Based on a couple of comments to my last post on the topic, it appears that some of you might not have grasped all of the issues behind the original question. So let me clarify the question.
Humans require food for two reasons: Calories and Nutrition. It is possible to get a decent amount of calories from a large range of foods. For example you can get all of your daily requirement of calories from cooked pasta with marinara sauce, however this diet will not provide you many of the essential nutrients required for growth, repair and optimal function. Furthermore a person who is outdoors and active requires larger amounts of both calories and nutrients.
Today we can get both calories and nutrients by going to a supermarket, a restaurant or ordering takeout. Canning, packaging and refrigeration also make it very easy to get seconds and thirds of what we want.
Now put yourself in an age before metal weapons, agriculture, technology and relative peace and ask yourself-
How could hominids, some of whom were supposedly dumber than us, be able to eat so well and survive for hundreds of generations without tools and methods even the most primitive modern humans take for granted.
Remember that hominids were not big cats or bears. While physically stronger, they were not that different from us and were certainly not adapted to kill animals as obligate carnivores or bears can do. The very fact that they can be found in the fossil records for tens of thousands of years implies that they were quite successful at whatever they were doing to survive.
While palaeontologists unearth the tools of these creatures and describe them in great detail, how many wonder if they could live and prosper under the conditions these hominids supposedly existed? Could you do that with the same tools and social organization under conditions of relative prey abundance?