Life on Earth began in the water. So when the first animals moved onto land, they had to trade their fins for limbs, and their gills for lungs, the better to adapt to their new terrestrial environment.
A new study, out today, suggests that the shift to lungs and limbs doesn’t tell the full story of these creatures’ transformation. As they emerged from the sea, they gained something perhaps more precious than oxygenated air: information. In air, eyes can see much farther than they can under water. The increased visual range provided an “informational zip line” that alerted the ancient animals to bountiful food sources near the shore, according to Malcolm MacIver, a neuroscientist and engineer at Northwestern University.
This zip line, MacIver maintains, drove the selection of rudimentary limbs, which allowed animals to make their first brief forays onto land. Furthermore, it may have had significant implications for the emergence of more advanced cognition and complex planning. “It’s hard to look past limbs and think that maybe information, which doesn’t fossilize well, is really what brought us onto land,” MacIver said.
MacIver and Lars Schmitz, a paleontologist at the Claremont Colleges, have created mathematical models that explore how the increase in information available to air-dwelling creatures would have manifested itself, over the eons, in an increase in eye size. They describe the experimental evidence they have amassed to support what they call the “buena vista” hypothesis in the Proceedings of the National Academy of Sciences.
MacIver’s work is already earning praise from experts in the field for its innovative and thorough approach. While paleontologists have long speculated about eye size in fossils and what that can tell us about an animal’s vision, “this takes it a step further,” said John Hutchinson of the Royal Veterinary College in the U.K. “It isn’t just telling stories based on qualitative observations; it’s testing assumptions and tracking big changes quantitatively over macro-evolutionary time.”
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