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With evolution, scientists must watch out for unexpected twists and turns

Column: We know a lot about life on Earth, but we're still learning fundamental insights all the time.

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Biologists have learned a lot about evolution since Darwin published his theory 100 years ago. But nature can still surprise them.

Sometimes it's a new fundamental insight. The discovery that an ancient merger of microbes opened an unsuspected evolutionary pathway for higher organisms gives biologists a new perspective on earthly life. In announcing this on August 20, molecular biologist James Lake said that it now is clear that "higher life would not have happened without this event."

Or, sometimes it's a tweak to our understanding of an evolutionary detail that has consequences for our time. A new look at 200 million years of marine clam evolution reveals that some closely related clusters of species are more vulnerable to extinction than are life forms generally. Announcing this research a few weeks ago, evolutionist Gene Hunt said this shows that big extinctions "tend to preferentially cull the more vulnerable lineages, leaving the resistant ones to proliferate afterward." The lesson for conservationists: if you want to preserve species diversity, seek out the vulnerable and give them extra protection.

The take away lesson for the rest of us is not to take present scientific knowledge of evolution for granted either in speculating about the development of life on Earth or in environmental planning. What we don't know can trip us up.

Commenting on discovery of that microbial merger over 2.5 billion years ago, Carl Pilcher, director of NASA's Astrobiology Institute, called it "a major advance in our understanding of how a group of organisms came to be that learned to harness the Sun and then affected the greatest environmental change Earth has ever seen."

Those organisms were the cyanobacteria that evolved photosynthesis. Their production of oxygen changed the atmosphere's chemical composition, preparing the way for evolution of more complex organisms including plants, animal, and humans.

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