Evolutionary theory does explain the origin of thought. We all share a common ancestor and over time what we describe as 'thought' has evolved to what we see today
Dude, if you think that is actually a scientific explanation for something I get why you don't think I know what science is.
It's like saying: Physics today know what dark matter is. It is some kind of field or particle which interact with other particles and pull them around, and at the same time they are hard to see in a telescope. This is my very scientific explanation, nothing to see here.
Ain't no scientific explanation...
Origin of thought is an open problem in evolutionary theory. deal with it. I for one am happy to admit there are things I don't know & can learn about.