As far as I know there aren't any meaningful controlled long term studies on caloric restriction with optimal nutrition in humans. This isn't simply eating a lower amount of calories. It's attempting to replicate what's been seen with a few other non-primates put on carefully controlled diets to maximize nutritional intake while at the same time decreasing calorie intake to a bare minimum. That's simply not going to happen long term in healthy subjects during the course of any other study. Even if one was willing to take self-reported dietary information seriously in the context of meta-analysis.  Plus the results are far from common knowledge and what's been shown in this study is quite different than if you'd just extrapolated the data from the rodent studies onto primates. Even more importantly, it's clearing up contradictory results from previous primate studies.  Much of the point is that there's a fundamental lack of understanding about the precise mechanism of action. It's questionable whether longer than expected lifespan might be due to an unknown factor already being active and as a result making caloric restriction ineffective or less effective in primates when compared to shorter lived species.