Crazy Yellow Ants Are, In Fact, Crazy


I love ants.

Okay, not in my kitchen. I hate ants in my kitchen.

But I love studying ants, at a distance. Even a little distance is okay. When I lived in Indonesia, a bunch of Weaver ants lived in a tree right outside my bedroom window. Weaver ants are some of the coolest effing ants on the planet. Those who live in my tree built what looked several green basketballs made out of leaves glued together. I loved to sit out on the balcony watching them.

Ants are hive animals; hive are such an incredibly power system of social organization, called eusociality, that it's really the only rival to the mammalian sociality that we use ourselves. So it's not surprising that aliens in Science Fiction are generally either shown as being much like humans... or much like ants. (Or bees or termites, the other hive bugs.)

The Formics, or "Buggers," in Orson Scott Card's "Ender's Game" series are insectoid aliens that are literally named after ants. In the television series "Babylon 5," the Vree live in a hive, communicate through pheromones and are highly skilled engineers. The Zerg in the video game series "StarCraft" are a race of insectoid aliens that are loosely based on ants. They have a queen that controls their behavior, and their units are organized into a series of castes, each with a specific role. The Tyranids in "Warhammer 40,000" attack in swarms.

And there are many, many other examples.

It may seem cliche, but like I said... the alternatives are to try to convince the reader that some herd social organization could make it into space, or try packs/prides of dog/cat people... or fall back on our own monkey troops.

Furthermore, the eusocial insects are just so fascinating, with so much variation within the basic hive organization, that there's endless room for inspiration.

Which brings us back to the crazy yellow ants.

Scientists have discovered a fascinating reproductive system in the yellow crazy ant that's different from what we see in most other organisms.

Syngamy is a biological process that occurs during sexual reproduction when the sperm and egg cells combine their genetic material to form a single cell called a zygote. This cell then begins to divide and grow into a multicellular organism. In simpler terms, syngamy is the fusion of the male and female gametes (sperm and egg) to form a new organism with a unique combination of genetic material from both parents.

So when this organism develops, it starts from the genes of both parents combined into a single fertilized egg. The egg splits into clonal cells--hundreds, then thousands, up to a million, in a typical ant, all clones of the original fertilized egg. (By comparison, a human body has around 40 trillion cells.)

Ants, on the whole, do things differently.

Most ant species determine the sex of an individual based on the number of chromosomes they inherit. Females have two sets of chromosomes (diploid), while males have only one set of chromosomes (haploid). This is because males develop from unfertilized eggs, while females develop from fertilized eggs. Weirdly, girl ants are created by stuff from both Dad and Mom, while boy ants are created by stuff only from Mom.

In some ant species, however, sex is determined by environmental factors such as temperature or the size of the brood chamber. For example, in some species of harvester ants, the temperature at which the eggs are incubated determines whether they develop into males or females. In other species, the presence of certain hormones or pheromones in the colony can influence the development of male or female individuals.

But the yellow crazy ant? They really do things their own way.

Male ants in this species are chimeras, which means they have haploid cells from two different lineages, R and W. Basically, this means that boy yellow ants, in contrast to most boy ants, DO get genes from both Mom and Dad, or R and W.  (Let's call them Ronda and Waldo.)

In their somatic tissues, the Ronda cells are overrepresented, while the Waldo cells are overrepresented in their sperm. This happens because the parental nuclei bypass syngamy, which is the process of combining genetic material from the two parents. Instead, they divide separately within the same egg.

When syngamy eventually takes place, the resulting offspring will either become a queen or a worker ant, depending on whether the oocyte is fertilized by a Ronda sperm or a Waldo sperm. This unique mode of reproduction may be associated with a conflict between the different lineages to preferentially enter the germ line.

"Chimeras have been found in other creatures, including humans, but it’s usually an accident," observed Prillaman, reporting on the study. "Yellow crazy ants are the first known species in which chimerism determines sex. But some scientists estimate there are around 20,000 ant species, and the reproductive systems of most haven’t been studied."

Weirder things yet could remain to be discovered.


“Invasive yellow crazy ants create male ‘chimeras’ to reproduce,” Science News, McKenzie Prillaman, April 6, 2023.


“Obligate chimerism in male yellow crazy ants,” H. Darras, C. Berney, S. Hasin, J. Drescher, H. Feldhaar, L. Keller. Science, 6 April 2023. Vol 380, Issue 6640, pp. 55-58.