Even on such a life-conducive planet as ours, the struggle for life is so fierce
and risky that the vast majority of species that have ever existed (over
99 per cent of them) are now extinct. A species close to us, the Neanderthals,
has long gone, leaving only bones and artefacts as testament to its lives and
struggles. Environments present animals with many different specific types of
threat, some of which a species cannot do anything about, especially if they
are infrequent and major (e.g. meteorites). It is when threats are constant or
build up slowly, and give species opportunities to evolve specific ways of
coping, that we see adaptation