A new theory attempts to explain why our ancestors left the aquatic environment

A team of American researchers publishes a study that provides a new theory at the heart of evolution, suggesting that it was enhanced vision that drove our aquatic ancestors out of the water before limbs appeared.

A joint team from Northwestern University and Claremont McKenna, Scripps and Pitzer Colleges publishes a study that challenges a theory related to evolution. She proposes a new hypothesis on what pushed our aquatic ancestors out of the water to reach the mainland.

According to them, it is an improvement in visual abilities that first comes into play to explain this turning point in evolution, before the appearance of limbs. Increased eye size and enhanced abilities would have allowed these crocodile-like animals to spot prey on land. Then their limbs evolved to be able to reach them.

Neuroscientist and engineer Malcolm A. MacIver along with biologist and paleontologist Lars Schmitz studied a fossil record of prehistoric animals, 59 fossil specimens covering the period before the transition from water to land, during the transition and after the transition. They measured the orbits and the head of the fossils and thus discovered that the size of the eyes almost tripled in size during the period preceding the transition.

Before the transition from water to land, the average size of the average orbit was 13 millimeters and around the transition period it was 36 millimeters. This period coincided with the change in the location of the eyes from the side of the head upwards.  » The tripling in size of the orbit took 12 million years. It’s the timeline of evolution, which is mind-boggling when you think about it. says Malcolm A. MacIver in a Northwestern University publication.

They then developed computer simulations of the animals’ visual environments, such as clear or cloudy water that show that the benefit of increased eye size only exists when the animal looks out of the water and not in the water. Indeed, with eyes above the water line, the animal could see 70 times farther in the air than in the water and tripling the size of the eye widened the visual space. of the animal a million times.

 » We found a dramatic increase in visual ability in vertebrates just before the transition from water to land. Our hypothesis is that the ability to see an unexplored cornucopia of food on earth, diplopods, centipedes, spiders, etc., would have driven evolution to develop limbs instead of fins. says Mr. Maclver.

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