Lecture 5: Hormones involved in Parental and Social Behavior Flashcards
Main Hormones associated with Parental and Social Behavior (1)
1) Prolactin
* Primarily produced by the anterior pituitary gland in response to prolactin-releasing factor produced by the hypothalamus.
* In females, prolactin plays a central role in lactation and milk production after childbirth (oxytocin does the release of milk). During pregnancy, prolactin levels rise steadily, preparing the breasts for lactation.
* In males, prolactin also serves various functions, including regulation of the immune system, metabolism, and reproduction. Its effects on reproductive function includes sperm production and regulation of testosterone levels. Helps regulate steroid sexual hormones.
Main Hormones associated with Parental and Social Behavior (2)
2) Oxytocin:
Produced primarily in the hypothalamus and released by the posterior pituitary gland. It is involved in:
* Labor and childbirth: Oxytocin stimulates uterine contractions during labor, facilitating childbirth, and promotes the ejection of milk during breastfeeding.
* Maternal behavior: Often referred to as the “love hormone” or “bonding hormone“. It is associated with intimate physical contact, such as hugging, kissing, and attachment (secure vs insecure attachment - oxytocin is related to more secure attachment style) .
* Stress regulation: helps modulate the body’s stress responses by attenuating the release of stress hormones like cortisol.
* Social behavior: Oxytocin influences social behaviors such as empathy, generosity, and social cognition.
Main Hormones associated with Parental and Social Behavior (3)
3) Estradiol (main female hormone - from same family from estrogen)
* Primarily produced by the ovaries in women. During the menstrual cycle, estradiol levels rise during the follicular phase, which occurs before ovulation.
* Positive effect on mood, improved mood, increased energy, boost in confidence and self esteem.
* Plays a crucial role in the development and maintenance of female reproductive tissues, and influences secondary sexual characteristics such as breast development and body fat distribution
* In men, estradiol is synthesized in small amounts primarily in the testes. This hormone is produced by testosterone (enzyme converts testosterone to estrodial). Testosterone, the main male sex hormone, is converted to estradiol through the action of the enzyme aromatase.
Main Hormones associated with Parental and Social Behavior (4)
4) Progesterone
* Second stage of menstrual process.
* Progesterone is mainly produced by the corpus luteum in the ovary after ovulation. It helps prepare the uterine lining for potential implantation. During pregnancy, the placenta becomes the primary source of progesterone production.
* In both men and women, small amounts of progesterone are also produced by the adrenal glands. These adrenal hormones play various roles in regulating metabolism, stress responses, and other physiological functions. Also produced in males.
Main Hormones associated with Parental and Social Behavior (5)
5) Cortisol - cortical steroid in animals, dexamethasone is its artificial name (synthetic form)!!
* Plays a role in long-term stress response. Released in response to stress 20 mins later, not immediate.
* It belongs to a class of hormones called glucocorticoids and plays a vital role in the body’s stress response and regulation of various physiological processes.
* It is often referred to as the “stress hormone” because it is released in response to stress and helps the body cope with stressful situations (long term stress response).
Main Hormones associated with Parental and Social Behavior (6)
6) Testosterone
* Steroid hormone belonging to the class of androgens, primarily produced in the testes in men and in smaller amounts in the ovaries and adrenal glands in women.
* It is considered the primary male sex hormone, although it also plays important roles in women’s health.
* It is involved in Secondary Sexual Characteristics; Libido and Sexual Function; Bone Health; Muscle Mass and Strength: Mood; Metabolism and Fat Distribution
* Messing with testosterone balance can lead to psychosis, mood and cancer.
Main Hormones associated with Parental and Social Behavior (7)
7) Vasopressin
* Also known as antidiuretic hormone (ADH), is a peptide hormone produced primarily in the hypothalamus and released by the posterior pituitary gland.
* It plays several important roles in the body’s regulation of water balance, blood pressure, and social behavior.
* Higher levels of vasopressin are associated with various aspects of social bonding and affiliation, including Pair Bonding; Parental Behavior: Aggression and Territoriality: Social Recognition and Memory
- more important in males for affiliation compared to females (where oxytocin is more important).
Different outcomes from similar zoo incidents
- female gorilla approaches chold and taps it on back - affection, protecting the boy
- carries injured boy to gate (oxytocin)
- depending on the sex of the gorilla, we had different response (Both females were lacting).
