ABSTRACT
In Chapters 2, 15, 16, and 24, the ties between Bacteria, Archaea, and Eukarya have been made and are clear from the trees of life determined by ribosomal RNA genes, as well as other conserved genes. Even from earlier times, trees and taxonomic schemes recognized that all life on the Earth was related. This means that as we move backward on the tree of life, we find that humans have a common ancestor with chimpanzees. If we move further back, we share a common ancestor with dogs, and further back, we have a common ancestor with tomatoes. Eventually, we find that we have a common ancestor with Escherichia coli and Salmonella. And, of course, ultimately, we all have the original cell as our ultimate ancestor. It survived and produced progeny that produced all life on the Earth. We also find that eukaryotes are essentially endosymbiotic and mutualisitc cooperating consortia of bacteria, archaea, and sometimes other eukarya. The combination of microscopy, sequencing, and bioinformatics has led to these conclusions. However, in the past several decades, genomic studies have moved the investigations of evolution to another, and often deeper, level.
