The Cost Benefit Analysis of Our Ancestors

Our ancestors didn't need to sense electric fields or magnetic fields, but the ancestors of birds and fish did. Can you not imagine any circumstance in which that would be an advantage to us using electric fields? So our ancestors were better off evolving big eyes that served them much better than an electric sense. Electric sensing is really, really complicated. It requires very, very specific organs in your body. If you really don't use them very much, then it's just not worth it.