Despite the widespread assumption that paternal investment is substantial in our species, previous studies have shown mixed results in relation to the impact of fathers on both offspring survival and reproductive outcomes. Using data from a large representative sample of British men, we tested whether father absence is associated with the timing of reproduction-related events among boys, while ...

Several hypotheses have been proposed to explain cyclic fluctuations in abundance of some small mammal populations. These hypotheses have been controversial, however, and there is no consensus among biologists as to why population cycles occur. In a demographically based model, we tested the potential influence of phase-specific changes in life history traits (age at maturity, fertility, juveni...

Background: Due to lack of detailed standards of sexual maturity in individuals with Intellectual, sensory and motor disability in Iran and the importance of timing of onset of puberty in these individuals, a study is necessary. By knowing the onset of puberty, physiologic and behavioral changes can be traced in these people, as well as the potential impact of the puberty on the underlying dise...

Young athletes frequently suffer from being seen as athletes first and children second. This has consequences for their legal, civil and human rights as children (Kelly et al., 1995) and for the way in which sport organisations choose to intervene on their behalf to protect them from physical, psychological and sexual abuses (Brackenridge, 1994). Sport careers peak at different ages depending o...

OBJECTIVE This research tests the influences of age, biological, and psychosocial factors on sexual expression in later life. METHOD The American Association of Retired Persons Modern Maturity Sexuality Survey collected data on diagnosed illnesses, treated illnesses, sexual desire, sexual attitudes, partner circumstances, and sexual behavior from 1,384 persons ages 45 and older. Ordered logis...

Eruption pattern of permanent teeth in Delhi boys was studied in 1800 well nourished children age 5-14 years. Relationship of height, weight and sexual maturity with eruption of teeth was calculated. Earliest teeth to appear were lower first molar (5.64 years) followed by lower central incisors (6.02 years), The sequence of eruption in maxilla was first molar, incisors-central then lateral, fir...

The effects of early thermal environment on growth, age at maturity, and sexual size dimorphism in Arctic charr (Salvelinus alpinus) are investigated. This study is a 654-day long rearing trial split into two sequential experimental phases termed EP1 EP2 lasting 315 339 days, respectively. started the end yolk sac stage when fish were divided three groups reared different target temperatures (7...

Puberty is an important stage of development as a child's sexual and physical characteristics mature because of hormonal changes. To better understand puberty-related effects on brain development, we investigated the magnetic resonance imaging (MRI) data of 306 subjects from 4 to 18 years of age. Subjects were grouped into before and during puberty groups according to their sexual maturity leve...