The specifics of evolution are constantly debated, debunked and revised but once the overall theory is contradicted by irrefutable evidence, it would cease to be a theory. However the evidence continues to accumulate. I don’t think there is a competing hypotheses with any observed support. The tripping point for most of us is to embrace the deep time necessary but that too as overwhelming factual support in geology, biology and physics. It’s a mind bender for a short lived person such as I to comprehend 100,000 years, let alone 4+ billion years.
Jim - The theory of gravity has been around about as long as evolution. There have been multitudes of advancements and refinements on the theory of gravity. Most of this is due to the comparatively easy experimentation on gravity vs. evolution.
Gravity, even though much more refined and tested than the theory of evolution, is still far from fully understood. Evolution, which is very hard to test experimentally, has many fine details ripe for scientific testing.
Gravity has never been thrown out, but it has been clarified hundreds of times, bringing the understanding down the subatomic level. Evolution does not need to be thrown out, but the understanding can be greatly refined.
In order to refine the theory - careful observation and reasoning must be put to work. These fleas, and their shifts in allele frequency, are not support for evolution.
Even though there is a good theory of evolution, this observation (the fleas) minimally supports, but does not advance the theory of evolution.
And neither Gravity nor Evolution are “settled science.”
PS - Yes, 4 billion years is a long time, but that is not evidence for evolution either. Oh, I happen to think that life will be found anywhere that liquid water exists over billion year time-frames, having studied Archaebacteria from black smokers, and bacteriophages.