We humans can be pretty intense about making sure our borders are secure, so we don’t get any stragglers from other countries crossing over and joining ours without our knowledge. It turns out there is another species out there that are even more strict about their border control.
Scientists have discovered two millipede species that have created a mysterious line in Tasmania, Australia that separates the two species, and the two groups rarely cross it. Scientists can’t find any explanation for the strict border other than that the two species have an agreement to each stay on their respective side. The line wasn’t naturally created due to specific land formations such as a river, but rather crosses rivers and goes up and down hills. The sharpness of the line can only be explained by some biological arrangement between the two species.
The boundary is 230 km long, and border crossing is so infrequent that it is much more effective than any borders we humans have created.
Why and how do you think these two species created this strict border?