Natural selection is posited as the only mechanism to lead to differential survival among individuals of varying fitness. However, if selection pressures cause mortality to occur in individuals who would soon be dead anyway, then natural selection is not really operating.
The hypothesis of the Harvesting Effect in epidemiology leads to this conclusion. I think this has so far only been explored in respiratory epidemiology, but hats off to them for bringing it up.
If the Harvesting Effect is real, then Darwinists must differentiate its effects from that of natural selection. So far this issue has not been addressed. Harvesting or the Harvesting Effect is a hypothesis in epidemiology. It occurs when an agent causes death in an individual who would die or enter a hospital in any case within a few days of exposure to the agent. The idea is that the agent – the assigned determining factor in death – is irrelevant. Had the patient been generally healthier they would not have succumbed to the agent. Again, had they not been exposed to the agent they would have been dead anyway within a short time. Therefore, assigning the agent as the cause of death is not truly correct.
This means that the agents of natural selection have to be distinguished from the harvesting effect. This has never been addressed in evolutionary biology. If a death cannot be attributed to a selection pressure, it is presumably a “wasted death” in terms of Darwinism. And natural selection must concern itself with accounting for deaths (as well as reduction in fertility and fecundity, etc.). If a death is attributed to harvesting rather than the selective pressure of the determining factor of death, then it leaves natural selection having to work its magic on other individuals who have not died in this way.
Here are two articles on harvesting: