Interesting article by Diana Hayward on yesterday’s ABC Science page:
Algae explosion 650 million years ago is why we’re here today, ANU researchers say
The key section:
That climatic catastrophe was a global thawing of what Professor Brocks calls a “Snowball Earth”.
Fifty million years before the algae began to bloom the Earth’s oceans were frozen.
But a global heating event caused the glaciers to melt and as they did they released nutrients into the ocean.
“This increased phosphate fertiliser in the oceans,” Professor Brocks said.
And when the Earth cooled to more hospitable levels it created perfect conditions for algae to spread.
“It appears this huge release of nutrients after the melting of this snowball Earth event triggered the evolution of this larger algae and replaced bacteria.”
“Algae are incredibly large in comparison to bacteria. And you need large and nutritious organisms at the base of the food webs to create the burst of energy towards higher and bigger organisms,” Professor Brocks said.
So it all started with global warming and the subsequent explosion in algae.
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4 thoughts on “The Origin of Large Life Forms”
650 MY ago the process “clicked” and despite many Natural setbacks has continued progressively ’til today.
The “possibility” remains that the process might have ‘clicked’ an Aeon or so earlier but
for the “regular” Natural setbacks.
Oh dear! It could happen again.
Articles like the above usually send me referring back to the Ernst Mayr and Carl Sagan debate on whether we are likely to be the only intelligent life in the universe and I always end up siding once more with biologist Mayr. We surely are the universe’s only (“freak”?) experiment with intelligent life.
I’m a bit of an “in betweener” on the subject. Based on what I’ve read/heard over the years I think that bacterial (or similar) life is fairly common (such as more than one site even in our solar system) and multicellular life is uncommon but does exist (like once per every 100 solar systems or something). Even some level of ‘intelligence’ (whatever that is)..like chimps, dolphins, octopuses and even homo erectus…may develop with multicellularity. The visible universe is huge and planets (or moons) with favorable conditions to produce such things must number in the multi billions. ‘Intelligence’ that can understand higher order math and develop formal scientific processes, though, is probably vanishingly rare. You don’t really need such abilities just for a species to survive. (Neither the dinosurian nor the mammalian lines did it for over 200 million years and we’re practically an accident.)
But…technological civilizations will be EXTREMELY rare. Homo sapiens barely squeaked through at least one major population bottleneck before we developed enough technology to resist the normal rounds of extinction. Even with advanced tech, we’re still vulnerable to asteroid strike, volcanic hot spot eruptions and other natural forces along with the dangers from our technology and our own nature.
I don’t think we’re the only such civilization to ever exist in the whole universe, but the frequency (to pull even more numbers out of some orifice or another) may be something like one such civilization develops per galaxy per every 5 billion years on average. I also don’t think that once you have a technological civilization that you probably won’t go extinct, such that any that ever existed would naturally have spread out into the rest of their galaxy and be detectable, either.
So I no longer expect to find ET out there.
My vote is for this wee bit better, evidence based explanation for larger life forms. Nick Lane’s, The Vital Question.
Or for a quicker Youtube intro: https://www.youtube.com/watch?v=PhPrirmk8F4&t=251s