There's quite an interesting analogy there. I guess you could have a four wheeled wagon structure similar to wooden wagons of old, then an engine added and now electronics added, as an analogy to the triune brain. It's not that modern cars are built on wagon chassis but that the basic body with four wheels structure is similar for functional reasons. Probably similarly with the 'reptilian brain.' Our bits are maybe similar because they do the same job rather than because they evolved from that.