Bristlecones are, after all, our eukaryotic cousins. About half of their genes are close relatives of ours. Yet they do not age. Oh, they add years to their lives—thousands upon thousands of them, marked by the nearly microscopic rings hidden in their dense heartwood, which also record in their size, shape, and chemical composition climate events long past, as when the eruption of Krakatoa sent a cloud of ash around the globe in 1883, leaving a fuzzy ring of growth in 1884 and 1885, barely a centimeter from the outer ring of bark that marks our current time.
