Gary’s Q&A

Listener question & Gary’s response · Transcript passage

Richard Short asks Loved your episode on mammals of Australia, and all three evolutionary branches of mammals are extant there. A semi-related question. Mammals evolved from reptiles, which evolved from amphibians, which evolved from fish, etc. What will evolve after mammals? What will a new class of animalia look like?

It is impossible to know this. Evolution takes place when creatures adapt to their environment. Adaptions that are successful get passed on, and those that are not successful die out. Mammals weren’t guaranteed to evolve from reptiles. Mammals arose because of the unique set of conditions that existed.

Without knowing what conditions might exist in the future, there is no way to know what sort of adaptations might arise.

Evolution isn’t on a set linear path. Many people think that humans are the natural end result of evolution, and that is not the case. There were countless, improbable things that resulted in the world we see today.

Mammals are pretty adaptable, so it is possible that there isn’t anything new and strange, but rather we just get better adapted and different mammals.

I should also note that mammals didn’t replace reptiles. Many reptile species died off, but reptiles as a whole are still with us.