ive heard alot of things, noone is 100% sure.
they are decended from a very old breed though, the aztecs used the techichi as a companion, a guard dog, a ratter, a bed warmer, sacred sacrificial item and food in tough times...
its belived that chis essentially decended from these dogs.
wouldnt suprise me, chis are very good at bug hunting.
but quite honestly, companionship is a VERY good purpose! and if thats all chis were bred for, then im ok with that.