Not all meat even, it's mostly red meats (and generally ruminants) that are found to be generally unhealthy. And one of the large reasons is that over time, we

Not all meat even, it's mostly red meats (and generally ruminants) that are found to be generally unhealthy. And one of the large reasons is that over time, we have started breeding these meats to be extremely fatty, because it tastes better. No cows 200 years ago would have the same fat -> protein profiles as what we see today, and all of those fats are saturated fats, which tend to have large negative health effects. All of the leaner meats and some fish (ones without pollution issues, harder to come by as time goes on) are generally measured with improved health effects when consumed in moderate quantities in diets like the Mediterranean diet or Okinawan diet.