Do you know that humans are “iteroparous” animals? I did know that, but I was not familiar with the term. I’ve been watching the monarch butterfly migration, which has been impressive this year, especially on the flowers at the Senior Center. It got me to thinking about their strange life cycle. They go through four or five generations from March through September as each generation flies a few hundred miles northeast, lays eggs, and dies. Then the final generation, called the “super generation”, hatches as far north as Canada. This generation goes through a process called “diapause”, or delayed reproduction.

As summer comes to an end, the nutrients in milkweed plants, the primary food for the monarch caterpillar, begin to dissipate such that when the caterpillar changes into an adult monarch, the reproductive system fails to mature.

Many animals, mostly insects like the butterflies or spiders (think Charlotte from “Charlotte’s Web”), reproduce only once and then die. This is called “semelparity”. Octopii and salmon also exhibit semelparity.

Because of the “one and done” nature of monarch reproduction, having a delayed maturing of the reproductive system allows the “super generation” to live for over eight months, hibernating through winter, and then emerging and feeding on the abundance of flowers in central Mexico. Those flowers do have the nutrients necessary to kick-start the reproductive systems. So the monarchs mate, lay eggs, and then die, going through four or five generations before the next “super generation” emerges up in Canada and starts its 3,000-mile trek back to Mexico.

You can understand why some animals have the “one and done” reproductive strategy. Reproduction takes a lot out of the females. Ask any pregnant woman. You can have a strategy of having a few offspring multiple times, or lots and lots of offspring a single time. Charlotte was a barn spider, and they can lay as many as 1,000 eggs in their single reproductive output. Animals that reproduce multiple times rarely produce that many total offspring so the “one and done” process gives a much better chance that at least a few of the offspring will live to reproduce themselves.

Reproducing multiple times is known as “iteroparity” and humans have what is called “continuous iteroparity” or the fact that we can reproduce all year around, The advantage of iteroparity is that the adults can provide more care for fewer offspring, thus giving them a better chance of survival. If we look at the average number of children produced by humans in the world, it is 2.3 per woman. Here in the U.S. it is 1.6 and here in Nebraska 1.8.

So humans have only a few kids…but as in all things, there is an exception to the rule. A Russian woman has the world record for the most kids…69! However, she only had 27 pregnancies (Only?). She gave birth to 16 sets of twins, seven sets of triplets, and four sets of quadruplets!

What got me to thinking about humans being iteroparous, or able to reproduce many times, were the butterflies, but I’m thinking maybe someone should have explained the “birds and the bees” to the Russian women!