A prime number is a whole number greater than 1 that cannot be formed by multiplying two smaller whole numbers. In other words, its only divisors are 1 and itself. For example, 5 is a prime number because it can only be divided by 1 and 5. The number 6, however, is not prime because it can be divided by 2 and 3.
While seemingly a purely mathematical concept, prime numbers appear in nature in fascinating ways, most famously in the life cycles of a particular insect.
Prime Numbers in Nature
The Cicada Life Cycle 🦗
The most striking example of prime numbers in nature is the life cycle of the periodical cicada, genus Magicicada. These insects spend most of their lives underground as nymphs, emerging en masse to mate and lay eggs only after long intervals of 13 or 17 years—both of which are prime numbers.
Scientists believe this is a highly effective survival strategy. By emerging in prime-numbered cycles, the cicadas avoid syncing up with the population cycles of their predators.
- Avoiding Predators: Imagine a predator with a 2-year life cycle. If the cicada cycle were 12 years, this predator would encounter the cicadas every single time they emerge. But with a 13-year cycle, the predator only syncs up with the cicadas once every 26 years (2 x 13). A prime number minimizes the frequency of encounters with predators having shorter, more regular cycles (e.g., 2, 3, 4, or 6 years).
This strategy, known as predator satiation, ensures that when the cicadas do emerge, their sheer numbers overwhelm any predators, allowing enough of them to survive and reproduce.
Other Mathematical Patterns in Nature
While the cicada example is the clearest instance of prime numbers, other mathematical patterns, like the Fibonacci sequence, are more widespread and hint at the deep connection between math and the natural world. In this sequence (1, 2, 3, 5, 8, 13,…), where each number is the sum of the two preceding ones, the numbers often correspond to:
- The number of petals on a flower.
- The spirals on a sunflower head or a pinecone.
Although not all Fibonacci numbers are prime, the sequence’s prevalence shows how mathematical rules govern efficiency and growth in nature.