FLUCTUATING ASYMMETRY IN CENTRAL AND MARGINAL POPULATIONS OF LYCHNIS VISCARIA IN RELATION TO GENETIC AND ENVIRONMENTAL FACTORS

Developmental instability in the form of increased fluctuating asymmetry can be caused by either genetic or environmental stress. Because extinctions can be attributed broadly to these factors, fluctuating asymmetry may provide a sensitive tool for detecting such stresses. We studied the level of fluctuating asymmetry of flowers of a perennial outcrossing plant species, Lychnis viscaria, both in natural and common-garden populations. The degree of flower asymmetry was higher in small, isolated, and marginal populations of the species range. These marginal populations also were the most homozygous. In the core area of the species' range, flowers were more symmetrical The level of asymmetry was correlated with both population size and heterozygosity. However, a partial correlation analysis revealed that when the impact of population size was controlled for, there was a negative relationship between fluctuating asymmetry and heterozygosity, whereas when controlling for heterozygosity, no relationship between population size and fluctuating asymmetry was found. This indicates that genetic consequences of small population size probably underlie the relationship between the level of asymmetry and population size. Results from a transplantation experiment showed that individuals subjected to a higher environmental stress had an increased level of asymmetry compared to control plants. In the common-garden conditions the level of fluctuating asymmetry did not differ between the central and marginal populations. This suggests that presumably both genetic and environmental factors affected to the higher level of asymmetry among marginal populations compared to central ones. In all we conclude that even though fluctuating asymmetry seems to be a sensitive tool for detecting stresses, results from studies focusing on only one factor should be interpreted with caution.     

Asymmetry of Mouth-Opening of a Small Herbivorous Cichlid Fish Telmatochromis temporalis in Lake Tanganyika

Direction of mouth-opening of a small herbivorous Tanganyikan cichlid, Telmatochromis temporalis, was studied. Each sample fish opened its mouth either rightward or leftward in some degree. The directions of mouth-opening were independent of the body curve directions, and the asymmetry will be due to asymmetric mouth morph individually specific. The degree of the mouth asymmetry was not related to body size, suggesting the asymmetry being not acquired characters. No fish opened the mouth in lateral symmetry, indicating that the asymmetry is different from "fluctuating asymmetry". This fish took algae on rock surface usually using right or left side of its mouth. However, strong relations between directions of mouth-openings and frequencies of mouth side used in foraging were not found, and the biological role of the asymmetry, if any, is not clear now.     

Parasites increase fluctuating asymmetry of maleDrosophila nigrospiracula: Implications for sexual selection

Fluctuating asymmetry (minor deviations from perfect bilateral symmetry) is manifested by individuals less able to buffer environmental stress during development. I utilized a system of two naturally-occurring parasites ofDrosophila nigrospiracula to test whether parasitic infection during host development yields elevated degrees of fluctuating asymmetry in two morphological traits of males. This hypothesis has important implications for sexual selection, as it may explain why asymmetric males are often found to be sexually disadvantaged. In my system, nematodes infect larvae and therefore are more likely to disrupt development than mites which only parasitize adult flies. As predicted, nematode-infected maleD. nigrospiracula had a higher degree of bristle asymmetry than did mite-infested and control (carrying neither parasite) males. There was also a significant relation between nematode number and degree of asymmetry. There was a significant negative relation between nematode load and size of adult males, implicating a causal link between nutritional stress during host development and fluctuating asymmetry. Patterns of wing length asymmetry were inconsistent with those of bristle asymmetry. Nematode-infected males did not differ in wing length asymmetry relative to mite-infested and control males, nor was there a significant relation between nematode number and wing asymmetry. This inconsistency in expression of asymmetry may reflect different intensities of selection operating on each morphological trait.     

