Playing the scientific record backwards.
I’ve done a lot of research on seasonal models. I’ve always enjoyed playing with the elegantly simple sinusoid function, which can fit a remarkable array of shapes with just a few parameters. Put enough sinusoids together and you can create any sound. When Fourier discovered this, it was considered too simple to be true.
A great number of diseases are seasonal, so these models are useful as well as being mathematically pleasing.