Of course they can.
You just don't like the explanations, because they don't fit your religious ideas.
Evolution facts include the confirmed observations of A) descent with modifications and B) natural selection.
Evolution theory is many-times confirmed in the fossil record, in DNA analyses and inputs from virtually every other branch of science.
And there is no other scientific theory to compete with Evolution.
Indeed, there is not even a serious alternate scientific hypothesis out there.
Yes, the origin of life on earth is the subject of several scientific hypotheses, most of them various possible types of abiogenesis.
Another two potential hypotheses have been mentioned, though neither is testable scientifically: panspermia (life arrived on meteors from outer space) and intelligent design (which is unspecified in scientific terms).
ARepublicanForAllReasons: "If they stuck to just the well established facts, evolutionists would have to admit they have no adequate theory to explain either life's origins or the flowering of so many species."
Evolution theory does not explain life's origins.
Evolution theory begins once life has started.
Several hypotheses for abiogenesis have been proposed, though none has yet been confirmed.
The "flowering of so many species" is a simple extension over time of basic evoloutionary processes: A) descent with modifications and B) natural selection.
I don't like the explanations because they are not explanations, just statements of dogma. All Darwin or any subsequent biologist has proved is that most forms of life are exquisitely adapted to their environment, and that it is very likely that changes within species have occured to explain the fine adaptation. Species-to-species evolution has not been observed (quite unsurprisingly), but more pertinently no theoretical models exist for how most of the changes happened.
For example, it is supposed, due to anatomical similarities, that elephants are cousins to the extinct woolly mammoth. Now I'm just asking how the woolly mammoth lost its wool, grew bigger and flappier ears for better ventilation, modified its tusks and changed its diet from grass to mostly tree limbs, in addition to a myriad of other changes. If you don't know, then you don't know. I never learned it in my biology classes. Are there some super-secret biology departments where these evolutionary changes have plausable models but are kept from being imparted to the general public. Of course not.
We cannot observe the Earth and Sun being formed, but astronomy has plausable models which are quite easily unstood by intelligent laymen, about how they did form. This is not true of speciation. We just hear the same old line that change occured at random in incremental steps until an entirely separate species, well-adapted to its environment, came to be. And you call that an adequate scientific explanation?
Ah, but TIME! Given enough time all the right mutations will come together and culminate in new species. Yes, possibly so, but IMO some intelligence either inherent in Nature or guiding Nature from a non-material realm is more plausible. Of course, I could be wrong and within a few years, using super-computers, the precise mechanisms of speciation may all be explained. Heck, science may even explain how carbon chains floating in a warm ocean can form themselves into extremely complex, self-duplicating DNA molecules, complete with protective cell membranes, RNA and mitochondria and all the other accoutrements necessary for the simplest life. Well, there are simple viruses which lack DNA and invade host DNA, but that presupposes that the more complex life form existed before the virus could arise, doesn't it?
(Note: The Panspermia theory suffers from the same problem, BTW. If life on Earth came from other stars or galaxies, how did the first life emerge? It just pushes the ultimate question further back. If you can guide me to books with real answers for these problems, please do so. But if you even mention Stephen Jay Gould, I will probably never reply to you again.
-- ARFAR