Animal source foods (ASF) have always been a constituent of human diets. Their pattern of use, however, changed in dramatic ways over the course of human evolution. Before 2 million years ago (mya), meat in particular was acquired opportunistically via hunting of small or young animals and scavenging of animals killed by other species. At some point after that time, humans began to hunt cooperatively, making possible the acquisition of meat from large game. The marked increase in human heights between 2.0 and 1.7 mya may be linked to more efficient means of acquiring meat, namely through hunting. The final pattern of meat (and other ASF) use before the modern era is associated with the shift from hunting and gathering beginning approximately 10,000 y ago. This fundamental dietary change resulted in a narrowing of diet, reduced consumption of meat and increased focus on domesticated grains. The study of archaeological human remains from around the world reveals that this period in human dietary history saw a decline in health, including increased evidence of morbidity (poorer dental health, increased occlusal abnormalities, increased iron deficiency anemia, increased infection and bone loss). Human populations living in developing and developed settings today rely on meats with lipid compositions that when eaten in excess promote cardiovascular disease. As humans become more sedentary and eat more high fat foods, we can expect to see increases in heart disease, osteoporosis and other diseases of "civilization."