Sex-Role Reversal Research in Insects Wins Ig Nobel Prize for Keio Professor

In 2012, Prof. Kamimura was first invited to join a research team led by Kazunori Yoshizawa, an associate professor at Hokkaido University, whose award-winning research focuses on cave-dwelling species of insect from Brazil that belongs to the genus Neotrogla. In most insects, the male penetrates the female reproductive organ to transfer seminal fluid, but for Neotrogla, it is the female that has a penis, which it uses to penetrate the male in order to receive seminal fluid and nutritional substances.

“Neotrogla are small, 3mm-long insects that inhabit caves in Brazil. Our first face-to-face encounter with these fascinating creatures was in 2016, when we donned headlamps and explored the caves in search of them. The caves they inhabit are quite dry and food is scarce, which forces them to rely on bat guano and mouse droppings to survive. We think that perhaps the male offers the female part of its own nourishment in the form of seminal fluid. In order to receive such a gift, we suppose that the female became more aggressive in mating, and that is what eventually led to the evolution of the reversed male and female copulatory organs.”

Insects are the most diverse group of animals in the world. Japan is home to more than 30,000 known species, but many more have yet to be discovered. “Many insects with similar traits are often distinguished by the shape of their genitalia. This is because genital shapes evolve rather rapidly. Why exactly is it so fast? That’s what we’re trying to understand,” explains Prof. Kamimura, whose love of living things goes back to when he was a child, when he would play in the family garden and nearby river looking for insects and fish. He says his interest in how earwig mothers care for their offspring is what led to his obsession with researching the strange shapes of earwig genitalia and those of insects in general. “I still go down to the Tama River and collect insects. I still see so many unexplained mysteries in the shapes of the bugs that surround us.”

At his seminar-style classes on Hiyoshi Campus, first- and second-year students at the Faculty of Business and Commerce read through Ig Nobel Prize research in English, which they later present and discuss.

“Being able to read articles written in their original English gives students first-hand access to much of the knowledge being created around the world. The barrier to entry can be quite high at first, but most people find the prize-winning research quite interesting, so students enjoy reading through the articles even without any expertise or prior background knowledge. That said, I never thought that I myself would one day receive the Ig Nobel Prize. I think the humor and amusement that this award celebrates are important for research and can even be a source of inspiration for students thinking about ideas for their bachelor’s theses.”

People are often impressed by the large circle of friends that Keio students possess. “In class, for example, students will conduct their own surveys, and when they show me the results, I’ll see that they’ve talked with a tremendous number of people. I’m always surprised and think that this kind of teamwork is one thing that really defines Keio. People are always there to help when you need it.”

“Our understanding of humanity only deepens when we look at other living creatures, including insects. The rapid evolution of insect genitalia is thought to be the result of arms race between males and females, who have conflicting interests in reproduction. This type of competition-driven change exists in the human world as well. In fact, our world is full of it—price wars between corporations and fiercely competitive school entrance exams are two examples. Just as in insect evolution, this kind of competition is a powerful force that drives our world. It is a methodology that holds just as much sway in biology as it does in socioeconomic analysis,” says Prof. Kamimura.

“Much of our research does not require large equipment, excessive manpower, or large sums of money. It consists of simple experimentation and microscopic observation. But I believe that simple research and simple questions are what give rise to new discoveries in any discipline.”

Yoshitaka Kamimura

1999 - Graduated from the Faculty of Science at Tokyo Metropolitan University
2001 - Completed the master’s program at the Department of Biological Sciences in the Graduate School of Science, Tokyo Metropolitan University
2003 - Completed credits for Ph.D. at the Department of Biological Sciences in the Graduate School of Science, Tokyo Metropolitan University

After serving as assistant instructor at the Faculty of Geo-environmental Science at Rissho University and as assistant professor at Research Faculty of Agriculture at Hokkaido University, Prof. Kamimura joined Keio University as assistant professor at the Faculty of Business and Commerce in 2008. He has served as associate professor at Keio since 2013. In 2017, he jointly received the Ig Nobel Prize in biology. His field of expertise is in evolutionary biology and entomology. He has authored books such as Konchu no Kobi wa Ajiwai-bukai (Insect Mating Is Fascinating).

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