As I heard it, Ayahuasca traditionally refers to the MAOI portion specifically. The MAOI will increase the activity of nearly any psychotropic drug and has some minor effects on it own, so it makes sense that the MAOI came first, and then adding other things things to it followed.

Fun fact: the ayahuasca alkaloids glow brightly under black light. I've never done ayahuasca, but I tried making some fluorescent body paint via crushed syrian rue seed "tea". It was extremely effective: glows very bright, soaks into the skin a bit so it stays for a couple days before fading, and is completely invisible under normal light. Kinda fun - could potentially cause minor psychotropic effects if you paint a large surface area, but I didn't notice any.

Many, though not all, participants and shamans report the presence of an intelligence that is distinct from their own.

That's been my experience with it. For me, the literalness of "plant spirit" is accepted reality. In the circles I hang out with, we don't put the term, plant spirit, in air quotes.

Generally, the two plants that are combined are the Ayahuasca vine, which contains the various MAOI, and Chacruna, which contains DMT. Many plants yield DMT, though only some plants yield a sufficient concentration to be useable.

From an experiential point of view, the plant material of Ayahuasca and Chacruna are the material body. They each have a specific intelligence that is sentient, and conscious, and responsive to the ikaros (the song sung in ceremony).

It does imply that, it should be possible to contact the intelligence named Ayahuasca by ingesting the vine alone, or without ingestion. After all, what is contacting the plant spirit (plant consciousness) is your own spirit (consciousness). That has happened with me as well.

To followup: Marijuana, the plant material, should also house a plant spirit, with its own intelligence, knowledge base, and purpose. Likely, also responsive to songs that are related to it. And indeed, that has also been my experience with it too. I call that spirit by the Sanskrit name, Ganja, and tried it with the Sanskrit mantra.

Actually the DMT containing plant is completely inactive orally without a MAOI. You wouldn’t get any effect short-term or otherwise.

For more on the shamans' claims that the plants communicate information through Ayahuasca experiences, see the work of Jeremy Narby, it's undeniable that the natives understanding of plants is extensive and however it was come by it's an invaluable source of knowledge that has been 'harvested' by big pharma for many contemporary medicines.

This lecture from Dr. Peterson was pretty fascinating and succinct: https://www.youtube.com/watch?v=Gol5sPM073k

My guess is they already knew about the MAOI to at least some degree and noticed that the effects of other plants were amplified when combining them. So when they found the DMT plant, someone figured it'd be worth seeing what happens when they combine them.

If it's true that the DMT plant has no psychoactive effects when taken alone, maybe someone had already had a routine of taking the MAOI and just eating most plants they came across, to see what would happen.

I heard an alternative is "yopo" where they blow it up each others nose via a straw and I don't think that needs an MAOI.

I heard there's a lot of barfing involved - made it seem kind of unappealing.