Sex Differences In Maturation Research Articles

Sex differences in maturation and aging of human personality on the basis of a recently developed complex hierarchical model of temperament and character

Objective The current study aimed to determine the changes in psychological function that come with age. The basis to assess psychological function was a hierarchical model of temperament, personality and character, previously developed by the authors. Methods 734 general population subjects completed the TEMPS-A, the TCI and the NEO-PI-3. Data were analysed with ANCOVA models. Results The top superfactors showed no age change, however, age-related changes were identified in the higher and lower modules. There was a pattern of differences between the two genders in all levels of the model. Conclusions While there is stability with the two top factors of personality, there are age-related changes in lower-level modules probably indicating maturation, adaptation or changes in orientation through the adult life span. Gender differences in all levels including the two top superfactors, higher and lower modules reflect and explain differences in multiple aspects of internal experience, interaction and behaviour in the two genders. The results are clinically essential for incorporating age and gender-related differences of experience and behaviour in understanding temperamental implications in affective disorders also impacting their clinical course and management. Key Points Based on the complex hierarchical temperament model four stages of maturation of human psychological function can be postulated. There is a very specific trait core of human mental function, which differs between genders and seems to be responsible for the longitudinal stability of the person’s internal experience with the passing of the years. The findings are clinically essential for incorporating age and gender-related differences of experience and behaviour in understanding temperamental implications in affective disorders also impacting their clinical course and management.

Sex Differences in Maturation and Attrition of Adult Neurogenesis in the Hippocampus.

Sex differences exist in the regulation of adult neurogenesis in the hippocampus in response to hormones and cognitive training. Here, we investigated the trajectory and maturation rate of adult-born neurons in the dentate gyrus (DG) of male and female rats. Sprague Dawley rats were perfused 2 h, 24 h, one week (1w), 2w, or 3w after bromodeoxyuridine (BrdU) injection, a DNA synthesis marker that labels dividing progenitor cells and their progeny. Adult-born neurons (BrdU/NeuN-ir) matured faster in males compared with females. Males had a greater density of neural stem cells (Sox2-ir) in the dorsal, but not in the ventral, DG and had higher levels of cell proliferation (Ki67-ir) than non-proestrous females. However, males showed a greater reduction in neurogenesis between 1week and 2weeks after mitosis, whereas females showed similar levels of neurogenesis throughout the weeks. The faster maturation and greater attrition of new neurons in males compared with females suggests greater potential for neurogenesis to respond to external stimuli in males and emphasizes the importance of studying sex on adult hippocampal neurogenesis.

Sex differences in age-to-maturation relate to sexual selection and adult sex ratios in birds.

Maturation (the age when organisms are physiologically capable of breeding) is one of the major life history traits that have pervasive implications for reproductive strategies, fitness, and population growth. Sex differences in maturation are common in nature, although the causes of such differences are not understood. Fisher and Lack proposed that delayed maturation in males is expected when males are under intense sexual selection, but their proposition has never been tested across a wide range of taxa. By using phylogenetic comparative analyses and the most comprehensive dataset to date, including 201 species from 59 avian families, we show that intense sexual selection on males (as indicated by polygamous mating and male‐skewed sexual size dimorphism) correlates with delayed maturation. We also show that the adult sex ratio (ASR), an indicator of the social environment, is associated with sex‐specific maturation because in species with a female‐skewed ASR, males experience later maturation. Phylogenetic path analyses suggest that adult sex ratio drives interspecific changes in the intensity of sexual selection which, in turn, influences maturation. These results are robust to alternative phylogenetic hypotheses and to potential life‐history confounds, and they provide the first comprehensive support of Fisher's and Lack's propositions. Importantly, our work suggests that both social environment and mate competition influence the evolution of a major life history trait, maturation.

Sex Differences in Maturation of Human Embryonic Stem Cell-Derived β Cells in Mice.

Pancreatic progenitors derived from human embryonic stem cells (hESCs) are now in clinical trials for insulin replacement in patients with type 1 diabetes. Animal studies indicate that pancreatic progenitor cells can mature into a mixed population of endocrine cells, including glucose-responsive β cells several months after implantion. However, it remains unclear how conditions in the recipient may influence the maturation and ultimately the function of these hESC-derived cells. Here, we investigated the effects of (1) pregnancy on the maturation of human stage 4 (S4) pancreatic progenitor cells and (2) the impact of host sex on both S4 cells and more mature stage 7 (S7) pancreatic endocrine cells implanted under the kidney capsule of immunodeficient SCID-beige mice. Pregnancy led to increased proliferation of endogenous pancreatic β cells, but did not appear to affect proliferation or maturation of S4 cells at midgestation. Interestingly, S4 and S7 cells both acquired glucose-stimulated C-peptide secretion in females before males. Moreover, S4 cells lowered fasting blood glucose levels in females sooner than in males, whereas the responses with S7 cells were similar. These data indicate that the host sex may impact the maturation of hESC-derived cells in vivo and that this effect can be minimized by more advanced differentiation of the cells before implantation.

