For hundreds of millions of years, a molecular switch called AMPK has helped living cells sense energy scarcity and adapt — a mechanism so fundamental it persists from yeast to human. Researchers at Queen Mary University of London have now found that caffeine, the world's most widely consumed psychoactive substance, appears to activate this ancient pathway, offering a cellular explanation for why its consumption has long been associated with healthier aging. The discovery reframes caffeine not merely as a stimulant but as a possible participant in the deep biological conversation between energ