Life Spans

[K-Kool]

What is it that will make one animal live longer than another.

 

I am more focused on the deterioration of the bodies functions than any outside variables such as predators, unhealthy diet, lack of medical care.

 

Why do some mammal's that weigh around the same as us die off in captivity much sooner than we do? Even under great care.

 

How come smaller animals such as cats or dogs go through a faster life cycle?

 

 

Thanks!

[mooeypoo]

I believe it has a lot to do with metabolism. Smaller animals have faster metabolism, usually, and they die faster. Larger animals have slower metabolism, and they live longer.

 

I'm not entirely sure it is the only cause, though.. I will try to find resources when I wake up, but seeing as no one answered, I thought to pitch in.

 

~moo

[DrP]

I read somewhere once it had something to do with a set (or close to) number of heartbeats. An elephant's heart beats very slowly compared to a hampsters which whizzes away. How true this is I am not sure though - could be an urban myth! I'll look it up.

 

OK - on a quick search it seems that mamals live for (very appox.) about 1 billion heartbeats. I'm not sure this counts for EVERY animal, but it is a rough guide for some from what I could tell (don't have time to look it up properly right now).

[mooeypoo]

Aren't the 'speed' / amount of heartbeats related to metabolism too, btw?

 

I can't find anything about this, but I'm sure I've heard this metabolism-lifespan relationship... anyone heard the same or knows about any resources for or against?

 

~moo

[Mr Skeptic]

I too have heard about the metabolism/lifespan relationship. I believe that it is also related to the life extension technique of caloric restriction. Caloric restriction however may have a large effect only on animals with short lifespans; it may be a failsafe to ensure survival through a famine.

[Donut.Hole]

When an animal grows, it produces more cells than are dying off. When reaching adulthood, it produces cells as quickly as cells are dying off, so the animal does not grow. If unaffected by disease, animals die from more cells dying than being created. Sooner or later, some organ will fail.

 

My guess is that for larger animals, cells die off more slowly (slower metabolism, as mentioned in the previous posts.) And is the "cell death rate" is the same regardless of size, then larger animals will not be affected by loss of the same number of cells as a smaller animal would. So they have longer lifespans.

 

If I'm right (and I'm probably not, someone confirm this), why do animals like the Galapagos turtle live longer than say a horse when it's smaller?

[DrP]

why do animals like the Galapagos turtle live longer than say a horse when it's smaller?

 

Because the turtle will have a slower heartbeat / slower metabolism - so it will take longer for it to reach its 1 billion heartbeats.

[mooeypoo]

I heard that too and cannot find reference, so please chip in, anyone who knows about this (or against this? am I wrong?):

 

As far as I know, metabolism has to do with "moving" and expending energy -- a creature that moves very quickly, spends a lot of energy, has a high metabolism --> lower lifespan (take a hamster, for instance).

 

A creature that moves slowly, spends very little energy, has low metabolism --> longer lifespan (like turtles).

 

I don't remember where I've read the comparison in terms of "movement" and lifespan as it relates to the metabolism, so I might be wrong, but it sounds plausible... I'll look up more info about it anyways.

[DrP]

http://www.billionheartbeats.com gives a brief overview. Type 'billion heartbeats' into google for loads of stuff. -- I havn't read any respected scientific journals regarding this but there is alot to suggest that it is a good approxination.

 

Humans however go way beond their billion heartbeats (science cheating nature??) - we get about 3 billion according to the pages I read.

[thedarkshade]

I think moo has given a good and rational thought on her first post. That is what I think too. Roughly, what organisms in general live for is to manage to somehow get the energy needed to perform metabolic processes.