I'm one of those dreadful animal-centric zoologically inclined biologists. Plants? What are those? Fungi? They're related to metazoans somehow. Lichens? Not even on the radar. The first step in fixing a problem, though, is recognizing that you have one. So I confess to you, O Readers, that my name is PZ, and I am a metazoaphile. But I can get better.
My path to opening up to wider horizons is to focus on what I find most interesting about animals, and that is that they are networks of cells driven by networks of genes that generate patterned responses of expression by cell signaling, or communication. See? I'm already a little weird. Show me a baby bunny, and I don't just see a cute little furry pal with an adorable twitchy nose, I see an organized and coherent array of differentiated tissues that arose by a temporal sequence of cell-cell interactions, and I just wanna open him up and play with his widdle epithelial sheets and dismantle his pwetty ducts and struts and fibers and fluids, oochy coo. And ultimately, I want to take apart each cell and ask why it has its particular assortment of genes switched off and on, and how its state affects its neighbors and the whole of the organism.
Which means, lately, that I've acquired a growing interest in bacteria. If I were 30 years younger, I could probably be seduced into a career in microbiology.
There are a couple of reasons why an animal-centric biologist would be interested in bacteria. One is the principle of it; the mechanisms that animal cells use to build complex arrangements of tissues were all first pioneered in single-celled organisms. We have elaborated and added details to gene- and cell-level phenomena, but it's a collection of significant quantitative differences, with nothing known that is essentially new in metazoan cells. All the cool stuff was worked out by evolution in the 3-4billion years before the Cambrian, a potential that simply blossomed in the past half-billion years into big conglomerations of cells. Understanding how the building blocks of multicellularity work individually ought to be a prerequisite to understanding how the assemblages work.
But there's another reason, too, a difference in perspective. It is our conceit to regard ourselves as individuals of Homo sapiens, a body of cells clonally derived from a single human cell. It's not true. It turns out that each one of us is actually a whole population of species, linked by our evolutionary history and lumbering through the world as a team. Genus Homo is also genera Escherichi and Bacteroidetes and Firmicutes and many others.