Populational differences in attractiveness judgements of male and female faces: Comparing British and Jamaican samples

In the UK and Japan, both men and women prefer somewhat feminised opposite-sex faces, especially when choosing a long-term partner. Such faces are perceived as more honest, caring, and sensitive; traits that may be associated with successful male parental investment. By contrast, women prefer less feminised faces for short-term relationships and when they are near ovulation. As genetic quality may be associated with facial masculinity, women may ‘trade-off’ cues between genetic quality and paternal investment in potential partners. No analogous trade-off has been suggested to influence men's preferences, as both attributions of prosociality and potential cues to biological quality are associated with facial femininity in female faces. Ecological and cultural factors may influence the balance of trade-offs leading to populational differences in preferences. We predicted that Jamaican women would prefer more masculine faces than British women do because parasite load is higher in Jamaica, medical care less common (historically and currently), and male parental investment less pronounced. Male preferences, however, were predicted to vary less cross-culturally, as no trade-off has been identified in female facial characteristics. We constructed masculinised and feminised digital male and female face stimuli of three populations (Jamaican, Japanese, and British) and presented them to men and women in Jamaica and in Britain. The results demonstrated that Jamaican women preferred more masculine male faces than their British counterparts did. Jamaican men tended to prefer more masculine female faces than did British men did, but this effect was complicated by an interaction suggesting that more feminised faces were preferred within culture.     

Vocal and visual attractiveness are related in women

We investigated the relation between visual and vocal attractiveness in women as judged by men. We recorded 34 women speaking four vowels and measured the peak frequency, the first five harmonic frequencies, the first five formant frequencies and formant dispersion. The women were also photographed (head shot), several body measures were taken and their ages were recorded. The voices were played to male judges who were asked to assess the women's age and vocal attractiveness from the recording. The men were then asked to assess the attractiveness of the photographs. Men were in strong agreement on which was an attractive voice and face; and women with attractive faces had attractive voices. Higher-frequency voices were assessed as being more attractive and as belonging to younger women (the lowest frequency produced is a good indicator of age in women in general). Larger women had lower voices and were judged as having less attractive faces and voices. Taller women had narrower formant dispersion as predicted. The results imply that different measures of attractiveness are in agreement and signal similar qualities, such as female age, body size and possibly hormonal profile. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.      

Differences among plant species in cuticular permeabilities and solute mobilities are not caused by differential size selectivities

Solute mobilities in cuticular membranes of six species (Hedera helix, Malus domestica, Populus alba, Pyrus communis, Stephanotis floribunda, Strophantus gratus) were measured using plant hormones, growth regulators and other organic model compounds varying in molar volumes from 99 to 349 mL · mol⁻¹ The dependence of mobilities (k*) on molar volume (V _x ) was exponential and could be described with equations of the type log k*=log k*⁰−^′ V _x . The y-intercepts (log k*⁰) represent mobilities of a hypothetical solute of zero molar volume. The parameter β′ is a measure of size selectivity of cuticular membranes and no differences among the six species were observed. At 25 °C the average β′ was 0.0095 mol · mL⁻¹. Solute mobility decreased by about a factor of 8.9 when molar volume increased by 100 mL · mol⁻¹ and the mobility of a compound with V _x  = 100 mL · mol⁻¹ was about 700-fold higher than the mobility of a compound with V _x  = 400 mL · mol⁻¹. Size selectivity decreased with increasing temperatures and for Strophantusβ′-values of 1.6 × 10⁻² to 8.0 × 10^-4 mol · mL⁻¹ were obtained for 10 and 30 °C, respectively. The-intercepts (log k*⁰) differed among plant species by 3 orders of magnitude and since size selectivity was the same for all species, solute mobilities for solutes having zero molar volumes were the sole cause for differences among species in solute mobilities and permeabilities. We argue that these differences in k*⁰ are related to tortuosity of the diffusion path. These results were used to derive an equation which predicts rates of cuticular penetration on the basis of k*⁰, the average size selectivity of 9.5 × 10⁻³ mol · mL⁻¹ and the driving forces of penetration. Received: 25 November 1997 / Accepted: 9 March 1998     

Song-related brain regions in the red-winged blackbird are affected by sex and season but not repertoire size

