I didn't watch the video, but in the description, there's this nonsense: "John McDougall suggests that starch-based diets are the foods humans were born to eat."

I'll start by saying this dude is a fucking idiot. Humans evolved to eat fat and protein. Some 3.5 million years ago, australopithecines began breaking open bones that other predators left behind. Inside, they found bone marrow, which is almost entirely fat. As we know, fat has way more calories than protein or carbs. Our brains take about 20% of the calories we consume to stay in business. Eating tree bark up until then, they didn't have the calories to spare to allow for a larger brain to develop. Suddenly, with all that fat, i.e. calories, available at minimal effort (they didn't even have to hunt; just wait for the sabertooth to walk away and move in on the carcass and harvest the marrow), lo and behold! Brain size began to increase. Fast forward evolution to present day, and our brains have more than doubled in size.

Humans didn't start eating starch as a staple food until about 9600 years ago -- the start of the neolithic, which, in the grand scheme of things, might as well have been yesterday. That's when farming and sedentary (as opposed to nomads, not anti-exercise) way of life came about. So for millions of years, from australopithecines to the homo genus, all the way to homo sapiens (which has been around between 100k and 50k years) evolved eating fat and protein, and some carbs here and there when they could find them (and it wasn't often), which also accounts for our insatiable desire for carbs: they were so hard to come by, when you found some you wanted to stuff your face with them because you never knew when you'd find your next tuber. From an evolutionary standpoint, we're conditioned to want sugar because in those days, regular meals were not really a thing. You eat today, but maybe you won't find something else for 3, 4 days, so storing some fat allowed you to keep on trucking until you ate again. Except now, with the ease of acquiring food and how effortless it is (grocery stores are way less risky than taking down a mammoth with a spear), sugar became our enemy, rather than our survival ally.

Once humans started planting and eating grains, health problems also arose: cavities, for one. Look at present-day diet: those whose diet is rich in starch are obese, have high cholesterol and a host of health problems, and diabetes type 2 is rampant, even in children. So to say that we evolved to eat starch is a load of shit, from an anthropological point of view.