Reproductive strategy, sexual development and attraction to facial characteristics

Sexual reproduction strategies vary both between and within species in the level of investment in offspring. Life-history theories suggest that the rate of sexual maturation is critically linked to reproductive strategy, with high investment being associated with few offspring and delayed maturation. For humans, age of puberty and age of first sex are two developmental milestones that have been associated with reproductive strategies. Stress during early development can retard or accelerate sexual maturation and reproduction. Early age of menarche is associated with absence of younger siblings, absence of a father figure during early life and increased weight. Father absence during early life is also associated with early marriage, pregnancy and divorce. Choice of partner characteristics is critical to successful implementation of sexual strategies. It has been suggested that sexually dimorphic traits (including those evident in the face) signal high-quality immune function and reproductive status. Masculinity in males has also been associated with low investment in mate and offspring. Thus, women's reproductive strategy should be matched to the probability of male investment, hence to male masculinity. Our review leads us to predict associations between the rate of sexual maturation and adult preferences for facial characteristics (enhanced sexual dimorphism and attractiveness). We find for men, engaging in sex at an early age is related to an increased preference for feminized female faces. Similarly, for women, the earlier the age of first sex the greater the preference for masculinity in opposite-sex faces. When we controlled sexual dimorphism in male faces, the speed of sexual development in women was not associated with differences in preference for male facial attractiveness. These developmental influences on partner choice were not mediated by self-rated attractiveness or parental relationships. We conclude that individuals assort in preferences based on the rapidity of their sexual development. Fast developing individuals prefer opposite-sex partners with an increased level of sexually dimorphic facial characteristics.     

Temporal variations of the postnatal rat urinary proteome as a reflection of systemic maturation

The rat kidney matures during the first 2 wk of life, suggesting that temporal variations in the urinary proteome may occur during this period. We describe the urine proteome during postnatal development in the rat and demonstrate specific proteomic changes corresponding to developmental milestones. Urine was collected from 30 rats at five postnatal (P) days of life (P1, P3, P7, P14, and >P30) by bladder aspiration. The proteome was assessed by nano-ESI-LC-MS/MS. For identification, we used stringent criteria to provide a 1% false positive rate at the peptide level. The proteins in common at each time interval decreased during postnatal maturation. When comparing all five developmental times, six proteins were ubiquitously present. We detected 14 proteins involved with cellular adhesion, structure, or proliferation and differentiation only during neonatal development. Additionally, 30 proteins were specific to adults, of which 13 originated from the prostate or seminal vesicle. This is the first MS characterization of the normal urinary proteome in early postnatal rodent development that demonstrates distinct differences correlating with different stages of tissue maturation. Further characterization of the normal urinary proteome may provide the basis for identification of urinary biomarkers of diseases of the urinary tract.     

Delay in motor development of twins in Africa: a prospective cohort study.

Twins are prone to developmental delay due to prematurity and low birthweight. However it is unknown if twinning is an independent risk factor for developmental delay. The objective of this study was to compare the attainment of a set of gross motor milestones in a cohort of twins and singletons in The Gambia. Eighty-four pairs of twins and 72 singletons were enrolled at birth and followed up until 18 months of age. The mean age at achieving milestones was higher in twins for each development outcome and the difference between twins and singletons was significant after adjustment for confounders for maintaining head, sitting without support and walking. In twins, we found a highly significant correlation within pairs for most milestones. When monozygotic and dizygotic twins were compared, a significant heritability was observed for crawling, sitting, standing and walking, with over 90% of population variance observed due to genetic factors rather than environmental factors. There was little evidence for a genetic contribution towards very early milestones. In conclusion, our data suggest that twinning is an independent risk factor for developmental delay in early life in The Gambia, and that genetic factors contribute strongly to certain motor development outcomes.     

Early development (5 to 48 months) in Williams syndrome. A study of 14 children.

