We’re always tickled to see unusual instances of math in nature, and this headline certainly had us grinning from ear to ear: Periodic Cicadas are Coming: Mathematical Bugs in the Prime of their Lives! While many 17-year-old humans spend springtime closing the books on high school, billions of juvenile cicadas are coming of age after 17 years spent maturing underground and leaving their subterranean burrows en masse!
Periodic or periodical cicadas are unique in that they have life cycles of either 13 (cicadas in the Midwest and South) or 17 years (cicadas in the northern U.S.). 13 and 17 are both prime numbers—as we mentioned here, a prime number is a whole number with exactly two distinct factors, namely 1 and itself. Interestingly, the article cites cicada research based on math models conducted by mathematician Glenn Webb, who “created a study in which he chose non-prime numbers, such as 10, 12 and 15, for the life cycles to see if the cicada population would be at a disadvantage. At those intervals he found that the cicada population would be ‘annihilated or significantly reduced.’” Clearly, the math works to the cicadas’ advantage!
Why prime numbers though? This video explains it beautifully (and is full of other fun cicada facts too):
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