Why You Have to Blink to Walk

When we picture the first tetrapods, or land vertebrates, crawling out of the ocean, we probably imagine they need legs. But evolution also had to bestow another important adaptation before they could leave the water: blinking!

Hosted by: Hank Green (he/him)
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[jrave]

Hard to watch a video about blinking without becoming immediately self-conscious about my own blinking

[dixiecup]

Not me trying to walk around my house not blinking before watching the actual video 👁️ 👁️

[Arcian]

Mad respect to Hank for continuing to do SciShow episodes while fighting cancer 🫡

[MrBebopChamploo]

I saw the title and thumbnail of this video and was like "am I weird for being able to walk without blinking? Wait, I can walk without blinking right? I'm pretty sure I can walk without blinking." I'm glad I watched the video before starting to test this.

[pigcatapult]

I was expecting this to be some bizarre thing about not being able to walk and not blink at the same time, but this is even better

[cronotosaur]

The bittersweet of seeing such outpouring of support and love for Hank. While also knowing he doesn't want to be known as the guy who has cancer

[alospm]

I don’t think I’ve ever thought of a mudskipper as “adorable” 😂 Hank is adorable as always though!

[YoungGandalf]

This is an example of evolution taking a step backwards. Two legs and opposable thumbs may be great, but now a human can never beat a fish in a staring contest.

[liseturner]

I've just recovered from a corneal injury that made blinking really painful, so I've been thinking about it a lot lately. It's such a cool thing we do constantly.

[justayoutuber]

Hank, glad to see you are still making content. Hang in there - you are doing good work!

[TheOvermind]

I'm happy to see you feeling well enough to host SciShow but also please don't over work yourself. Never the less, thank you for all you do!!!! ❤

[swannman]

Hank your constant effort and fight through cancer is inspiring.

[omilus]

The way the frog blinked when Hank said blink was 🤌, great job!

[cpbejzv]

I love you hank and everybody that puts this show together, thank you all so much!

[ethan-loves]

I thought this was going to be something about how our eyes process our terrestrial surroundings, like how they skip when looking around but move smoothly when tracking a moving target. Maybe blinking gives our brains time to process more complex environments, idk! 😆

[MalcolmToll]

Can whales and dolphins blink? If not, this means cetaceans lost the ability to blink somewhere along the way, right?

[deviltree]

You've put me on manual blink mode! How could you!

Jokes aside, it's fascinating to me that even vertebrates that don't blink (and I'm thinking snakes here) do still have eye adaptations that seem to be angled in a similar sort of evolutionary direction. Snakes, instead of eyelids, have a fine transparent scale protecting their eyes, probably preventing damage, locking in moisture, and keeping them clean. Life on land is just grubby and grungy, I guess!

[astralb.]

This is how you can tell legless lizards from snakes! Snakes don't blink, they have no eyelids as their eyes are protected by modified scales, but lizards do have eyelids and blink.

[sportsman]

We love and appreciate you Hank! I hope youre feeling well enough as you navigate life's challenges.

[Clairvoire]

My theory is that it's not primarily those three reasons, but instead has to do with sight itself. Blinking keeps the moisture coating of the eye uniform so that it doesn't interfere with how we see; Too moist, and the water beads up and causes our vision to blur. Underwater, it's not so much an issue since the water can't bead up when there is so much of it.