At what age do children with Williams syndrome (WS) achieve major developmental milestones? Is their early development harmonious or are some of the typical discrepancies described in older children already noticeable? To address these questions we analysed information gathered over a five year period on 14 children with WS. Each child was evaluated at least twice between the ages of 5 and 48 months, using the Bayley Scales of Infant Development and during more informal observation sessions. Parents and professionals were also interviewed. This analysis provided us with an outline for "developmental norms" for children with WS and allowed us to conclude that, even before the age of 4 years, children with WS display a typical profile in their abilities. Expressive language skills are less delayed in contrast to the important delay in language comprehension and fine motor skills.     

A theory of follicle selection: I. Hypotheses and examples

A theory of follicle selection is developed in which all follicles, ovulatory and atretic, inherit the same developmental plan for responding to circulating concentrations of estradiol and gonadotropins. In the model, this plan is represented by a maturation surface that determines the rate of follicle growth as a function of follicle maturity and circulating hormone concentration. Examples of maturation surfaces are constructed for single and multiple spontaneous ovulators. When model follicles are activated from the reserve pool at random times, spontaneous and coordinated cycles of maturation develop in which the number of ovulatory follicles is controlled within a small and predictable range. For a given maturation surface, this range is nearly independent of the number of follicles in the interacting population, their activation times, and their initial maturities. The theory is therefore consistent with Lipschütz's Law of Follicular Constancy. The theory can account for certain statistical effects that occur with age on the timing of ovulation and the control of ovulation number. Maturation surfaces are also constructed that exhibit spontaneous transitions from cyclic to steady anovulatory behavior. The theory predicts an important regulatory role for atretic follicles in controlling both the timing of maturation and the number of follicles that reach ovulatory maturity.     

Neonatal Milestones,Behavior and Growth Rate of Sumatran Rhinoceros (Dicerorhinus sumatrensis) Calves Born and Bred in Captivity

The birth of Sumatran rhino calves at the Cincinnati Zoo and Botanical Garden offered a unique opportunity to study early development and cow–calf behavior in this elusive, critically endangered species. Study goals were to: (1) record developmental milestones of newborn calves; (2) characterize cow and calf behavior during the first year following birth; (3) compare trends in the behavioral development of a male vs. female calf; and (4) record weight gain and footprint size throughout the first year. In addition to recording eight neonatal milestones, more than 450 hr of behavioral data were collected on each of the two calves (one male and one female) and their dam during the first 12 months of life. Neonatal milestones were achieved within 24 hr of birth with the exception of first defecation, which occurred at 16–18 days. Although nursing bouts decreased slightly in the second half of the year (from once every 90 min to once every 2 hr), they continued to occur frequently throughout the day and night. Therefore, calves grew rapidly from approximately 33 kg at birth to 400 kg at 12 months. Average daily weight gain for the first week was approximately 2.0 kg, whereas average daily weight gain for the remaining 12 months was slight (<1 kg) and did not differ between calves. Eating and resting occupied 70–80% of the Sumatran rhino cow and calves' time and no gender biases in either maternal investment or developmental parameters were noted. Finally, footprint measurements proved valuable for estimating calf age. Zoo Biol 31:546‐560, 2012. © 2011 Wiley Periodicals, Inc.     

Differential development of human brain white matter tracts

Neuroscience is increasingly focusing on developmental factors related to human structural and functional connectivity. Unfortunately, to date, diffusion-based imaging approaches have only contributed modestly to these broad objectives, despite the promise of diffusion-based tractography. Here, we report a novel data-driven approach to detect similarities and differences among white matter tracts with respect to their developmental trajectories, using 64-direction diffusion tensor imaging. Specifically, using a cross-sectional sample comprising 144 healthy individuals (7 to 48 years old), we applied k-means cluster analysis to separate white matter voxels based on their age-related trajectories of fractional anisotropy. Optimal solutions included 5-, 9- and 14-clusters. Our results recapitulate well-established tracts (e.g., internal and external capsule, optic radiations, corpus callosum, cingulum bundle, cerebral peduncles) and subdivisions within tracts (e.g., corpus callosum, internal capsule). For all but one tract identified, age-related trajectories were curvilinear (i.e., inverted 'U-shape'), with age-related increases during childhood and adolescence followed by decreases in middle adulthood. Identification of peaks in the trajectories suggests that age-related losses in fractional anisotropy occur as early as 23 years of age, with mean onset at 30 years of age. Our findings demonstrate that data-driven analytic techniques may be fruitfully applied to extant diffusion tensor imaging datasets in normative and neuropsychiatric samples.     

