Precambrian on the brain

Spent a few hours living in the past during visit to Museum of the Earth (Ithaca, NY).

Did a sketch on the progression of the Precambrian period which is rarely represented to any extent in museums.

Which is weird because that is when life first appeared. Sure, it didn't have the fantastic creatures that started appearing in the Cambrian Radiation (I don't use the more common 'Explosion' because it insinuates all life magically happened in an instant). But to me it is more intriguing. Partly because we know less about it.

Yet, we do know that what we consider life first began before oxygen filled our atmosphere. Life then was anaerobic: without oxygen. And appeared only in water, not surprising since the planet was mostly covered with water back then. Water is H2O (hydrogen dioxide), but the two hydrogen atoms are tightly held on to the oxygen. So there was little oxygen in our atmosphere (which was then water vapor, methane, and ammonia).

Bacteria, and their appearance, is what we call the first 'life'. The cog in the wheel is that it depends on how we define 'life', but that's another long topic (which is embroiled in debate within the scientific community). Finding fossils of bacteria have been difficult: partly because they are so small, and partly that most of the rocks from that time period are also rare.

Our planet formed 4.6 billion years ago; a ball of gas, water vapor and hot molten minerals. The planet cooled enough for water to appear ~4.4 bya and cover the planet. A mineral crust began forming ~4.04 bya (called the Hadean eon) and the earliest fossils found are dated 3.5 bya.

Between that time (4.2-3.5 bya) the fist single cells formed. The Last Universal Common Ancestral (LUCA) cell population from which all subsequent life forms descended is estimated to be 3.5 bya. This is estimated from genome compilation (which implies that genes had to be present!).

But! before then was a first universal common ancestor (FUCA). A non-cellular entity is proposed that was the earliest organism with a genetic code capable of performing biological translation of RNA molecules to protein formation through peptides synthesis. In other words, it had to contain enough information to copy itself and evolve. Well, how did that come about?

And that is where my keen fascination is ignited. Hence, my interest in the Precambrian period. But all this is also absent from the museums. However, a few hypotheses are tossed around and debated on the process of how life originated. Yet, if we restrict it to the conventional definition (really a perspective) of life, it excludes possible candidates that were integral in that process.

I'm following two scientists active in this search: biochemist Nick Lane and astrophysicist Sara Imari Walker. They think outside the box. But more on that later.