Exaptations

Humaira Marzia Alam
Junior
School of Life Sciences
Independent University, Bangladesh

Lucy is my best friend, but I am jealous of her. I envy the way she flies from one part of the sky to another using her feathered wings. Oh! Lucy, she is a bird and she is blue in color. One day while sharing how envious I am about Lucy's flight with my uncle asked me a question: where do feathers come from? It actually made me wonder, and led me to read the latest research papers on the subject. Since you're also probably wondering the same now, let me tell you how feathers came about.

To understand the evolution of feathers, we need to go millions of years back when dinosaurs used to dominate this world. Fossils tell us that many dinosaurs had feathers but could not fly. What were these terrestrial animals doing with feathers? Current research indicates that their primary purpose in the beginning was insulation. Feathers have pockets where air can be stored, and could have protected cold-blooded dinosaurs from heat loss. Some scientists believe feathers could even have served as ornamentation to attract mates. With time, these animals evolved increased feather cover throughout their bodies, perhaps for better insulation. It’s the same reason that mammals have fur or hair!

Reconstruction of a feathered dinosaur. Chung-tat Cheung and Yi Liu

One day, while chasing its prey, a dinosaur with feathers raised it arms and the action not only increased its speed but also allowed it to glide through the air. Now, having such feathers equipped these dinosaurs with a distinct advantage over less-feathered competitors while catching prey! Over millions of years, natural selection optimized the feathers for gliding, ultimately allowing the animals to completely take off from the ground and fly!

This example of transformation of the function of feathers from insulation to flight is known as exaptation, a theme in evolutionary biology where a tool or structure that had evolved for a specific function became coopted for a completely different function by chance or accident. The dinosaurs as we think of them no longer exist. Some combination of asteroids, supervolcanoes, and infections wiped most of them off from the face of the earth, but their innovation still thrives in our world through a few surviving lineages. Due to the exaptation of feathers for flight, Lucy the bird, a descendant of the dinosaurs, is able to roam our skies.

Sources to explore more:

Carl Zimmer article on the evolution of feathers
Quanta article on exaptations


Humaira writes: 

"I just want to get lost in my own world where I will live my life riding a bicycle and with undying enthusiasm that I have for life science. I wish to create the best in myself as a biochemist. Besides my passion in biochemistry I like writing, reading and sports!"

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