[donh]

stellar evolution, biological evolution, and language evolution are all based on synchronic observaton.

Um, aren't all the signals we receive from distant stars millions to billions of years old, just like fossils?

[Doctor Stochastic]

Yes, but what we see are lots of stars at different ages rather than a single star observed over a long period of time.

It's like examining a bunch of people and inferring that one proceeds from being a baby to an oldster. It's not too hard.