By applying the theory, we have invented...
... insulin and penicillin.
Animal testing started in the late 19th century. It assumes that mammals, being closer to humans evolutionarily, will have much the same biochemistry. To find out what the human pancreas does, in 1889 Oscar Minkowski and Joseph von Mering operated on a dog and took out the mysterious organ. The side effect was the dogs got diabetes. Back in 1869 Paul Langerhans had speculated that the pancreas was producing some unknown chemical he named as "insulin." It took till 1921 when Nicolae Paulescu isolated it and tested it on a diabetic dog, stopping the symptoms.
The Nobel Prize for it was awarded to 2 Canadians in 1923 even tho they were 8 months later and Paulescu had a patent on his process.
In 1939 Rene Dubos proposed that since bacteria had been around for millions of years the theory of evolution implied that they would develop predators to feed on them. So looking for a natural antibiotic he found gramicidin which could be used against gangrene but only topically.
Alexander Fleming then did a double take and declared he had found one of those what-do-you-call-its in 1928 and had named it penicillin. Other people immediately made the crucial experiments (during the Blitz no less!) and sent the results to America where Americans simply made a big version of their equipment to start processing it. Fleming flew to America to get in a photo-op and crowed on both sides of the Atlantic what a genius he was.
But it was Dubos working straight from the theory of evolution who started the ball rolling.
Dubos later warned that evolution would mean that the antibiotics would lose their effectiveness as bacteria out-evolved them.
Penicillin was discovered by accident ("it just flew in the window"). It didn't evolve, it was around like everything else. And this proves evolution how? We're looking at putting a pigs heart into humans - and this proves evolution how?