what biological aspects that cause one species to live longer than another species?

[Animalistic]

We're not going to discuss about psychological aspects that contribute in longer lifespan such as stress-free environment, adequate nutrition, health care, social stimulation, living in captivity VS nature, etc. We're going to see things from other fields/point of views.

 

Take this as simple example:

A small chihuahua can live far longer than a big St. Bernard since it requires less effort to sustain its heart and other vital organs, etc. A rat that is almost the size of a chihuahua live no more than 2 years. The lifespan of an elephant could be as long as the average lifespan of human. Cold-blooded species could live longer due to decreased metabolic rate (let us ignore them for awhile and focus on mammal, for now). Etc,etc. There are many other argumentative examples that I couldn't write all of them here.

 

So I want to hear your personal scientific explanation/opinions toward this matter. Please don't just say it's already in genetic. You could be as argumentative as you want.

 

I'm sorry if It's poorly written. English isn't my official language.

[granpa]

I have heard it said that most organisms have approximately the same number of heartbeats in a lifetime

[Chalky]

Apparently it's possible to be immortal (if you're a jellyfish). Story on the BBC here

[StrontiDog]

From an evolutionary perspective, I propose that lifespan and breeding rates would be one factor for selection of longer-lived individuals in any population.

 

Consider rats that would routinely live in excess of a hundred years (like some sea turtles). Now consider their breeding rates.

 

Malthus wasn't wrong, he just didn't anticipate all the variables.

 

Perhaps such species have existed. What are the odds they'd still be around, today?. One true drought, worldwide ice age, volcanic winter, etc., could wipe-out such a species even if the regular overpopulation/95% wipe-out cycle were not broken.

 

One of the evolutionary advantages of mortality is that the older generation dies and clears the way for the younger, once they're able to care for themselves. If not, older individuals compete with their own offspring for limited resources.

 

It's one thing for sea turtles, which lay many eggs but for which few live to adulthood, to have a longer breeding lifespan. That makes sense from an evolutionary standpoint. Low survival rate of offspring is generally the same thing as low breeding rates. It's more about success, than potential.

 

So I posit that long lifespan and high (successful) breeding rates are counterproductive, from evolution's standpoint.

 

One or the other, not both.

 

There's one reason. . .

Edited June 4, 2011 by StrontiDog

[swansont]

Typical lifespan for (non-human) animals is roughly a billion heartbeats.

[CharonY]

I am not sure whether this extends beyond mammals. However it indicates that energetics is a limiting factor (i.e. high metabolism inversely correlates with life expectancy).

 

of the evolutionary advantages of mortality is that the older generation dies and clears the way for the younger, once they're able to care for themselves. If not, older individuals compete with their own offspring for limited resources.

This does not hold water, even if the elders successfully compete with their youngs, on average they would still have more offspring with higher genetic identity to themselves.

[swansont]

I am not sure whether this extends beyond mammals. However it indicates that energetics is a limiting factor (i.e. high metabolism inversely correlates with life expectancy).

 

Yes, that may be the case. I have seen the claim (for this and for Kleiber's law of metabolism scaling) that it applies to all animals, but when examples/data are given, it always seems to be mammals.

[CharonY]

I was under the same impression. I can imagine that e.g. when considering extreme sizes the heartbeat may not be a good (or comparable) indicator of metabolic rate , likewise depending on the kind of metabolism different energetic constraints may apply. It fits well for mammals since they have got a very similar basic metabolism. This is even more complicated for animals with different life stages. The reproductive stage of some animals only lasts a few hours, for instance.

 

Just as an example, mayflies have a heart rate of around 30 bpm (according to an old paper by Fox and Simmonds, 1932). However, they get away with that because diffusion plays a bigger role (due to their small size) plus their metabolic requirements i lower as e.g. do not need to maintain body temperature. Still they do not live longer than 3 years (all stages combined).