Is menopause an adaptation or is it maladaptive?
Plan
Paragraph 1 – Introduction
- Relevant information
- What menopause is
- Signpost the essay
- What does it mean for it to be adaptive or not
- Brief intro to different theories for menopause
- Very brief answer to the question – it is an adaption that was previously helpful
Paragraph 2 – Life history theory + grandmother effect
- Meant to explain lifetime allocation of time and energy between growth, reproduction and maintenance
- Through out the different stages of life, there are trade-offs between the aforementioned categories
- Classical hypotheses suggest that either development or fertility has excess energy assigned to each respectively, so a higher juvenile growth rate should correspond positively with a higher reproductive rate.
- But this trend does not apply to humans as there is a high reproductive rate but slow growth
- Where does the energy unused in juvenile growth go
- The juveniles instead contribute to the indirect reproductive effort, meaning that individuals with higher reproductive and calorific are more able to contribute to the direct reproductive effort
- Net increase in energy contribution
- The theory of classical life history would predict greater allocation to female reproduction later in life at the expense of maintenance
- However the fecundity of human females actually decreases before menopause (while the body is not senescent)
- How wo we explain the decrease in energy allocation to reproduction in women before menopause
- The mother is the final common pathway (FCP), as her physiology is the rate limiting step because only she can gestate and suckle young
- This means that to increase inclusive fitness, metabolic investment of the group must flow towards the mother (FCP)
- The pooled energy budget is combined energetic allocation of all members of a reproductive community that might result in direct or indirect reproductive effort
Is menopause an adaptation or is it maladaptive?
