Well, Einstein, since you are such a stickler for terminology you should probably figure out that you’ve given the definition for micro evolution, which no one denies, instead of evolution.
Yes, the problem is time scale. A man lives for maybe 100 yrs and can witness microevolution during his lifetime, so has no problem with the concept.
Mankind has "species memory" through oral traditions and written words which goes back maybe 10,000 years. Which is simply not enough time to record speciation, unless of course one is witnessing an extinction level event. In which case no one would survive to tell what went before.
But the micro evolution we witness over 100 years, easily yields new species if continued over one million or ten million years. And many branches of new species, genus, or even families over multiple millions of years.
As to mutations being lethal, I can name three new genes which appeared in the lineage of homo sapiens which lead to enhanced abilities and eventually spread throughout the species.
At one point in time a new gene appears in recovered bones of Home sapiens. That gene has been identified with development of the language center in the brain. Archeologists and paleontologists have discovered evidence that shows by the impression the brain leaves on the inside of the skull that the language center of the brain increased in size during the same time the gene appeared. They have also discovered evidence that suggests spoken language appeared at the same time.
The second mutation I will mention in the human genome is a gene which enhance artistic expression. Once again it has been shown that the lobe of the brain which gives artistic talent became enlarged at the same, and cave paintings appeared at that point in history.
The third mutation I will mention occured much more recently and is for a gene which allows production of the enzyme "lactase" in the human adult. Human populations which acquired this gene over came their competitors in the environment by adopting dairy animals and having consumable proteins and vitamin rich milk available year round.
The interesting thing about the lactase gene. It has appeared not once, but multiple times in disparate populations. Each time a totally different gene, but causing the body to produce lactase in each case.
Each case an example of a beneficial mutation furthering the evolution of the human species.
And, no, a harmful mutation does not wipe out a species. It is only harmful to the individual carrying the harmful mutation. That individual may reproduce at a slower rate, fail to reproduce, or even die. But in the grand scheme, the species does not notice the loss of an individual.
But when a beneficial mutation occurs and offspring carrying that new gene begin to overwhelm their conspecifics, that does impact the species as a whole. Therefor mutations can not harm a species, but they can help it.
People who choose to brew up their own storms bitch loudest about the rain.
