 Thanks. Thank you for choosing to hear Man the Fat Hunter. The amazing epistemological phenomena called the paleoblogosphere deserves a lecture of its own. Here I would like to recognize Dr. Michael Eads and Dr. Barry Groves, whose clever blogs had a significant contribution to my work. The lecture is based in part on a paper by the same name written with my colleagues, Professor Avi Gofer, Professor Isail Hirschkowitz and Dr. Ranbar Ka'i, which was published in December in plus one. Just google the name. It's free access. Many people don't realize how extraordinary large our brain is. It stands out in the animal kingdom like the neck of a giraffe. A few years ago, I asked myself, like many did before me, why we have such big brain? Why a very successful 900 CC brain Homo erectus, who lasted for 1 and 1 half million years, had to develop a brain that is 50% larger still to become Homo sapiens, while the chimpanzee managed with the same brain size for seven million years and counting. I have come to the conclusion that man was actually a fat hunter. And if I follow the fat, I'll find the answer. Other people came to the conclusion that man was really after fat first and foremost. The first is John Speth, a very well respected zoo archaeologist who wrote in a must read book about hunting and fat in 2010. Early in his career, he reached the conclusion that, and I quote, fat, not protein, seems to play a very prominent role in the hunter's decision about what animal male versus female to kill and which body parts to discard or take away. Another archaeologist, Jack Brink, writes in a book devoted to mass hunting methods of paleo-Indians in Alberta. Fat, not meat, was the food source most sought after by all plain aboriginal hunting cultures. And last but not least, because he really hit the nail on the head, Tyndale writes about the Australian aboriginals, quote, after killing the animal, they immediately feel the body for the evidence of the presence of cow fat. If the animal is fat less, it is usually left behind. So now we know that man was really after fat and that obtaining the limited quantity of meat that man can digest to energy was not his main problem. A yellow and wheeler proposed that high quality food allowed our brain, our big brains, and that our big brains enable us to obtain high quality food. It became clear to me that fat was a critical part of that high quality food. But all this doesn't explain why we evolved from Homo erectus to Homo sapiens. For that, we need to understand why fat was so essential. The child describes the diet of two Homo erectuses living in two different environments. For both of them, protein consumption is physiologically limited to 35% of calories regardless of the diet. They, just like us, don't have enough liver enzyme to convert more than a few hundred grams of protein to energy. This leaves a minimum of 65% to be supplied by plants and animal fat. Our brothers from the Mogongo and Palm oil fruit land will need to obtain little animal fat and all in all, say, 50% of his calories from hunting. On the other hand, his brother from the land of little plant food and plenty large animals will hunt for 70% of his calories, but most probably, and I hope you can see it by comparing the blue and red areas in the two columns. Most importantly, he will have to hunt fatter animals than his Mogongo's brother. If 70% of his calories are coming from animals and no more than 35% can come from protein, he needs an animal that can supply equal quantities of fat and protein. These are not many of those, and they are usually the larger animals. Luckily, according to paleontologists, they were abundant when our rectus ancestors roamed the Earth. I would just mention in passing that according to recent analysis published in my blog, chimpanzees receive 20% of their nourishment from protein and 50% from bacteria produced fat and only 30% from glucose and fructose. So the macronutrient composition of the nourishment is very similar to that of our Homo erectus friend on the right. As I said, hunting for fat has implication on prey size. Let's look at the third and more concrete Homo erectus brother who lived in the southern Levant, present day Israel, and whose energetic requirements were 2,700 calories a day. The winter rains have arrived, and there are plenty of pistachio nuts and olive trees and figs, so he managed to obtain 1,300 calories a day from plants. His protein is limited to 35% of 2,700. Hence, 950 calories. This leaves 550 calories to be supplied by fat. Now here comes the significant part of the model, and the reason why I go into such detail with this example. An optimal animal for our Levantine Homo erectus to hunt will be one that supplies the exact ratio relation of fat to protein that he needs. In our example, it's 37% for every 950 calories of protein, a 37% fat animal will provide the 550 calories of the fat he needs. Below is a chart showing animal