As a result of the experiment scientists did with Mexican tetras, it seems likely that their first hypothesis about blindness in the tetras is right. Explain how the result of the experiment supports their first hypothesis.

The scientists' first hypothesis is that blindness gives the fish some sort of evolutionary advantage, but not directly.

The experiment was: The scientists transplanted a lens from the eye of a surface tetra embryo into the eye of a cave tetra embryo. The result was striking—the surface tetra lens into the cave tetra caused all of the surrounding tissues to develop into a healthy eye.