I found a good article on Science Daily about how researchers are using technology to see what early Humans or Hominins ate millions of years agao. Yeap they ate meat. Of course we know the meat back then was superior to what we see today as it was high in Monounsatuated fatty acids and Conjugated Linoleic Acid.
For me i eat lean meats and add lots of Olive Oils to get these healing fats into my Cell Membranes and Mitochondria's to keep me thriving at my high energy exercising routines and hopefully longevity.
ScienceDaily: The Evolution Of Human Diet