Previous work in songbirds has delimited a neural system responsible for song production and control. Earlier studies have suggested that functional capacity in the song system may be related to the mass of the system in an animal's brain, and that adult plasticity in this neural system may be related to adult capacity for behavioral modification. We now test these hypotheses in adult red-winged blackbirds (Agelaius phoeniceus), a species in which song is produced primarily by males, new song types are added to the male's repertoire in adulthood, and there are substantial differences among males in song complexity. We find that the song system in males is much larger than in females. Song system nuclei become smaller in both sexes as the animals experience shorter days. We do not find any association between repertoire size and size of any of the song system structures examined. Thus, although sex differences in song may be related to differences between sexes in the mass of song system structures, individual differences in song do not appear to be directly related to mass within males. Seasonal change in song system structures in male redwings is consistent with there being a relation between adult plasticity in anatomy and in behavior; the large seasonal change in these structures in females suggests large seasonal changes in the function of these nuclei.     

Testosterone increases perceived dominance but not attractiveness in human males

Recent evidence suggests that certain features on the human face indicate hormonal levels during growth, and that women judge the attractiveness of potential partners based on the appearance of these features. One entrenched notion is male facial features that are affected by testosterone are used as direct cues in mate preference. Testosterone may be particularly revealing as it is purported to be an honest indicator of male fitness. Increased testosterone may impose an immunocompetence handicap on the bearer and only the best males can carry this handicap. To date, tests of this theory have been indirect, and have relied on digital manipulations that represent unrealistic continuums of masculine and feminine faces. We provide a much more direct test by manipulating digitally male faces to mimic known shape variation, caused by varying levels of testosterone through puberty. We produced a continuum of faces that ranged from low to high levels of testosterone in male faces and asked women to choose the points on the continuum that appeared most attractive and most physically dominant. Our data indicate that high testosterone faces reveal dominance. However, there is no evidence of directional selection for increased (or decreased) testosterone in terms of attractiveness to the opposite sex. We discuss the relevance and applicability of evolutionary interpretations of our data and, contrary to predictions, provide evidence of stabilizing selection acting on testosterone through mate preferences.     

Male attractiveness, fertility and susceptibility to oxidative stress are influenced by inbreeding in Drosophila simulans

Inbreeding frequently leads to inbreeding depression, a reduction in the trait values of inbred individuals. Inbreeding depression has been documented in sexually selected characters in several taxa, and while there is correlational evidence that male fertility is especially susceptible to inbreeding depression, there have been few direct experimental examinations of this. Here, we assessed inbreeding depression in male fertility and a range of other male fitness correlates in Drosophila simulans. We found that male fertility and attractiveness were especially susceptible to inbreeding depression. Additionally, levels of testicular oxidative stress were significantly elevated in inbred males, although sperm viability did not differ between inbred and outbred males. Copulation duration, induction of oviposition, and the proportion of eggs hatching did not differ for females mated to inbred or outbred males. Nevertheless, our results clearly show that key male fitness components are impaired by inbreeding and provide evidence that aspects of male fertility are especially susceptible to inbreeding depression.     

Male attractiveness is influenced by UV wavelengths in a newt species but not in its close relative

Background

Functional communication in the UV range has been reported in Invertebrates and all major groups of Vertebrates but Amphibians. Although perception in this wavelength range has been shown in a few species, UV signalling has not been demonstrated in this group. One reason may be that in lentic freshwater habitats, litter decomposition generates dissolved organic carbon that absorbs UV radiation and thus hinders its use for visual signalling. We tested the effect of male UV characteristics on female sexual preference in two newt species that experience contrasting levels of UV water transmission when breeding.

Methodology/Principal Findings

We analysed water spectral characteristics of a sample of breeding ponds in both species. We quantified male ventral coloration and measured male attractiveness under two lighting conditions (UV present, UV absent) using a no-choice female preference design. UV transmission was higher in Lissotriton vulgaris breeding sites. Male UV patterns also differed between experimental males of the two species. We observed a first common peak around 333 nm, higher in L. vulgaris, and a second peak around 397 nm, more frequent and higher in L. helveticus. Male attractiveness was significantly reduced in L. vulgaris when UV was not available but not in L. helveticus. Male attractiveness depended on the hue of the first UV peak in L. vulgaris.

