question as the rate of cuckoldry varies across populations and studies have mostly been on Western populations. Two additional factors complicate our conclusions, 1) current estimates of the rate of cuckoldry in humans may not reflect our past behaviour as adultery can be concealed by the use of contraceptives; and 2) it is difficult to obtain samples that are random with respect to their paternity certainty. Studies that combine genealogies with Y-chromosome haplotyping are able to circumvent some of these problems by probing into humans’ historical behaviour. Here we use this approach to investigate 1273 conceptions over a period of 330 years in 24 families of the Afrikaner population in South Africa. We use haplotype frequency and diversity and coalescent simulations to show that the male population did not undergo a severe bottleneck and that paternity exclusion rates are high for this population. The rate of cuckoldry in this Western population was 0.9% (95%CI 0.4 – 1.5%) and we argue that given the current data on historical populations we have to conclude that, at least for Western human populations, cuckoldry rate is probably in the range of 1%.National Research Foundation (NRF) grants 65696, 72737 and 77256 to JMG. JCE was supported by a free-standing NRF scarce skills grant.http://www.nature.com/hdy2016-05-31hb201

The influence of behaviour and physiology on abundance and distribution relationships

Abiotic factors, biotic factors and dispersal ability affect distribution and abundance. Due to their intimate host association, pollinating fig wasps are expected to occupy the entire distribution of their host fig. However, Ceratosolen galili (non-pollinator) has been suggested to be rarer than the pollinating Ceratosolen arabicus in drier areas due to different desiccation tolerance. Both species are closely related and utilise the same oviposition sites on Ficus sycomorus. We question what form of rarity (distribution, abundance or both) is present and the potential mechanism(s) for this. We used ecological niche modelling to determine whether C. galili covers the range of F. sycomorus and whether it is consistently rarer than C. arabicus. We examined emergence times, critical thermal limits, desiccation and starvation tolerances of the wasps to determine the potential behavioural and physiological underpinning of rarity. The suggested rarity of C. galili relates to lower abundance in certain months and at certain localities but a similar number of occurrence records within the distributional range (except in arid regions, e.g. Namibia). Competitive interactions between the species means that the wasp species with highest abundance at a specific time will ‘close’ the figs to entry by the other species, lowering the abundance of the second species. In contrast to C. galili, C. arabicus has a wider thermal range, lives longer under hydrating and dehydrating conditions and is a nocturnal flier. The synergistic effect of physiological tolerances and flight time differences exacerbate the less favourable conditions available to C. galili during flight and location of receptive figs. These factors enable C. arabicus to survive for longer than C. galili, meaning that they are more likely to disperse to trees that are flowering further away in space and time. Combining correlative and mechanistic approaches has aided us in understanding the ecological niches of these species

Testing models of facultative sex ratio adjustment in the pollinating fig wasp Platyscapa awekei

Female hymenoptera are renowned for their ability to adjust offspring sex ratio to local mate competition. When two females share a patch, they frequently produce clutches that differ in size, the female with the larger clutch optimally producing a more female-biased sex ratio and vice versa. Females can base their sex allocation on their own clutch size only (“self-knowledge”) or on both females’ clutch sizes (“complete knowledge”). Few studies have genotyped offspring so that each mother’s contribution can be considered separately while none has found that both sources of information are used simultaneously. We genotyped 2489 wasps from 28 figs and assigned their maternity to one of the two foundress females. We argue that likelihood is a very convenient method to compare alternative models, while fitness calculations help to appreciate the cost ofmaladaptation.We find that the pollinating fig wasp Platyscapa awekei simultaneously uses its own as well as the other females clutch size in allocating sex. Indeed, the complete knowledge model explains the data 36 times better than the self-knowledge model. However, large clutches contained fewer males than the optimal predictions leading to a median selection coefficient of 0.01.The running costs were funded by National Research Foundation (NRF) grants 2053809 and 2072974 to JMG. DVKN was supported by a freestanding Masters scholarship from the NRF.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1558-5646nf201