Richard Dawkins once claimed in "The Richard Dimbleby Lecture: Science, Delusion and the Appetite for Wonder (1996):
For the first half of geological time our ancestors were bacteria. Most creatures still are bacteria, and each one of our trillions of cells is a colony of bacteria.
Hm, "each one of our trillions of cells is a colony of bacteria"? Sorry, I couldn't leave this glaringly inept bit unchallenged. I'll try to keep it short and only say a couple of things for now:
- What does Dawkins mean by "each one"?
a. For starters, "each one" of our cells is a single cell, not a "colony" of cells (let alone bacterial cells). But maybe Dawkins simply expressed himself poorly here.
b. Or does Dawkins mean all the constituent parts of a cell within a single cell are themselves "a colony of bacteria"? If so, then that's just dumb. Are the constituent parts of a bacterial cell likewise "a colony of bacteria" within a single bacterial cell such that we have an infinite regress of "colonies of bacteria"? It's turtles (or bacteria) all the way down!
- By the phrase "each one of our trillions of cells," I presume Dawkins is referring to a group of the same type of cells within the human body. Say brain cells like neurons. But how are neurons equivalent to "a colony of bacteria"?
a. Does Dawkins mean neurons are literally "a colony of bacteria" residing in our brains? If so, there are several problems. For one, it fails to distinguish between self and non-self. If neurons are indeed "a colony of bacteria" in humans, then wouldn't we expect our immune system to recognize them as such and deal with them accordingly? (Or are they like gut flora, which if so would raise other issues which would appear to contradict established medical science?)
b. Does Dawkins mean evolutionarily speaking neurons originated from "a colony of bacteria"? If so, that's a pretty big ask. And of course there are many arguments against neo-Darwinian theory as a whole (such as from the ID community).
As an aside, if we are "a colony of bacteria," does that make the Earth a Petri dish (or at least the appearance of a Petri dish)? :-)