The Mediterranean diet is pretty much nothing like people in the Mediterranean eat today either. Very old people had a radically different diet during most of their life.

I might be missing something but AFAIK that is not true. I live adjacent to the Mediterranean and I still see folks eating at home what is considered their diet.

Can you elaborate what you meant?

I'm Greek, and we cook what my mom used to cook, which is what my grandma used to cook. It's something like "meat once a week, fish twice, vegetables the rest". My favorite dishes are peas, beans, lentils, and I don't tend to like steak much, for example.

If we do use meat, we use it in dishes with lots of vegetables, e.g. stuffed zucchini with rice and mincemeat (though the mincemeat is optional).

The old diet had very little meat for example. The modern diet has meals daily that would be eaten on special occasions only a few generations ago. My great grandmother for example fed her family (more than ten people!) on one pig and a couple of chicken per year. Now the meat consumption in her home country is nearly seventy kilograms per person.