Fluctuating asymmetry,leaf thickness and herbivory in <Emphasis Type="Italic">Tibouchina granulosa</Emphasis>: an altitudinal gradient analysis

Gradient of stressful conditions affect plant physiological and morphological traits. Previous studies have shown that plants located at higher altitudes might exhibit higher levels of both fluctuating asymmetry and leaf thickness. Although it is expected that higher fluctuating asymmetry levels should be accompanied by higher leaf consumption by herbivores, lower herbivory could be expected for elevated leaf thickness. Aiming to investigate this contradiction our objective was to determine the effects of altitude on fluctuating asymmetry and leaf thickness, and evaluate the importance of these two morphological traits on herbivory levels of Tibouchina granulosa Cogn. (Melastomatecea) in Brazilian Atlantic Forest. The study was conducted in southern Brazil, along a continuous altitudinal gradient raging from 1275 to 1950 m, where we measured fluctuating asymmetry, leaf thickness and herbivory from leaves of 29 individuals of T. granulosa. There was a positive effect of altitude on both fluctuating asymmetry and leaf thickness but only fluctuating asymmetry was related to herbivore. Our results suggest that as altitude increases plants face more stressful conditions, leading to higher fluctuating asymmetry. This may lead to a higher nutritional quality of leaves and herbivores may use leaf asymmetry as a cue for plant quality. The lack of a relationship between leaf thickness and herbivory gives us evidence that, in the studied location, leaf thickness is not primarily used as plant defense and probably has other functions related, for example, to water, solar radiation, and nutrient stresses. These results may be considered a baseline for the understanding on how altitudinal stress and potential herbivory pressure influence plant populations.     

Lopsided Fish in the Snake River Basin — Fluctuating Asymmetry as a way of Assessing Impact of Hatchery Supplementation in Chinook Salmon, Oncorhynchus tshawytscha

The use of developmental instability (an individual's failure to produce a consistent phenotype in a given environment) was evaluated to detect the effects of outplanting hatchery fish on wild salmon. Juvenile chinook salmon were collected in 1989, 1990, and 1991 from five drainages in the Snake River Basin. In each drainage we attempted to collect fish from streams with no hatchery supplementation (wild), naturally spawning fish from streams with hatchery supplementation (natural), and fish collected at a hatchery. Forty fish were collected per site and the number of elements in bilateral characters were counted on each side of the fish. Indices of fluctuating asymmetry (FA), a measure of minor, random deviations in perfect symmetry of bilateral counts, were calculated as an estimator of developmental instability. Analysis of character counts from seven paired characters revealed normal distributions. Only one of the characters displayed counts that were statistically larger on one side than the other, indicating that directional asymmetry (DA) or antisymmetry was not a major bias of FA. However, the means of all individual characters revealed a non-statistically significant left side bias. We analyzed our data using two indices of FA (FA1 and FA5) with different levels of sensitivity to DA. Differences in both FA indices were found among years, with collection sites in 1989 having significantly larger FA values than in 1991 (FA p < 0.01). Levels of FA among wild, natural, and hatchery fish were comparatively small (FA1 p = 0.17). This suggests developmental conditions were different in the first year of the study than in the last. The cause of these differences may be linked to either genetic or environmental variation or to gene—environment interactions, but the general population declines of salmon that occurred during this time obscures more specific conclusions.     

Development and altered gravity dependent changes in glucose-6-phosphate dehydrogenase activity in the brain of the cichlid fish Oreochromis Mossambicus

Glucose-6-phosphate dehydrogenase activity was studied in the brain of the cichlid fish Oreochromis mossambicus during early ontogenetic development. In general a slight but continuous decrease in enzyme activity was found (9.5 ± 0.5 nmol substrate cleaved per mg protein and per min at developmental stage 13 {=1 day post hatch at 28°C} to a value of 7.9±0.6 in adult brain). In order to investigate the possible influence of altered gravity during early ontogenetic brain development, fish larvae were exposed to an increased acceleration of three times earth gravity (3 g) or to functional weightlessness in a fast-rotating clinostat for 7 days. A significant increase of brain G6PDH activity of approx. 15% was found after exposure to hyper gravity, whereas a significant decrease of the enzyme activity, 10%, was detected following functional weightlessness in respect to the corresponding 1 g controls.

Analyses concerning the regain of normal control enzyme activity of the larvae revealed dramatic fluctuations within the first 5 h after exposure to an increased acceleration of 3 g. Thereafter, between day 1 and day 3 after exposure, brain glucose-6-phosphate dehydrogenase decreased slowly. At day 3 after exposure no further differences of the hyper-g larvae compared to the controls were found. Only slight changes in total brain glucose-6-phosphate dehydrogenase activity occur during ontogenetic development of cichlid fish. This suggests that a more or less constant enzyme activity is important during brain development, but is reacting very sensitively to changes in the environmental factor gravity.     

