The origin of complex life is one of science’s greatest mysteries. How could the first small primitive cells evolve into the diversity of advanced life forms that exists on Earth today? The explanation in all textbooks is: Oxygen. Complex life evolved because the atmospheric levels of oxygen began to rise app. 630 — 635 million years ago.
However new studies of a common sea sponge from Kerteminde Fjord in Denmark shows that this explanation needs to be reconsidered. The sponge studies show that animals can live and grow even with very limited oxygen supplies.
In fact animals can live and grow when the atmosphere contains only 0.5 per cent of the oxygen levels in today’s atmosphere.
Essentially, the appearance of complex animals was assumed to be caused by the rise in oxygen levels; it may have only coincided with it.
Sea sponges, a type of animal that dates back to that era, grew in the lab with only .5% of current oxygen levels. Could the contemporaneous comb jellies do so?
So what took animals so long?, the researchers wonder:
“Perhaps the ancient Earth lacked animals because complex, many-celled bodies are simply hard to evolve,” says Daniel Mills.
S’okay. Don’t feel bad. Our pile of rusty tin cans didn’t self-organize into a Porsche over the winter either. Must have left something out.
See also: The Science Fictions series at your fingertips (origin of life)
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