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Chapter 5: Reproduction

Chapter 5: Reproduction. Wide range of reproduction/fertility rates Book lists 1.2 for Russia to 8.0 for Niger. In Conambo it is 9! Species-Specific patterns Loss of Estrus In estrus all of the time The sex contract (Helen Fisher). Bipedalism and Big-Head Babies

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Chapter 5: Reproduction

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  1. Chapter 5: Reproduction • Wide range of reproduction/fertility rates • Book lists 1.2 for Russia to 8.0 for Niger. • In Conambo it is 9! • Species-Specific patterns • Loss of Estrus • In estrus all of the time • The sex contract (Helen Fisher)

  2. Bipedalism and Big-Head Babies • Must give birth to immature infants • Menopause and the Grandmother Hypothesis • Adaptation or by-product? • Early Menarche • Age 8 is considered “normal” for US • Food? • Hormones? • Other factors?

  3. Inter Birth Interval (IBI) • Fertility rates and adaptations • Physiological Adaptations • Food/Nutrition • Physical activity • Cultural practices • Post-partum sex taboos • Birth control • Sterilization • Abortion

  4. Laws • Socially imposed monogamy • Men vs Women • One child • Age at Marriage • Birth defects • Less births • Diseases • Biological Adaptations • Pregnancy Sickness (covered earlier) • Post Partum Depression (Ed Hagen)? • Infanticide • Birth defects (Ache in book) • IBI too short • Twins • Abandonment • Sex of Child • Trivers-Willard Hypothesis • Sex of Parent

  5. When a mother calculates the costs and benefits of how much to invest, or whether or not to invest, in a particular offspring she is weighing the reproductive value of this offspring against the reproduction value of existing offspring or future offspring. • Most insects and fish strategies is to not invest in offspring beyond laying and fertilizing eggs and perhaps a onetime investment to start them off, and instead put their energy into having lots of offspring each with low chances of survival. (R vs K Selection Species)

  6. When a mother calculates the costs and benefits of how much to invest, or whether or not to invest, in a particular offspring she is weighing the reproductive value of this offspring against the reproduction value of existing offspring or future offspring. • Most insects and fish strategies is to not invest in offspring beyond laying and fertilizing eggs and perhaps a onetime investment to start them off, and instead put their energy into having lots of offspring each with low chances of survival. (R vs K Selection Species)

  7. When a father is making the same calculation he must also factor in: • the possibility that this offspring my not be his (PATERNAL UNCERTAINTY HYPOTHESIS) • whether or not his investment is critical to this child’s survival and future success (ABANDONABILITY HYPOTHESIS) • and the reproductive potential of continuing to invest in the children he has with this mate vs. his opportunity to invest in offspring with an other mate with greater reproductive potential (MATING OPPORTUNITY COST HYPOTHESIS)

  8. Three General Factors that influence parental motivation: • Genetic relatedness of offspring (KIN SELECTION) • Ability of the offspring to convert parental care into fitness (RETURN FOR UNIT OF INVESTMENT) • Alternative uses of the resources (WEIGHING DIFFERENT RETURNS FOR DIFFERENT INVESTMENTS)

  9. Evolutionary theory predicts that among biological parents, infanticide is more likely to be committed by young unmarried women when the baby is in the first year of life. • Children sleeping in parents bed?

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