Age at maturity in wild baboons: genetic, environmental and demographic influences

The timing of early life-history events, such as sexual maturation and first reproduction, can greatly influence variation in individual fitness. In this study, we analysed possible sources of variation underlying different measures of age at social and physical maturation in wild baboons in the Amboseli basin, Kenya. The Amboseli baboons are a natural population primarily comprised of yellow baboons (Papio cynocephalus) that occasionally hybridize with anubis baboons (Papio anubis) from outside the basin. We found that males and females differed in the extent to which various factors influenced their maturation. Surprisingly, we found that male maturation was most strongly related to the proportion of anubis ancestry revealed by their microsatellite genotypes: hybrid males matured earlier than yellow males. In contrast, although hybrid females reached menarche slightly earlier than yellow females, maternal rank and the presence of maternal relatives had the largest effects on female maturation, followed by more modest effects of group size and rainfall. Our results indicate that a complex combination of demographic, genetic, environmental, and maternal effects contribute to variation in the timing of these life-history milestones.     

Developmental Changes in Memory-Related Linguistic Skills and Their Relationship to Episodic Recall in Children

This longitudinal study of nine children examined two issues concerning infantile amnesia: the time at which memories for events experienced before the age of 3–4 years disappear from consciousness and whether this timing of memory loss is related to the development of specific aspects of episodic and autobiographical memory. This study followed children from infancy to early childhood and examined the central role of three verbal–cognitive milestones related to autobiographical memory: the age at which children begin to report autobiographical memories using the past tense (Milestone 1); the age at which they begin to verbally acknowledge past events (Milestone 2); and the age at which they begin to spontaneously use memory-related verbs (Milestone 3). As expected, memories of events that occurred before 3–4 years of age were affected by infantile amnesia. Achievement of these milestones followed almost the same developmental progression: Milestone 1 (1 year; 10 months (1;10) to 3 years; 4 months (3;4)) was followed by Milestones 2 (3;1 to 4;0) and 3 (3;5 to 4;4). Milestone 2 was typically related to the onset of infantile amnesia, whereas Milestone 1 occurred during the period for which the children became amnesic as they aged. These data suggest that linguistic meta-cognitive awareness of personal memory is the key feature in infantile amnesia.     

Analysis of developmental preformation in the alpine herb Caltha leptosepala (Ranunculaceae)

Developmental preformation is ubiquitous among alpine and arctic tundra plant species and may cause a delay in plant morphological responses to environmental variation. The duration of preformation and seasonal pattern of development were examined in Caltha leptosepala to identify characteristics of architecture and development that may influence the timing of plant responses to environmental cues, both within a single growing season and between years. All structures in C. leptosepala are preformed: leaves are initiated one or two growing seasons before they mature and flowers are initiated one growing season before maturation. Features of development and architecture in C. leptosepala, however, appear to differ from the determinate growth patterns of other exclusively preforming species, and may allow within-season variability in the seasonal development and maturation of structures. Cohorts of leaves initiated are asynchronous with maturation cohorts, and each year the number of leaf primordia per plant at snowmelt exceeds the number to mature aboveground. Therefore, some flexibility in whether leaves complete a 2-yr or 3-yr developmental trajectory might occur. Plasticity in reproductive phenotype might also occur via the process of floral abortion. Despite developmental characteristics that might facilitate the expression of phenotypic plasticity, only slight variability was observed in the duration of preformation or in the seasonal pattern of initiation and emergence of structures. Growth patterns of C. leptosepala thus appear to be fundamentally constrained, and limitations to annual growth may assure that sufficient preformed primordia remain belowground at the end of each growing season for maturation of a full cohort during the subsequent season.     

