Another very common primitive cooking method is to wrap the food in green leaves and bury it with coals or place it in the hot ashes of the fire. While you couldn’t boil water this way, you can put a variety of vegetables and/or proteins in with the grains, which will then absorb the liquid the other elements release during cooking.
My sense is that this would have been the first method. A hunter/gather lifestyle would naturally produce a daily mix of small animals and vegetable matter (including beans and grains) which would be yummiest and easiest to digest if cooked together.
But obviously, all of these cooking styles would have developed in parallel by different groups, as well being shared among trading partners. Given that our first “technology” was stone based, I’m betting the first pots were just soft stones with a depression chiseled into them by harder stones. But it might have evolved differently in an area with good clay soil and hard woods.
Never underestimate what our forebears could do with stone. They were just as smart as we are, and many of their methods have been lost to time. We look at much of what they built and can’t figure out how they did it.
In California, which had neither any metallurgy nor ceramics, water was boiled in water-tight baskets (their basket weaving techniques are unsurpassable) by adding heated rocks. That’s how they cooked their acorn mush.
This isn’t strictly accurate. Both at the Southern and Northwestern extremes, ceramic-using cultures existed - the Owens Valley Brown Ware of the Paiute, for example, or the ceramics of the San Diego Kumeyaay.
Sorry, too broad a brush. California is a long state. The desert peoples partook of cultures farther east and south, and the Northwest tribes started merging into the cultures of the Pacific NW, of course. The point I was trying to make is that cultures with almost no resemblance, technologically speaking, to those of Europe, managed to cook food perfectly well without any of what we think of as necessary objects.
I grew up in Sierra Leone, West Africa. When we went into native villages, we would see young women pounding something (and often chanting to keep the rhythm) in what amounted to a large wooden mortar and pestle. The ‘mortar’ was a hollowed-out log, maybe a foot or more in diameter and the ‘pestle’, was another log. It looked like hard work.
All kinds of grain were pounded in this way and used to make a king of porridge which was their staple food. Meat might be added if it was available. Rice was de-husked by beating it on a mat and fanning to blow the lighter husks away.
Haven’t read the whole thread, but wouldn’t it make sense that the first way humans “cooked” beans was by just sprouting them? Keep the beans wet for a few days, wait for them to split open and for yummy soft edible bits to emerge by themselves?