Author Topic: Why do animals have shorter lifespans?  (Read 205 times)

ragarth

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Why do animals have shorter lifespans?
« on: December 07, 2009, 05:49:03 AM »
Or phrased more properly, what mechanism results in animals having shorter lifespans than humans?

Science/Evolution has a few ideas out on this, such as the shorter lifespan being a product of environmental influences upon the genetics of the animal, the shorter lifespan being directly advantageous, or the shorter lifespan being a byproduct of other advantages.

On the religion side of things, however, I'd like to know more.

MariaEvri

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Re: Why do animals have shorter lifespans?
« Reply #1 on: December 07, 2009, 06:48:13 AM »
from personal observations, Id say the smaller the size, the shorter the life span. And not all animals live shorter lives than humans. Bowhead whales are thought to live more than one hundred years and lets not forget the age old tortoises of th galapagos.

Lets see the scientific explanations of the fellow forum members :)
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joeactor

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Re: Why do animals have shorter lifespans?
« Reply #2 on: December 07, 2009, 07:48:50 AM »
Quote from: "MariaEvri"
Lets see the scientific explanations of the fellow forum members :)

... because we eat them.

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AlP

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Re: Why do animals have shorter lifespans?
« Reply #3 on: December 07, 2009, 07:56:40 AM »
There's a list of the lifespans of various species here. The Hexactinellid sponge wins at an estimated 15,000 years. That's one creepy looking animal! I think that's a maximum longevity; humans are listed as having a longevity of 122.5 years. I don't know the causes of aging.
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ragarth

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Re: Why do animals have shorter lifespans?
« Reply #4 on: December 07, 2009, 09:04:48 AM »
That's an interesting site, thank you. :-)

To the critique above, I didn't say all animals, I said 'animals'. I felt it would be assumed that some animals do indeed have longer lifespans than humans: whales, sea turtles, etc. And the assertion that smaller animals live longer based upon size is incorrect, certain forms of captive bird can live in the 100 year range whereas dogs do not have that form of longevity.

Still though, this discussion is lacking the answers I'm really looking for, the religious ones.

AlP

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Re: Why do animals have shorter lifespans?
« Reply #5 on: December 07, 2009, 09:30:06 AM »
You mean, why would an intelligent creator design an animal with a lifespan shorter than a human? I'm sure I could make something up if it's a problem ;).
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MariaEvri

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Re: Why do animals have shorter lifespans?
« Reply #6 on: December 07, 2009, 10:12:16 AM »
Quote from: "joeactor"
Quote from: "MariaEvri"
Lets see the scientific explanations of the fellow forum members :)

... because we eat them.

(yum!),
JoeActor

do they at least taste good or should I get the sauces ready?
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karadan

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Re: Why do animals have shorter lifespans?
« Reply #7 on: December 07, 2009, 10:23:56 AM »
In the case of mammals, i seem to remember there being a corellation between the size of the animal, its lifespan and the frequency of its heart beat. The larger the animal, the less times its heart beats per minute, the longer it lives.
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SSY

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Re: Why do animals have shorter lifespans?
« Reply #8 on: December 07, 2009, 12:36:24 PM »
I have heard the rough rule of thumb that an animals heart can beat a billion times before it dies. Obviously this is just a rough generalisation, with no actual scientific reasoning, but kinda cool none the less.

Also, why would you come to an atheist website to ask us the religious reasons, for a god we don't believe in, to decide on the length of time an animal lives for?
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ragarth

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Re: Why do animals have shorter lifespans?
« Reply #9 on: December 07, 2009, 02:20:39 PM »
Several large breeds of dogs have shorter lifespans than their smaller counterparts

And I see theists post on this forum, so I figured I'd see their reaction. The only christian webforum I know of that gets good volume and allows atheists is christianforums.com, and I stopped posting there because I got fed up with certain types of BS. If you know of a decent forum for discussions such as this, then let me know, otherwise having a creationism/evolution board on here is pointless. I can see the conversation now:

"Creationism sucks, darwin rocks"
"Yup, I agree"
"Decidedly"
"Most certainly!"

Not nearly as fun as a forum like this should be. :-)

McQ

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Re: Why do animals have shorter lifespans?
« Reply #10 on: December 07, 2009, 02:32:58 PM »
Quote from: "ragarth"
That's an interesting site, thank you. ;)

And yes, as far as mammals go, larger animals tend[/b] to live longer than smaller ones. Same is true for many other types of animals, insects, and even plants. But it is a generalization, of course.

There are no perfect or hard and fast numbers for the natural life expectancy of many animals because of the changes in natural habitat over history, in particular the time period in which humans began to actively study and note life expectancies of organisms. Essentialy we changed the rules for life spans just by being here and being predators.

One of the things that does effect life expectancy is size, but not for the reasons you may think. Size makes a difference in how easily an animal becomes a prey animal. Larger animals do have an advantage over smaller ones simply by virtue of their mass. Predatory animals go for the easiest meal they can get. But metabolism and many genetic factors play roles in life expectancy too. Some other information that came to light about ten years ago is here too: http://www.jlr.org/cgi/content/full/39/10/1989

A nice, short, layman's piece can be found here: http://www.tpwd.state.tx.us/publication ... ife_spans/
 
As for religious reasons, there are none. The bible mentions humans living to many hundreds of years from time time of Adam and Eve up until after the flood. According to Genesis, it seems that our becoming carnivores put the kaibosh on those long lives. After the flood, we went down to 70+ years. But since that is all bullshit, it can't be used to scientifically answer the question.

Additionally, human life expectancy was not always this high. Resorting to Wiki (because I'm in a hurry) you can see in the chart on this page how it has increased.
http://en.wikipedia.org/wiki/Life_expectancy

Hope this helps.
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Higgle

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Re: Why do animals have shorter lifespans?
« Reply #11 on: December 15, 2009, 06:22:14 PM »
well, humans ARE animals just for the record.

McQ

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Re: Why do animals have shorter lifespans?
« Reply #12 on: December 15, 2009, 08:42:26 PM »
Quote from: "Higgle"
well, humans ARE animals just for the record.

Yep. Mentioned that in my post, just above this one. But a worthwhile point to reiterate.

By the way, welcome to the forum!
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Ellainix

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Re: Why do animals have shorter lifespans?
« Reply #13 on: December 16, 2009, 12:19:56 AM »
I don't think animals have modern medicine to the same degree as humans or genuine sanitation.
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Re: Why do animals have shorter lifespans?
« Reply #14 on: December 16, 2009, 12:59:28 AM »
Quote from: "MariaEvri"
Lets see the scientific explanations of the fellow forum members ;)
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