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Hank Davis (22)

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PSYC 3100
Hank Davis

Lecture 21 Chapter 13 (Continued) - Sex ratio, male: female - we believe it is roughly 50/50, but it isn’t for specific reasons. - Core reason: females are much better bet for reproductive success than males (humans) - Females are more likely to breed successfully - sexual selection among our species has made it tougher on men. - Women have easier time to have sex than men. - In humans, the sex ratio at birth is males (more of them) - you need more men to get a 50/50 change - not all males will make it to breeding. - Not a cultural problem - biological issue - mirrored in other species. - In process of competition - they are taking each other out. - Pre-reproduction is high in males for sexual reproduction. Austad’s Study - Possum can actually bias their sex ratios based on their living conditions (Epigenetics) - could just stay at 50/50 but something takes in the living conditions which are translated to how many female/male she has in each litter. - If environment is rich in food and resources, then they have 40% increases in sons. - When possum moms are sick, when environment is love, they have 80% more daughters. - If there is high predation, they have short life - breed once with many kids, low self-repair and die young. - If life is good, they live long, have multiple litters, each litter is small, and if they are sick - they self-repair. - Nematode - 1000 cell, simple organism. - A single gene controls lifespan. - Maybe lifespan is a facultative adaption, maybe it is not an immovable wall, and maybe it reads environmental cues. - Think of lifespan as an adaptation not a number. Cinderella Factor by Martin Daly - Infanticide and child abuse - clearly not random occurrences. - Differential parental solitude is an important adaptation in humans. - We are not randomly generous with out parenting; we don’t want to start taking in all of our neighbour’s kids. - Bats - 83% of them nurse from their mom, not another mom - vocalization and smell. - Lions, monkeys, mice - mom has babies but dad dies - new man comes along to be with mom but kills the babies - why waste my r
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