A benefit TO the environment seems like going too far, because that statement itself is an entry into the philosophical, but an increased survival rate is a metric for benefits IN the environment: The greater survival of organisms with a certain trait in a certain environment over that of organisms without it suggests a natural, mechanical and non-directed selection for such traits generally. Without guidance, traits that help an organism in a given environment come to predominate over those that either don't help or even harm organisms, because organisms with helpful traits live longer and breed more than others. The scientific test of the theory is whether we can observe the results it predicts over time: If we do, that's evidence the theory is valid; if not, that's counterevidence (bearing in mind, as always, that evidence does not necessarily reach the level of conclusive proof).

That's just one laymans limited understanding though, so take it for what it's worth; there's a reason I didn't leap up to give my opinion.