How did Life Grow in Size from Bacteria to the Blue Whale? Experts See Two Great Leaps

All life on Earth all sprang from the same single-celled organisms that first populated the planet, so how did life grow in size from bacteria to the blue whale?

"It happened primarily in two great leaps, and each time, the maximum size of life jumped up by a factor of about a million," said Jonathan Payne, assistant professor of geological and environmental science at Stanford.

Payne, along with a dozen other paleontologists and ecologists at 10 different research institutions, pooled their existing databases, combed the scientific literature and consulted with taxonomic experts in a quest to determine the maximum size of life over all of geological time. In addition to quantifying the enormity of the two leaps in maximum size, the researchers also pinned down when those leaps took place. Both leaps coincided with periods when there was a major increase in the amount of oxygen in the atmosphere.

The first fossilized bacterial cells date to approximately 3.4 billion years ago, although life likely originated several hundred million years before. Between 2.7 and 2.4 billion years ago, cyanobacteria, formerly known as blue-green algae, originated and were of particular evolutionary and geological importance because they excrete oxygen as a waste product during photosynthesis. So far as science can tell, they were the first and only organisms to evolve oxygen-producing photosynthesis.


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