Ray Audette made an interesting comment in a previous digest, noting that a man with 6 dogs and an atlatl would have been a formidable predator capable of mass extinction of large pleistocene mammals. Much has been written on man's role in the wide scale extinctions of large mammals that occurred at the end of the pleistocene: 1. Stuart AJ. Mammalian extinctions in the late pleistocene of northern eurasia and north america. Biol Rev 1991 66:453-62. 2. Martin PS. The discovery of America. The first Americans may have swept the western hemisphere and decimated its fauna within 1000 years. Science 1973 179:969-74. 3. Diamond J. The American blitzkrieg: a mammoth undertaking. Discover 1987 June:82-88. 4. Diamond J. The golden age that never was. Discover 1988 Dec:71-79. 5. Martin PS. 40,000 years of extinctions on the planet of doom. Palaeogeography, Palaeoclimatology, Palaeoecology 1990 82:187-201. 6. Haynes CV. Elephant hunting in North America. Sci Am 1966 214:104-112. 7. Grayson DK. The chronology of North American late Pleistocene extinctions. J Archaeol Sci 1989 16:153-65. 8. Mosimann JE, Martin PS. Simulating overkill by paleoindians. Am Sci 1975 63:304-313. During this period, which presumably coincided with increasing technological development and increasing human populations, South America lost 46 out of 58 genera (80%) of mammals exceeding 44 kg; Australia 15 out of 16 (94%); North America 33 out of 45 (73%). For Europe and Africa the figures are considerably lower (7 out of 24 - 29%) and (2 out of 44 - 5%) respectively. These mass extinctions affected large terrestrial mammals exclusively, whereas invertebrates, small to medium terrestrial vertebrates, plants and marine vertebrates continued almost unscathed. Martin and others believe that human overkill was largely responsible for the extinction of these large mammals and that many of these huge behemoths were wastefully killed and only certain portions of the carcass were selectively consumed. Present day hunter gatherers prefer fatty portions of the carcass (organs, brains, marrow, tongue, fat depots, fatty cuts of meat) , and it is likely that our ancestors did as well. Butcher marks on mammoths in a number of european sites indicate cut marks which suggest that tongues were highly prized. Ray Audette suggested that many of the mammals that became extinct during this period were those which stored the most adipose tissue, and hence were selectively preyed upon. Although, we have no way of determining the body composition of extinct animals, it is likely that high northern and southern latitude mammals probably had to store fat similar to modern mammals living in seasonal climates to survive through the winter. Given modern man's preference for fat, it is no less likely that our ancestors did not seek out fat and fatty animals as well. Further, because of selective utilization of animal tissues (both pre-historically and in present day hunter-gatherers), the fat content of the human diet could have easily exceeded estimates of 15-20% of the total caloric intake which have been widely used as a model for the paleolithic diet. The other point worth noting here is that for most "paleolithic meals" protein and fat would have almost always occurred together (since these two elements always were present with the kill - except for small stores of liver and muscle glycogen, animals are virtually devoid of carbohydrate) , whereas carbohydrates from collected plant foods would have more often been eaten separate from the protein/fat combination. The health implications of these ancestral macronutrient combinations are critical for modern man. Recent studies show that high fat, high CHO meals tend to increase post-prandial lipemia compared to lower CHO meals, and that elevated blood lipid levels in the post-prandial period are a significant risk factor for CHD (Chen Y.D. et al. Effect of variations in dietary fat and carbohydrate intake on postprandial lipemia in patients with noninsulin dependent diabetes mellitus. J Clin Endocrin Metabol 1993 76:347-51.). Taken together with Wolfe's data (Wolfe BM. Potential role of raising dietary protein intake for reducing risk of atherosclerosis. Can J Cardiol 1995 11:127G-131G) showing isocaloric replacement of CHO with animal based protein results in lowered total CHOL, LDL, VLDL, TG and increased HDL, these experiments tend to confirm that our ancestral eating habits of combining fat with high amounts of protein produces a less atherogenic profile than combining high levels of carbohydrate with high levels of fat. Preliminary data from our laboratory utilizing game meat consumption confirms this general concept (Tillmans C, Cordain L, Harris et al. Game meat is an effective dietary component in lowering serum cholesterol. Proc Rocky Mtn Chapt ACSM; abstract, 1995). Cordially, Loren Cordain, Ph.D.