# Cicadas and Prime Numbered Year Birth Cycles
**URL:** https://boards.straightdope.com/t/cicadas-and-prime-numbered-year-birth-cycles/814213
**Category:** Factual Questions
**Created:** [May 15, 2018, 1:51pm UTC](https://boards.straightdope.com/t/cicadas-and-prime-numbered-year-birth-cycles/814213 "2018-05-15T13:51:57Z")
**Posts on this page:** 3
**Page:** 1
### Author:  [@Jackknifed\_Juggernaut](https://boards.straightdope.com/u/Jackknifed_Juggernaut)
#### Post date: [May 15, 2018, 1:51pm UTC](https://boards.straightdope.com/t/cicadas-and-prime-numbered-year-birth-cycles/814213/1 "2018-05-15T13:51:57Z")
I remember reading a great explanation, perhaps even here, on why certain cicadas have birth cycles that are prime years apart. It had something to do with preventing predators from correctly timing their births. Can someone provide the reason in layman’s terms? Are there other similar examples in nature?
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### Author:  [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)
#### Post date: [May 15, 2018, 2:13pm UTC](https://boards.straightdope.com/t/cicadas-and-prime-numbered-year-birth-cycles/814213/2 "2018-05-15T14:13:34Z")
Stephen Jay Gould wrote about this in one of his books. I believe the point is to prevent cicadas from not only being in synch with predators, but with successive generations of predators.
> [@](#):
>
> According to the paleontologist Stephen J. Gould, in his essay “Of Bamboo, Cicadas, and the Economy of Adam Smith,” these kind of boom-and-bust population cycles can be devastating to creatures with a long development phase. Since most predators have a two-to-ten-year population cycle, the twelve-year cicadas would be a feast for any predator with a two-, three-, four-, or six-year cycle. By this reasoning, any …
> **[The Cicada’s Love Affair With Prime Numbers](https://www.newyorker.com/tech/annals-of-technology/the-cicadas-love-affair-with-prime-numbers)**
>
> Any cicada that tries to break the pattern is simply taking her offspring’s life into her own hands…
(Sorry – page won’t let me copy more, and I’m too lazy to type it all out)
Lots of other references, too:
[http://www.baltimoresun.com/bal-te.ms.cicada10may10-story.html](http://www.baltimoresun.com/bal-te.ms.cicada10may10-story.html)
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### Author:  [@septimus](https://boards.straightdope.com/u/septimus)
#### Post date: [May 15, 2018, 2:38pm UTC](https://boards.straightdope.com/t/cicadas-and-prime-numbered-year-birth-cycles/814213/3 "2018-05-15T14:38:06Z")
It is for vaguely related reason that [gears often have a prime number of teeth](http://reprap.org/wiki/Gear_design#Number_of_Teeth).