[b112]

I wonder, for when I look here:

https://en.wikipedia.org/wiki/Inca_agriculture

They not only used wood, but llama dung for fires. I wonder how much C4 ended up in the food via their dung, just from the smoke and air rising from the fire, as it would be rich in it.

Still a neat way to try to validate diet.

[IAmBroom]

OK, first: food is rich in C4. Food is made from carbohydrates, which as the name suggests is made from Carbon, and the amount of C4 in the carbon is homogenous across compounds.

So the answer to your question is: insignificant amounts of smoke occur in fire-cooked foods, and the C4 composition wouldn't be affected anyway.

[IAmBroom]

I am incorrect: C4 is not homogenous, per the comment above yours, but really there just can't be that much smoke IN food ingested.