That's actually a wonderful analogy for evolution. If you think (as I've been guilty of myself) that it's a simple progression from Anglo-Saxon to Chaucerian English to Shakespearean English to fully Modern English, the striking thing is how sweeping the early changes are. Beowulf to Chaucer seems like a huge jump, from a practically Old German language to something we can almost but not quite read without footnotes. If it were a linear progression, it would seem to have started with an amazing saltation.
It's more complicated than that because Pre-Chaucerian Britain was incredibly balkanized compared to the later editions more familiar to us. Never mind the large unassimilated Celtic populations and the Dane/Viking settlements. Even the Anglo-Saxon areas (Essex, Wessex, Suffolk... I forget) had peculiar dialects coexisting and evolving in separate directions. Much of the changes were "hidden," you might say "unfossilized," by not being written down while more conservative versions were being recorded as literary forms.
It's a tree, not a straight line progression, and the record is fragmentary. Still, you can piece together what happened if you've a mind to see it.
The radiation of languages that grew from the original Latin is also a good analogy to evolution. You can trace the roots of words back to their origins, somewhat like DNA. There's a field of linguistic archeology (or whatever it's called) that carries this back quite a ways, to Sanskrit and maybe earlier. I think it's been largely superseded by DNA tracing, but I believe the field still exists.