Single rays as indicators of fin vestigialization in coho salmon: patterns and perspectives

Although finrays in salmon normally contain a pair of elements (biramous), finrays with a single element (uniramous) occasionally develop. Exposure to chronic stress during character development has been shown to increase fluctuating asymmetry, suggesting the occurrence of single finrays may be stress‐induced. On the other hand, single finrays may be evolutionary atavisms, reflecting fin vestigialization caused by reduced selection pressure. To assess the merits of these hypotheses, cleared and stained paired and median fins were examined for single finrays in juvenile coho salmon (Oncorhynchus kisutch Walbaum) from two compatible hatchery stocks and their reciprocal hybrids which had been exposed to different patterns of chronic temperature fluctuation throughout embryogenesis. In the median fins, uniramous secondary finrays predominated, and single primary finrays were infrequent. Single finrays in the median fins did not respond to thermal treatment or cross, suggesting the fins were evolutionarily stable and under strong developmental control. The paired fins were observed to contain only primary finrays. Frequencies of single pelvic finrays increased under thermal stress, as did fluctuating asymmetry, suggesting increased sensitivity to stress due to reduced developmental control in this fin. However, the presence or absence of single finrays in the paired fins did not alter the statistical significance of the conclusions regarding levels of fluctuating asymmetry, the number of asymmetric fish, or the contribution to meristic variation from asymmetry. Locations of single finrays in the paired fins were unaffected by thermal treatment or cross. Single finrays were most commonly observed in the trailing margins of both paired fins, a finding consistent with vestigialization theory. Frequency histograms of single pectoral finray locations revealed a second peak in the leading quarter of the fin. The esults support the hypothesis that single primary finrays are evolutionary atavisms, and that reduced selection pressure is differentially influencing the paired fins.     

Minor anomalies: Diagnostic clues to aberrant human morphogenesis

Assessment of the degree of fluctuating asymmetry has been used in a variety of organisms as a measure of genetic and/or environmental stresses encountered during embryonic development. However, fluctuating asymmetry has not been widely used in humans in the diagnosis of congenital anomalies. Rather, assessment of patterns of minor anomalies has been utilized to infer the degree of embryonic developmental instability accompanying either genetic or teratogenic insults. A minor anomaly is a structural feature seen in less than 4% of the general population, which is of no cosmetic or functional significance to the affected individual. Minor anomalies may or may not have functional or diagnostic significance when taken in the context of the entire child. In dysmorphology, minor anomalies have been useful in three distinct ways. First, some minor anomalies have been external markers of specific occult major anomalies. In addition, the vast majority of malformation syndromes in clinical genetics are recognizable as patterns of minor anomalies. Finally, although 15% of normal newborns have one or more minor anomalies, the finding of three or more minor anomalies is distinctly unusual. The risk of having a major occult abnormality increases proportionately with the number of minor defects present, with three or more minor anomalies signalling a 20% risk of a major occult structural defect. In summary, just as fluctuating asymmetry may be a marker of abnormal environmental or genetic stress in the developing embryo, the presence of minor anomalies can be utilized to assess developmental instability.     

Use of a geometric morphometric method to determine the developmental stability of <Emphasis Type="Italic">Betula pendula</Emphasis> Roth

A geometric morphometric method has been proposed to test the fluctuating asymmetry and the developmental stability of Betula pendula Roth populations. The main factors affecting the developmental stability were the industrial emission level, the relief altitude, and the interaction of both these factors. A strong correlation between the fluctuating asymmetry indices obtained by the normalizing difference method and geometric morphometric method has been revealed. The fluctuating asymmetry determined by the geometric morphometric method is sensitive to the presence of directional asymmetry, which makes it possible to use this method for precise bioindication mapping of the developmental stability.     

Sexual dimorphism,asymmetry, and the effect of reproduction on pelvis bone in the bank vole, <Emphasis Type="Italic">Myodes glareolus</Emphasis>

Sexual dimorphism in anatomical traits has been widely studied in animals. Although pelvis dimorphism was mostly studied in humans, it occurs also in many other mammalian species. Here, we investigated sexual dimorphism in the pelvis of the bank vole Myodes glareolus using individuals with known sex and reproductive status of females (parous vs nulliparous). The analyses revealed that the size and shape of pelvis differed significantly between sexes, as well as between nulliparous and parous females. In comparison with males, females had a significantly longer pelvis and pubis bones and a longer obturator foramen length, but a smaller pubis width. Interestingly, the difference between parous and nulliparous females resembles that between females and males: parous females had bigger pelvis, which probably resulted from changes during pregnancy and after birth. Left bones were on average larger than right ones, but the magnitude of directional asymmetry was not different between sex and reproduction group. Moreover, we noticed that fluctuating asymmetry of pelvis and pubis length was higher in females than in males and higher in parous than in nulliparous females, what is presumably associated with locomotor performance. A discriminant function analysis performed for the four bone size traits showed that the traits can be effectively used for a nearly perfect recognition of sexes and also a quite reliable recognition of the reproductive status of females.     

