What times of day do Hunter-Gatherer’s eat?
Since we probably can’t know about the meal-times of archaic people, I will ask this about the remaining primitive groups. I mean primitive in the sense of no agriculture or food-storage technologies.
I would think a meal upon waking up is universal. You can’t eat while you sleep no matter how much technology you have, so you will wake up hungry.
I usually start burrowing for grubs just after I wake up and stretch out. Typically, I like to first wander down to the stream, bang some rocks and sticks together to praise the gods, and then get a good drink of water before I go grub-hunting. I prefer a good protein filled breakfast.
Sometimes, when the sun just starts clearing the tree limbs, (I believe you call it 10:AM), I’ll start setting snares for my midday meal. While I’m waiting for prey to fall victim, I’ll forage for nuts and berries. After extensive research (i.e. trial and error), I’ve found that 90% of blue colored berries are edible, while only 3% of red ones are. IANAL, and YMMV. Other conditions dictate what species of nut and berries are around. I recommend finding what more evolved humans call “books” and “read” about which ones are safe (I have yet to learn these skills). I just know by my advanced senses what is safe and what isn’t. After a bit of foraging, I usually get a squirrel or rabbit, and then bang some more rocks together to make a fire to cook it on. Thus is my midday meal - something light so as not to distract me from my cave painting or petroglyphing (the ladies of the other tribe love my wild buffalo hunting scenes).
In the evening, when the sun touches the horizon towards the far-off mytical land known as “Montana”, I usually get hungry enough to want to eat a full-sized animal: something with hooves usually suffices. Again, I bang some rocks and sticks together, beat my chest, and am off to the hunt! A throw with my atlatl or two later, and I have a full-sized deer, or a baby buffalo of some sort. A few more sticks and rocks, and voila! A fire to roast upon. On occasion, marauding tribes from the outlands can see my fire and they come try to take my food. Sometimes I’m unlucky enough to be overrun, beaten with a large club or rock, and lose my food. Other times, I take the high ground and beat my opponents taking what food they have. Why, just three moons ago I forced back some wild wooly “South Dakotans” and took some softer beans they called ‘grain’. One of my prisoners said that if I took their ‘grain’, put it in the ground and covered it up, a mighty plant would grow and would provide me a great bounty. I tried this, and four suns later I said, “Aw the hell with it!” and moved on.
Sometimes if I’m spry and crafty, I will fashion a spear and go to the river. If the water gods smile upon me, I will supplant my lunch or dinner with tasty delights from the sea. I’m not very good at this though - my chosen bodies of water often have people on them with great bent sticks and small circular rocks. They wear colorful clothing and call themselves “hockey”. This tribe scares me so . . .
Anyway, that’s what I usually do. Such is the way of a trained Warrior. So let it be written, so let it be done.
Tripler
Someone once showed me a ‘microwave’. I beat it with my club in fear.
Heh. 
No cite, sorry, Djbdjb, but I’ve watched a few National Geographic specials on folks like the !Kung bushmen, and I believe it’s basically “snack and nibble all day”.
And, a “meal upon waking up” is by no means universal. I know lots of people who can’t stand the sight of food before about 10 a.m., so they basically just eat lunch and supper. Not everybody wakes up hungry, especially if you had a protein-and-fat-rich supper the night before. Your digestive tract is still working on that at 6 a.m. the next day.
How do you pronounce the !?
Make a clicking sound with your tougue.
Make that “tongue” … .
[hijack] It is actually a (post) alveolar click, meaning the tip of your tongue goes just behind that ridge that is just behind your upper teeth when you make the sound. I mention this as there are a number of distinct “click” sounds utilized by speakers of various languages in sub-saharan Africa - including bilabial, dental, palatoalveolar, and alveolar lateral clicks.
[/hijack]