Are We Fish?

One TED Talk I watched recently was Four Billion Years of Evolution in Six Minutes by Prosanta Chakrabarty, an ichthyologist who studies fish, evolution, and the history of life on Earth. The talk starts the question that if humans evolved from monkeys, why are there still monkeys? Chakrabarty explains that the question itself is based on the misunderstanding that humans evolved from the monkeys alive today. In reality, we only share common ancestors with them.

I liked his explanation that evolution is not a straight line because it is more nuanced than the diagram where an ape gradually becomes more upright until it turns into a modern human. That image makes it seem like evolution was always heading toward humans. Chakrabarty instead describes life as a huge branching tree. Every species alive today is at the end of its own branch, and humans are only one of millions of those branches. His image reminds me of iTOL, often known as the Interactive Tree of Life. It is a website used to build evolutionary trees and one I used in my Diptericin research. I utilized iTOL by inputting sequences of amino acids for different fly species into IQ-TREE and then graphing it visually in iTOL using the .treefile files. 

Chakrabarty even goes so far as to call humans “fish.” He pointed out that the first vertebrates were fish, and every later vertebrate group inherited that ancestry. Our backbone is one piece of evidence connecting us to that much older history. This TED talk describes Chakrabarty’s main argument as showing that humans are a small part of a roughly four-billion-year evolutionary process, not its final result.

The talk made me think differently about what it means for humans to be “advanced.” Evolution does not have a finish line. A species survives because its traits work well enough in its environment, not because it is moving toward some perfect form. Humans may have unusual abilities, but we are still one small branch connected to an enormous history of life that started billions of years before us.