A lot of people might already know this, but many species of Cicadas have evolved to come out in cycles of a prime number of years (13 and 17 being the most common). Those two were specifically. Evolutionarily “chosen” for because it makes it difficult for predators (ie bird species or other bugs) to sync up an integer number of years in order to catch and eat the broods. For example, a 15yr life cycle for cicadas would allow predators with 5yr cycles to have access to 1 brood every 3 cycles.
Buy it: Will You Shut Up Man Joe Biden 2020 Shirt
The smaller prime # cycles didn’t become common because certain species would still be able to sync up with them and the larger primes didn’t happen because it’d be too long of a life-cycle to be energy efficient for the cicadas.
See more: Shop Trending Shirt