Evolution of Life was Stalled for 2 Billion Years

A coherent picture of the environmental conditions that led to the evolution of animal life is finally emerging. Scientists say that oxygen deficiency and a lack of the heavy metal molybdenum in the oceans had blocked the evolution of life on Earth for nearly two billion years.

The molybdenum record shows that the second step occurred around 600 million years ago, when the entire ocean became oxygenated, which enabled the rise of multi-cellular life called eukaryotes -- the category that includes plants, humans and other complex creatures.

"These molybdenum depletions may have retarded the development of complex life such as animals for almost two billion years of Earth history," said Timothy Lyons, a professor at University of California Riverside. "The amount of molybdenum in the ocean probably played a major role in the development of life."

Deprived of molybdenum, bacteria cannot fix nitrogen efficiently -- and this in turn affects multi-cellular, or animal, life which depends on bacteria for their own nitrogen intake.

Molybdenum levels are also a reliable indicator of oxygen levels in ocean chemistry. The deficiency of molybdenum over this long period also mirrors a deficiency in oxygen.

Posted by Jason McManus.

Link:

http://english.people.com.cn/90001/90781/6381913.html

Comments

[Timeby]

Whenever I see articles concerning the crucial role that molybdenum plays in life I can't help but recall Bertrand Russel's short story satirizing religion where the prophet was a woman Molly B. Dean and the sacrament was Molybdenum.

[jim rooney]

molybdenum may be a rare metal and involved in some enzymes, but oxygen levels and low Mo levels didn't hinder life. what hindered advancement of life to complex forms was the lack of a nucleus. prokayotes like bacteria are alive, have evloved, and have colonized many, many ecological niches, but they could not then, nor could now progress beyond their present MO (modus operandi) because of the lack of a nucleus. it is possible (?likely) that this event occurred once and only once in the history of life, 2 billion years ago- and that event permitted complex life forms capable of progressing to the greater complexity we enjoy today. jim