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I want to understand a mechanism how at the first times when the life began on earth evolution helped the new species to arise through selection while the same organism also continued to live as not evolved. If natural selection favors survival of the fittest, than why after a living evolves to a new fittest form, the older form still exists while it should be counted as unfit for survival and extinct, I am not sure but bacteria may be an example perhaps and I am not asking about the situations where the unfit form has extinct but both organisms continued to live.

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  • $\begingroup$ Related question. $\endgroup$ – Alan Boyd Jul 31 '17 at 15:53
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    $\begingroup$ Imagine people playing in a sports league. Some people, because of their (potentially newly developed) abilities (due to practicing), will be able to move on (evolve) to higher levels of competition within the sport, whereas those who are not developing new abilities (but perhaps are still skillful enough to keep playing in their current league) stay where they are. The question then becomes: how do some organisms gain new (more adventagous) traits, and others don't? Answer: genetic variation (either through sexual reproduction or rapid generational evolution) combined with random opportunity. $\endgroup$ – user22020 Jul 31 '17 at 15:57
  • $\begingroup$ Thanks for the answer and showing the related question, I specifically didn't want to give an example like apes to humans evolution but the evolution that happened during the times when the life has begun. Could it be that life has started in different locations and in one habitat mutations that were favorable to survive through selection were not necessarily the fittest in another habitat and the same species was already fit to survive and mutations that lead to new species were not the fittest in that location? $\endgroup$ – bbb android Jul 31 '17 at 17:24
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    $\begingroup$ @Charles: And some people find they aren't good at baseball, so they invent a new "evolutionary" niche like basketball instead :-) $\endgroup$ – jamesqf Jul 31 '17 at 17:37
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I want to understand a mechanism how at the first times when the life began on earth evolution helped the new species to arise through selection while the same organism also continued to live as not evolved.

Well, this beginning is not grammatically correct so it is hard to make much comments on it.

If natural selection favors survival of the fittest, [..]

Selection is the process by which fitter individuals increase in frequency in the population. survival of the fittest is a layman phrasing of the process that is natural selection. Natural selection therefore does not favour survival of the fittest, but it is represented by the phrasing survival of the fittest.

[..] th[e]n why after a living evolves to a new fittest form, the older form still exists

It does not. The older form is called an ancestor. The ancestor does not exist today. If there was a speciation events, then the ancestral lineage would have giving rise to more than a single lineage today. Some of these modern lineages may 'look more' like the ancestors than others but it does not mean that any ancestor still exist.

For example, the chimpanzee is not an ancestor of humans. Chimpanzees (and bonobos) and humans share a common ancestor that is about 8 millions old. To consider another example, humans and an oak tree share a common ancestor. This ancestor was neither a human, nor an oak tree. This ancestor lived about 1.6 billions years ago.

If you want to know why I am using term 'lineage' rather than 'species', you can have a look at this post

See below linked Biology.SE posts for more information

the older form still exists while it should be counted as unfit for survival and extinct

Don't forget that different lineages may (and will be at equilibrium due to the competitive exclusion principle) be adapted to different ecological niche. As such, one lineage will not necessarily outcompete the other one.

Source of information on StackExchange

There is a lot you can learn on the subject. You should start with an introduction to phylogenetics such as the one provided in the post

You can also have a look at

You should also have a look at

Reading your post, it sounds like you may have too a pan-selectionist view of evolution. Related to this point, you might want to read

Source of information external to StackExchange

Understanding Evolution is a good introductory course to evolutionary biology.


Response to comment

Thank you for the very descriptive answer, as you have figured out easily I am very new to evolution. I will read the references you have provided carefully

You're welcome!

is after evolution of a specie through natural selection,

This show again that you have too a pan-selectionist view of evolution.

unfit ancestor extinct and this is explained through phylogeny ?

From wikipedia

Phylogenetics is the study of the evolutionary history and relationships among individuals or groups of organisms (e.g. species, or populations).

A phylogeny is a tree of life of a given taxon. For example here is a phylogeny of placental mammals.

To be able to fully answer your own question, you need to understand the relationships between lineages and therefore you need to have some understanding in phylogenetics.

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  • $\begingroup$ Thank you for the very descriptive answer, as you have figured out easily I am very new to evolution. I will read the references you have provided carefully, but I think the main answer to my question is after evolution of a specie through natural selection, unfit ancestor extinct and this is explained through phylogeny ? $\endgroup$ – bbb android Jul 31 '17 at 17:37
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    $\begingroup$ It's also important to remember that "survival of the fittest" is essentially a circular definition, because organisms prove that they are "fittest" by surviving to reproduce. Also "fittest" is variable: an orca may be a supremely fit top predator in the ocean, but it's quite unfit to survive in the Mojave Desert. $\endgroup$ – jamesqf Jul 31 '17 at 17:43
  • $\begingroup$ @bbbandroid See edit to address your comment. $\endgroup$ – Remi.b Jul 31 '17 at 17:45
  • $\begingroup$ @Remi.b I have just started by watching the video you have mentioned in your post "If you want to know why I am using term 'lineage' rather than 'species', you can have a look at this post" and there is a video in the end of that post named "What Makes a Species a Species?" and i have watched in ending says biological species concept is not an absolute rule $\endgroup$ – bbb android Jul 31 '17 at 18:07
  • $\begingroup$ Yep.... any question about it?! You should maybe read the post if this is unclear to you. $\endgroup$ – Remi.b Jul 31 '17 at 18:34

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