- male gorilla was however agressive and hurt child (testosterone).
Define Parental Behavior
Parental behavior: behaviors performed in relation to one’s offspring that contribute directly to the survival of fertilized eggs or offspring that have left the body of the female. Can be distinguished into Maternal or Paternal Behavior. Varies in terms of sex, developmental stage and context.
Parental care is critical for infant survival among many species, including humans, and hence is critical for the reproductive success of the individual parent(s)
What is the currency of reproductive success from an evolutionary perspective?
From an evolutionary perspective, the only currency of reproductive success is the production of successful offspring, that is, offspring that themselves manage to survive and produce descendants. The offspring of many animal species require assistance from one or both parents to attain maturity and reproduce themselves.
- Parental behaviour is necessary for reproduction.
What is the optimal strategy for each parent? Parental Investement theory = the amount of assistance needed for offspring success.
- The amount of assistance that parents provide varies widely, both among and within species, and reflects an optimal evolutionary strategy for maximizing fitness.
- The optimal strategy for each parent is to provide sufficient care but no more than is absolutely necessary to produce successful offspring.
Define parental investment theory?
Parental investment: the extent to which parents compromise their ability to produce additional offspring in order to assist current offspring.
Parental behavior: Behaviors performed in relation to one’s offspring that contribute directly to the survival of fertilized eggs or offspring that have left the body of the female. Can be distinguished into Maternal or Paternal Behavior.
Generally, the sex making the larger investment in the offspring is the choosier about potential mates. Whereas individuals of the sex that contributes fewer resources to offspring success compete among themselves to be chosen. In most species of mammals, females are generally the choosier sex and invest the most parental care.
How does Parental investement vary?
- How the offspring comes to the world is also important, it will influence how much parental behaviour influences the offspring.
- Parental investment varies according to the offspring’s maturity at birth, number and survival fit of the offspring
- Precocial Born Offspring: Born or hatched at an advanced stage of development. Precocial young require little or no parental intervention for survival. Does not mean that they do not require any parental care!
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Altricial Born Offspring: Born or hatched at an early stage of development. Altricial offspring are generally quite helpless and require substantial parental care to survive.
- (ie, kangooros - cannot thermoregulate).
- Wood shavings in rats replicates the heat (helps thermoregulate), if we remove these wood shavings we can mimick a poor environment (poverty for rats).
PIT: Humans are Semiprecocials
Humans are Semiprecocials: We are born in an intermediate state between altricial and precocial. In semiprecocial species, the offspring are born with some degree of development and independence but still requires parental investment.
Babies are able to thermoregulate - this is was differentiates us from altricial. We have a thin layer of fat which allows us to do it. This is why prenatal babies are put in a incubator because they dont have this ability to thermoregulate yet.
How animals learn how to parent?
In animals that display parental care, ideally the behaviors must be performed correctly, with little margin for error; they initially must be performed without previous experience, and they must usually begin immediately after the hatching or birth of the offspring.
Dogs parental behavior
Dogs are altricials.
Atricial puppies are blind and partially deaf, their coats are not completely established, and their thermoregulatory and locomotor abilities are not fully developed. Without learning some species show this behavior that is important for species development.
Main maternal behaviors in dogs:
o A day or two prior to giving birth, a pregnant dog builds a nest into which her puppies will be delivered (use resources, t-shirts, tissues…).
o As each pup is born, the mother behaves solicitously toward it, licking off the amniotic fluid, membranes and the anogenital region (to stimulate the elimination of wastes and other physiological processes).
o They know how to lay down to expose her nipples to nurse.
o She will retrieve pups if they go far away;
o They show maternal aggression to intruders. In the absence of pups, they do not get territorial. There is something in the pups.
Influence of hormones on animal parental behavior
- Hormones associated with pregnancy and lactation regulate the onset of mammalian parental behavior, affecting motivation to engage in parental care. Importance in initiating and maintaining maternal care.
- The hormones that trigger parental behavior wane soon after the arrival of the young, and with it many maternal behaviors, including nursing, completely disappear after a few additional weeks.
- Hormones correlate with this reduction of maternal behavior. This implies a correlation.
Sex differences in parental behavior: is maternal or paternal care more common?
Maternal care is much more common:
* With the exception of most bird and some fish species, paternal behavior is rather rare in the animal kingdom; This happens because female and males differ on how they can best maximize reproductive success.