Parasites differentially increase the degree of fluctuating asymmetry in secondary sexual characters

The degree of fluctuating asymmetry has been demonstrated to reflect the ability of individuals to cope with different kinds of environmental stress (Parsons 1990). Parasites and diseases are one kind of environmental stress which most individuals encounter during their lifetime. Parasites have also been suggested to play an important role in sexual selection and the development of ornaments, since the full expression of ornaments may reflect the ability of hosts to cope with the debilitating effects of parasites. Here I report for the first time that a parasite, the haematophagous tropical fowl mite Ornithonyssus bursa (Macronyssidae, Gamasida), directly affects the degree of fluctuating asymmetry in a secondary sexual character of its host, the elongated tail of the swallow Hirundo rustica (Aves: Hirundinidae). I experimentally manipulated the mite load of swallow nests during one season by either increasing or reducing the number of mites, or keeping nests as controls. The degree of fluctuating asymmetry was measured in the subsequent year after the swallows had grown new tail ornaments under the altered parasite regime. The degree of fluctuating asymmetry was larger at increasing levels of parasites for male tail length, but not for the length of the shortest tail feather or wing length or for tail and wing length in females. These results suggest that the degree of fluctuating asymmetry in tail ornaments, but not in other feather traits, reliably reveals the level of parasite infestation. This has important implications for the ability of conspecifics to use the size and the expression of ornaments in assessment of phenotypic quality and thus in sexual selection.     

Dermatoglyphic asymmetry and diversity in some pathologies

The evaluation of dermatoglyphic asymmetry represents a specific estimate of the stability of intrauterine development. In the present study, we analyzed the level of asymmetry and diversity in the radial and ulnar counts of each finger in 400 health Sardinian individuals and in 469 Sardinian subjects with four common diseases in Sardinia: type 1 diabetes, type 2 diabetes, arterial hypertension and multiple sclerosis. To measure the asymmetry, we used three indices: fluctuating asymmetry, the index of asymmetry and the index of diversity. The differences from the control group are only rarely significant. The values of fluctuating asymmetry do not present a particular distribution in relation to the pathologies, while the values of {ie139-1} and diversity are usually higher in the pathological groups. The differentiation is especially evident in the subjects with multiple sclerosis, intermediate in the diabetics and practically nil in the hypertense individuals.     

Development of fluctuating asymmetry in tail feathers of the barn swallow Hirundo rustica

Fluctuating asymmetry represents usually small, random deviations from symmetry in bilateral morphological characters. The ontogeny of asymmetry in morphological characters may reveal information about developmental processes in a general sense. I studied the development of fluctuating asymmetry in feather characters of the barn swallow Hirundo rustica, that are developed repeatedly during the single annual moult, with the following results. First, the side developing a larger feather was found to be partially biased, as demonstrated by one side consistently developing a larger feather under natural and experimentally induced growth episode events. Second, asymmetric feathers were found to consist of asymmetric daily growth increments, and the size of the increments developing under different environmental conditions were positively correlated. Third, fluctuating asymmetries of feathers developing under different environmental conditions were positively correlated, although the level of asymmetry was larger under adverse environmental conditions. Fourth, individual asymmetries in tail length and growth bar length were unrelated to the duration of the developmental period, although late growth increments were smaller and more symmetric than early increments. These observations suggest that fluctuating asymmetry partially arises as a consequence of a random bias in the feather follicles and differences in environmental conditions during ontogeny of feathers.     

Jamaican Symmetry Project: long-term study of fluctuating asymmetry in rural Jamaican children.

