why animals reproduce? Like the more healthy offspring is raised doesn’t mean more competition for food and survival?
In: Biology
An organism’s goal is to reproduce, not to survive. Survival is its second goal, because if it lives longer it has more time to reproduce. This is a very philosophical question and I think the answer is the same for the meaning of life. I am no scientist so don’t quote me on this.
Imagine you have two species competing for the same resources. One reproduces. The other does not.
Over time what will happen is that the reproducing species will drive the non-reproducing species to extinction because it will simply overwhelm it with numbers.
Taken over millions of years, this means the only species that manage to survive to the current day are the reproducing ones – all the non-reproducing species were out-competed.
The point to reproduce is to pass on your genes. There a two basic strategies for this. Produce a few offspring at a time and spend a lot of time and energy raising them to reproductive age. Or put very little energy into raising them and produce a lot. First way, you don’t have many offspring but you give them a better chance of surviving and passing on their (and also your) genes. Second strategy you increase the odds of your genes continuing through sheer number of offspring. As far as competition, I think it would be similar to altruism. They’ve found that altruism in nature is found more among related individuals. The more closely related, the higher the incidence of altruism because you share genes, so helping a relative helps pass on some of your genes indirectly. So, yes, more offspring means more competition, but more likely your genes will continue getting passed on.
All life basically has one “rule” that has driven it from the very beginning, replicate. (Why is a whole other question)
With that as a basis, we can work out why they reproduce. So let’s invent two animals:
Animal A doesn’t reproduce, and it’s functionally immortal, it will live forever.
Animal B is not immortal, but can reproduce.
Over time, the population of animal B will increase exponentially, while the population of animal A will slowly decrease as they die to random chance accidents, or due to predation from species B as it grows and requires more sustenance.
Over time, animal A will die out, whereas animal B will thrive. Of course, plenty of animal B will die of starvation once they overstretch their resources, but overall the species will have been more successful than species A. Nature can be cruel, it cares very little for individual animal B’s, but rather the species as a whole. A species can have 95% of its newborn members die, but so long as more survive than die, it’s a successful species.
And that’s all survival of the fittest is really. What species can continue its line, and what species die out and dissapear. Immortality seems to lose out to reproduction, especially when reproduction allows for random mutations that could well make an even better version of Animal B, where animal A would never evolve further, as it makes no new generations.
Not necessarily. Nature balances out. If a particular animal becomes too successful, either it’s predator(s) also become successful, balancing it out. Or it’s food supply (prey) runs short and there isn’t enough food for that animal, again balancing out.
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