It is true that evolution cannot be proven. But that is because proof is a formal procedure applicable to axiomatically complete systems of deductive logic. Such
as mathematics and syllogisms. It does not apply to science as that is primarily an inductive discipline. Science only references disproof not proof. But this aside evolution has probably the largest body of evidence to support any scientific theory. As not only does it occur but it can do so within a human lifetime. Between
1988 - 2014 experiments conducted at Michigan University by Richard Lenski from only an initial dozen populations of E coli produced 60 000 generations. Which resulted in variation within speciation and the evolutionary development of new traits not present in the original samples. And this is merely one example of the absolutely overwhelming evidence for evolution which has been observed at both macro and micro levels. Indeed it has so much evidence for it it needs no more
There are three distinct ways the genetic information in the DNA can be changed and generate a mutation that could contribute to evolution.
1. It involves no new additional genetic information being formed, but it involves the loss of preexisting information that results in changes.
2. It involves the transfer of new genetic information from one organism to another, which translates, it can produce a new strain of an organism but not a new type of organism.
The E. coli bacteria was still E. coli bacteria, it had not evolved into another species
3. Would involve the generation of totally new useful genetic information within the DNA code of an organism by some supposed process in nature.
Dr Lenski's experiments revolve around the use of existing genetic information and that the potential to produce the new traits were already encoded for in some latent manner in the DNA. On the basis of the levels of mutations observed by Dr Lenski the probability of all this new genetic information arising by chance is so close to zero as to be impossible. In Wikipedia when documenting Dr Lenski's experiments it reads:
Other researchers have experimented on evolving aerobic citrate-utilizing E. coli. Dustin Van Hofwegen et al., working in the lab of Scott Minnich, were able to isolate 46 independent citrate-utilizing mutants of E. coli in just 12 to 100 generations using highly prolonged selection under starvation, during which the bacteria would sample more mutations more rapidly. In their research, the genomic DNA sequencing revealed an amplification of the citT and dctA loci, and rearrangement of DNA were the same class of mutations identified in the experiment by Richard Lenski and his team. They concluded that the rarity of the citrate-utilizing mutant in Lenski's research was likely a result of the selective experimental conditions used by his team rather than being a unique evolutionary speciation event.