Fluctuating asymmetry, small deviations from perfect bilateral symmetry, is negatively correlated with health and positively correlated with sexual selection in human adults, but the accumulation, persistence, and fitness implications of asymmetries during childhood are largely unknown. Here, we introduce the Jamaican Symmetry Project, a long-term study of fluctuating asymmetry and its physical and behavioral correlates in rural Jamaican children. The project is based on an initial sample of 285 children (156 boys and 129 girls), aged 5 to 11 years. We describe the design of the project and the methodology of measuring 10 paired morphometric traits. All traits except hand width showed fluctuating asymmetry. Fluctuating asymmetries of the legs tended to be related and were less than half as great as fluctuating asymmetries of the arms and ears. Therefore the legs may show high developmental stability resulting from selection for mechanical efficiency. A fluctuating asymmetry composite score revealed that boys have significantly lower fluctuating asymmetry than girls and that this effect resides mainly in the elbows. There were significant positive relationships between composite fluctuating asymmetry and age, height, and weight, but multiple regression analyses showed that age was negatively related to fluctuating asymmetry, whereas body size was positively correlated. These findings are compared with results from recent English studies.     

Genetic and phenotypic correlation between fluctuating asymmetry and two measurements of fear and stress in chickens

The purpose of the present study was to estimate the genetic and phenotypic correlation between fluctuating asymmetry and two measurements of fear and stress in chickens which had not deliberately stressed in any way, using the restricted maximum likelihood procedure. A total of 1073 36-week-old birds from two generations with complete pedigree of the Quail Castellana breed was used. Fluctuating asymmetry of several traits (leg, wing, and feather lengths, and ear-lobe and wattle areas), tonic immobility duration (indicator of fear), and heterophil to lymphocyte ratio (indicator of stress) were measured. The estimated genetic relationship between relative fluctuating asymmetry for the different traits and tonic immobility tended to be positive, that between the combined relative asymmetry of all traits and tonic immobility being near to +1; no significant phenotypic relationship was found between relative fluctuating asymmetry and tonic immobility. The genetic relationship between relative fluctuating asymmetry and heterophil to lymphocyte ratio was not consistent across the traits, ranging from +1 to −1, although the genetic correlation between the combined relative asymmetry and the heterophil to lymphocyte ratio was near to +1 too; no significant phenotypic relationship was found between relative fluctuating asymmetry and heterophil to lymphocyte ratio either. Relative fluctuating asymmetry and body weight were genetically negatively correlated for leg length and ear-lobe area but positively for feather length; the genetic correlation between the combined relative asymmetry and the body weight being near to −1; phenotypic relationships were not significantly different from zero. A significant negative genetic correlation between tonic immobility and heterophil to lymphocyte ratio was found, although the phenotypic association between these two measurements was zero. Phenotypic correlations always near to zero suggest that fluctuating asymmetry was not associated with duration of tonic immobility and heterophil to lymphocyte ratio in birds that have not been deliberately stressed.     

Seasonality of glycogen phosphorylase activity in crucian carp (<Emphasis Type="Italic">Carassius carassius</Emphasis> L<Emphasis Type="Italic">.</Emphasis>)

Seasonal changes in the activity of glycogen phosphorylase (GP), a rate-limiting enzyme of glycogen degradation, were examined in an anoxia-tolerant fish species, the crucian carp (Carassius carassius L.). In muscle and brain, the activity of GP remained constant throughout the year when tested at 25°C. In contrast, the activities of liver and heart GP displayed striking increases in summer. When seasonal temperature changes are taken into account, the activity of GP during the anoxic mid-winter is only 4–6% of its summer time activity in the muscle, heart and liver, and 13% in brain. In winter-acclimatized fish, experimental anoxia (1–6 weeks) caused sustained depression of the GP activity in heart and gills. In liver and muscle, a transient depression of GP activity occurred during the first week of anoxia but later GP activity recovered back to the normoxic level. GP of the brain was completely resistant to anoxia. In all studied tissues, the constitutive activity of GP is more than sufficient to degrade glycogen deposits during winter anoxia without anoxia-induced activation of GP. The seemingly paradoxical summer-time increase in the activity of liver and heart GP could be related to active life-style of the summer-acclimatized fish (growth, reproduction), the increased demand of energy and molecular precursors of anabolic metabolism being satisfied by preferential degradation of glycogen. The high glycogen content of winter-acclimatized crucian carp is not associated with the elevated GP activity or anoxic activation of GP.     

