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Riled Up is a journal of science, the environment, exploration, new technology, and related commentary.  Contributors include scientists, explorers, engineers, and others who provide perspectives and context not typically offered in general news circulation.  For interested readers, additional resources are included.

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One Step At A Time

One Step At A Time

Bichir fish, Polypterus sp. (credit: Wiki-commons)

We now know from geologic records that life evolved in the ocean approximately 3.5 billion years ago. Did some creature just crawl out and start walking on land? Was there something particularly attractive on land? A coffee shop, perhaps? Or are species more adaptable than we might have thought?

Publishing several years ago in Nature, researchers raised a very adaptable species of small ray-finned fish, Polypterus. The investigators raised the species on land and measured their developmental plasticity and other physical responses. For a year, they observed changes that allowed the fish to maneuver more easily on land. Their bodies grew stronger in certain areas to make it easier to walk on land. It is easy to see how the physical changes that happened to them during the study could become solidified by evolution through natural selection. The environmentally induced physical adjustments in Polypterus may represent the 'origin story' of traits that led to tetrapods, creatures with limbs. With billions of years of evolutionary time along the way, you go from little fish to humans.

Evolution also have also led to some 'dead ends' which are no longer here because the natural process is not always an upwards ascent. Carl Sagan provides his own viewpoint on how molecules became fish and then man, one step at a time. Reilly Capps

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