To op.
I got to throw my 2 cents in this
First of all, I read a nice text a long time ago (I could find the reference if needed) that proposed a different angle of Darwinism, or more of a new way to study and analyse traits. It is in no mean against it or trying to argue with it, but its pointing out the fact that theres some kind of paradigm in evolutionary biology that considers every traits as an adaptation. Every time a distinctive trait is observed in nature, we tend to immediately ask
Why? The idea here is to point that it is a very teleological way to see the biological world. As if every trait was developed for that particular function.
So from what I read, there would be what they call exaptations. An exaptation is a trait that could develop for a certain purpose, or even for no purpose at all, and later be use for a totally different reason. Birds feathers is a common example of this, as they are thought to have appeared for internal temperature regulation before being adapted for flying.
I wanted to point this out because of the text under the picture. First of all, its says that the fingers prune underwater ''for'' an enhanced grip, which comes from an evolutionary trait. As pointed out before, it could have been an exaptation that would later become very useful since it enhanced our grip underwater. I dont know the whole research that has been made to make this statement, so I cant really argue with it, but I just wanted to say that it might not have evolved ''for'' this in the sense that it was the exact purpose of this trait.
Second thing about the text under the picture is how they give two different reasons for fingers to prune underwater, and those two reasons are, in essence, pretty different. For the first one, that is said to be false, fingers prune cause it absorbs water (ok I dont think this is true, we are just talking to talk
). The reason why fingers change from a normal state to this state is because they absorbed water. We are talking about what effects occur on the finger so it becomes prune. In the second part of the text, its said that fingers prune for an enhanced grip. Here we are talking about what effects can have prune finger on other things.
The first part propose that the prune fingers are the EFFECT of a cause, water. Then the second part says that the finger prune is the CAUSE of an effect, an enhanced grip.
My point? Saying that fingers prune ''because'' it enhances grip does NOT falsify by itself the fact that what it could prune ''because'' it absorbs water or loses its oil.