Endometriosis and polycystic ovary syndrome are diametric disorders.

Evolutionary and comparative approaches can yield novel insights into human adaptation and disease. Endometriosis and polycystic ovary syndrome (PCOS) each affect up to 10% of women and significantly reduce the health, fertility, and quality of life of those affected. PCOS and endometriosis have yet to be considered as related to one another, although both conditions involve alterations to prenatal testosterone levels and atypical functioning of the hypothalamic-pituitary-gonadal (HPG) axis.

Revisiting the wandering womb: Oxytocin in endometriosis and bipolar disorder.

Hippocrates attributed women's high emotionality - hysteria - to a 'wandering womb'. Although hysteria diagnoses were abandoned along with the notion that displaced wombs cause emotional disturbance, recent research suggests that elevated levels of oxytocin occur in both bipolar disorder and endometriosis, a gynecological condition involving migration of endometrial tissue beyond the uterus. We propose and evaluate the hypothesis that elevated oxytocinergic system activity jointly contributes to bipolar disorder and endometriosis.

How are autism and schizotypy related? Evidence from a non-clinical population.

Both autism spectrum conditions (ASCs) and schizophrenia spectrum conditions (SSCs) involve altered or impaired social and communicative functioning, but whether these shared features indicate overlapping or different etiological factors is unknown. We outline three hypotheses (overlapping, independent, and diametric) for the possible relationship between ASCs and SSCs, and compare their predictions for the expected relationships between autistic and schizotypal phenotypes using the Autism Spectrum Quotient and the Schizotypal Personality Questionnaire-Brief Revised from a large non-clinical sample of undergraduate students. Consistent with previous research, autistic features were positively associated with several schizotypal features, with the most overlap occurring between interpersonal schizotypy and autistic social and communication phenotypes.

Estrogen receptor 1 promoter polymorphism and digit ratio in men.

Objectives: The 2D:4D digit ratio, the relative lengths of the index and ring fingers in humans, is a widely used proxy measure for prenatal testosterone exposure. Varying distributions of androgen and estrogen receptors on the second and fourth digits, both of which regulate digit development, appears to be the basis for this effect. Polymorphism in a tandem repeat in the gene coding for the estrogen receptor α (ESR1) in zebra finches (Taeniopygia guttata) not only explains a significant amount of variation in digit ratio but also seems to explain the significant correlation between digit ratio and sexual behavior in these birds.

Aggression, digit ratio and variation in androgen receptor and monoamine oxidase a genes in men.

Variation in prenatal exposure to androgens is thought to be responsible for some of the individual differences in aggressive behavior among adults. A putative indicator of prenatal testosterone exposure, 2D:4D (the index to ring finger length) ratios have shown a weak correlation with aggression. Variation in sensitivity of the androgen receptor, resulting from polymorphism in the AR gene, is also thought to influence the relative expression of sexually dimorphic traits within each sex, including aggressive behavior and 2D:4D.

Sex differences in the relationship between aggressiveness and the strength of handedness in humans.

Cerebral lateralisation, the partitioning of cognitive functioning into one hemisphere of the brain, was once considered unique to humans; however, recent research in a variety of taxa suggests that lateralisation is an evolutionarily ancient adaptation. Handedness is the most obvious manifestation of cerebral lateralisation in humans. Much of the literature on handedness has focused on the direction, rather than the strength, of this lateralisation.