Welcome to Clip from Spiral logo

Interactive video lesson plan for: Why Don't Humans Have Tails?

Activity overview:

Whether they’re swatting away horseflies or helping a monkey swing through the forest, tails are a pretty amazing adaptation. So why don’t humans have them?

Learn more at HowStuffWorks.com:
http://science.howstuffworks.com/life/evolution/atavism.htm

Share on Facebook: http://goo.gl/oZcki8
Share on Twitter: http://goo.gl/T2RbKf
Subscribe: http://goo.gl/ZYI7Gt
Visit our site: http://www.brainstuffshow.com

Heads… or tails? As far as appendages go, tails are pretty much amazing. Over time, different animals have evolved various, highly-specialized tails. A horse uses its tail to swat flies, for instance, while a bird uses its tail to steer during flight. Which leads us to today’s question:

If these specialized limbs are so useful… why don’t humans have them?

There are two answers. First: we don’t really need them. In many quadrupedal, or 4-legged, creatures – like a cat, for example – a tail helps with balance. Fish and marine mammals, on the other hand, use their tails for steering or locomotion.

Some lizards and primates use their prehensile tails to grip things, while crocodile store fat in their tails, kind of similar to the way camel store fat reserves in their humps.

But let’s look at humans: we’re bipedal, meaning we walk on two legs. Our center of gravity passes vertically down our spine, so we don’t need a tail to counterbalance the weight of our heads.

And, unlike some other primates, we don’t need a tail to help us hold onto stuff while we swing through trees, because as a species we don’t regularly Tarzan our way around the forest anymore. And why have a tail if you don’t use it? It’s just another thing that takes energy from the rest of the body.

But here’s the second answer. Our ancestors did have tails, and, at some point, you had a tail, too. You can find evidence of our 5-limbed past in the skeleton of every human being. Each of us has a coccyx, or tailbone, made of fused vertebrate. In other primates, this coccyx leads to the tail, but, again, we don’t really need it. It’s a vestigial organ.

Now, I know what you’re saying: “C’mon, Cristen! I may not be a doctor, but I’m pretty sure I don’t have a tail.” Well, maybe not now – but you did while you were in the womb.

All mammals have a tail at some point in development. When you were about 30 days old in the womb, you had a tail-like structure sprouting out of your body. If you’re like most people, you reabsorbed this structure as you developed.

It’s extremely rare, but a few modern people have been born with actual tails. This is what’s called an ‘atavism’, a trait of distant ancestors that reappears in the modern day. Usually these tails are a just a few centimeters long, and often removed shortly after birth.

SOURCES:

http://science.howstuffworks.com/life/evolution/atavism1.htm

http://health.howstuffworks.com/human-body/parts/vestigial-organ1.htm

http://www.sciencefocus.com/qa/why-dont-we-have-tails

http://www.washingtonpost.com/lifestyle/kidspost/ever-wonder-why-animals-have-tails/2012/10/12/23c17198-b3d9-11e1-98e9-bbf4aa4074bb_story.html

http://www.evolutionnews.org/2014/05/do_human_tails_085451.html

https://www.youtube.com/watch?v=XfwMjTcaz64

Tagged under: brainstuff,brain stuff,howstuffworks, stuff works,science,technology,cristen conger,stuff mom told ,tails,atavism, humans tails, humans tails,tail,prehensile,prehensile tail,animals,humans,evolution,vestigial structures,vestigial organ,people tails,coccyx,tailbone, animals tails

Clip makes it super easy to turn any public video into a formative assessment activity in your classroom.

Add multiple choice quizzes, questions and browse hundreds of approved, video lesson ideas for Clip

Make YouTube one of your teaching aids - Works perfectly with lesson micro-teaching plans

Play this activity

1. Students enter a simple code

2. You play the video

3. The students comment

4. You review and reflect

* Whiteboard required for teacher-paced activities

Share on:

Share Why Don't Humans Have Tails? on Google+ Share Why Don't Humans Have Tails? on Twitter Share Why Don't Humans Have Tails? on Facebook Pin Why Don't Humans Have Tails? Email Why Don't Humans Have Tails?

Ready to see what else Spiral logo can do?

With four apps, each designed around existing classroom activities, Spiral gives you the power to do formative assessment with anything you teach.

Quickfire

Carry out a quickfire formative assessment to see what the whole class is thinking

Discuss

Create interactive presentations to spark creativity in class

Team Up

Student teams can create and share collaborative presentations from linked devices

Clip

Turn any public video into a live chat with questions and quizzes

1000s of teachers use Spiral to deliver awesome, engaging activities that capture students' understanding during lessons.

Now it's your turn Sign up

Spiral Reviews by Teachers and Digital Learning Coaches

Spiral
Review of Spiral by teacher: Kathryn Laster @kklaster

Tried out the canvas response option on @SpiralEducation & it's so awesome! Add text or drawings AND annotate an image! #R10tech

Spiral
Review of Spiral by teacher: Room 220 Math Stars @3rdgradeBCE

Using @SpiralEducation in class for math review. Student approved! Thumbs up! Thanks.

Spiral
Review of Spiral by teacher: Miss Ord @ordmiss

Absolutely amazing collaboration from year 10 today. 100% engagement and constant smiles from all #lovetsla #spiral

Spiral
Review of Spiral by teacher: Adam J. Stryker @strykerstennis

Students show better Interpersonal Writing skills than Speaking via @SpiralEducation Great #data #langchat folks!

Spiral
Review of Spiral by teacher: Dr Ayla Göl @iladylayla

A good tool for supporting active #learning.

Spiral
Review of Spiral by teacher: Brett Erenberg @BrettErenberg

The Team Up app is unlike anything I have ever seen. You left NOTHING out! So impressed!

Get the Clip Chrome Extension & Create Video Lessons in Seconds

Add Clip to Chrome