Most of vertebrates (including human's ancestors) lost the 6th sense of electric fields in process of the evolution. Apparently 6 is not always better than 5 from the nature's point of view. Moles went further to loose sight as well.
I don't think that's quite right, evolution makes trade offs and allocates scarce resources, it's not necessarily because such things would not be beneficial.
It's not clear what "beneficial" means if you consider it separately from the resources required to achieve it.
E.g. it's beneficial to be stronger I guess, and gorillas are always strong whether they use their muscles or not. However for humans nature chose a different path where only the muscles you actively use are strong. This approach seem to work great so far, even though it results in many individual muscles of the body being weak. For each and every of these muscles you can argue that making it stronger would be "beneficial" but as a whole it doesn't seem to work out.
> Most of vertebrates (including human's ancestors) lost the 6th sense of electric fields in process of the evolution.
Human ancestors are not human. Also, the ancestor you are referring to was a fish, and could only sense electric fields under water. Why would the ability to sense electric fields under water be an evolutionary advantage for humans who don't live in water? If it's not an evolutionary advantage, then there is no reason it would propagate.
When I said 5 senses are better than 4, I was clearly referring to senses that are useful in our environment. Answer this question: is a deaf person, all else equal, more likely or less likely to survive and procreate relative to a hearing person?
> Moles went further to loose sight as well.
Moles have eyes and can see. Their vision is just not as detailed as humans. Highly detailed sight isn't an advantage for creatures that live in the dark. However, hearing is a huge advantage for people who live in an environment where sound waves exist.
You're clearly wrong here. Stop reaching so hard and just move on.
No, I'm not wrong, I just don't like relying on "obvious" statements like "5 senses are better than 4". We can't know for sure what was "better" until the human race experiment is finished (and then we won't know either obviously).
Consider this: hereditary autoimmune diseases are usually seen as a disadvantage. However they were a huge advantage during the bubonic plague in Europe, increasing the chances of survival by estimated 40% [1]
If we manage to eradicate these disadvantageous genes we may not survive the next pandemic. I don't have the knowledge to predict whether deafness genes or some other property entangled with them will be advantageous 10000 years from now and neither do you. That's all. Now you can enjoy listening to music all you like, it's just beyond the point.
Hereditary autoimmune diseases are not a sense, and are irrelevant to this discussion about whether hearing is an objective advantage or not.
I’ll ask again, since you must have missed this question: is a deaf person, all else equal, more likely or less likely to survive and procreate relative to a hearing person?
> I’ll ask again, since you must have missed this question: is a deaf person, all else equal, more likely or less likely to survive and procreate relative to a hearing person?
You know the answer: it can be both ways depending on circumstances.
* In the prehistoric world I think he was less likely to survive. The difference doesn't seem to be dramatic though since these genes were not eradicated from the population.
* In the modern world the difference is close to zero with an unknown sign. Given that in developed countries probability to procreate seem to be limited by a desire to procreate, I can't rule out that e.g. deaf people for some reason have 0.1% more desire to have kids, or any other side-effect. So answer to your question is unknown, requires a study to figure this out.
* In the future hearing can be an advantage or a disadvantage depending on how the circumstances evolve. We see that species gain and loose senses depending on the environment.
EDIT: I would also like to clarify this part:
> Hereditary autoimmune diseases are not a sense, and are irrelevant to this discussion about whether hearing is an objective advantage or not.
It's a human trait which was "obviously good" in the past and is "obviously bad" now. Hence I don't trust statements that other human traits like deafness are obviously good or bad. It's interesting to discuss but it's not granted.