* Females will tend to put the majority of their reproductive effort into parental care, because each offspring represents a substantial proportion of a female’s lifetime investment of time and resources. ie, humans: cost and investement is much greater for womens (9 months to generate offspring and fertility can be further delayed because of lactation).
Costs for women
Pregnancy lasts 9 months, and lactation-induced infertility can delay further reproductive efforts for another year or two. During this same time, a man could potentially fertilize hundreds of women.
HIGH COST for women which is related to generating the baby and to lactation.
Lactational amenorrhea
Lactational amenorrhea (menstruation interruption), is the temporary postnatal infertility that occurs when a woman is breastfeeding
* High levels of prolactin due to stimulation of oxytocin.
* prolactin feedbacks to hypothalamus and inhibits the release of GnRH.
* Sometimes the stimulus of the nipple is not enough to create prolactin to inhibit.
Inducing Lactation without pregnancy
- It’s more common than we think, some individuals go over hormonal treatment to lactate.
- Induced lactation typically involves hormonal therapy, breast stimulation, and regular breast pumping or nursing to mimic the conditions that promote milk production. This process is often used by adoptive mothers, surrogates, or individuals in same-sex partnerships who wish to breastfeed their babies.
- Prolactin and estrogen and galactogis hormones all needed for this
- Men can do this…requires androgen blockers as well.
Factors associated with sex differences in parental behavior:
1) Efforts in mating or parental behavior:In females mating with additional males while pregnant or lactating typically does nothing to increase reproductive success unless this provide resources to the female or the offspring.
- Males’ reproductive success depends on the number of females he fertilizes. Thus, evolutionary speaking males weight on if it is more advantageous to forgo additional mating opportunities or to help raise his offspring
2) Birth developmental stage of the offspring: Depending on the demanded level of care of the offspring, in some situations two adults are required to guarantee the survival of the young, as is the case for many avian species.
- This can be observed if parental males achieve higher reproductive success than nonparental males
3) How males are able to meet offspring’s demands: For example, male birds are as capable as females of providing parental care(nest construction, incubation of the eggs, and feeding). This ability of avian fathers to feed their young—usually by regurgitating the results of recent meals contrasts sharply with most mammalian species, in which only the mother can meet the nutritional demands
Endocrine correlates of Avian (birds) parental behavior
Birds display enormous diversity in parental behavior, and offspring development at birth (hatch)
- Biparental
- Females only (chicken)
- Adoptive (alloparental care- provided by individuals other than their genetic parents, strangers provide care to offspring that is not theirs)
Endocrine correlates of Avian (birds) parental behavior: Discovery of prolactin effects on parental behavior.
Discovery of prolactin effects on parental behavior: first evidence that hormones are important for parental behaviours comes from birds.
1-Blood serum from a broody hen (ovulating hem- has fertilized egg) could induces a no incubating hen to sit on a clutch of eggs. This is related to the prolactin hormone. Injection of prolactin in females will lead to this behaviour. So after maternal behaviour has been initiated by hormones, virtually any contact we see is sufficient to maintain normal brooding behaviour. Brooding behaviour is when they use their wings and feathers to thermoregulate and take care of offspring.
2-Increased blood concentrations of prolactin are
associated with broodiness in all female birds studied to date
Why are birds so studied (hens in general):
- high prolactin levels when engaging with maternal behaviours . If prolactin levels are high this influences GnRH. When the hens are engaging in maternal behaviours, they are not producing eggs.
Prolactin will inhibit neurons in the hippothalamus that are responsible for GnRH, which in turn inhibits LH (same as in humans) that are responsible for ovulation.
Prolacting levels are related to the Crop milk. more prolactin = more crop milk from crop sac.
Prolactin destimulates the ovaries, the ovaries weight is much smaller if they are receiving prolacting
Endocrine correlates of Avian (birds) parental behavior: Sex steroid hormones
- Sex steroid hormones usually increase coincident with the onset of courtship behavior, peak during the time of egg laying (oviposition), and rapidly decrease to baseline prior to incubation.
- If the egg is fertilized, Prolactin concentrations begin to increase at the time of egg laying, remain high during incubation, then drop off gradually to baseline concentrations during post-hatching care.
Endocrine correlates of Avian (birds) parental behavior: Prolactin concentrations
- Release of prolactin to help with the care of adoptive offspring
- Prolactin concentrations correlate with the amount of care provided to the offspring in Penguins and Florida scrub jays (a species that exhibit alloparental care).
