Why Are Periodical Cicadas So ... Periodical?

Certain cicada species in North America emerge from the ground by the millions every 13 or 17 years. But why those specific intervals? Are cicadas secretly prime-number-loving mathematicians?!

Hosted by: Michael Aranda

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[Gulgathydra]

Every 221 years, these cycles sync up.

That is when the cicada armies will rise to destroy us.

[richardpowell]

Michael's looks over the years are like a Pokemon Evolution. His hair continues to get longer and more luscious.

[anjulikamins]

Anyone else tune in too see Michael's hair? I adore everything about scishow, but I'm also here for the hair

[murielvaillancourt]

During my childhood in France, we had a lot of cicadas each summer and their song stays in me as the best souvenir, followed by all the horse chestnuts that were falling on the ground each autumn. We picked them up and play with them for weeks, making some little animal figures with them and with acorns.

[weareorigin]

They are math teachers, teaching about division by prime 13 and prime 17.

[lyndsaybrown]

Tired of being told that "the best years of their lives were behind them" cicadas evolved to spend most of their lives as youngsters.

Humans do not understand this. Cicadas do not care.

[georgecrutchfield]

They are past their peak here in North Georgia. I could barely hear them when I went outside today and last week they were so loud, one could barley hear their own thoughts.

[delliardo]

The front of my car is covered in cicada guts. Those little bugs really love the highways.

[Evergreen]

The 17 year ones just disappeared over the last week here. The noise of the ones far away is weird. It reflects off things and sounds like the invasion in War of the Worlds.

[joshuasims]

My question is, how do they manage to come out after exactly 17 years? Do they just have a very reliable life cycle? Or do they have some biological mechanism to wait that exact amount of time before emerging? This may be one of those unanswered questions...

[IntrepidFraidyCat]

I've always loved cicadas. Of course, I don't live where the hordes of the red eyed ones come out. We have the cute green ones every year.

[silversam]

First time I found the molted shell of a cicada, I thought it was an alien. I mean... Still not completely convinced they aren't, but y'know.

[MakeMeThinkAgain]

Thanks for that last video sequence of the cicada molting and leaving it's old shin behind. Those empty shells on tree trunks is what I remember about them from when I was a child in Kentucky.

[DylanMatthewTurner]

I was driving home from college after graduation (Indiana to Texas), and my family just happened to travel into the handful of counties in Illinois where the 17 year cicadas just happened to be appearing at that exact moment. It was cool to see them up close!

[johnkabiro]

There is risk in everything, so be prepared for ups and downs.

[Lorenzconnok]

This is fascinating!
The 13 year lifespan and the 17 year lifespan cicadas will interbreed at their respective frequencies, then every 221 years they're guaranteed to overlap and guarantee genetic variance and a population boon. Kind of a cool life tactic.
I wonder if there is a third, fourth etc. type with life cycles of other prime numbers🤔

[dougalexander]

The content of this channel intrigued me. Thank you and stay awesome.

[pkmn]

I haven't watched this show in a while, glad to see Michael looking good!

[aniruddhthakar]

Ah yes an American football field....the unit of measurement larger than a standard banana

[rodefshalom]

I live in a college town near campus, so I’m used to the ear splitting shrieks of millions of bug looking for a mate.