Developmental evaluation of children born to mothers occupationally exposed to waste anesthetic gases

BACKGROUND: The etiology of developmental delay in children is frequently unknown. Increasing evidence supports the possibility that environmental and occupational factors might be part of the basis for such delays. This study focuses on the development of children born to mothers who were exposed during their pregnancy to waste anesthetic gases. METHODS: The study population included 40 children aged 5-13 years born to female anesthesiologists and nurses working in operating rooms (OpRs) exposed to waste anesthetic gases, and 40 unexposed children born to female nurses and physicians who worked in hospitals during their pregnancy but did not work in OpRs. The unexposed group was matched for children's age and gender and maternal occupation (nurses vs. doctors). By means of standardized developmental tests, the present study population was evaluated for their medical and neurodevelopmental state. Questionnaires were given for the detection of attention and activity levels as perceived by the parents. Additional questionnaires dealt with information concerning developmental milestones, maternal and fetal morbidity, and gynecological history. RESULTS: No differences were noted between the groups as newborns or in developmental milestones at the age of 5-13 years; however, the mean score of gross motor ability was significantly lower in the exposed versus the unexposed group. Additionally, the mean score of the DSM-III-R Parent-Teacher Questionnaire (PTQ) (i.e., measure of inattention/hyperactivity) was higher in the exposed group. The level of exposure, as measured by the number of weekly hours in the OpRs, was significantly and negatively correlated with fine motor ability and the score of IQ performance. CONCLUSIONS: Our study supports the hypothesis that occupational exposure to anesthetic gases might be a risk factor for minor neurological deficits of children born to mothers who work in OpRs and therefore indicates the need for more studies in this area and perhaps more caution among OpR pregnant women and employers.     

Developmental variation in salmonid populations

Salmonid life-history patterns vary within and between species, and within and between populations. Two major developmental conversions ( sensu Smith-Gill) occur in the life of salmonids: smolting, in which freshwater adaptations are exchanged for marine ones; and sexual maturation. Each process is circannual, endogenously rhythmic but synchronized by photoperiod. Each involves a choice of developmental route, whose direction depends on the individual's responses to prior feeding opportunity, and its current metabolic performance. Data are presented from laboratory and farm experiments on Atlantic salmon, Salmo salar L., designed to test this developmental model. The findings are used to interpret variation in these developmental characteristics, and their consequences for life-history patterns, evident over the geographical range of Atlantic salmon and other salmonids.     

牛卵母细胞体外成熟的研究

牛卵母细胞的成熟过程中,包括细胞膜、细胞质、细胞核的成熟。其中细胞质的成熟最为复杂。线粒体、皮质颗粒数量的变化和位移,脂滴类型的变化和形态改变,空泡形态学的变化等是鉴别卵母细胞幼稚、成熟和老化的重要特征。透明带随着培养而外侧疏松,内侧致密,母卵细胞膜上伸出的微绒毛为膨大泡状和细长毛状两种。在培养１４小时后颗粒细胞与透明带脱离联系。根据综合指标判定,１８小时这前为成熟生长期,１８￣２６小时为成熟期,     

Heart-rate variability in children. Spectral analysis of developmental changes between 5 and 24 years

The variation in instantaneous heart rate is most prominent in infants and younger subjects. In a preliminary study of the effects of maturation on heart rate, we compared the heart rate variations of 29 children and young adults in three groups between 5 and 24 years of age. We used spectral analysis to determine the intensity of the variations in each of the two main frequency bands in which variations occur: HF, 0.15-0.45 Hz, and LF, 0.03-0.15 Hz. Three-minute segments of continuous instantaneous heart rate were recorded for each subject in standing and supine positions. The group mean LF and HF amplitudes and the L/H ratio decreased between 5 and 10 years of age in both positions, significantly for LF and L/H in the supine position (p less than 0.05). Half of the youngest group of children had adult LF amplitude values by 5 years of age; the others had much higher levels, indicating increased low frequency variation at this age. Thus the high variation in heart rate in very young subjects is most prominent in the LF range. These preliminary results, considered with previous pharmacological studies, suggest that many children have a significant decrease in sympathetic activity between 5 and 10 years of age and possibly a slight decrease in parasympathetic activity. Spectral analysis of heart rate appears a promising technique for investigating the development of neural control of the heart.     

