Lesson Overview
Featured Article: “How Humans Lost Their Tails” by Carl Zimmer
Have you ever wondered why you don’t have a tail?
Why do most primates have tails while humans and apes don’t? This was a mystery Charles Darwin first posed 150 years ago. And a new study suggests that a single genetic mutation some 25 million years ago helps explain why. “This dramatic anatomical change,” writes science reporter Carl Zimmer, “had a profound impact on our evolution.”
In this lesson, you will learn the answer to the question of where our tails went, explore the consequences for our ancestors, and imagine what your life would be like if humans had kept their tails.
Warm-Up
What if you had a tail?
Whether it was short, long, bushy or striped — how would your life be different? Would you use it to swing through the trees like chimpanzees? Wrap it around yourself in the wintertime like the snow leopard? Or simply swat flies with it like the zebra?
Take a few minutes to write down at least five cool things you would do if you had a tail.
Then, share your list with a partner and discuss: What might be the advantages of having a tail? How might it get in the way? On the whole, do you think your life would be better? Would you want a tail — even if for just a day?
Questions for Writing and Discussion
Read the article, then answer the following questions:
1. The article begins, “For half a billion years or so, our ancestors sprouted tails.” Why does Mr. Zimmer start the story so long ago? What does the evolution of life from hundreds of millions of years ago on Earth have to do with human beings and their missing tails?
2. How did Charles Darwin shock audiences some 150 years ago? What did he realize about the human structure known as the coccyx?
3. How did a team of scientists in New York solve a key piece in the mystery of our missing tails first identified by Darwin? What role did mice play in providing an answer?
4. How did the loss of a tail millions of years ago have a “profound impact on our evolution,” according to Mr. Zimmer? What connection does it have to the human ability to walk?
5. How did a bad Uber ride inspire Bo Xia, a graduate student at N.Y.U. Grossman School of Medicine, to search for an answer to our missing tails? How did he and his colleagues try to find an answer to his question? What did he discover about a gene called TBXT?
6. Now that the how has perhaps been answered, the article ends with the next big question in the mystery — the why:
“It’s very confusing why they lost their tail,” said Gabrielle Russo, an evolutionary morphologist at Stony Brook University in New York who was not involved in the study. “That’s the next outstanding question: What on earth would the advantage be?”
Use what you know about evolution and early human history to speculate: Why do you think it was evolutionarily advantageous for apes and humans to lose their tails? How might human evolution and society have developed differently had we had tails? What questions do you still have about the human tail or the lack of it?
Going Further
Option 1: If you could have any animal feature what would it be?
What characteristics or traits of an animal would you choose — at least for a day?
A trunk, a tail, wings or stripes? How about the acute vision of an owl? Or the speed of a cheetah? Eight arms like an octopus? Gills to allow you to breathe underwater? Bat ears for echolocation in the dark? The ability to change color and camouflage like chameleons?
Explain how your life would be different and what you would do with your new animal powers.
If you are interested in joining a conversation with other students, share your thoughts in our related Student Opinion prompt.
Option 2: Learn more about other aspects of human evolution.
Why are humans awed by beauty? How did we evolve to be able to run? Could early humans speak? What questions do you have about the long and often odd path of human evolution? Read one of the recent Times articles on human evolution below:
Then, write or discuss with a partner: What is your reaction to the article? What was the most provocative, surprising or memorable thing you learned? How does it add to your understanding of evolution? What further questions does it raise for you?
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