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Question 1

Across species, sexual selection usually acts more strongly on males than on females.
Explain why this occurs

Answer 1

• Generally men are the low investing sex, females are the high investing sex. Males have to compete more for access to females. Females have the same amount of reproductive success because you can only have a couple of babies at the same time

Question 2

Intrasexual selection

Answer 2

competition among members of the same sex for access to mating opportunities (male vs. male/female vs. female)

Question 3

Intersexual selection

Answer 3

Selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex

Question 4

explain how each process can account for this trait (strong jaw)

Answer 4

• Intrasexual selection:
o Having a strong jaw can act as protective gear for your face. You’ll have a better chance of winning in fights of male to male.
• Intersexual selection:
o Women would prefer facial features which suggest strength and dominance

Question 5

Describe two types of data scientists would need to collect in order to test these possibilities (one type of data for each possibility), and explain your rationale for each

Answer 5

• Intrasexual selection:
o Set up scenarios for men in relation to a situation to show their male dominance (like with their girlfriend) ask if they would pick a fight with a guy. Have them rate their own jaw and ask them to rate the jaws of others guys and see if they’re more likely to challenge a guy that has less of a strong jaw than others.
• Intersexual selection:
o Scientists could show pictures of varying jaw lines to females and see which they prefer on a scale of attractiveness

Question 6

Compared to other mammalian females, women are unusual in that they seem to exhibit a
number of sexually selected morphological traits. Describe two functionally distinct and
prominent morphological traits that distinguish human females and explain how these may have been produced by sexual selection

Answer 6

• smaller feet in proportion to male feet
o because your feet expand with age, so smaller feet suggest youth
o feet expand with pregnancy—shows turn-off for men
• less reproductive potential
• boobs and firmness
o suggests youth and sexual maturity

Question 7

Given that sexual selection appears to have shaped human female morphology, explain how aspects of human reproduction have altered the general pattern addressed in (a).

Answer 7

• humans participate in long-term pair bonds, so women need quality partners that are going to take care of the kids. Need long parental investment. Someone that will be there.
• Both women and men have a goal to reproduce. Women want the best men that will take care of them, so they have to compete within their gender to attract the best male. And the male wants to reproduce with the best female, and has to show that he’s more competitive.

Question 8

) Two different processes have been proposed as explanations for how sexual selection could produce a wide variety of traits that do not enhance the chances of survival. Name and describe each of these processes, and explain how they differ from one another.

Answer 8

• Handicap principle: men who have traits that show that because they’re able to have these traits but still survive show that they have good genes.
o holds that the fact that the male of the species is able to survive until and through the age of reproduction with such a seemingly maladaptive trait is effectively considered by the female to be a testament to his overall fitness. (• Handicap principle and facial hair. Needs high level of testosterone—which means that it sacrifices energy spent on the immunity system.)
• Newbility hypothesis—breasts with women