- Levels are increased in breeding(red) individuals and helpers (blue)
Endocrine correlates of Avian (birds) parental behavior: Plasma Prolactin concentrations
- Correlation between prolacting and the weight and composition of the crop sack (gland like organ that helps produce Crop Milk). Higher prolactin= more crop milk produced at crop sack. Decrease of prolacting = crop sack has more and more sources of foods like seeds and insects. This is very correlated with hormonal levels.
- Plasma prolactin concentrations increase post-laying and are associated with elevated food consumption by the breeding pair, presumably to support foraging for insects for the squab. As prolactin falls, the crop mixture changes from crop milk at hatching to mainly seeds and insects
Endocrine correlates of Avian (birds) parental behavior: prolactin cycle of breeding birds
Although all avian species display elevated prolactin concentrations during incubation, in many precocial species, prolactin concentrations decline at the time of hatching, while in altricial species prolactin concentrations remain high throughout chick rearing.
Prolactin cycle of breeding birds with different reproductive modes:
- Precocial (ex: ducks, geese) –> prolactine levels decrease earlier
- Altricial with short absence from the nest (ex: starlings, and doves) –> prolactine levels last longer because need more care.
- Altricial with long absence from the nest (ex: penguins, albatrosses, etc) –> prolactine levels last longer because need more care.
Endocrine correlates in mammals
Prolactin was initially considered to be the critical hormone underlying maternal behavior, but its increase is only observed close to parturition. Was considered the main parental hormone becasue of lactation.
Mammalian species display elevated estrogen concentrations around the time of birth, and these hormones are important, if not critical, for the onset of maternal behavior. Important for the maintenance!!! and rises with prolactine after birth
Pregnancy in humans
In contrast to other species, pregnancy in humans is characterized by high concentrations of both estradiol and progesterone throughout pregnancy, followed by a precipitous drop in the concentrations of both steroids at parturition.
The drop in progesterone and estrogen levels after birth is believed to contribute to the onset of postpartum depression in some women, although the exact mechanisms are not fully understood
Steady drop of progesterone and estrogen in humans. Prevalent mood disorder after birth (post-partum deppresion) is due to the drop of estrogen and progesterone.
Other hormones associated with
pregnancy and maternal behavior
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Oxytocin and endorphins increase around
the time of parturition and is maintained after. This hormone is important in the smooth muscle contractions necessary for giving birth. Important at the time of birth and maintained after for muslce contraction but also for the bond between mother and offspring. - The role of endorphins (opioids) remains controversial; they may reduce pain during childbirth, and they may be involved in quality of maternal behavior.
Other hormones associated with
pregnancy and maternal behavior
In pregnancy is observed increases in concentrations of ACTH and cortisol (glucocorticoids). The elevation of cortisol concentrations may serve to lower progesterone concentrations in addition to suppressing immune reactions of the mother toward her fetus.
There are functional aspects of cortisol during child birth: anti-imflammatory action (prevent contamination), acts as a boost in immune system.
Experiential influences on maternal behavior
Initially the prolactin experimental manipulation performed in birds failed to induce maternal behavior. This raised the hypothesis that experiences can also influence maternal behavior.
In nulliparous (individuals that have never given birth) rats, transfusion of blood from a new mother is associated with maternal behavior only if sensitization (blood of one female could be exchanged with that of another for 4 to 6 days). Thus, sensitization is required to induce maternal behavior in nulliparous females.
Some studies with blood transfusion = does not elicit maternal behaviour unless there is sensitization of surrogate mother. Only works for individuals that have given birth, if they have not, we must sensitize them for 4-6 days in order for the blood transfusion to work.
Maternal will only start if there is a preperation for that behaviour.
How to measure parental Behavior in humans? Use of questionnaires, some interesting findings
- Hedonic ratings of a variety of infant-associated odors (e.g., general body, urine, feces) were found to be more pleasant by new mother than nonmothers.
- Mothers and father were more likely to correctly identify t-shirts that had been worn by their own infants.
- Mothers and fathers could also discriminate between the odors of two samples of amniotic fluid—both parents could identify the amniotic fluid associated with their own infant.
SMELL, olfactory function seems to be important!!!
How to measure parental Behavior in humans? Use of questionnaires, some findings
- Hormone concentrations and learning, seems to be important in the establishment of a mother’s attraction to her newborn infant’s odors. Sense of smell seems to be important.
