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Oh no, not this question again. Why doesn't anybody use the Search button?
Let me address two separate issues (the first part is modified from another answer):
1) The pattern of evolutionary processes that can be seen (in the fossil record and living species)can be of two types:
In _anagenetic_ (meaning "that generate upward movement") events, an entire population evolves in one direction and becomes so different that at some point the people who study it give it a different name. This is encountered in paleontological research and the decision to separate one from the other is ultimately arbitrary.
_Cladogenetic_ (meaning "that generates branches") events entail a population that splits into different sub-groups; each of these then evolves independently from the others. We share A COMMON ANCESTOR with living apes, but we have not evolved from them directly.
Our direct ancestors are fossil hominid species.
All the species that are living today have their separate evolution and history; also they all (including humans) share common ancestors from which they (we) have inherited our common traits. And apes have their own ancestors that are closer to them than to Homo sapiens; the fact that apes are our closest living relatives does not exclude the existence of more related _extinct_ relatives.
2) What you're stating is one of the arguments that many creationist use, namely, that change within a species (adaptation, i.e. microevolution) is possible (they are astute in not denying this, because the proofs are overwhelming!), but a species cannot transform into another (macroevolution).
This is based on a mistaken concept of "species". Most people think in terms of the biological species concept, which is based on reproductive isolation. That is, individuals of each species cannot hybridize succesfully with individuals of other species. However, there is not a single path for the rise of the mechanisms for recognition or isolation that we perceive as the "real boundaries" of a species. What the taxonomist calls a species may respond to different species concepts (such as morphological, evolutionary, biological (isolation), paleontological, recognition, etc,), and there are many examples of populations in which speciation (total isolation) is on the way, and there's a thin line between "subspecies" or "geographical races" and valid species (just ask an expert in systematics, which I am not).
Evolutionary processes are long-term phenomena, and it may seem that there are "evolutionary leaps" from one species to the other. But although there are particular cases of "instantaneous speciation", most of the "leaps" are due to the fragmentary nature of the fossil record. So many populations become extinct or become something else and their former existence is not recorded anywhere! But although the record is fragmentary, life is continuous.
Sorry for the lengthy answer, I hope you find it useful.
Hi. This question has already been asked here, both in the Science and in the Religion categories. The best answer I can provide is the same I gave then.
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