I'm looking up definitions, and the first one I came across is this (short and sweet) --
"the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth."
Do you agree with it?
God can't be proven (except by psychic prediction).
Why, then, must we define evolution? This is tantamount to putting the burden of proof on scientists.
Twilight Hue mentioned that the environment is also a factor. Consider SETI (Search For Extra Terrestrial Intelligence), which focuses somewhat on earth-like environments (water, etc.) Of course, that is a search for life as we know it....but what about life as we don't know it?
InfraBenji said that evolution relies on natural selection. Entirely? Could there be a fluke in which a less able species dominated? Not everyone has married a perfect mate....some mates are terrible.
The Chixulub impact changed evolution. It dimmed the sun, which killed or weakened a lot of plants, and that greatly altered the food chain, so the biggest carnivores at the top of that chain were harmed the most (wiped out, except their offspring (birds, lizards, and mammals) still exist).
The K-Pg layer (formerly KT layer) poignantly demarks the impact and mass extinctions, but also delineates the "punctuated equilibrium" that ensued. Punctuated equilibrium is a hitherto unexplained speciation at the boundary. I think that I can elucidate this speciation: When many members of a species die off, the surviving members must mate to procreate. Yet, that produces more inbreeding, and that inbreeding produces more mutations, which gives "natural selection" more choices to winnow out. Once mass extinction occurred, there were new ground rules for natural selection (didn't have to evade huge dinosaurs if huge dinosaurs no longer existed). So, some mutations gained a greater foothold than others, thus accelerating evolution.
In summary, natural selection was not the only factor stimulating evolution, but diminished population created more mutations for natural selection to select.
Deeje asserted that we have no proof that whales were once small land mammals about the size of dogs. I agree....they could have been the size of blue whales, treated like dogs, but not properly trained to not jump on their owners or others while walking them. As a consequence, the owners of the dog/whales could have ordered them into the ocean (you don't want a pet blue whale jumping on you). If it lifts a leg......run.
How did we start with apes, which blended perfectly with their environment, then evolve to man, who's Republicans deny Global Warming, rape the environment, poison the streams, cut the timber, constantly assert that they are fighting evil (thou shalt not kill) and assert that they have a greater intelligence? Didn't evolution go in reverse?
The first thing people did when they realized that the melting poles allowed a polar bear to mate with a brown bear was to shoot (kill) the child. Good thing we're so smart, right?
Suave says that evolution (to a different species) is about not being able to procreate with another species. Yet, there are plenty of different species that do (horses and donkeys). Mule offspring can "sometimes" mate, though there is a chromosome mismatch.
Lions and tigers breed ligers and tigons which can have offspring.
Sometimes (especially in the case of insects), inability to procreate is a matter of geometry....the sexual apparatus physically won't fit (like playing Tetris with the wrong pieces).
List of genetic hybrids - Wikipedia
