Mental activity requires a lot of glucose, whereas muscles can run on fat, protein or glucose. Additionally, people are adapted to minimise their mental output. So if you're low on blood glucose, producing a lot of mental output for >6 hours is a real stretch.

Really? I've spear hunted fish when I was a kid and shot targets with a bow (if I were a proto-human it could have been small animals instead) and both were pretty damn easy and not mentally taxing at all.

I love bow-fishing! But shooting targets as a child is hardly the same.

Getting a powerful, accurate shot in itself takes a lot of concentration. But when hunting for sustenance it means getting up before dawn, tracking animals for miles on rough terrain, and managing to approach the animal in complete silence. Once in sight you have to stalk the animal and look for the one perfect opportunity because if you miss or are too loud it will run and you will have to repeat the whole process again. Add in the stress that you and your small group have to be successful or your tribe might go hungry and it's a whole different ballgame then shipping code at the end of the day.

What was the risk of getting mauled while doing this?

The majority of edible animals are not big game (by nature of the food pyramid), and a even a decent chunk of big game are not predators of humans. Plus, it's easy to overwhelm them if you have more than one person.

I've never hunted before, but I can't imagine at all that it's a fair fight. Humans have been known to trap them, net them, flank them, shoot them at a distance, lure them, corner them, smoke them out etc. etc.

None of which requires a whiteboard, drafting paper or a calculator.

Are you really going to argue that any human with any semblance of intelligence (and I don't mean deep thought here) would have to risk mauling to hunt for subsistence?

Your post specifically said SPEAR hunting. You do not hunt small game with a spear. Trapping is usually the most effective way of getting meat in the wild.

Off topic but some of the best traps are large modern mouse-traps. Just make sure to drill a hole and tie it to a tree with a strong rope so the animal doesn't pull it away. Set it, and you will almost certainly capture a small mammal within a day.

He might have edited it, but I read "spear hunted fish", not "spear hunted". That does not look dangerous on TV.

Makes me wonder: when did trapping start? 5,000 years ago? 20,000?

Probably closer to 200,000+. Fishing net's are at least 80,000 years old.

If you dropped me in a forest and required me to hunt animals with a spear, there would be significant higher-order mental involvement. For someone who has been doing it their whole life, I expect that is not the case in the typical hunt.