Natural history

At the Museum of Science today, found myself thinking in astonishment once more:

Multicellular life as we know it has only existed during the Phanerozoic eon, about the last half-billion years.

Which is only one-ninth of the age of the Earth.

Which is expected to remain habitable for at least another 500 million years.

Which means there’s time enough for the whole process–from the trilobites right up to us–to happen again.