Conclusion/Significance

Our study is the first report of functional UV-based communication in Amphibians. Interestingly, male spectral characteristics and female preferences were consistent with the differences in habitat observed between the two species as L. helveticus often breeds in ponds containing more UV blocking compounds. We discuss the three hypotheses proposed so far for UV signalling in animals (enhanced signal detectability, private communication channel, indicator of individual quality).     

Mopane diaspores are not dispersed by epizoochory

The mode of dispersal of the diaspores of Colophospermum mopane has always been ascribed to epizoochory due the slightly sticky nature of mopane diaspores. The stickiness results from the plentiful supply of resinous compounds in developing structures on a mopane plant. Epizoochory as the mode of dispersal for both seeds which had the pod removed and diaspores of C. mopane is disproved, and experimentation shows the most likely agents of dispersal of mopane diaspores to be water and wind.     

Telomere Length Profiles in Humans: All Ends are Not Equal

Telomere length is an important parameter of telomere function since it determines number of aspects controlling chromosome stability and cell division. Since telomeres shorten with age in humans and premature aging syndromes are often associated with the presence of short telomeres, it has been proposed that telomere length is also an important parameter for organismal aging. How mean telomere lengths are determined in humans remains puzzling, but it is clear that genetic and epigenetic factors appear to be of great importance. Experimental evidence obtained from many different organisms has provided the basis for a widely accepted counting mechanism based on a negative feedback loop for telomerase activity at the level of individual telomeres. In addition, recent studies in both normal and pathological contexts point to the existence of chromosome-specific mechanisms of telomere length regulation determining a telomere length profile, which is inherited and maintained throughout life. In this review, we recapitulate the available data, propose a synthetic view of telomere length control mechanisms in humans and suggest new approaches to test current hypotheses.     

Mate discrimination by females in the burying beetle Nicrophorus orbicollis: the influence of male size on attractiveness to females

1. Female burying beetles behave differently towards males of different sizes, avoiding mating with large males that are not defending resources but mating with small males regardless of the presence of resources. Females of the burying beetle Nicrophorus orbicollis were therefore examined to determine whether they discriminate among males using only pheromonal signals. The influence of female size on its own mate choice was also examined. 2. Females do use male pheromonal signals to discriminate among males and these signals do appear to convey information about male body size to females. Overall, females were more likely to be attracted to larger males than to smaller males. 3. Female choice of a male was influenced by both the female's own body size and the size of the female relative to the size of the two males available to it. 4. While there is an overall mating advantage for larger males, resulting from female preferences based on odour cues, smaller males are also attractive to some females under some circumstances. 5. It is argued that there are different costs and benefits of mating with different sized males, leading to the evolution of context‐dependent mate choice for females and the need to be able to discriminate males of different sizes from a distance.     

Speech movements do not scale by orofacial structure size.

The potential role of a size-scaling principle in orofacial movements for speech was examined by using between-group (adults vs. 5-yr-old children) as well as within-group correlational analyses. Movements of the lower lip and jaw were recorded during speech production, and anthropometric measures of orofacial structures were made. Adult women produced speech movements of equal amplitude and velocity to those of adult men. The children produced speech movement amplitudes equal to those of adults, but they had significantly lower peak velocities of orofacial movement. Thus we found no evidence supporting a size-scaling principle for orofacial speech movements. Young children have a relatively large-amplitude, low-velocity movement strategy for speech production compared with young adults. This strategy may reflect the need for more time to plan speech movement sequences and an increased reliance on sensory feedback as young children develop speech motor control processes.     

Longevity is not influenced by prenatal programming of body size

Insulin‐like growth factor (IGF) signaling is essential for achieving optimal body size during fetal development, whereas, in the adult, IGFs are associated with aging and age‐related diseases. However, it is unclear as to what extent lifespan is influenced by events that occur during development. Here, we provide direct evidence that the exceptional longevity of mice with altered IGF signaling is not linked to prenatal programming of body size. Mice null for pregnancy‐associated plasma protein‐A (PAPP‐A), an IGF‐binding protein proteinase that increases local IGF bioavailability, are 60–70% the size of their wild‐type littermates at birth and have extended median and maximum lifespan of 30–40%. In this study, PAPP‐A^?/? mice whose body size was normalized during fetal development through disruption of IgfII imprinting did not lose their longevity advantage. Adult‐specific moderation of IGF signaling through PAPP‐A inhibition may present a unique opportunity to improve lifespan without affecting important aspects of early life physiology.