The 720 Sexes: A Masterclass in Dating

In the human world, binary gender is the norm. In the animal world, it’s the standard. But in the world of the Physarum polycephalum, things are… more diverse.

Much, much more diverse.

Recent research popularized by the Parc Zoologique de Paris and scientific leaders like Audrey Dussutour has revealed that the “Blob” possesses 720 different mating types.

The Math of Compatibility

This isn’t about physical appearance or roles. It’s a genetic lock-and-key system.

The mating type of a slime mold is determined by three specific locations (loci) on its DNA:

1. Locus matA: Has at least 16 different versions (alleles).
2. Locus matB: Has at least 15 different versions.
3. Locus matC: Has 3 different versions.

If you multiply these combinations (16 x 15 x 3), you get 720 unique genetic signatures.

How They “Date”

When a slime mold is ready to reproduce, it produces millions of microscopic spores. These spores burst and release tiny swarm cells or amoebae.

Think of these tiny cells as single-celled dating hopefuls.

• Two of these cells can fuse together to create a brand-new blob only if their matA, matB, and matC alleles are completely different.
• Because there are 720 variations in the population, the chance of two random cells being different enough to mate is 99.5%.

Why did evolution do this?

Most organisms face the risk of “inbreeding” or not finding a partner when their population is sparse. By having 720 sexes, the blob has evolved the ultimate insurance policy.

• Survival: It ensures that almost any two spores that meet in the wild can create a new, genetically diverse generation.
• Genetic Mixing: It maximizes the mixing of DNA, allowing the species to adapt quickly to new environments (like learning to solve a different kind of maze).

The Laboratory Reality

In the lab, we often keep “pure strains.” If you have two cultures of the same strain, they are essentially the same “sex” and will fuse together into one big body instead of mating.

If you want to see them mate and produce spores, you usually have to introduce a “wild” blob from a different location to find a compatible partner.

Fun Fact: This massive genetic variety is one of the reasons the blob is being studied for Biomimetics—the science of copying nature to solve human problems. If a cell can solve “dating” this efficiently, surely it can help us solve logistics and networking.

Curious about how they learn? Check out our article on Non-Neural Intelligence.