The figure below is from my PhD defense. The y-axis on the graph is pubmed citations. Most search terms on pubmed probably follow a similar trajectory, but I think the graph is still indicative of growth in the field of aging research. The categories described are painted with very broad strokes, and are intended to help people understand the history of the field. Apologies for any inaccuracies or omissions.

Steve Austad told me that (paraphrasing) “for 50 years after DR extended rat lifespan, the field was trying to figure out how that worked.” The yellow phase, “Genetic Breakthroughs,” is when the field figured that out. Genetic screens in model organisms like yeast, worms, flies, and mice showed that DR worked through a handful of major genetically-encoded signaling pathways.

Always worth remembering that we only figured out what DNA was around 1955. We’ve come really far, but we’re still in the early stages of tremendous knowledge. Aging/longevity isn’t necessarily a difficult problem- nature just never had a reason to solve it in humans.