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I don’t think that slower aging will decrease the numbers. Quite contrary! The main problem of a species where some members age too slow is that certain alleles will become too dominant in the species. That is, the genetic diversity decreases, putting the species at the risk of extinction. Imagine a wolf that significantly ages slower than the rest of the pack. This wolf will most likely become the alpha. If this wolf ages very slow or doesn’t age at all, all offspring in the pack will have very similar genomes after a certain time. If the pack then encounters a new deadly pathogen, the entire pack will be eradicated in no time. I believe the main function of aging is to increase genetic diversity.

I also don’t think that that the fertility rates in developed economies have anything to do with life spans. People don’t choose to have fewer kids just because they have a better life expectancy. There are a variety of socio economic reasons for lower fertility rates but they are all not directly linked to aging.

Michael, You are right that increasing life span in a by product of an improvement in the standard of living in developed economies. Sorry I didn’t make that clear. Together they influence fertility rates for socio economic reasons for which the list is long.

It doesn’t necessarily mean a species goes extinct it may just cause an decline in numbers until supply and demand come back into balance. For instance an increase in human live span where culture plays an important role has caused fertility rates to go negative in developed economies as a matter of choice. As human life span increases from where it is today fertility rates will likely drop further.

I am unsure where you disagree.

Life spans in the animal kingdom are driven by what works best for species survival.

This is exactly Mitteldorf’s point. If the life span is too long, that is, if animals don’t age fast enough, the species becomes extinct because it depletes the resources of the ecosystem.

Mitteldorf appears to have run into a dead end based on your report for the following reasons:

A behavior can become hardwired when it proves  to confer a survival advantage. This is obvious in yeast and bees and becomes less obvious and more subtle the higher you go in the species cognitive pyramid.

Animals with shorter life spans can often adapt more quickly and therefore have a survival advantage over long lived animals when the environment changes rapidly due to multiple causes including but not limited to climate change and competition.

Life spans in the animal kingdom are driven by what works best for species survival. We could not have evolved to become modern homo sapiens if we had been limited to  the lifespan of a mouse.  On the other hand life span can very dramatically between a mouse and a bat as a result of the bats reduced rick of predation.

It sounds as if Mitteldorf’s scientific theories on evolution are being driven by his political views.