Which is the first domesticated plant? Are there plants regularly grown before being domesticated?
Generally, the oldest examples of domestication are considered to be emmer, einkorn and barley in the middle east, squash in Mexico, all at about 10,000 years BP. We can’t say which of these was first because we can’t date domestication more precisely.
Domestication is the modification of traits in the target species by humans. It may be accidental or deliberate, but it requires human agency and the end result must benefit humans in some way. It’s a long incremental process of adding more favorable traits over thousands of years, so you can understand that the very earliest examples would be very close to the wild form and show very few evidences of domestication. This is what makes precise dating so hard.
The best we can say is that emmer, einkorn, barley and squash show clear evidence of domestication at 10,000 years BP, therefore the process must have been started somewhat earlier. Can’t say which was first or if they were simultaneous.
are there plants regularly grown before being domesticated?
Humans have been eating these same plants we later domesticated for tens of thousands of years. We have archaeological remains of these same cereals 30,000 – 50,000 years old in contexts where it’s clear humans were eating them. But they were just gathering them from wild plants.
Humans probably did plant them too, long before domestication. Humans were nomads at the time, hunting/gathering their way through the landscape, exhausting one area and moving on to another. They couldn’t stop to farm, but they could certainly toss a handful of seeds on some likely spot in the hope that when next they returned, some seeds may have grown and escaped molestation by other herbivores, and thus provide some return on investment. There was no domestication, but there was probably deliberate planting.
For that matter, it’s very possible that agriculture also began long before the 10,000 BP date, perhaps 20,000 or 30,000 years ago. However, it didn’t take. See, what happens is that domestication requires a sustained effort over many generations in order to produce stock that is significantly better than its wild form. But humans may not have the chance to stay put and keep farming for two thousand years, or however long it takes to produce a worthwhile domesticate. So you may have many aborted attempts at farming where humans settled down to farm, even proceeded a little bit towards domestication, but the experiment ended when they were forced to move, and any changes reverted back to the wild.
In fact, there is some evidence of this, for example, see this 23,000 year old date:
A commonly offered theory is that such experiments failed because climate was too variable, so people would have to move on because it became too hot or too cold or too dry. It’s only since the Holocene about 12,000 years ago that climate has stabilized.
So as you can see, the history of plant domestication is hazy. Humans were deliberately gathering plant products including cereals at least 50,000 years ago, grinding them, pounding them, probably cooking them. Humans may have started early farming and domestication attempts 20,000 – 30,000 years ago, but didn’t get very far, and any domestic traits they managed to breed in were subsequently lost when farming was abandoned.
Beginning around 10,000 – 12,000 years ago, a longer lived experiment with agriculture began, and by 10,000 years BP we have archaeological remains of at least four crops with identifiable traits associated with domestication.
The figure I linked at the beginning showing the dates of domestication for different plants is from this source:
