ThirstyFish

Commuter bike riding in NYC is growing. Many are riding in style. A phenomenon observed in many places worldwide is safety in numbers: The more cyclists, the safer it is to cycle, and conversely, the fewer cyclists, the more dangerous it is to cycle. You can read more interesting facts about bicycle safety on the Bicycle Universe site.

Safety in numbers is an interesting hypothesis that postulates "an individual is proportionally less likely to be the victim of a mishap or accident when he or she is part of a larger group". An explanation for safety in numbers is that mass behavior makes individuals more predictable and known to "others". Another explanation is predator satiation.

Cicadas live most of their lives underground as nymphs. They fly poorly and can not defend themselves against predators such as birds, wasps and praying mantises. Some species exhibit an unusual defense mechanism. They emerge simultaneously after being underground for 13 or 17 years (primes?). Their numbers exceed the amount predators can eat and consequently the remaining cicadas breed in peace. This defense is known as predator satiation. Should they have emerged in small numbers over an extended period of time, there would be many happy and fed predators, and no cicadas.

Cicadas crawl out of their underground hideouts every 13 or 17 years, depending on the species. These prime cycles have attracted the attention of many mathematicians and scientists. Some claim that their prime cycles are another defense against extinction. An event that may occur if their cycles coincide with the life cycles of their predators. But a natural question that arises is, why not other primes such as 11 or 19? To date, there has been no clear scientific explanation to the cicada life cycle mystery.