|
Challenge Hypothesis
The challenge hypothesis outlines the dynamic relationship between testosterone and aggression in mating contexts. It proposes that testosterone promotes aggression when it would be beneficial for reproduction, such as mate guarding, or strategies designed to prevent the encroachment of intrasexual rivals. The positive correlation between reproductive aggression and testosterone levels is seen to be strongest during times of social instability. The challenge hypothesis predicts that seasonal patterns in testosterone levels are a function of mating system (monogamy versus polygyny), paternal care, and male-male aggression in seasonal breeders. The pattern between testosterone and aggression was first observed in seasonally breeding birds, where testosterone levels rise modestly with the onset of the breeding season to support basic reproductive functions. However, during periods of heightened male aggression, testosterone levels increase further to a maximum physiological level. Thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aggression
Aggression is behavior aimed at opposing or attacking something or someone. Though often done with the intent to cause harm, some might channel it into creative and practical outlets. It may occur either reactively or without provocation. In humans, aggression can be caused by various triggers. For example, built-up frustration due to blocked goals or perceived disrespect. Human aggression can be classified into direct and indirect aggression; while the former is characterized by physical or verbal behavior intended to cause harm to someone, the latter is characterized by behavior intended to harm the social relations of an individual or group. In definitions commonly used in the social sciences and behavioral sciences, aggression is an action or response by an individual that delivers something unpleasant to another person. Some definitions include that the individual must intend to harm another person. In an interdisciplinary perspective, aggression is regarded as "an ensem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estrogen
Estrogen (also spelled oestrogen in British English; see spelling differences) is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal activity: estrone (E1), estradiol (E2), and estriol (E3). Estradiol, an estrane, is the most potent and prevalent. Another estrogen called estetrol (E4) is produced only during pregnancy. Estrogens are synthesized in all vertebrates and some insects. Quantitatively, estrogens circulate at lower levels than androgens in both men and women. While estrogen levels are significantly lower in males than in females, estrogens nevertheless have important physiological roles in males. Like all steroid hormones, estrogens readily diffuse across the cell membrane. Once inside the cell, they bind to and activate estrogen receptors (ERs) which in turn modulate the expression of many ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paternal Care
In biology, paternal care is parental investment provided by a male to his own offspring. It is a complex social behavior in vertebrates associated with animal mating systems, life history traits, and ecology. Paternal care may be provided in concert with the mother (biparental care) or, more rarely, by the male alone (exclusive paternal care). The provision of care, by either males or females, is presumed to increase growth rates, quality, and/or survival of the young, ultimately increasing the inclusive fitness of the parents. In a variety of vertebrate species (e.g., about 80% of birds and about 6% of mammals), both males and females invest heavily in their offspring. Many of these bi-parental species are socially Monogamy, monogamous, so individuals remain with their mate for at least one breeding season. Exclusive paternal care has evolved multiple times in a variety of organisms, including invertebrates, fishes, and amphibians. Mammals Male mammals employ different beh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concealed Ovulation
Concealed ovulation or hidden estrus is the lack of any perceptible change (e.g., a change in appearance or scent) when an adult female is fertile and near ovulation. Some examples of perceptible changes are swelling and redness of the vulva in baboons and bonobos, and pheromone release in the feline family. In contrast, the females of humans and a few other species that undergo hidden estrus have few external signs of fecundity, making it difficult for a mate to consciously deduce, by means of external signs only, whether or not a female is near ovulation. Human females In humans, an adult woman's fertility peaks for a few days during each roughly monthly cycle. The frequency and length of fertility (the time when a woman can become pregnant) is highly variable between women, and can slightly change for each woman over the course of her lifespan. Humans are considered to have concealed ovulation because there is no outward physiological sign, either to a woman herself or to o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovulation
Ovulation is an important part of the menstrual cycle in female vertebrates where the egg cells are released from the ovaries as part of the ovarian cycle. In female humans ovulation typically occurs near the midpoint in the menstrual cycle and after the follicular phase. Ovulation is stimulated by an increase in luteinizing hormone (LH). The ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be fertilized by sperm. If it is not, it will break down in less than a day. Meanwhile, the uterine lining ( endometrium) continues to thicken to be able to receive a fertilized egg. If no conception occurs, the uterine lining will eventually break down and be shed from the body via the vagina during menstruation. Some people choose to track ovulation in order to improve or aid becoming pregnant by timing intercourse with their ovulation. The signs of ovulation may include cervical muc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexually Receptive
Sex is the trait that determines whether a sexually reproducing organism produces male or female gametes. Sex, SEX or sexual may also refer to: *Sexual intercourse, a sexual activity Arts and entertainment Film and television * ''Sex'' (1920 film), an American silent drama * ''Sex'' (2024 film), a Norwegian drama * ''Sex'' (TV series), an Australian series * "Sex", a 1997 TV episode of '' Brass Eye'' * "Sex", an episode of ''Kath & Kim'', 2002 * '' Sex: The Annabel Chong Story'', a 1999 documentary film Literature * ''Sex'' (book), by Madonna and Steven Meisel, 1992 * ''Sex'' (manga), a Japanese manga series by Atsushi Kamijo * ''Sex'' (play), by Mae West, 1926 *''Sexes'', an MDPI academic journal Music *SEX, pseudonym of American rapper Young Thug Albums * ''Sex'' (Elli Kokkinou album), 2005 * ''Sex'' (Telex album), 1981 * ''Sex'' (The Necks album), 1989 * ''Sex'' (The 1975 EP), 2012 * ''Sex'' (Tila Tequila EP), 2007 * ''Sex'' (Vintage album), 2009 Songs * "Sex" (The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endocrine System
