At the time point reported 50% of control fed animals survived compared with 80% survival of CR animals

That line from the abstract is an outright lie. Check out the graphs. The actual survival rate was something like 50% vs 60%. CR won, but it was not statistically significant. What this really showed was a trade-off between "age-related mortality" and frailty, although the latter is usually considered "age-related" in humans.