Ridwan Asher said:
So here is my question : what is it that sets the founder crops apart from the rest of domesticable plants ? Why do humans have to go through them in order to be able to shift from hunting-gathering to agriculture society ? Why cannot people domesticate other plants before at first domesticate the founder crops ? Is domesticating founder crops exceptionally easier compared domesticating other plants ? Why is that ?
Founder crops is basically shorthand for a group of crops which, taken together, are enough to allow people to leave the hunter-gatherer lifestyle and take up a farming lifestyle, either part of the year or a full year. (There can be a hunter-gardener stage, probably, although that's not certain.)
In terms of being easier to domesticate, that's certainly part of it. They need to be ones where unconscious selection through human action is enough to change their genomes into a form which is usable by humans as a farming crop. The first farmers don't have any conscious examples of domesticable crops before them, of course, so the process of selection needs to start out as an unconscious action.
Another part is that the plants need to be able to be stored properly, and/or be available for harvest all year round. The big advantage of cereals is that, properly stored, they can be kept for years. Some tubers can be kept for a year or more, in the right conditions, but it depends on the tuber and the climate.
The third key thing is that the combination of plants, together, need to be able to sustain a complete diet. This is hard with a lot of plants, since plants are often rich in carbohydrates and sometimes fat, but are often poor in protein or other essential nutrients.
Getting these combination of things is often difficult, and the process of unconscious selection can also take a while before it turns plants into a useable form. Maize probably took several thousand years longer than the Old World before it grew into a form which was large enough (in combination with squash etc) to sustain a complete diet.
In LRG, I addressed it by the red yam working as a crop for hunter-gardeners, then having them borrow the aquaculture techniques of the *Gunditjmara (which did exist in OTL) to give them enough protein to settle down more or less permanently, and only then did they start on other crops.
In more general terms of domestication, remember that not a single culture anywhere in the world domesticated any crops before the end of the last Ice Age (technically, the start of the current interglacial period). Why this is so is a good question - presumably it has something to do with climatic instability during the Ice Age, although no-one's quite sure. Regardless of the reason, though, it means that the 20,000+ years that the Australoid peoples in New Guinea lived without domesticating crops is not really anything to take into account, one way or the other. It's only the time difference after the last interglacial ended that really matters.
With Indonesia in particular, a big problem with tropical climates is that food is very hard to store, since there's dampness and heat all year round, not to mention more insect and rodent pests. This is one reason that very few domestications started in the tropics - New Guinea is about the only one that's known for sure (and
maybe West Africa). It's quite significant that New Guinean agriculture appears to have started in the highlands, though - cooler, easier to store food, and so on.
I don't know enough about the particular plants in Indonesia to know what combination of plants might work as founder crops, but they will need to manage all of the above issues.
Fruit orchard are unfortunately quite useless as founder crops
unless there's a fruit which can be stored for a decent length of time, ie until the next harvest. Since most fruit trees only flower once a year, and keeping fruit edible in a tropical climate is nearly impossible without refrigeration, that's going to be tough.