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I dispute that natural selection is a tautology. If it was, they shouldn't have been able to make these predictions:

Can Human Aging be Postponed? Michael R. Rose, Scientific American, Dec 1999
Aging does not occur because of some universal defect in all cell types. If some singular, unavoidable flaw caused every cell to fail eventually, no animal would escape aging. But some do. For example, asexual sea anemones kept for decades in aquariums do not show failing health. Nor does aging derive from a genetic program designed by nature to block overpopulation. Instead senescence is the by-product of a pattern of natural selection that afflicts humans and other vertebrates but not vegetative sea anemones. More specifically, aging arises in sexually reproducing species because the force of natural selection declines after the start of adulthood.
This concept follows logically from general evolutionary theory. Heritable traits persist and become prevalent in a population - they are selected, in evolutionary terms - if those properties help their bearers to survive into reproductive age and produce offspring. The most useful traits result in the most offspring and hence in the greatest perpetuation of the genes controlling those properties. Meanwhile traits that diminish survival in youth become uncommon - are selected against - because their possessors often die before reproducing.
In contrast to deleterious genes that act early, those that sap vitality in later years would be expected to accumulate readily in a population, because parents with those genes will pass them to the next generation before their bad effects interfere with reproduction. (The later the genes lead to disability, the more they will spread, because the possessors will be able to reproduce longer.) Aging, then, creeps into populations because natural selection, the watchdog that so strongly protects traits ensuring hardiness during youth, itself becomes increasingly feeble with adult age.
[For example, progeria, which strikes children with premature aging, are very rare, compared to Huntington's Disease, which strikes during middle age.]
In the 1940s and 1950s, J. B. S. Haldane and Nobelist Peter B. Medawar, both at University College London, were the first to introduce this evolutionary explanation of aging. W. D. Hamilton of Imperial College and Brian Charlesworth of the University of Sussex then made the thesis mathematically rigorous in the 1960s and 1970s.
In their most important result, Hamilton and Charlesworth established that for organisms that do not reproduce by splitting in two, the force of natural selection on survival falls with adult age and then disappears entirely late in life. Because natural selection is the source of all adaptation, and thus of health, the hardiness of older organisms declines as natural selection fades out. Eventually, with the continued absence of natural selection at later ages, survival may be so imperiled that optimal conditions and medical care may be unable to keep the older individual alive.
Since the 1970s the original mathematical proofs have been confirmed experimentally many times, most often by manipulations that deliberately prolong the period of intense natural selection in laboratory animals. Investigators extend this period by delaying the age at which reproduction begins; they discard all fertilized eggs produced by young animals and use only those produced late in life. As a result, only individuals who are robust enough to reproduce at an advanced age will pass their genes to the next generation.
If the declining strength of natural selection after the start of reproduction really does explain the evolution of aging, then progressively retarding this drop for a number of generations in a test population should lead to the evolution of significantly postponed aging in that lineage. This prediction has been shown to be true in fruit flies of the genus Drosophila that have had reproduction delayed across 10 or more generations. As a result of these experiments, scientists now have stocks that live two to three times longer than normal and are healthy longer as well.
The flies that display postponed aging are surprisingly perky. They do not merely sustain normal biological functions for longer periods; they display superior capabilities at all adult ages. In youth and later, they are better able to resist such normally lethal stresses as acute dessication and starvation. They also show more athletic prowess than their like-aged counterparts do, being able to walk and fly for longer periods.

But this is another evolutionary "just-so story": if an ecological niche were occupied by 'immortal unless slain' creatures, evolutionary biologists would devise another story to show how the survival strategy of perserving individual organisms and replacing them only at a slow rate was vastly superior in the face of the survial pressures faced in that ecological niche to competing survival strategies of more prolific reproduction and short life-spans.

I am, perhaps, being a little too scornful in calling it a "just-so story". I call it this because it is claimed to be a "prediction" of a general theory--which I would argue it is not precisely because evolutionary biologists would behave as I have indicated. In fact, the account given is a proper scientific theory in its own right, which can be tested and falsified (by finding a population of slowly reproducing 'immortal unless slain' organisms), modified to account for the contrary data (provided the new modification is still testable) and so forth.