Sex Differences in Brain Maturation as Measured Using Event-Related Potentials

Little is known about how sex influences functional brain maturation. The current study investigated sex differences in the maturation of event-related potential (ERP) amplitudes during an auditory oddball task (N = 170; age = 6–17 years). Performance improved with age. N200 amplitude declined with age: parietal sites showed earlier development than temporal and frontal locations. Girls showed greater bilateral frontal P300 amplitude development, approaching the higher values observed in boys during childhood. After controlling for age, right frontal P300 amplitude was associated with reaction time in girls. The findings demonstrate sex differences in ERP maturation in line with behavioral and neuroimaging studies.

Age estimation of adolescent and young adult male and female skeletons II, epiphyseal union at the upper limb and scapular girdle in a modern Portuguese skeletal sample

This study completes previously reported ages for timing of epiphyseal union in the postcranial skeleton in a recent sample, with data from the scapula, clavicle, humerus, radius, and ulna. A sample of 121 individuals between the ages of 9 and 29 (females = 65, males = 56) was derived from the Lisbon documented skeletal collection. Epiphyseal union was scored at 16 anatomical locations, using a three-stage scheme: 1) no union; 2) partial union; and 3) completed union, all traces of fusion having disappeared. In the upper limb, the epiphyses of the elbow are the first to fuse at around 11 to 15 years of age, followed by those of the shoulder and wrist. In the scapular girdle, the coracoid area is the first to fuse, followed by the glenoid surface and remaining epiphyses, with the medial clavicle fusing last, by the age of 25-27. There is a sex difference in maturation, with females showing an advance relative to males of about 2 years in the upper limb. Sex differences in maturation are less noticeable in the scapular girdle, but data suggest that females are also ahead of males. Results suggest overall similar age ranges for stages of union as previous dry bone observations, but some studies show significant divergences which seem to derive from methodological issues. Although some radiographic reference standards provide comparable age ranges, they should probably be avoided when aging skeletal remains.

Sex differences in brain size, stature and intelligence in children and adolescents: some evidence from Estonia

Abstract Sex differences in brain size and stature decrease from the age of 7 through 13–14 years and increase from the age of 15 through 18 years in Estonia, as they do in the United States. Sex differences in intelligence show a somewhat similar decrease and increase although they do not move precisely in synchrony with the morphological trends. The results are interpreted as suggesting that sex differences in maturation determine the magnitude of sex differences in physical and mental development during childhood and adolescence.

Seasonal Sex Ratio Trend in the European Kestrel: An Evolutionarily Stable Strategy Analysis.

We present an evolutionarily stable strategy (ESS) model to analyze selection on seasonal variation in the brood sex ratio, as observed in several species of raptorial birds. The model is specifically tailored to the life history of the European kestrel, and it reflects the maturation time hypothesis, the idea that a seasonal sex ratio trend has evolved because of sex differences in the dependence of age of first breeding on date of birth. First we show how to derive a fitness function in the context of a seasonal environment. Model parameters are estimated from field data in order to derive quantitative predictions. Since little is known about constraints on sex ratio control in birds, we analyze three scenarios, each corresponding to a different strategy set. We consider a model without constraints on sex ratio control, a model where the sex ratio trend is constrained to be linear, and a mechanistic model incorporating a plausible mechanism of sex ratio control in birds. One of the models yields an ESS sex ratio trend that closely resembles the trend observed in the field. However, the predictions are very sensitive to the choice of strategy set. Moreover, the selective forces generated by sex differences in maturation are rather weak. In fact, the mechanistic model shows that seemingly negligible costs of sex ratio control may be sufficient to overcome the adaptive value of adjusting the sex ratio.

Seasonal Sex Ratio Trend in the European Kestrel: An Evolutionarily Stable Strategy Analysis

We present an evolutionarily stable strategy (ESS) model to analyze selection on seasonal variation in the brood sex ratio, as observed in several species of raptorial birds. The model is specifically tailored to the life history of the European kestrel, and it reflects the maturation time hypothesis, the idea that a seasonal sex ratio trend has evolved because of sex differences in the dependence of age of first breeding on date of birth. First we show how to derive a fitness function in the context of a seasonal environment. Model parameters are estimated from field data in order to derive quantitative predictions. Since little is known about constraints on sex ratio control in birds, we analyze three scenarios, each corresponding to a different strategy set. We consider a model without constraints on sex ratio control, a model where the sex ratio trend is constrained to be linear, and a mechanistic model incorporating a plausible mechanism of sex ratio control in birds. One of the models yields an ESS sex ratio trend that closely resembles the trend observed in the field. However, the predictions are very sensitive to the choice of strategy set. Moreover, the selective forces generated by sex differences in maturation are rather weak. In fact, the mechanistic model shows that seemingly negligible costs of sex ratio control may be sufficient to overcome the adaptive value of adjusting the sex ratio.

Neuropsychological Development in Adolescents: Cognitive and Emotional Model for considering Risk Factors for Adolescents with Cleft

This article reviews neurologic, endocrinologic, and neuropsychological developments that affect our understanding of the adolescent patient. Neuroimaging and neuroradiologic techniques have assisted in identifying brain-behavior relationships and how different neuropsychological patterns result in different ways of thinking. Psychoneuroendocrinologic studies have shown that sex differences in maturation and hormonal effects on behavior need taking into account. At adolescence, the individual with a cleft or craniofacial condition may be at risk for adjustment problems due to earlier developmental events, which may affect language, behavior, and self-esteem.