fat percentage as a function of their weight. Now let's see which animal can supply this ratio of fat in our Levantine winter. It seems that a mixture of big animals with 53% fat and small animals with 35% to 25% fat will be just perfect. Following the pleasant Levantine winter, the six months dry summer sets in. Plants dry out, and the consumption goes down by, say, 25% to 900 calories per day. Protein is limited to its ceiling, so obligated fat is now 850 calories, 300 calories of fat higher than in the winter. For animal size, from animal size point of view, we are climbing the ladder, and we need a mix that will give us 48% fat. Since the larger the animal, the less fat it loses in the summer, we would like to put our hands on the largest possible animal to compensate for the smaller animal that do lose fat. Elephants are ideal, large and fat winter and summer. Many summer go by, and the population of large animals diminish slightly every year. It becomes more and more difficult to find elephants. Larger distances have to be covered in the summer heat in order to find fat-bearing animals and carry meat with the fat back to camp. Increased locomotion causes a daily caloric requirement to go up, say from 2,700 to 3,000. Most of that increase likely come from fat, as plants are very limited in mid-summer. Obligated fat is now 1,150 calories, and he needs to hunt the very large animal containing 55%, but these are the ones that are going extinct. What is a Homo erectus to do in the face of such dire circumstances? It turns out that there is a way to get 56% fat from a small deer, but it requires a hunter with a very capable brain. I came to this answer when I examined the archaeological record of a very interesting cave in the south of Israel, coupled with the result of a brilliant analysis by the one and only J. Stanton at Knowles.org. As it turned out, I lived 15 minutes drive from one of the most interesting archaeological sites when it comes to Homo sapiens evolution. And what's more, it is being excavated by my older acquaintances from Tel Aviv University, Professor Avi Gofer and Dr. Amber Krey. This fortunate situation provided me with the opportunity to test my hypothesis. The cave was occupied starting 400,000 years ago and ended 200,000 years ago by a very unique group of people, the Acheloia Broodian. The previous period, or as we call it, culture, the Achelion is associated with Homo erectus. While in the Levant, the Achelion ended 400,000 years ago. In Africa, it lasted additional 150,000 years. This fact alone indicates that changes probably happened first in the Levant. The Achelion Broodian culture was not a variant of the Achelion, as the name may suggest, but a completely new culture. The stone tools, which in Kesson Cave are dominated by flint blades and quina scrapers, are not found in the preceding Achelion, but are found again much later in more recent advanced cultures. The blades form a set of cutlery manufactured to handle the different stages of butchering, deflashing, and meat cutting. Controlling fire and signs of meat sharing on animal bones also indicate relatively advanced behavior. But the most exciting find in the cave were eight human teeth, that after a lot of work and debate among scientists were assigned in a recent paper to Homo sapiens lineage. Actually, the fine shouldn't have been so surprising, as in 1925, a part of a skull, which is shown there, was found in Zutie, another Achelion Broodian cave in the north of Israel. This year, a paper by some of the most respected physical anthropologists suggested that the morphology present in the Zutie skull may characterize a population immediately post-dating the divergence of Neanderthals and Homo sapiens. The teeth from Kessam cave had weight to the proposition that the divergence was in the direction of Homo sapiens. So can we help with our hypothesis to find out what happened in the Achelion Broodian? For that, we had to follow the fact. Three facts about Kessam cave are telling in this regard. The first, there are no bones of elephants. In Kessam, or any other site in the Levant, post-dating for 100,000 years. The second is that 80% of the animal bones in the site belong to fallow deer. That profile of smaller animals by itself points away from Neanderthals, who hunted almost exclusively big animals. The third, and as it turned out, the most important fact in explaining the reason for the transition was that most of the bones of the fallow deer belong to mature individuals. Now that we understand the importance of big animals to our Homo erectus friend, let's see what happened to them in the transition. Blue in the chart marks animals above 200 kilograms, and red marks animals below 200 kilograms. Sampling six sites from the Achelion period in the Levant, we found that over 60% of the animal caloric contribution came from seven tons elephant, and only 15% from smaller animals like deer. In contrast, at