For me, building a bit on this post.
NYT Magazine thanks to Judith Curry: Carl Woese deserves credit for three discoveries:
1. archaea are a form of life distinct from bacteria and eukaryotes (eukaryotes include us).
2. genes can be transferred "horizontally"--between living organisms--as well as vertically--through sexual or other reproduction. This might be more rare in complex organisms than in simple ones, but it does happen.
3. "Primitive" organisms provide more information on evolution over billions of years--before the parts that interested Darwin--than do organisms that are more apparent to us.
4. Three notions now need to be questioned: an individual that does not change "biologically" or genetically in its lifetime; a species, distinct from other species, ditto; and a tree of life in which branches, once distinct, do not fuse together in whole or in part.