I probably spend too much time thinking about the Pre-Cambrian. I know, it’s harmless at some level, and we all do it, usually furtively, but at some point I need to let go of the fact that for roughly 3 billion years the Earth was habitable but boring. Like, really Dullsville from pole to pole. If you had lived in the pre-Cambrian you would have been thrilled to see something as scintillating as a trilobite, or a sponge, or a clam. Life had not invented the new maneuver called multi-cellularity. It was a world of bacteria, of blue-green algae, with a vast ocean devoid of a single fish — nary a minnow.
This is worth remembering when we talk of exoplanets that are roughly Earth-sized and in the “habitable zone.” The fact that I may exist on a Saturday night does not necessarily imply that I can tell you about “the nightlife.” Even after the Cambrian explosion, the continents of Earth spent many millions of years devoid of plants or animals. That required a whole new set of evolutionary adaptations, and didn’t really kick in until the Devonian, which began 419 million years ago. So keep that in mind: Earth is 4.6 billion years old but for the first 4.2 billion you didn’t have a single lizard.
Although we focus on individual organisms and species when we talk about evolution, the process is more ecological than that. You have to have something to eat. You need a system. A guy alone in a gymnasium with a ball isn’t enough for a basketball game. So it is that, when I see the jelly doughnut on Mars, I find myself unable to agree with those on the Internet who suggest that it is some kind of fungus. In case you missed it, this rock wasn’t there back in December, but then it suddenly turned up in January. Scientists think it may have been kicked there by the turning wheel of the Opportunity rover — or maybe it fell there off a hill.
If that thing is alive, it must be really lonely. Where’s the ecosystem?
Also I want to see it do something. Like grow. If that thing grows before our eyes and then emits spores, or something crawls out of it and wanders up to Opportunity’s camera and licks it, I’ll START to entertain the idea that this isn’t a rock.
Life on Mars is Lucy pulling back the football, as has been noted in this space previously. Among the things seen on Mars that didn’t actually exist, or weren’t what they initially appeared to be to some folks with active imaginations: Canals, seasonal changes in vegetation, methane plumes, lichen, the letter “B” written on a rock, a giant stone face, and an ancient city.
And one jelly doughnut.