What does "immutability of species" mean, and who showed that this notion is wrong?
Scientists thought that every type of creature that exists today has existed throughout history. Consider dogs, for example. Scientists of this time period and before thought that Saint Bernards, dachshunds, and chihuahuas always existed. Each of these breeds of dog lived throughout history, essentially unchanged. This idea was called the immutability of the species. Charles Darwin showed it was wrong.