Sometimes I think people think too much inside the box when to comes to what our ancestors used to eat. Meat, fish, vegetables, fruit, grains.

It's most likely they ate whatever was even remotely edible. Anything that flew, walked or crawled, grew above or below ground. Insects, roots, fungi, berries...whatever. Everything was at one time tested for edibility. We are all overbred city folks. Most of us wouldn't survive six months in the wildnerness. We'd probably starve to death, if the elements didn't get to us first. We'd starve to death with food all around us, because it wouldn't occur to us it's food. So I think our assumptions as to what our ancestors ate on a daily basis are too much based on what can be found in our modern supermarkets.

I'm sure meat was a source of high quality food for our ancestors. But meat is unreliable, you need to catch it first, and that relies on skill, luck and avalaibility. There were surely periods where luck failed. The diet was probably heavily supplemented with easier stuff. Stuff that didn't run away from you.

Also I often hear people say that fruits and vegetables availability was limited by the seasons. Well that's only in the northen climates. If you believe the current evolutionary theory, humans emerged from Africa, which is not a temperate climate.

These are just random thoughts, I'm not an expert. I know the earth went through a must colder period, how that impacted the climate in Africa. We really need more data and less assumptions.