Age- and sex-related characteristics and mechanisms of adaptations during the prepubertal and pubertal periods of development

Integrated study of the functional state of the sympathoadrenal system and the adrenal cortex in children of both sexes aged 10–15 years. The study was conducted on the basis of the daily adrenaline, noradrenaline, 17-ketosteroid, and 17-oxycorticosteroid excretion values, which allowed certain synchrony to be established in the manifestation of the activity of the transmitter link of the sympathoadrenal system and the adrenal cortex androgenic and glucocorticoid functions with age, during sexual maturation. The heterogeneous character of maturation was found in the sex groups: in girls at an age of 10 and 12 years and in the boys at an age of 14–15 years. Changes in the excretion of the hormones and hormone metabolites with different directions and rates in the age-sex groups were observed throughout the academic year. In 14- to 15-year-old boys, a sharp increase in the daily excretion of the glucocorticoid metabolites accompanied by a substantial decrease in the age-related noradrenaline excretion values and the sex hormone metabolite values at an age of 15 years was observed. In the girls, these values varied within the age range, which indicates a more perfect character of the neuroendocrine regulation of their physiological functions in the period of sexual maturation.     

Development of natural growth regimes for hatchery-reared steelhead to reduce residualism, fitness loss, and negative ecological interactions

Wild steelhead (Oncorhynchus mykiss) typically spend two or more years in freshwater before migrating to sea, but hatchery steelhead are almost ubiquitously released as yearlings. Their large size at release coupled with life history pathways that include both male and female maturation in freshwater present ecological risks different from those posed by hatchery populations of Pacific salmon. Yearling hatchery reared steelhead that fail to attain minimum thresholds for smoltification or exceed thresholds for male maturation tend to ‘residualize’ (i.e., remain in freshwater). Residuals pose ecological risks including size-biased interference competition and predation on juvenile salmon and trout. Three hatchery populations of steelhead in Hood Canal, WA were reared under growth regimes designed to produce a more natural age at smoltification (age-2) to aid in rebuilding their respective natural populations. Mean smolt sizes and size variability at age-2 were within the range of wild smolts for two of the three populations. The third population reared at a different facility under similar temperatures exhibited high growth rate variability and high male maturation rates (20% of all released fish). Experimentally comparing age-1 and age-2 smolt programs will help identify optimal rearing strategies to reduce the genetic risk of domestication selection and reduce residualism rates and associated negative ecological effects on natural populations. Investigations of Winthrop National Fish Hatchery summer-run steelhead will measure a) selection on correlated behavioral traits (‘behavioral syndromes’), b) degree of smoltification, c) changes in hormones that regulate gonad growth at key developmental stages, and d) conduct extensive post-release monitoring of fish reared under each growth regime.     

Genome-Wide Association Study (GWAS) for Growth Rate and Age at Sexual Maturation in Atlantic Salmon (Salmo salar)

Early sexual maturation is considered a serious drawback for Atlantic salmon aquaculture as it retards growth, increases production times and affects flesh quality. Although both growth and sexual maturation are thought to be complex processes controlled by several genetic and environmental factors, selection for these traits has been continuously accomplished since the beginning of Atlantic salmon selective breeding programs. In this genome-wide association study (GWAS) we used a 6.5K single-nucleotide polymorphism (SNP) array to genotype ∼480 individuals from the Cermaq Canada broodstock program and search for SNPs associated with growth and age at sexual maturation. Using a mixed model approach we identified markers showing a significant association with growth, grilsing (early sexual maturation) and late sexual maturation. The most significant associations were found for grilsing, with markers located in Ssa10, Ssa02, Ssa13, Ssa25 and Ssa12, and for late maturation with markers located in Ssa28, Ssa01 and Ssa21. A lower level of association was detected with growth on Ssa13. Candidate genes, which were linked to these genetic markers, were identified and some of them show a direct relationship with developmental processes, especially for those in association with sexual maturation. However, the relatively low power to detect genetic markers associated with growth (days to 5 kg) in this GWAS indicates the need to use a higher density SNP array in order to overcome the low levels of linkage disequilibrium observed in Atlantic salmon before the information can be incorporated into a selective breeding program.     

How good is general practice developmental screening?

