I’ve spent most of the last week amazed by the story of Harriet, the giant Galápagos land tortoise whose 175th birthday was celebrated this week. She’s an animal who is said to have been brought back from Ecuador by Charles Darwin himself in 1835; she was born the same year as Emily Dickinson, the year that Greece gained independence, and, incidentally, the year that her native country of Ecuador separated from the Republic of Colombia. Biologists claim that Harriet is the oldest known living animal on the planet; thinking about how long Harriet has lived leaves me in awe, both as a scientist and as a fellow inhabitant of Earth.

Talking about Harriet also led Shannon to tell me about Lonesome George (or, in his native tongue, Jorge Solitario), another tortoise whose name tells a sad story. All giant Galápagos land tortoises are thought to belong to a single species, Geochelone elephantopus, but there are either fourteen or fifteen recognized “races,” or subspecies, of G. elephantopus. (In all actuality, the question if whether they’re subspecies or bona fide species is just that, a question.) Of that number, only eleven remain, and Jorge Solitario is the very last known member of his subspecies, G. elephantopus abingdoni. Despite efforts to either find a female member of the subspecies or mate him with a female from another, closely-related subspecies, George has resisted efforts to carry forward his genetic lineage, so with him might die his entire subspecies of giant tortoise. He’s currently estimated to be around 75 years old (making him middle-aged!), and lives at the Charles Darwin Research Station in the Galápagos Islands. (Shannon’s actually visited him there!) It’s incredible to me that we know we’re likely to be (slowly) watching the end of a genetic line, and can’t really do anything about it.