You see, what all of those cambrian fossilized pier posts made of cyanobacteria were doing, for OVER A BILLION YEARS STRAIGHT, was turning the atmosphere's 20% CO2 into 20% Oxygen, give or take.
That had the effect of cooling things off, and at the same time, the sun grew warmer! Amazing coinkidink! And! Andand and... even after the days of cyanobacteria were over, there were still plenty of cyanobacteria floating around, making mudflats full of them instead of fossilized pier posts.
So we were arguing about that.
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YEARS LATER... in 1997 scientists decided that I was right to question cyanobacteria as plants being ancestors of plants! It had gone through all the stages of hypothesis to theory to well questioned and analyzed possible fact, and in 1997 they decided it was fact.
It works like this: ENDOSYMBIOSIS
Amazing stuff they did not teach us older folk back in the day because they did not yet know...
One kind of cyanobacteria also evolved to dig into other bacteria for extra food, probably after nitrogenous and phosphate minerals. Apparently, one of those times it learned not to kill its prey, but instead, MOVED IN! You can bet that at first it was parasitic. But, if you are nice to your host your host may be nice to you. So, apparently one time the cyanobacteria and its host decided to make a good team!
AND NOW IT GETS COMPLICATED!
See, the question comes up, WHY AND HOW COULD THIS HAPPEN? We got the WHEN kind of down to around 1.75 billion years ago, last I heard. That's ALSO when the first CELL NUCLEUS appears. Ohhhhhhhhhhh boy, that was a huge invention! The complicating thing is, NOW AND WHY did the cell nucleus get invented by evolution??? A cell nucleus takes SO MUCH FOOD AND ENERGY TO FEED! There HAS to be a VERY GOOD REASON for a cell to keep one of those things, and only one by the way.
Wellp, right now, 2013, there is still a HYPOTHESIS, that another ENDOSYMBIOTIC EVENT HAPPENED FIRST before the cyanobacteria moved in, or else was it one time that it was SIMULTANEOUS MULTIPLE ENDOSYMBIOSIS?
What is a nucleus? It's where the CHROMOSOMES live. Where did chromosomes suddenly come from????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????
See? That's the new question that's still in the hypothesis stage of getting answered.
And, to figure where plants and animals came from, that question needs to be addressed and answered. It has not yet been answered for sure. Not quite. Almost.
Plant and animal chromosomes are a lot alike. Sure enough the dna in them is different, but there are even basic similarities. Same kind of dna, organized the same way. Most of them even divide up and replicate the same ways.
So, looks like SOMETHING ELSE MOVED IN TO A LARGE BACTERIA CELL FIRST, PROBABLY ACTUALLY SIMULTANEOUS...AN AMAZING EARTH HISTORY MOMENT!
That's the hypothesis. What was it that also moved in and made the chromosomes?
A SPIROCHETE. Spirochetes are basically dna with a cell membrane, and are actually shaped like chromosomes. Tey have almost no liquid cytoplasma in them. Very little. Syphillus happens to be one species of spirochete bacteria. They also evolve rapidly.