Life on Earth jumped up in two leaps by factor of a million

December 23rd, 2008 - 12:09 pm ICT by ANI  

Washington, Dec 23 (ANI): In a new study, scientists have determined that life on Earth jumped up from bacteria to blue whale in two leaps, both of which were a million-fold.

Earths creatures come in all sizes, yet they all sprang from the same single-celled organisms that first populated the planet.

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, according to the research.

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.

All of the oxygen in the atmosphere ultimately exists because of the evolution of cyanobacteria, Payne said. Plants that produce oxygen today during photosynthesis, their ability to do that is ultimately derived from cyanobacteria, he added.

Single-celled bacteria remained the largest life form on Earth, cranking out the oxygen, until about 1.6 billion years ago. At that point, a new life form shows up in the fossil record.

The first jump in maximum size happens when the first eukaryotic organisms show up as fossils, Payne said. And those fossils are approximately a million times bigger than anything that had come before on Earth, he added.

For approximately the next billion years, life on Earth stayed about the same size, with only modest increases.

Then about 600 million years ago, at the same time as another major boost in the amount of oxygen in the atmosphere, life leaped in size again.

This time, it was a million-fold size leap of multi-cellularity. (ANI)

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