Levi Strauss said that people have a tendency to believe that newer thoughts are always better and more correct than older ones.
And this is totally but totally wrong.
In the old days we thought that species were constant and unchangeable. Now we (think we) “know” they are not. Take for example bacteria or viruses, which change in a fast pace  in order to respond to our bacteria-fighting medicine. Right? Wrong! Because even if bacteria change, they STILL REMAIN that specific bacteria! As tapeworms have remain unchanged for almost 250 million years now , maintaining a recipe which has proved successful, many other species also remain unchanged (see crocodiles or tortoises for example).
Yes. Species do change!
But besides the mechanism of change, there is also a mechanism which tries to maintain species the same! Discovering the first, does not have to make us believe that the latter is obsolete or no longer valid…