I’m currently reading a book called A Zoologists Guide to the Galaxy by Arik Kershenbaum. In it, the author uses logic and critical thinking to establish universal laws of biology. They then apply those laws to creatures on Earth and extrapolate into what life might be elsewhere.
It is a fascinating book and a wholly new perspective that I recommend to everyone. In it, Kershenbaum brings up a period of time in Earth’s history that I hadn’t heard of and it captivated me. And as this blog is about my thoughts, hopefully it will captivate you.
The Ediacaran Period directly preceded the far more commonly known about Cambrian Explosion; the huge eruption of life on Earth that is well marked by fossils all over the world. Unlike that sudden display of life, the Ediacaran Period seems to have been slow moving, involving lifeforms that came and went without such flash and fury.
The majority of the lifeforms that evolved during the Ediacaran Period are believed to have been sessile. This means that they didn’t move and yes, I did have to google the word when I read it for the first time. This fact in itself is mind-blowing.
Can you imagine a planet filled with creatures that were seemingly not pressured by their environment to move? They swayed, stayed in spot, and photosynthesised or filter fed for their whole lives. What kind of a world would give rise to this type of biology? One where movement wasn’t needed and predation was thought to not occur (there is a caveat to that, there is one fossil, that of the Kimberella, could have possibly fed in a limited way on some lifeforms during the Ediacaran Period however this is still contested).
Close your eyes for a moment and imagine a world of swaying, not quite plant-like organisms; no hunting, no foraging, just lifeforms existing in the space they grew in with the energy available to them.
Is that not truly an alien thought?
But obviously, this peaceful utopia was not to last. Something in the environment of the Ediacaran Period changed and caused it to end and the Cambrian Explosion to begin. This was around the times continents were breaking apart, sea levels were risings and temperatures were changing. Just one of those things, given enough time, could have lead to the balance being shifted away from the relaxed Ediacaran and into the hectic, omnivorous Cambrian.
What can this tell us about life on other planets?
Mostly, the lesson as it appears to me is that life could form in anyway. Depending on the environment of the planet, life there could exists for millions of years as drifting, plant-like structures that feed off the sun or off the organisms floating past them in the ocean. If there was no evolutionary kick like Earth received, then who is to say that anything would changed given an environment in equilibrium?
But perhaps life, no matter where it forms, is determined to be active, to be in motion, and regardless of the changes in the planetary environment, life will evolve into, for want of a better term, a more dog eat dog world.
The Ediacaran Period last for roughly 100 million years before given way to the Cambrian Explosion and most of that time is lost.
We may never know the true nature of the organisms that existed all those years ago, however, they can still teach us about life, on our own planet, and others.
Astrobiology may seem like guesswork to most people. But it is a vastly interesting field that delves just as deep into evolutionary biology as it does into the atmospheres of exoplanets.
How will we recognise life when we find it? We assume life must be water based, as that is the only life we know but is that the case? Should we not prepare ourselves as best we can to recognise life wherever it turns up and in whatever form?
That is what astrobiology can do for us; it will prepare us for the greatest discovery in the history of humankind.
Life on other planets.
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