I seem to have this psychotic need to bring people up to speed on Evolution theories. I think it's because of Neil Tyson's groupies throwing so much hate and ignorance around the internet.
First off, the typical reason for these threads is an attempt to make people who are religious seem "unscientific". Simply put, the atheist media icon known as Neil deGrasse Tyson said in an interview on Big Think that there is no conflict between science and religion. It's only a minority of religious people who try to create a conflict.http://bigthink.com/videos/neil-degrasse-tyson-on-science-and-faith
Another thing these threads typically do is assume that "evolution" has explained how life began and why things are the way they are now. "Evolution" itself is often divided up into the origins of life, macro evolution, micro evolution, etc etc. This usually leads to someone trying to argue in favor of some small point and claiming that everything else with the word "evolution" attached to it is true by association. Another reference comes from Tyson is seen in Season 1 Episode 2 of the Cosmos reboot, "some of the things that molecules do". Near the end Tyson is speaking about early earth and says,
"Nobody knows how life got started. Most of the evidence from that time was destroyed by impact and erosion. Science works on the frontier between knowledge and ignorance. Not afraid to admit what we don't know. There's no shame in that. The only shame is to pretend that we have all the answers. Maybe someone watching this will be the first to solve the mystery of how life on Earth began."
That quote tends to shut down the "evolution explains all life everywhere ever" crowd. But that's about the origins of life, and not about adaptive mutations and "natural selection".
Another bit from Tyson was in a Tweet he made. He was speaking about the classic question of which came first, the chicken or the egg? He suggested that what laid the chicken egg was not quite a chicken. This is a reference to mutations creating new species. A few of us responded that significantly different creatures either cannot produce offspring or they create hybrids. So if it was a chicken that came from the egg, the only organisms around it could then breed with would not be chickens. This leads into the problems we see with white tigers.
A sexually reproducing organism that is governed by hereditary traits that experiences a significant mutation, that then breeds back with the general population that does not share that mutation, will produce hybrids. Further breeding of those hybrids with the general population that does not share that mutation will see that mutation "bred out" of the line. We see this in white tigers in that we have to inbreed them to preserve that mutation. This in turn has led to research that attempts to show how mutations can somehow build up among a group of organisms and enough of them experience simultaneous mutations to create a sufficient population to preserve the mutation without inbreeding.
This is a reason that Charles Darwin said, “If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down". Quoting that sends most evolutionists into a rage, as people continue to explain things as being "small steps" and using the theory of "co-opting genetic material". The thing is, even if an organism "co-opts" genetic material, it has to have a sufficient pool of other organisms to breed with to continue that mutation, else it gets "bred out". Thus the research on how traits might re-emerge in a large group of organisms.
A problem comes in with the people echoing the idea that things evolve in direct response to their environment, as if DNA had some level of intelligence and could re-write itself like a geneticist creating better GMOs. It doesn't work like that.
Another problem is with the people in the "it's all completely random" camp, that don't get the whole white tiger thing. That goes along with the research showing that mutations tend to occur along areas of the genetic code called "hot spots". Certain markers tend to cause mutations to be focused in those areas, thus preserving the basic traits of a species and only allowing slight changes such as size or coloration. So "evolution" is random, but that randomness in our time appears to be locked into certain regions of the code. No real evidence on this being the case or not millions of years ago.
So saying that "evolution" has been absolutely scientifically "proven" is a false statement. There's plenty of evidence, but there's still research being done to fill in the holes. Until that research is completed, it is "scientific" to question any results.