Comment by valuegram

What's weak about the grandmother effect? Selective pressure absolutely applies outside of reproductive phases of the individual. Evolution happens at the genetic level, not only at the level of the individual organism. If a related organism is able to increase the reproductive chances of another organism with shared DNA (i.e. a child, grandchild, sibling, etc.), the related organism won't be directly reproducing, but it will absolutely be affecting the genetic material being passed down.