1. Sexual & Reproductive behaviors Dr. Kline FSU

2. I. Mating Behaviors What is the main reason animals mate? What is the main reason animals mate? For most animals (excluding human beings), mating serves one purpose: the reproduction of offspring. For most animals (excluding human beings), mating serves one purpose: the reproduction of offspring. Mating behavior is necessary because it leads to conception & subsequently the birth of offspring. Mating behavior is necessary because it leads to conception & subsequently the birth of offspring.

3. Who controls mating behavior? Males or Females Mating & sexual behavior are largely under the control of the female of a species. Mating & sexual behavior are largely under the control of the female of a species. This includes human beings. This includes human beings.

4. The Traditional view of Female Sexual Behavior Historically, females have been viewed as sexually “receptive” to male advances. Historically, females have been viewed as sexually “receptive” to male advances. That is, the female will passively accept rather than resist male sexual overtures, & mating will result. That is, the female will passively accept rather than resist male sexual overtures, & mating will result. Males are always viewed as available & motivated to copulate; while females are usually reluctant to mate, but will occasionally “give in.” Males are always viewed as available & motivated to copulate; while females are usually reluctant to mate, but will occasionally “give in.” Recent research (lab & field) has shed light on the problems with this traditional view. Females are far from passive recipients. Recent research (lab & field) has shed light on the problems with this traditional view. Females are far from passive recipients.

5. Modern view of Female Sexual Behavior 1. Females are active initiators of mating; not passive recipients. Called proceptivity, the female may exert great effort to achieve sexual contact with a male. 1. Females are active initiators of mating; not passive recipients. Called proceptivity, the female may exert great effort to achieve sexual contact with a male. (E.g., Females dart in front of indifferent males hopping & wiggling her ears to signal interest.) (E.g., Females dart in front of indifferent males hopping & wiggling her ears to signal interest.) Females rodents also control the timing of mating & copulate relatively indiscriminately with all males that respond. Females rodents also control the timing of mating & copulate relatively indiscriminately with all males that respond.

6. 2. Females are not “inherently” monogamous as was once thought. 2. Females are not “inherently” monogamous as was once thought. In many species, females will choose to mate with several males. In many species, females will choose to mate with several males. While females tend to be “selective” in who they mate with, this shouldn’t be confused with monogamy. While females tend to be “selective” in who they mate with, this shouldn’t be confused with monogamy. E.g., Female monkeys mate with several males, not just the dominant monkey. E.g., Female monkeys mate with several males, not just the dominant monkey. *It has been shown that some female birds will choose a partner to “nest with,” but actually reproduce offspring by mating with another male. *It has been shown that some female birds will choose a partner to “nest with,” but actually reproduce offspring by mating with another male.

7. 3. Females do not always put more investment into reproduction. Female spotted sandpiper displays & defends breeding territory, duties assumed by the male in most birds species. Female spotted sandpiper displays & defends breeding territory, duties assumed by the male in most birds species. Female lions do most of the pride’s hunting (not the male) & share responsibility for each others cubs. Female lions do most of the pride’s hunting (not the male) & share responsibility for each others cubs. Male seahorses carry the young in their bodies. Male seahorses carry the young in their bodies.

8. II. When are non-human females most likely to engage in sexual behavior? During estrus (in non-human animals). During estrus (in non-human animals). During estrus the non-human female is: During estrus the non-human female is:*fertile *receptive to mating *receptive to mating *proceptive *proceptive *sexually attractive (pheromones) *sexually attractive (pheromones)

9. What influences the estrus cycle? Hormones!!! Estrogen & progesterone increase over a period of a few days prior to ovulation. Hormones!!! Estrogen & progesterone increase over a period of a few days prior to ovulation. Estrus is initiated following the increases in these hormones. Estrus is initiated following the increases in these hormones. Removing the ovaries (ovariectomy) in rats, will produce a rapid decline of both proceptive & receptive behaviors in females. Removing the ovaries (ovariectomy) in rats, will produce a rapid decline of both proceptive & receptive behaviors in females. This can be reversed with injections of estrogen & progesterone. Thus the role of hormones in the estrus cycle is critical. This can be reversed with injections of estrogen & progesterone. Thus the role of hormones in the estrus cycle is critical.

10. When are human females most likely to engage in sexual behavior? Unlike the estrus cycle, in the menstrual cycle sexual interest can occur throughout the cycle. Unlike the estrus cycle, in the menstrual cycle sexual interest can occur throughout the cycle. However, women are more likely to report increased sexual interest during the periovulatory period when ovulation occurs. However, women are more likely to report increased sexual interest during the periovulatory period when ovulation occurs. This four day period corresponds to the highest surge of estrogen. This four day period corresponds to the highest surge of estrogen.

11. Evidence that women are more sexually excited during periovulatory period. Two studies have reported that women initiate more sexual activity (with partner or by auto- erotic means) during the periovulatory period than at other times of the month. Two studies have reported that women initiate more sexual activity (with partner or by auto- erotic means) during the periovulatory period than at other times of the month. Women rate an erotic video as more pleasant & arousing if they watch if during the periovulatory period than at other times (Slob et al., 1996). Women rate an erotic video as more pleasant & arousing if they watch if during the periovulatory period than at other times (Slob et al., 1996).

