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Suffering is a byproduct of evolution by natural selection, an inevitable consequence that may worry us in our more sympathetic moments but cannot be expected to worry a tiger - even if a tiger can be said to worry about anything at all - and certainly cannot be expected to worry its genes.

Richard Dawkins (2009). “The Greatest Show on Earth: The Evidence for Evolution”, p.392, Simon and Schuster
Suffering is a byproduct of evolution by natural selection, an inevitable consequence that may worry us in our more sympathetic moments but cannot be expected to worry a tiger - even if a tiger can be said to worry