Darwin had two theories that he thought worked in concert. The first was a theory that postulated through mutations that new genetic information was being added to life forms continuously. The second thesis was that because these differences would also differ in survivability, those that were unsuited would become extinct. To him this represented a continuing "upward" evolution of life.
The second theory seems supported by evidence that we are losing genetic information as species become extinct.
However in the 150 years since Darwin first presented his ideas, no one has observed a favorable mutation in a plant or animal. Mutations do occur such as with cancer and tumors. However, for a favorable mutation one would need millions of coincidental changes to all take place at the same time and in a reproductive cell so that those changes could be passed on.
The second theory seems supported by evidence that we are losing genetic information as species become extinct.
However in the 150 years since Darwin first presented his ideas, no one has observed a favorable mutation in a plant or animal. Mutations do occur such as with cancer and tumors. However, for a favorable mutation one would need millions of coincidental changes to all take place at the same time and in a reproductive cell so that those changes could be passed on.