[VadeRetro]

Does an operative principle intended to result in a survivable population introduce a gene that shortens life and does not allow for reproduction? To most folks with a little common sense a gene such as this would be considered "deleterious."

Senescence.

If an allele has a beneficial effect early in life, and a detrimental effect late in life, it will still be favored

Some things take more than half a second of thought. Maybe "common sense" is being too shallow in its analysis.

[Fester Chugabrew]

If an allele has a beneficial effect early in life, and a detrimental effect late in life, it will still be favored.

What part of "it will still be favored" means anything less than "beneficial" when it comes to natural selection?