- Within the CNS, receptors for oxytocin and vasopressin are found within the olfactory system, limbic-hypothalamic system and ventral forebrain, and in the brainstem and spinal cord. Vomeronasal organ has receptors for oxytocin. This can trigger a cascade of neuronal activation in the amygdala and another two regions that are thought to be implicated in maternal behaviours. They are called the maternal circuitry in the brain: one is the medial preoptic area in the hypothalamus. The other one is the bed nucleus of the stria terminalis which is part of the limbic system. This would be a pathway in which activation mediated by oxytocin could be leading to neural adaptations and functioning that are associated with maternal behaviours.
- Lesions anywhere along this pathway interfere with chemosensory processing of the maternal behaviour.
- The medial preoptic area is crucial for the onset and maintenance of maternal behaviour; this area is activated when nursing, licking , grooming and retrieving the offspring.
- Neurons in this medial preoptic area is sensitive to oxytocin and prolactin because they are more activated during this maternal behaviour.
- bed nucleus of the stria terminalis which is part of the limbic system. So it is involved in regulation of stress and anxiety but also in social behaviours. Maternal behaviour is a form of social behaviour. This region is very relevant in processing emotionally salient stimuli. Ie: you put a women in an MRI and show them a picture of their infant. This region is activated and the amygdala is deactivated. If you put a picture of the infant crying then the amygdala will be activated. Depending on the behaviour of the infant, you deactivate or activate this cicuitry (parental circuitry of the brain).
- In rodents this depends predominantly on pheromonal olfactory cues detected by the Vomeronasal organ and transmitted to the accessory olfactory bulb and thus to the amygdala these structures are rich in oxytocin receptors (Keverne, 1999)
How to measure parental Behavior in humans? Use of behaviour analysis, some findings about cortisol and parental behaviours
Approach Behavior - (behaviour between mother and kid) patting, cuddling, or kissing the baby, talking, singing, or cooing to the baby –showed correlations with hormones.
* Cortisol was positively associated with approach behaviors. In other words, women who had high concentrations of blood cortisol, in samples obtained immediately before or after nursing, engaged in more physically affectionate behaviors (led to more approach behaviors) and talked more often to their babies than mothers with low cortisol concentrations (Fleming et al 1987)
* Cortisol does not induce maternal behaviors directly, but it may act indirectly on the quality of maternal care by evoking an increase in the mother’s general level of arousal. Cortisol may just be increasing a mothers arousal in general. Relation between cortisol and attraction to infant odors is found only in first-time mothers, in whom hormonal effects would presumably be most necessary (more experienced mothers do not show this association).
* Saliva samples of cortisol from first-time mothers were compared with their hedonic ratings of their infants’ T-shirt odors. Mothers with higher cortisol concentrations found their infants’ odors more appealing
Oxytocin and affection
- Parents with high Oxytocin levels displayed significantly more affectionate contact compared to parents with low Oxytocin. They constructed the interaction towards readiness for social engagement by increasing social salience in response to infant social gaze.
- Women with the greatest increases in oxytocin as their pregnancies progress show the highest levels of maternal bonding when observed with their infants. It is not always the case that oxytocin levels rise during pregnancy.
Some mice species exhibit paternal care.
Some mice species exhibit paternal care. Behavior and hormonal levels are associated depending on the status of males.
Different mice groups exposed to new-borns shows:
❑ Unmated males displayed relatively low parental
behavior (19%)
❑ Expectant fathers displayed average levels of
parenting (56%)
❑ Fathers displayed high parental behavior (80%)
Testosterone action is not straight forward!
- Unlike in birds and most mammals, in which higher testosterone levels are associated with low paternal care and even infanticide, testosterone appears necessary for paternal behavior in California mice.
- Castration reduced their paternal behavior,
whereas testosterone replacement maintained high levels of paternal behavior. - Testosterone promotes paternal behavior in
these mice through its conversion to estradiol (Trainor and Marler, 2002). - California mouse fathers have more aromatase activity than nonfathers in the MPOA (medial preoptic area), a brain area known to regulate maternal care
Aromatase converts testosterone to Estradiol. This conversion does not happen in the blood, it happens in the brain. Higher testosterone levels are being converted to estrogen in mice.
The hormonal correlates of human paternal behavior resemble the factors associated with
paternal behavior in other mammals, namely, testosterone, prolactin, and cortisol.
