Anything but the line-up

You all know I’m always pondering how progressive thinking sneaks into how we talk about evolution.  And how if we could break some of these habits, we might begin to dismantle the ladder-of-life, which is so deeply engrained. Here is a common thing I see in lots of science communication that I think is one of these (relatively) easy to break habits – lining up some organisms when you talk about how some *trait* evolves. Let’s say you were talking about the evolution of multicellularity and went with a diagram like this:

 Evolution of Multicellularity

Show this and the audience is likely to walk away with any number of ladder-y misconceptions. Or feel that any ladder-y notions they came with are totally fine. Like humans evolved from 'simple' things like bacteria. Like being unicellular is less ‘advanced’. Like humans are the most complex, really impressive, best species so evolution has stopped. We could go on, but what would be some ways to dismantle any of these and still talk about what we wanted talk about? Here’s an easy one – refocus on the character states!

Now this is still feeling pretty progressive, but perhaps the notions that some living taxa are ancestors of other living taxa are disrupted a little? I also suspect that labeling these states might trigger us to wonder about the evolutionary complexities here. How many times have these kinds of transitions happened? Is evolution really so directional or can lineages revert to being unicellular? Are these states fairly thought about as bins or is it more of a continuum? Now this, this is really thinking about evolution. Understanding such character transformations was a primary motivation for developing phylogenetic methods in the first place!

And in fact we have plenty of information to suggest that the stepwise directional path above is not right. We know that there have been evolutionary transitions to and from multicellularity. There are plenty of lineages where we have a heck of a time trying to classify them because the cells sometimes stick together and sometimes go their own ways. So if we are going to be fair, it’s probably more like a spectrum or even something non-linear altogether. What’s for sure is that we will never understand the diversity of life forms, nor how and why this diversity came to be, if we enter with the ladder-of-life mindset at the top.

My broader point here is to say we do our field no favors by playing on misconceptions. I get it, we want to make things simple, draw on ideas that will ‘click’ with audiences. But we are selling evolution so short when we do it.  I am convinced that any talk or paper can be just as compelling, if not more, by stepping away from the linear narrative. I know we can handle breaking the norms and our audiences can too.