The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant Organ (biology), organs. In vertebrates, the hypothalamus is the neural control center for all endocrine systems. In humans, the major endocrine glands are the thyroid gland, thyroid, parathyroid gland, parathyroid, pituitary gland, pituitary, pineal gland, pineal, and adrenal glands, and the (male) testis and (female) ovaries. The hypothalamus, pancreas, and thymus also function as endocrine glands, among other functions. (The hypothalamus and pituitary glands are organs of the Neuroendocrinology#Neuroendocrine system, neuroendocrine system. One of the most important functions of the hypothalamusit is located in the brain adjacent to the pituitary glandis to link the endocrine system to the nervous system via the pituitary gland.) Other organs, such as the kidneys, also have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paternal Care
In biology, paternal care is parental investment provided by a male to his own offspring. It is a complex social behavior in vertebrates associated with animal mating systems, life history traits, and ecology. Paternal care may be provided in concert with the mother (biparental care) or, more rarely, by the male alone (exclusive paternal care). The provision of care, by either males or females, is presumed to increase growth rates, quality, and/or survival of the young, ultimately increasing the inclusive fitness of the parents. In a variety of vertebrate species (e.g., about 80% of birds and about 6% of mammals), both males and females invest heavily in their offspring. Many of these bi-parental species are socially Monogamy, monogamous, so individuals remain with their mate for at least one breeding season. Exclusive paternal care has evolved multiple times in a variety of organisms, including invertebrates, fishes, and amphibians. Mammals Male mammals employ different beh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estrus
The estrous cycle (, originally ) is a set of recurring physiological changes induced by reproductive hormones in females of mammalian subclass Theria. Estrous cycles start after sexual maturity in females and are interrupted by anestrous phases, otherwise known as "rest" phases, or by pregnancies. Typically, estrous cycles repeat until death. These cycles are widely variable in duration and frequency depending on the species.Bronson, F. H., 1989. Mammalian Reproductive Biology. University of Chicago Press, Chicago, IL, USA. Some animals may display bloody vaginal discharge, often mistaken for menstruation. Many mammals used in commercial agriculture, such as cattle and sheep, may have their estrous cycles artificially controlled with hormonal medications for optimum productivity. The male equivalent, seen primarily in ruminants, is called rut. Differences from the menstrual cycle Mammals share the same reproductive system, including the regulatory hypothalamic system tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life History Theory
Life history theory (LHT) is an analytical frameworkVitzthum, V. (2008). Evolutionary models of women's reproductive functioning. ''Annual Review of Anthropology'', ''37'', 53-73 designed to study the diversity of life history strategies used by different organisms throughout the world, as well as the causes and results of the variation in their life cycles.Flatt, T., & Heyland, A. (Eds.). (2011). Mechanisms of Life History Evolution : The Genetics and Physiology of Life History Traits and Trade-Offs. Oxford, GB: OUP Oxford. It is a theory of biological evolution that seeks to explain aspects of organisms' anatomy and behavior by reference to the way that their life histories—including their reproductive development and behaviors, post-reproductive behaviors, and lifespan (length of time alive)—have been shaped by natural selection. A life history strategy is the "age- and stage-specific patterns" and timing of events that make up an organism's life, such as birth, weaning, matu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pair Bonding
In biology, a pair bond is the strong affinity that develops in some species between a mating pair, often leading to the production and rearing of young and potentially a lifelong bond. Pair-bonding is a term coined in the 1940s that is frequently used in sociobiology and evolutionary biology circles. The term often implies either a lifelong socially monogamous relationship or a stage of mating interaction in socially monogamous species. It is sometimes used in reference to human relationships. Varieties According to evolutionary psychologists David P. Barash and Judith Lipton, from their 2001 book ''The Myth of Monogamy'', there are several varieties of pair bonds: *''Short-term pair-bond:'' a transient mating or associations *''Long-term pair-bond:'' bonded for a significant portion of the life cycle of that pair *''Lifelong pair-bond:'' mated for life *''Social pair-bond:'' attachments for territorial or social reasons *''Clandestine pair-bond:'' quick extra-pair copulations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Fence Lizard
The eastern fence lizard (''Sceloporus undulatus'') is a medium-sized species of lizard in the Family (biology), family Phrynosomatidae. The species is found along forest edges, rock piles, and rotting logs or stumps in the eastern United States. It is sometimes referred to as the prairie lizard, fence swift, gray lizard, gravid lizard, northern fence lizard or pine lizard. It is also referred to colloquially as the horn-billed lizard. One of its most notable behaviors is that of its escape behavior when encountering fire ants, which have been known to invade and negatively affect many of their populations. Taxonomy The Genus, generic name, ''Sceloporus'', is derived from the Ancient Greek, Greek ''skelos''/σκελος, meaning "leg", and the Latin ''porus'', meaning "hole", referring to the enlarged femoral pores found in this genus of lizards. The specific name, ''undulatus'', is Latin for "wave", referring to the transverse dark crossbars on the backs of these lizards.Henry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
