great oxygen event

Life seems to have existed on Earth for over 4 billion years, but for much of that time it was primarily microscopic. And although multicellularity is known to have independently evolved multiple times, large complex forms didn’t really get started until around 600 million years ago, with the strange Ediacarans being some of the most famous early examples.

But that may not have been the first time such an evolutionary experiment happened.

A collection of fossils discovered near the city of Franceville in Gabon appear to represent an even earlier example of large multicellular life. Known as the “Francevillian biota” or “Gabonionta”, these fossils are over three times older then the Ediacarans, dating to a staggering 2.1 billion years ago during the Paleoproterozoic Era.

Over 400 specimens have been collected, representing a variety of different forms — including discs with ruffled edges, rods, rounded clusters of blobs, and elongated shapes that are sometimes attached to long “strings of beads” — with the largest reaching lengths of about 17cm (6.5”). Their age places them somewhere around the origin point of the earliest eukaryotes, and they may represent a completely unique kingdom of life unlike anything alive today.

These organisms’ appearance in the fossil record came shortly after the Great Oxygenation Event, suggesting the evolutionary development of large complex bodies is directly linked to the amount of available oxygen for aerobic respiration. Later, atmospheric oxygen dropped again, and the Francevillian biota disappeared into extinction, leaving us with only these mysterious fossils hinting at a surprisingly diverse and alien-looking period in life’s deep past.

anonymous asked:

Whats the great oxygenation event??

Oh boy! So, this all takes place around 2.3 billion years ago. Up until then, life had been pretty much chilling for a billion or so years. Pretty much everything was a single-celled organism back then. Also, the planet was a whole lot different. There was no ozone layer, so UV radiation was constantly reaching the surface. That kills stuff, by the way, in high concentrations. Methane gas was also being spewed into the air by various volcanic eruptions. So, not a very nice place. Most importantly, oxygen wasn’t much of a thing. The little there was existed in the ocean and bonded with the iron molecules that were floating around to make rust.

(Home sweet home.)

The organisms that were alive got along just fine without oxygen, for the time being. These are called anaerobic organisms, and some of them still exist today. A lot are in your stomach right now. Anyways, along comes this little thing called a cyanobacteria. It’s unclear how they evolved, but the point is, they can do this neat trick we like to call photosynthesis. As you probably know, a byproduct of photosynthesis is oxygen.

Cyanobacteria were incredibly successful - they could make up to 16 times as much energy as anything else. So, they started multiplying. Pretty soon, there was a bunch of extra oxygen floating around, and not enough iron to bond with it. Then things started dying. See, to a lot of anaerobic organisms, oxygen is incredibly deadly. And now there were billions of cyanobacteria constantly spewing it out. 

(The killers themselves. Look at them. Not an ounce of remorse.)

Long story short, almost everything besides cyanobacteria died. The survivors either adapted to be able to live with oxygen, or went and lived in places without it, like underground or in sulfur vents (those guys are still around today!). The cyanobacteria were literally so successful that they changed the chemical makeup of the atmosphere. This also led to a decrease in greenhouse gases and started the longest ice age the world has ever seen. Go cyanobacteria!

Sources: (x) (x)

Climate Change is Isfet

It goes like this.

Life cannot exist in perfect, sterile, unchanging balance. The only time the universe will be in complete balance is during its heat death, when all reactions have reached equilibrium and there is no longer any free energy. Chaos and entropy are terrifying conceptually, but necessary.

I refuse to believe that a perfect world is a stable world. A stable world is a dead world. A world without change is a stagnant, decaying, wretched world. Maybe in an afterlife, this is different, but in our current, living one? Hard pass.

There is, however, a limit to the amount of change and chaos that life can cope with before it gets overwhelmed. We typically refer to an excess of chaos as acatastrophe or acataclysm. When natural disasters strike and cause a massive loss of life, when species are hunted to extinction or ethnic groups are slaughtered en masse, when oil spills ruin a patch of water and sand for years to come, when plagues sweep across the land these things can overwhelm life, beat it down, and perhaps even destroy it.

And we see this in Egyptian mythology as well. The land of the gods is said to be the land of pure maat, perfect balance and justice and order. The land of mankind contains both isfet and maat, and a balance must be struck between the two. An excess of isfet, chaos, will lead to the fall of our world and ourselves.

So where does climate change come into this?

Keep reading

Of course there’s no aliens on Earth

I mean sure, theoretically, aliens could have noticed any time from the Great Oxygenation Event 2.3 billion years ago onwards that life was probably happening here, which might be reason enough to investigate, and sure, in principle, if there were aliens who were significantly longer lived than us, visiting more-or-less nearby places around the galaxy might be a very possible thing to do even with, yknow, currently-known-possible-by-earthlings technology; 

And sure, hypothetically, given a few thousands or maybe millions of years head-start in technical development, they would probably find it easy to, like, biosynthesize human or other animal bodies to drive around and explore this weird rock, and sure, it’s possible that some of them might have come here with weird ideas about what are better or worse ways of arranging this world that have nothing to do with the views of its current inhabitants, and i mean sure, in principle, those who wouldn’t have come with those ideas would be really really sorry about what those other people did.

But there’s no aliens on Earth, people! You do not need to suspect anyone of being a nearly immortal alien! Such people cannot be found on Earth and do not need to be searched for!