12. The effect of hormones on men’s sexual behavior? Male sexual arousal is highest when testosterone levels are highest. The peak is between 15-25 yrs. Male sexual arousal is highest when testosterone levels are highest. The peak is between 15-25 yrs. This declines with age. This declines with age. Oxytocin also plays a role in male sexual behavior; large amounts are released during orgasm (also increases pair bonding behavior). Oxytocin also plays a role in male sexual behavior; large amounts are released during orgasm (also increases pair bonding behavior). Question: It is known that men fall in love more easily & out of love more slowly than women, could this be influenced by oxytocin??? Food for thought!!! Question: It is known that men fall in love more easily & out of love more slowly than women, could this be influenced by oxytocin??? Food for thought!!!

13. Will changing testosterone levels influence sexual activity in men? Yes!!! Increase levels increases interest; decreasing levels decreases interest. Yes!!! Increase levels increases interest; decreasing levels decreases interest. (e.g., castrated males show less interest in sex.) (e.g., castrated males show less interest in sex.) Testosterone reduction has been used as a means to control sex offenders & has shown some success (although on average their levels were normal). Testosterone reduction has been used as a means to control sex offenders & has shown some success (although on average their levels were normal).

14. III. Pheromones: chemicals secreted from one organism to another, having sexually attracting or repulsing effects. chemicals secreted from one organism to another, having sexually attracting or repulsing effects. Pheromones are secreted by the body (urine, feces, sweat glands) & at low concentrations can act at fairly long distances. Pheromones are secreted by the body (urine, feces, sweat glands) & at low concentrations can act at fairly long distances. (e.g., Male luna months have antenneae capable of sensing pheromones released by females.) (e.g., Male luna months have antenneae capable of sensing pheromones released by females.) Humans have evidence of vomeronasal organ (VNO) in nose, our pheromone detecting structure, suggesting we respond to pheromones.

15. Do humans respond to pheromones? It appears there is some evidence that pheromones influence our behaviors. It appears there is some evidence that pheromones influence our behaviors. McClintock effect (1970s, 1998) : female college students living in a dorm for 7-8 month period synchronize menstrual cycles. McClintock effect (1970s, 1998) : female college students living in a dorm for 7-8 month period synchronize menstrual cycles.

16. IV. Hormones: IV. Hormones: chemicals released by glands Two types of glands: 1. Exocrine- release substances into outside world. (E.g., sweat glands) 2. Endocrine- release hormones into body’s circulatory system. Travels to target organ to exert its effects. E.g., pituitary gland, ovaries & testes

17. V. Gonads *testes for males - produce sperm cells *ovaries for females- produce ova (eggs) After copulation, a single sperm cell may combine with an ovum to form a zygote zygote- contains all information necessary for growth of a complete adult organism. Except ova & sperm cells, each cell has 23 pairs of chromosomes

18. VI. Sex Chromosomes- VI. Sex Chromosomes-the genetic programs that direct sexual development *Females- XX shaped chromosomes. *Males -have one X & one Y shaped chromosome. Male determines child’s chromosomal sex. Each ovum has an X, sperm may be an X or a Y. Gonads - also produce & release hormones. **Ovaries & testes release same hormones; androgens, estrogens, & progestins.

19. VII. Is it a boy or a girl??? Both genetic male & females are programmed to develop female bodies (female is the prototype). Programmed development of the female body must be overridden in order for a male to develop. This occurs via hormones (androgens) that must be present at right time for the male body to develop. Otherwise, a chromosomal male will have a female body.

20. It’s a Boy!!!!! Six weeks after fertilization- male & female embryo have same structures. Primordial gonads- medulla- may develop into testis cortex- may develop into an ovary Y-chromosome -triggers manufacture of a protein called H-Y antigen. This causes medulla to develop into a testis. *Lack of H-Y antigen leads cortex to develop into an ovary (no antigen is needed for female development).

21. Internal Reproductive Ducts Six weeks after fertilization, both males & females have two complete sets of reproductive ducts. Male- Wolfian system Female-Mullerian system In 3 rd month of fetal development, testes of male fetus secrete androgens. This stimulates Wolfian system, inhibits Mullerian system. Without presence of testosterone, Mullerian system develops. Opps, it’s a girl!!!!!

22. VIII. It’s a boy, it’s a girl, it’s Pat!!!! There are some individuals who are not exactly male or female, but intermediate. There are some individuals who are not exactly male or female, but intermediate. For instance, some are born chromosomally male or female, but have a defective gene that leads to the development of an ovary & a testis, or two testes, or a mixture of testis & ovary tissue on each side. For instance, some are born chromosomally male or female, but have a defective gene that leads to the development of an ovary & a testis, or two testes, or a mixture of testis & ovary tissue on each side.