If the environment was rich enough in resources, they wouldn't have needed agriculture.
One of the advantages early humans had in the Middle East was wild grain in sufficient quantities to harvest without planting.
There are a couple of theories on this, one that humans developed an early taste for beer, and another that they really did plant these wild grains only just scattering sort of like you scatter grass seed on your lawn.
Think about it. If you gather seed, and store it, if it gets wet it will sprout. If it gets very wet, it will ferment.
So it's easy to imagine that a cache of wild grain got wet, sprouted, and some genius figured that if you put the seeds on the ground you'll get more grain.
Another genius figured out that if you put a lot of water on grain in a hole in the rock, it will ferment and you can get high.
We know this happened in the Middle East, we just don't know exactly when.
Again the godless liberal claim that man was so stupid back then...
Instead, Scripture says he was so brilliant, he actually named everything, from the animals to the plants, which is quite a feat if you look at a biology or agriculture textbook index.
Why the persistent claim that early man had less than current brain power? Because if you admit that they were like us, you are by inference admitting that part of Scripture is true, and by inference if you admit it's God's word, then you should be following it, but you aren't, so it's easier just to shut Him out entirely, and lie.
Christians understand the thinking, because we too are sinful humans. The distinction is, we now have a new nature, and want truth, and can see it, when you can't.