1. Sexual Selection and Mortality Rates
Yvette Aranas & Mercedes Pineda
Dr. Mills
Psych 452
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

2. Why Women Live Longer Than Men.
Video:
Why Women Live Longer Than Men.
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

3. Introduction: The Study
Looked at the lifespan in 20 different countries and the past 70 years, in only 5 of those countries.
Results show similarities of MR among the different countries across all causes of death.
Differences with sexual selection interaction, along with aspects of culture and environment contributes to the high male MR.
Mortality ratio increases as general mortality rates decrease.
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

4. Main critical points Females live longer:
Males tend to have competition amongst themselves for chances at sexual reproduction.
Males are willing to risk more & invest less time in the repair capacity.
The survival of offspring depends on maternal care rather than paternal care.
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

5. Continued…
Historical changes significantly affected the mortality rate:
Decline of infectious diseases.
Increase of mortality [in]directly caused by behavior through:
Increase population size
Mobility
Domestication of animals
Public health measures
Medicine
Increase availability of tobacco, cars, weapons, etc.
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

6. Continued… In modern days:
Male lifespan peak at young adulthood rather than in later adulthood as in females;
Highest differences for direct behavioral causes of death
Mortality is now due to more external causes compared to earlier times.
Explain what the difference is of external and internal causes of death are.
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

7. Figure 1: 2000 M:F MR by Age and Cause in the USA
From: 2000 United States mortality data from the National Center for Health Statistics
Double Y-axis graph of the M:F MR for each cause of death, representing absolute M/F mortality rates on the left side, and M:F MR on the right ratio scale.
The Y-intercept is set at 1.0, so any points above the Y-axis represent mortality rates that are higher for men than for women.
For all causes in the USA: shows a higher male mortality rate than females across the lifespan.
OVERALL: Mortality rate peaks at 2.94 in the year age range and slowly decreases from there on out.
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

8. Figure 2: Composition of Excess Male Life Years Lost by Cause
Cardiovascular disease accounted for the greatest proportion [26%].
Internal causes of death comprised 41% , external causes of death accounted for 35% - and the other 23% causes were not accounted for in the study.
The ratio of male to female total life years lost from death before the age of 80 is 1:58 to 1.
In the same scenario, before the age of 50 the ratio is a dramatic difference. For every 10 premature female deaths, 16 men died prematurely.
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

9. Figure 3: M:F MR in 2000 by Age in 20 Countries
Graph shows the cross-national comparison among all 20 countries.
Shows higher male than female mortality rates for nearly all ages - all peaking around the same, at sexual maturity.
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

10. Time to test your knowledge!
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

11. 2. Which one is NOT a historical or cultural influence on M:F MR?
1. This study examined the M:F MR over the course of a lifespan in ___ countries. 10 5 20 15
2. Which one is NOT a historical or cultural influence on M:F MR?
Domestication of animals
Availability of automobiles
Availability of antibiotics
Feminism
Answers:
1. C
Feminism
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

12. 3. From an evolutionary perspective, why do women generally outlive men?
Women are not wired to take any risks at all.
The survival of the offspring depends more on maternal care.
Culture tells males to take more risks; the fact that males take these risks has nothing to do with evolution at all.
Actually, women DON’T out live males, males outlive females.
3. B - offspring depend more on maternal care.
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,

13. 4. In humans, females generally have a higher mortality rate than males.
True
False
5. The results showed that the peak of external causes for mortality rate in males generally occurred during young adulthood.
6. M:F MR are exactly the same in all countries examined in this study.
4. False
5. True
6. False
Kruger, D.J. & Nesse, R. M. (2004). Sexual selection and the Male: Female Mortality Ratio. Evolutionary Psychology. 2,