Kessam cave, 60% of the calories came from a 90 kilogram fallow deer, and less than 40% from large animals. As you can imagine, hunting plenty of elusive fallow deer is a completely different ball game than hunting a few elephants that previously supplied the meat and fat. As I said, the strange thing about this fallow deer was that most of them were mature males and females. This is a bizarre profile for a predator. Lions hunt randomly, and their prey age profile resemble that of the prey population, while long chasers, like wolves, hunt typically young and old animals. Here we have a predator that constantly picks up the most difficult age group to hunt. And letting younger and older animals, he encounters sleep by. This looks like an energetically wasteful strategy, and as we previously saw, the small increase in energy requirements require a significant increase in obligated fat, since most, if not all, of the increase had to come from fat. Well, the reason for this bizarre behavior is, of course, fat. In his post, Jay Stanton brings a chart that describes the fat content of mature bulls, young bulls, and mature female among caribou deers throughout the year. He calculated that if a hunter hunts mature female in November to April, and then mature male in May to October, he can obtain 56% fat. Instead of the 36% fat he would obtain had he hunted randomly. Hunting primed dals is a pattern that was not known before the Archeria brudium, but was very common ever since. It is impossible to overestimate the sophistication of mind that is required for the efficient performance of that pattern of hunting. Here is a herd of fallow deer. We, of course, could not tell a fat from a non-fat animal. Even hunter find it difficult to do, as Jack Brink notes about the Palaeo Indian. And I quote, not only did the hunters know the natural patterns of the bison followed, they also learned how to spot fat animals in the herd. An experienced hunter would pick out the pronounced curves of the body and hide the sheen of the coat that indicated the fat animal. In short, it takes brains to spot fat animals. One should learn and become experienced. And one last point on hunting small animals and brain. Animal tracking increased efficiency of hunting compared to random encounters tremendously. In the army many years ago, I used to work with bedding trackers. I noticed that they, in performing their tasks, they had to continually form and revise hypotheses based on the incremental information they gathered from very few clues, which could have different meanings under different weather and soil conditions. The book, Mammals, Tracks, and Sign, contains 792 pages. A good hunter probably stole at least that amount of information which he acquires by learning. And more important, use it time and again during changing hunting situation to form hypotheses and revise them. As you may know, the human average brain size today is 1,350 cc, is smaller than at its peak, which was about 1,500 cc. The reason may be that agriculture does not require the intensive forming and reforming of hypotheses under time pressure. Farming, to my mind, demands a brain that operates like a simple computer program, performing the same orders over and over again in step with the seasons. Industrial work, for the most part, is even less demanding. So to summarize, in the Levant 400,000 years ago, following the extinction of his main fat source, the elephant, men found a solution to obtaining the vital fat he needed from smaller animals, hunt them when they are at their prime fat-carrying season. This solution demanded an increased mental capability. So only those whose brain was large enough survived. In time, they were called Homo sapiens. I'm sure that you will not be surprised to learn that in Africa, as in the Levant 150,000 years earlier, elephants disappeared from a archaeological site together with the Ashulian. 50,000 years later, when in the Levant, the Ashelyabrudin was winding down, the first Homo sapiens is found in Africa. On a more general note, most of the world's organic energy is stored in the form of fiber, in trees, and other plants. Much less is stored as protein, and still less is in the purest form of an organic energy, fat. Evolution has caused us to lose our ability to process much fiber to energy. But in return, gave us the brains that enable us to obtain fat. We can now propose a refinement to a yellow and wheeler hypothesis of 1995 by substituting fat for what they term high-quality food. So it is fat that allowed our big brains, and our big brains allow us to obtain fat. Human prehistory over the next 200,000 years, following the Ashelyabrudin and until the agricultural revolution, is the subject of my present research. I can already tell you that animal fat continues to play a significant role in it. The practical implication is clearly evident, however. We have evolved to eat animal fat. Thank you. Have you found it?