"... What I found at Chernobyl instead was an astonishing new ecosystem that defied my gloomy imaginings. * * * It is Chernobyl's most profound paradox. The worst nuclear disaster in history wreaked havoc with people's lives and rendered a vast territory uninhabitable. But in the absence of humans, Chernobyl's wildlife is not just doing fine. It is flourishing, beautiful—and radioactive." (From Mary Mycio, Chernobyl Paradox, in Natural History, Apr. 2006, p. 80.)
If you ask me, this is a data point supporting an optimistic view of life in the long term.