Look at this. What this means is that Gpuccio will look at some particular protein sequence, and if we don’t know of other protein sequences that can perform the same function, he will define the FI to be high because the target space is small.
So he will say a protein with this function could not have evolved, because the target space is too small to have been found by a sort of “blind search”.
If we then show that in fact the protein could have evolved from other proteins with different functions, or perhaps that there are many other proteins that can perform the same function, Gpuccio will then say the target space is huge, but that means the FI is low and so the function evolving is trivial.
So Gpuccio has defined his 500-bits rule such that if something has 500 bits, it can’t evolve, and then says it’s our job to prove him wrong. If we then do that, he says we’ve just proven it doesn’t have 500 bits.
But then what use is it to bother with this whole FI nonsense? Why not just say the target space is either big or small, and this is what has implications for the probability of evolving the function. The whole deal with FI is a sideshow. It looks like it’s invented just to make it sound fancy and technical, but adds nothing to our understanding of the proteins, or the function, or the evolvability of it.
And more importantly, how does Gpuccio know the size of the target space? If you look at how Gpuccio derives the FI for some protein, he’s looking at sequence conservation for the protein in the known diversity of life. Gpuccio is taking the number of sequences currently used in extant living organisms as a proxy for how many possible proteins there are with a similar function. Obviously that doesn’t tell us anything at all about whether there are other possible proteins with a similar function
Every time Gpuccio declares that some protein exhibits 500 bits of FI because of how many similar protein sequences with the same function he can find in some public database, he’s essentially claiming to know that there are no, or not enough, other alternative protein sequences that can perform the same function, and so the target space is too small to have been found by blindly sampling sequence space from an arbitrarily picked position. Should we happen to find evidence that there ARE such other functions out there, Gpuccio will simply include those in his FI calculation which will then reduce the amout of FI exhibited by the sequence.
The whole 500-bits thing is a question-begging assertion. The whole concept has hidden the claim that evolution could not have produced X away behind a smokescreen of fancy-sounding, but ultimately vacuous technobabble.