Thursday, April 11, 2024

Why Don’t Humans have Tails? Scientists Find Answers in an Unlikely Place

A common feature amongst most animals with backbones is a tail, something that humans lack. This has been mystery and questioned by many. In animals with tails, they are used for balance, propulsion, communication, and defense against biting insects. About 25 million years ago, primates said goodbye to the tails when they split from Old World monkeys. They no longer had a use for the tail. Our transition to bipedalism was thought to be connected to the loss of our tails, but we hadn’t known the genetics behind it. 

Now researchers have found new information that changes the trajectory of our thinking. They have found that our tail loss was due to a short sequence of genetic code that is abundant in our genome but was seen as junk DNA. Junk DNA is a sequence that serves no biological purpose for us. The identified snippet is an Alu element which is in the regulatory code of a gene associated with tail length called TBXT. Alu can switch their location in the genome which can trigger or undo mutations. At some point the Alu jumped into the TBXT gene in great apes and humans. Evolution is an interesting topic because it explains a lot of the world around us today. It was interesting to learn how we evolved to have no tail and how it no longer became any use to us. 

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