Unless we include progressives there doesn’t seem to be any close relationship between bacteria (a prokaryote) and humans (a member of the eukaryote group). In fact, even something as humble as a fungus has more in common on the cellular level with humans than it does with bacteria. Assuming that bacteria were here first (which is an assumption that needs to be tested) it isn’t clear how the jump happened from the bare bones simplicity of the prokaryote to the remarkable complexity of even the most simplistic eukaryotic cell. Recent discoveries in the organisms that fall somewhere in between these two groups (archaea) is fueling additional controversy. According to one theory the archaea are the ancestor of the eukaryotes and therefore sort of our multi-great grand uncles. This rubs a lot of biologists the wrong way. There are even feuds based on this disagreement. I don’t have a dog in this fight but I am interested in advancements in the understanding of how life evolved on Earth. An interesting aspect of the story is that certain components of the eukaryotic cell (like the mitochondria and the chloroplasts) started out as independent bacterial cells that were ingested by some ancient organism but somehow survived inside the cell and formed a symbiotic and permanent arrangement. And many modern biologists see similar symbiosis between the bacteria living in our intestines and our human selves. Both species profit from the relationship and in our cases couldn’t survive without the other. What a strange and remarkable world we live in. Interesting read.
The Trickster Microbes that are Shaking Up the Tree of Life by Traci Watson