The hormonal correlates of human paternal behavior resemble the factors associated with
paternal behavior in other mammals, namely, testosterone, prolactin, and cortisol.]
* Testosterone levels low in fathers and estrogen levels are higher in fathers.
* fathers hearing baby crying are more sympathetic and alert than non-fathers.
* Fathers with lower testosterone and higher prolactin felt a greater need to respond to crying (and sympathy) compared to fathers with higher testosterone and lower prolactin.
Father with high prolactin concentrations were more alert and responsive to cries. These studies indicate that human fathers are more responsive to infant cues than non-fathers. And, the responses of fathers to infants are associated with hormonal values and previous caregiving experiences.
Brain areas implicated in parental
Behavior
1) Prefrontal Cortex (PFC): Plays a role in the regulation of parental behaviors and the processing of social cues related to offspring.
2) Amygdala: Known for its role in emotional processing and social behavior, the amygdala is involved in the regulation of maternal and paternal
behaviors, as well as the processing of social cues related to offspring.
3) Bed Nucleus of the Stria Terminalis (BNST): This brain region, part of the extended amygdala, is involved in stress responses, social behaviors, and reproductive behaviors, including parental care. It is activated when a parent hear a baby cry
4) Hypothalamus: This region regulates various physiological processes and is involved in the release of hormones related to parenting, such as oxytocin and vasopressin. It plays a crucial role in
maternal and paternal behaviors, including nest building, pup retrieval, and caregiving.
4) Medial Preoptic Area (MPOA): Located within the hypothalamus, the MPOA is particularly implicated in the regulation of parental behaviors, including maternal and paternal care, mating, and sexual behavior. Called the paternal circuitry.
5) Mesolimbic Dopamine Pathway: This neural pathway, including regions such as the ventral tegmental area (VTA) and the NAc, is associated with reward and motivation. It is involved in the reinforcement of parental behaviors and the processing of rewarding aspects of caregiving. Interacting with babies reinforces this patway.
Affiliation: Social familiarity
Social familiarity
o The first stage of social bonding is the formation of social familiarity.
o In rodents this depends predominantly on pheromonal olfactory cues detected by the Vomeronasal organ and transmitted to the accessory olfactory bulb and thence to the amygdala, these structures being rich in oxytocin receptors.
o Such behaviors show a marked increase when another stranger is introduced. Such characteristic and easily observed behaviors are thus used as a quantitative assessment of social recognition memory.
If we block oxytocin genes on those regions, they do not develop this social familiarity.
Oxytocin and partner preferences
females go back to familiar males even though new male is better
Sex differences (oxytocin and vasopressin)
- Although exogenous administration of both oxytocin and vasopressin facilitates pair bond formation in both sexes, endogenous oxytocin seems to be more important in pair bond formation in females
whereas endogenous vasopressin appears to be more important for males - The mechanism underlying this sex difference is mysterious because the distribution of oxytocin and vasopressin receptors is similar in both sexes.
Oxytocin and partner preferences
- Feelings of positive regard for a romantic partner are associated with higher oxytocin plasma concentrations.
- Couples displaying high interactive reciprocity scores had elevated plasma oxytocin concentrations 3 months into the relationship. Individuals in couples had higher oxytocin concentrations than singles. Quality of their relationship, more reciprocity in correlation with oxytocin.
Oxytocin can give a “boost” in romantic perception
Inject oxytocin intrabasily, males perceived the female partner as more attractive.
Oxytocin can give a “boost” in romantic perception - in dogs
Affiliation rate in dogs after being treated with intranasal oxytocin or saline
Sex steroid hormones variation and affiliation with same sex peers: seasonal variations
Summer: High circulating sex steroid hormone concentrations tend to be associated with low tolerance for close proximity of same sex peers
Winter: Low circulating sex steroid or reduction in concentrations permits social tolerance and prosocial interactions.
Aggressive
Behavior
Testosterone
* An androgen often associated with aggressive behavior. Higher levels of testosterone are correlated with increased aggression across various species.
* Testosterone influences neural circuits and neurotransmitter systems involved in aggression, although this can be influenced by factors such as social context and sex.
Aggressive
Behavior
An androgen often associated with aggressive behavior. Higher levels of testosterone are correlated with increased aggression across various species. Testosterone influences neural circuits and neurotransmitter systems involved in aggression, although this can be influenced by factors such as social context and sex.