All developmental screening in Somerset is performed by general practitioners and health visitors. A retrospective review of a cohort of 1504 7 year old children living in semirural Somerset found that the development assessment by a health visitor at age 3 1/2 years had a sensitivity of 45% for identifying the 103 children with special educational needs, whereas the sensitivity of the preschool examination by a general practitioner was 56%. There was no relation between results of preschool developmental assessment and later reading ability. Of the 23 children in special schools, 22 had been identified independently of the developmental screening programme before starting school. Intervention was started at a mean age of 1 year 5 months (range 2 months to 3 years) for children with severe learning difficulties, and 3 years 9 months (2 years 3 months to 6 years 6 months) for children with moderate learning difficulties. The preschool medical examination revealed fairly minor medical problems: 29 of 81 children referred for specialist opinions were shown to be medically normal, and for only seven of the medically abnormal children was information about their conditions given to their teachers. In Somerset screening the development of all children at predetermined ages has not been very useful.     

Abnormal germ cell development in cryptorchidism.

BACKGROUND: Previous studies suggest that two fundamental, probably androgen-dependent, steps in maturation of germ cells normally occur in the prepubertal testis: the disappearance of gonocytes (the fetal stem cell pool) and the appearance of adult dark spermatogonia (the adult stem cell pool) at 2-3 months of age and the appearance of primary spermatocytes (the onset of meiosis) at 4-5 years. Previous studies of small series of cryptorchid boys suggest that both steps are defective in undescended testes and to a lesser degree in descended testes contralateral to unilaterally undescended testes. The purpose of this study is to confirm the previous findings of defective germ cell maturation in a large series of boys with unilateral undescended testes. PATIENTS: Seven hundred and sixty-seven boys with unilateral cryptorchidism who had orchidopexy and bilateral testicular biopsies between birth and 9 years of age were studied. MATERIALS AND METHODS: Total and differential germ cell counts were performed on semithin histologic sections of the biopsies. The results from the undescended and contralateral descended testes were compared using the Wilcoxon signed-rank test and the Wilcoxon-Whitney-Mann U test. RESULTS: Gonocytes failed to disappear and adult dark spermatogonia failed to appear in undescended testes under 1 year of age indicating a defect in the first step in maturation at 2-3 months resulting in failure to establish an adequate adult stem cell pool. Primary spermatocytes failed to appear in undescended testes and appeared in only 19% of contralateral descended testes at 4-5 years of age indicating a defect in the onset of meiosis. CONCLUSION: Unilaterally undescended testes fail to establish an adequate adult stem cell pool which normally occurs at 2-3 months of age and fail to establish adequate meiosis which normally occurs at 4-5 years of age. Similar but less severe changes are seen in the contralateral descended testes. Defects in the two pubertal steps in germ cell maturation are associated with reduced total germ cell counts.     

Developmental Trajectories of Social Skills during Early Childhood and Links to Parenting Practices in a Japanese Sample

This study used data from a nationwide survey in Japan to model the developmental course of social skills during early childhood. The goals of this study were to identify longitudinal profiles of social skills between 2 and 5 years of age using a group-based trajectory approach, and to investigate whether and to what extent parenting practices at 2 years of age predicted developmental trajectories of social skills during the preschool period. A relatively large sample of boys and girls (N > 1,000) was assessed on three social skill dimensions (Cooperation, Self-control, and Assertion) at four time points (ages 2, 3, 4, and 5), and on four parenting practices (cognitive and emotional involvement, avoidance of restriction and punishment, social stimulation, and social support for parenting) at age 2. The results indicated that for each social skill dimension, group-based trajectory models identified three distinct trajectories: low, moderate, and high. Multinomial regression analysis revealed that parenting practice variables showed differential contributions to development of child social skills. Specifically, Cooperation and Assertion were promoted by cognitive and emotional involvement, Self-control by social stimulation, and Assertion by avoidance of restriction and punishment. Abundant social support for parenting was not associated with higher child social skills trajectories. We found heterogeneity in developmental profiles of social skills during the preschool ages, and we identified parenting practices that contributed to different patterns of social skills development. We discussed the implications of higher-quality parenting practices on the improvement of child social skills across early childhood.