OK, 12K years not ten. I wouldn't call that science- while observation and trial and error necessary, they aren't sufficient. What was done to turn teosinte into maize was more of... a large scale, long-term, unintentional engineering experiment.
I'm not sure you can have engineering without some at least rudimentary approximation of a scientific method. Maybe that's a nitpick though.
Either way, I don't see a fundamental aspect of the scientific method missing from an observation -> trial -> results loop. I also don't see crop cultivation as unintentional, although I'm not clear what you meant by that. What wasn't intentional? Deciding to experiment with planting seeds would have been a deliberate choice. Probably based on some observation that where wild grains were gathered together and and little things fell off of them, sometimes the same type of plant would grow. Followed by the idea that putting those things in different places might produce the same effect. Etc.
I don't think you get from wild gathering in a nomadic lifestyle to settled agriculture without observing, coming up with ideas about what you observed, testing those ideas, and checking the results. That is. A scientific process.
Toesinte turning into maize would may have simply been a blind generations long domestication process, but not that spark of insight and experimentation that led to stationary agricultural societies.
