The Enduring Question of Cicada
Cicadas and prime numbers may seem unrelated initially, but they share a fascinating connection that has intrigued biologists and mathematicians. Cicadas are insects from the Hemiptera order, known for their distinctive songs and unique life cycles. One particular group of cicadas, known as periodical cicadas, have a fascinating trait: their life cycles revolve around prime numbers. Prime numbers are natural numbers greater than one that can only be divided by one and themselves, such as 2, 3, 5, 7, 11, etc. Periodical cicadas have two primary life cycle durations: 13 and 17 years. These durations are prime numbers. The cicadas emerge en masse from the ground, breed, lay eggs, and then die. The eggs hatch and the larvae burrow into the ground, feeding on the roots of plants until they emerge again 13 or 17 years later. The reason behind this prime-numbered life cycle is still not completely understood, but one prevailing hypothesis is that it helps the cicadas avoid predators. By having a life cycle based on a prime number, the cicadas reduce the chance of synchronizing with the life cycles of their predators, who usually have shorter and non-prime-numbered life cycles. This makes it difficult for predators to depend on cicadas as a regular food source, giving the cicadas a better chance of survival. In addition, the prime-numbered life cycle reduces the chance of interbreeding broods of cicadas (groups that emerge in other years). This helps maintain genetic diversity within the population.
My question is, however, why are they related to non-competition or predators? I am confused with the "offset." For example, even if they breed every 13 years, wouldn't cicadas from 2010 breed in 2023, cicadas from 2011 breed in 2024, and so on? So why does it "avoids" such an issue? Is it simply just a particular species that can be observed every 13 years? No one helped me understand such question 😭