Monday, February 3rd, 2014 Chapter 5 - Concealed Ovulation Why did concealed ovulation evolve in human species? - Primate traits - Hominin Traits o biomechanics o behavior and social organization o visual indicators o olfactory indicators - Modern human traits Concealed Ovulation: the exact timing of female ovulation is unknown to both the male and female of a species. Humans are said to have Concealed Ovulation. (Humans have concealed ovulation) Estrus: increase in female sexual behavior (proceptivity) and attractiveness at the period of highest fertility just before ovulation. Period of pronounced genital swelling. "In Heat". (very subtle in humans). -In primates, estrus is more prominent Receptivity: readiness to copulate when solicited by a male Proceptivity: female actively seeking copulation (for primates this only happens during estrus) Attractiveness - Females become sexually exciting to males o During estrus males find females sexually attractive, thus initiating copulations. o Most of the female PRIMATE menstrual cycle is characterized by sexual disinterest from males (until estrus). Primates show dramatic increase in mating during estrus. The genital swellings are visual in nature and attract males. (proceptive and attractive during estrus) Humans have concealed ovulation. There is constant sexual receptivity, proceptivity, and attractiveness. (constantly) Wednesday, February 05, 2014 Swelling in humans does not exist because since we walk in two legs, it would be uncomfortable, painful, and not as easily notices as in primates. (we're bipeds)Bipedalism features - Vertebral column has S curve - Pelvis rotates forward in humans - femur angles inward to knee - foot arch - Big toe - Biomechanics - With the evolution of bipedalism, the female's genitals moved to under the pelvis, and reducen in swelling to maintain efficiency. Visual Cues -By reducing in swelling and movement of genitals, the visual cue indicating ovulation is no longer advantageous. -Males cannot see if females are ready to become pregnant. Physical indications of swelling - Human males have unnecessarily larger penises Olfactory Cues - Hair loss in hominins. We still have hair in armpits and generals. - Sweating - Hair hold onto smells (armpit, pubic area) - Can you smell someone's pubic area when standing? Armpit is closer to the nose - Olfactory cues is one of the arguments against loss of estrus. - Males more often prefer a females odor during ovulation. Singh and Bronstad 2001: study in which men smelled female t-shirts and most found the ones during follicular stage more attractive smelling. -Women respond more favorably to flirtation and offers to dance when in fertile phase. -Lap dancers got more tips when they were ovulating and not using contraceptives. Auditory Cues to estrus-During fertile stage, higher pitch (more attractive) In conclusion, Estrus in humans has not been completely lost. Ovulation is definitely concealed, but there are subtle shifts in behavior, preference, and attitude. Theories about concealed ovulation 1. Concealed ovulation reduces male-male competition and enhances cooperation among male hunters. Males cannot compete for the females that are ovulating because they don't know when they are. This leads to working together and food sharing. 2. Concealed ovulation enhances bond between man and woman by making woman continuously receptive, proceptive, and attractive. Males use less energy mating with a single female all the time- to insure paternity. (This way, the female ensures paternal care, food sharing, etc) 3. Concealed estrus may ensure steady food supply. Since males don't know when females are ovulating, they may provide more food to win favor. 4. Concealed estrus exploits male paranoia over paternity, enhances pair bond. This prevents infanticide. Females play with male paranoia over paternity in order for them to stay more. 5. Concealed ovulation increases the chance for male paternal care. With male care-giving, the female can have children more often and therefore increase her reproductive success. Friday, February 7th Concealed Ovulation - Hazda believed women could become pregnant right after menstruation (which is not true) o This is because after waiting for menstruation to end, they were "ready to go" - -Ovulation may be even more concealed within the Hazda since everyone smells like fire. - They believed females were fertile AFTER menstruation. Menstrual Huts - The Huaulu believed that menstruation was pollution o They do not do anything related to any male (touch them, cook for them, etc) o They would go to a "menstrual hut" until their menstruation ended. - Young children are allowed to stay in the hut Kodi- Blue Dye - "Blue dye" was cursed. Came from female side of the family. Males "get hurt" with blue dye.- Similar to Huaulu's ideals on menstruation being deadly. - Associated it with witchcraft. Wednesday, February 12th Chapter 6 - Mate Preferences With concealed ovulation: - Decreased sexual dimorphism - Decreased male-male competition - Increased reliance on male provisioning - Increase in pair bonding Mate Preferences (Expectations) - Females invest more on offspring - There are traits that females prefer in males and males prefer in females - We don't think in an evolutionary way Biological Traits - Personality - Facial features - Smell - Men prefer younger women, women prefer older men Overall, females prefer a more feminized face during luteal phase. This may indicate increased parental care (lower testosterone levels). For the short term, during ovulation they preferred more masculine males. During Menstrual phase - Prefer masculine men around ovulation - Feminine men at other times- Similar patterns of change during the menstrual cycle have been observed for voice preferences. (lower pitch during ovulation) - Females prefer facial overall regardless of relationship length - men prefer facial attractiveness more when in long term relationships Odor - Females rank odor a bit higher than males - Body odor serves as a cue for health - Ovulating women preferred the scent of symmetrical men - Females prefer a men with dissimilar immune system to themselves - Major Histocompatibility factor: we prefer mates with different immune systems. Age - On average, females prefer slightly older males and males younger females. - Teenage males prefer females that are