UnSpace

http://www.unspace.net/2018/05/05/the-big-problem-with-searching-for-new-trees/

http://www.unspace.net/?p=317

We only know of one Tree of Life: Earth. That’s a single data point. Thermodynamics, chemistry, biology, and astronomy help us to put some limits on what to look for and what might be possible. But beyond that, astrobiology a lot of guesswork.

We don’t even know exactly how life began on Earth. Did life begin in warm tidal pools that underwent periodic drying? Or did life start at the bottom of the oceans around “grey smokers” where dissolved chemicals passed over porous rock? Or is it some combination? We don’t know. And there’s the possibility life didn’t begin on Earth….

In these posts, I’ll try to point out the gaps in our knowledge, and where we’re guessing.  I’ll mention in passing some of the oddball possibilities, but the further we get from the data point we know, the less we can reliably say.

You’ll notice all the lines in the graph above are straight lines. I got tired of working in Photoshop, and so I left out parabolas, hyperbolas, sine waves, and some bizarre graphs. I’d like to think the drawing gets across the main point:

Scientists are doing the best they can with very limited data. If anything, it’s amazing what they have accomplished with so little information.

http://www.unspace.net/2018/05/04/searching-for-new-trees/

http://www.unspace.net/?p=314

Are microbes slumbering in the buried ice of Mars? Does primitive life cluster around the hidden volcanoes under the oceans of Enceladus? Do primitive creatures slowly grow on the ice-sandy shores of methane lakes of Titan? Do bacteria float in the clouds of Venus? These are places where Earth scientists suggest new trees of life might live.

All earth life is related. From archaea (bacteria-like cells) to trees to animals to we ourselves, we are all related. Approximately 4.1 billion years ago, there lived a cell from which all life descends. That cell has been named LUCA–the Last Universal Common Ancestor. All of LUCA’s descendants form a “Tree of Life,” branching out in a myriad different forms.

Now, if you know your history…your really ancient history, the number 4.1 billion is puzzling. 4.1 billion years ago, Earth was still being bombarded by comets. Thanks to Jupiter and Saturn “dancing through the solar system (long story), the Earth was pelted by comets in something called the Late Heavy Bombardment. If you look at the moon, many of the craters not in the seas of lava are from that bombardment. 4.1 billion years ago, the surface of the Earth had barely cooled from the Earth’s formation and that impact that produced the Moon–and probably drove most of the water from the Earth. The comets were bringing new water to Earth. The Late Heavy Bombardment was slowing down but had yet to end. And THIS is when life started? Less than 500 million years since the Earth formed?

That’s fast. Maybe not on your weekly calendar fast, or Sidney Crosby fast. But for biology and geology and astrophysics, that’s shockingly fast. It’s almost like making life is easy. 500 million years doesn’t sound easy, but once again, we’re using different time scales than you use every day.

The formation of life appears even easier when you consider that life probably formed and went extinct multiple times thanks to one of those cosmic rocks and a bad location.

Life might be everywhere.

And so we look for life in our solar system. Maybe if life is easy, we’re not the only life.

Maybe there are other trees. Maybe those trees might be in our own cosmic backyard.

But if scientists find something, before they declare “We have found a new tree of life!”, there are a couple questions that must be answered:

• Is it alive?
• Is it really a different tree?

I think the questions–and the ways they will look for answers–are fascinating.