Bite Force Performance,Fluctuating Asymmetry and Antisymmetry in the Mandible of Inbred and Outbred Wild-Derived Strains of Mice (<Emphasis Type="Italic">Mus musculus domesticus</Emphasis>)

Developmental instability, as measured by fluctuating asymmetry is generally considered to increase with genetic and environmental stresses. Few studies have, however, addressed the role of asymmetry in altering organism performance. Here, we measured bite force performance in three strains of inbred and outbred mice derived from wild ancestors. We quantified size and shape directional, and fluctuating asymmetry, as well as inter-individual variation of their mandibles using geometric morphometrics. We also developed a way to estimate shape antisymmetry, to filter it out of the fluctuating asymmetry component. Contrary to our expectations, we found no significant link between bite force and asymmetry levels. Inbreeding did not produce any clear and significant increase or decrease in neither inter-individual variance, nor fluctuating asymmetry. Furthermore, fluctuating asymmetry levels were unrelated to inter-individual variance levels, although these two types of variation affected the same areas of the mandible. We did not highlight any impact of inbreeding depression on bite force. Fluctuating asymmetry was reduced in the mandible, which we argue may be linked to its functional relevance. We found some significant but very reduced antisymmetry possibly linked to lateralization. This lateralization did not relate to any bite force difference. Our results show that neither inbreeding, nor asymmetry (combining fluctuating, directional asymmetry and antisymmetry) significantly affect bite force performance in mice, and that despite affecting the same morphological regions, developmental stability and canalization are independent.     

GEOMETRIC MORPHOMETRICS OF DEVELOPMENTAL INSTABILITY: ANALYZING PATTERNS OF FLUCTUATING ASYMMETRY WITH PROCRUSTES METHODS

Although fluctuating asymmetry has become popular as a measure of developmental instability, few studies have examined its developmental basis. We propose an approach to investigate the role of development for morphological asymmetry by means of morphometric methods. Our approach combines geometric morphometrics with the two-way ANOVA customary for conventional analyses of fluctuating asymmetry and can discover localized features of shape variation by examining the patterns of covariance among landmarks. This approach extends the notion of form used in studies of fluctuating asymmetry from collections of distances between morphological landmarks to an explicitly geometric concept of shape characterized by the configuration of landmarks. We demonstrate this approach with a study of asymmetry in the wings of tsetse flies (Glossina palpalis gambiensis). The analysis revealed significant fluctuating and directional asymmetry for shape as well as ample shape variation among individuals and between the offspring of young and old females. The morphological landmarks differed markedly in their degree of variability but multivariate patterns of landmark covariation identified by principal component analysis were generally similar between fluctuating asymmetry (within-individual variability) and variation among individuals. Therefore there is no evidence that special developmental processes control fluctuating asymmetry. We relate some of the morphometric patterns to processes known to be involved in the development of fly wings.     

Growth and fluctuating asymmetry of human newborns: Influence of inbreeding and parental education

Historically, medical concerns about the deleterious effects of closely inbred marriages have focused on the risk posed by recessive Mendelian disease, with much less attention to developmental instability. We studied the effects of inbreeding (first‐cousin marriage) on growth and fluctuating asymmetry of 200 full‐term infants (101 inbred and 99 outbred) whose parents were of similar socioeconomic status in Sivas Province, Turkey. In addition to differences in their mean inbreeding coefficients (f = 1/16 for first cousins and f < 1/1,024 for unrelated parents), the consanguineous parents were less well educated (3 years, on average for both husbands and wives). We measured weight, height, head circumference, and chest circumference of the newborns, as well as four bilateral traits (ear width, ear length, and second and fourth digit lengths). After taking education into account, none of the measures of size (weight, height, head circumference, and chest circumference) and fluctuating asymmetry differed between the inbred and outbred groups. Male children of well‐educated parents, however, were larger and had less fluctuating asymmetry. Female children of well‐educated parents weighed more than those of less well‐educated parents, but were otherwise indistinguishable for height, head circumference, chest circumference, and fluctuating asymmetry. We conclude that inbreeding depression causes neither an increase in fluctuating asymmetry of full‐term newborns, nor a decrease in body size. Unmeasured variables correlated with education appear to have an effect on fluctuating asymmetry and size of male children and only a weak effect on size (weight) of female children. Am J Phys Anthropol 153:45–51, 2014. © 2013 Wiley Periodicals, Inc.