I've recently picked up an interest in the evolutionary need for aging. I realized that we seem to age intentionally as all different animals have different aging rates. I've done some reading but my idea hasn't come up and I want to know if it's been researched.
Because resources are scarce, the size of a population of any given creature is limited. As a result creatures with a long life expectancy essentially prevent large youthful populations and necessarily must reproduce at a slower rate(right?). My hypothesis is this: Let's say creature A has a long life expectancy while creature B has as short one. Creature B gets to be naturally selected several times per creature A generation. These shorter lived creatures would evolve more quickly and so they would eventually outcompete A and could cause its extinction. Has this benefit of aging been tested? rejected? Are there sources? Any logical flaws in my hypothesis?
2006-09-12 13:51:35 · 9 answers · asked by JonFugeEverybody! 2 in Science & Mathematics ➔ Biology
You are off to a good start. The rate of evolution is not controlled by generation time alone. Mutations increase with age, so long lived A will have more new genes per generation than B. B will shuffle its genes to discover better combinations faster. The optimal lifespan is a trade-off between these and other factors, such as parental care. For more information about mutation rates read The Cooperative Gene, Mark Ridley.
2006-09-12 14:05:59 · answer #1 · answered by d/dx+d/dy+d/dz 6 · 0⤊ 0⤋
Hi. Good question but a flawed hypothesis. Lets look at humans for a minute. We live for a certain number of heartbeats, about 3 billion maximum. And a certain number of years, say 100 maximum. We are unique in that we have a society, language, family or village type of artificial lifestyle. So lets rule us out. In the natural world there are many examples of evolution that has accelerated due to environment. Take the white moths in England that live in or near birch trees. When the industrial revolution took place the trees became sooty and the white moths stood out. The darker ones (same species) had a higher survival rate. If they had a greater lifespan then the "parents" would be mostly eaten by birds. Since they didn't, the species survived. Also look at germs and the current spate of antibiotic resistant germs found in hospitals. My point is that if the lifespan of creature A prevents it from evolving fast enough to overcome natural obstacles then the will not survive. Good thoughtful question!
2006-09-12 20:54:04 · answer #2 · answered by Cirric 7 · 0⤊ 0⤋
You assume that evolution has an aim. But it doesn't. There is no final perfection that is selected for. The only thing that matters is a creature that is well adapted to its environment and is able to also adapt to changes. Within that framework nothing much ever has to change. And in geologic times actually things change very slowly (before man, I mean). Climate change would take countless seasons, giving even slow breeders enough time to adapt. And sudden changes (volcano eruptions, meteors) would definitely favour animals that can adapt very quickly, never mind their generation span.
Otherwise, how could sharks have survived practically unchanged for eons? They are perfectly adapted to their environment but can change to meet any changes therein. It doesn't seem that they were outcompeted by anything else for years innummerable.
2006-09-13 00:46:58 · answer #3 · answered by kate 4 · 0⤊ 0⤋
As long as individuals are reproductively active, there is no advantage to having them die off.
I.e. if A has a long life expectancy, but continues to reproduce throughout that time, then it will outcompete the creature B in producing offspring. So in that case A will do better.
2006-09-12 20:56:54 · answer #4 · answered by secretsauce 7 · 0⤊ 0⤋
I see no flaws in your hypothesis. Just think of how bacteria becomes resistant to medications. If they only reproduced once a year, this would not be a problem.
A long lifespan may be beneficial if conditions are stable and help you out-reproduce other species, while a short lifespan is beneficial when the environment change fast and there is a need for adaptation.
2006-09-12 21:02:56 · answer #5 · answered by Anonymous · 0⤊ 0⤋
Interesting idea. I don't know if anyone has followed up on it. From my limited understanding, evolution might not "care" what the life span of an animal is once it has reproduced, unless grandparents can help care for young or they compete with the young for resources, as you mentioned.
2006-09-12 20:55:42 · answer #6 · answered by mollyneville 5 · 0⤊ 0⤋
the flaw is this "These shorter lived creatures would evolve more quickly and so they would eventually outcompete A and could cause its extinction" use humans as creature A and roach for creature B. roach wont cause our extinction. just a thought
2006-09-12 20:58:21 · answer #7 · answered by fn_49@hotmail.com 4 · 0⤊ 0⤋
There are variables you left out - are they competing for the same resources? If so, are similar resources available to one but not the other? Are they a predator-prey relationship? We would need more details.
2006-09-12 20:57:47 · answer #8 · answered by JBarleycorn 3 · 0⤊ 0⤋
Are you neglecting "food chain".
Birds live longer than insects.
Insects multiply more often and in greater numbers than birds.
Birds eat insects.
2006-09-12 21:01:12 · answer #9 · answered by ed 7 · 0⤊ 0⤋