A while back when I was at the gym and doing heavy dead lifts, I ripped a callus off the base of my right middle finger.
It hurt like a [insert your favourite cuss words here].
It happened on the upward pull, right at the friction point, where all the weight loaded on the bending barbell was deciding whether or not I deserved to overcome the ever-present forces of gravity.
I did deserve it, in the end. But at great cost. There’s always a cost.
Now a bit more about my callus. It was not just any ordinary callus, but had been transformed from a blood blister callus the week prior. On the same lift. In the same gym. Maybe even on the same barbell.
To make it even more extraordinary, when it ripped off, there was already another callus underneath it, adapted to take more force, more stress. Almost the same, but different. Ready to take its place.
If there isn’t any more proof of evolution than that, I don’t know what will convince you.