The Hebrew University identifies molecular factors that enable birds to fly but keep the rest of us on solid ground


Photo credit: Baruch Haimson

For centuries, scientists, aviation designers, and the adventurous have tried to reproduce the qualities that enable birds to fly, namely wing structure and balance. However, without an external mechanism such as a hot air balloon or airplane, humans remained earthbound and unable to use their own bodies to launch themselves into the stratosphere.

While researchers have long focused on structural factors such as wings that define the category of birds, a study was recently published Scientific advances by Professor Avihu Klar of the Medical Faculty of the Hebrew University of Jerusalem and Prof. Claudio Mello of the Oregon Health and Science University found that there are specific molecular features that distinguish birds from animals in the sky.

In previous studies, researchers found that mammals and reptiles’ ability to walk is anchored in their spinal cord. In this new study, the scientists found that the ability to fly is anchored in the spinal cord of birds. The team carefully examined the neural networks of chicken and mouse embryos and found that the genetic coding of the ephrin-B3 molecule in birds is fundamentally different from that in mammals and reptiles.

“The molecule Ephrin-B3 is present in mammals, but mutated or absent in birds. This simple but profound difference enables birds to flap their wings and fly, ”Klar said. Animals, such as rodents, present this molecule in its full form and therefore move in a stepping motion from left to right with their front and rear limbs. On the other hand, mice with an Ephrin-B3 mutation move with a synchronous jump movement from left and right at the same time, similar to birds.

These results supported her theory that evolution – genetic changes over time – has helped birds develop a network of neurons that activate a very coordinated pattern of movement, namely the simultaneous flapping of wings.

“Our study provides a clue to the evolutionary puzzle: How did the nervous system evolve to support kicking, flying and swimming,” said Klar. “It paves the way for future experiments to uncover the development of neural networks that enable the various types of movement of legs and hands, a characteristic of two-legged animals such as birds and humans.”


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Tali Aronsky

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