On that note, you may also wanna check out, "Australopithecus Not Much of a Nutcracker," which is directly related to research on Paranthropus boisei's diet I reported on a couple days ago. The piece is a bit more thorough though, providing a summary of the,

"different analytical methods suggest that robust australopithecines didn't eat hard nuts and seeds routinely as had been thought, and that robust and gracile hominids actually ate similar fare."

Last but definitely not least is an interesting news piece on the paleohistory of tuberculosis. In the news report, Ann Gibbons discusses how DNA, coming from early humans were infected with strains of Mycobacterium tuberculosis, prior to the emergence of pastoralism. This suggests that humans were the primary vector that transmitted the disease to bovids and other animals and not vice versa. This kinda shakes up the hypothesis that Razib has been thinking about -- that importance of vitamin D was selected as an important immune system component after the Neolithic revolution, when humans began to be pastoralists and agriculturalists.

All three news pieces are short and sweet, a total of three pages long. Check'em out.

Gibbons, A. (2008). AMERICAN ASSOCIATION OF PHYSICAL ANTHROPOLOGISTS MEETING: Tuberculosis Jumped From Humans to Cows, Not Vice Versa. Science, 320(5876), 608a-608a. DOI: 10.1126/science.320.5876.608a

Gibbons, A. (2008). AMERICAN ASSOCIATION OF PHYSICAL ANTHROPOLOGISTS MEETING: Australopithecus Not Much of a Nutcracker. Science, 320(5876), 608b-609b. DOI: 10.1126/science.320.5876.608b

Gibbons, A., Culotta, E. (2008). AMERICAN ASSOCIATION OF PHYSICAL ANTHROPOLOGISTS MEETING: Snapshots From the Meeting. Science, 320(5876), 609-609. DOI: 10.1126/science.320.5876.609

The results indicate that marks on the teeth of Paranthropus boisei do not correspond with the size and shape of its teeth. This observation suggests that structure of the skull, mandible, and teeth are not enough to infer dietary preferences. Furthermore, evolutionary adaptation for eating may have been based on scarcity rather than on an animal's regular diet.

The paper, "Dental Microwear and Diet of the Plio-Pleistocene Hominin Paranthropus boisei," is authored by Peter Ungar, Frederick Grine, and Mark Teaford. Brian, from Laelaps, has written up a very excellent and thorough review of the research. You should check that out.

Why did the authors look at dental microwear on the surface of the teeth? They explain that dental microwear offers direct evidence of the mechanical properties of food item, and that makes a lot of sense. During mastication, the food an organism eats abrades with the surface of the teeth. The texture of the food may scratch and dent teeth, especially if really hard foods like nuts, roots, and tubers are chewed. Likewise, softer foods affect teeth less.

Based upon the size and morphology of Paranthropus boisei teeth, many previous researchers thought they ate tough foods. Hell, the type specimen for P. boisei has been nicknamed "Nutcracker Man." They have saggital crests similar to gorillas They also have very large teeth with thick layers of enamel. Coupled with the massive jaws, many people thought that P. boisei consumed really dense, fibrous plants.

As I've said, the results of the microwear analysis indicates that P. boisei did not eat the hard abrasive foods that we thought they did. Using a confocal microscope, engineering software and scale-sensitive fractal analysis the authors analyzed the around 54 molars from seven specimens of P. boisei. These seven specimens came from different areas, Ethiopia, Kenya, and Tanzania, respectively. Also, these specimens cover over 1 million year of P. boisei existence. Any similarities or differences in the microwear on P. boisei teeth from these temporally and spatially different locations woulda screened out variations in diet reflected to time or environment.

For your viewing pleasure, the authors provided this photograph of detailing the degree of microwear of the teeth of the seven different specimens.

Here's the legend: (A) KNM-CH 1, (B) KNM-ER 729, (C) KNM-ER 3230, (D) KNM-ER 3952, (E) KNM-WT 17400, (F) OH 5, (G) Omo L7A-125. Clearly you see scratches...

... But what Ungar et al. were looking for was the degree, complexity and directionality of wear textures. Again, hard, brittle foods like nuts and seeds tend to lead to more complex tooth profiles, while tough foods like leaves lead to more parallel scratches, which corresponds with directionality. Comparisons of the the dental microwear profiles of P. boisei to the microwear profiles of extant primates indicates they didn't eat the same type of foods. Grey-cheeked mangabeys and brown capuchins sometimes rely on hard nuts or palm fronds, as do the mantled howling monkey and silvered leaf monkey. Also included in the comparison was microwear analysis on teeth of Australopithecus africanus.

The P. boisei teeth show light wear, suggesting that none of the individuals ate extremely hard or tough foods in the days leading up to death. The microwear patterns are more consistent with modern-day fruit-eating animals than with most modern-day primates. This conclusion is a fundamental shift in the way we think about the diets of early hominins.

Before you write off the anatomical and evolutionary mantra "form = function," please consider this: I did not read any discussion on other possible causes for the lack of deep pitting from hard foods.

This is unfortunate. I wonder if the depth of the pits coulda have been buffed out over the millions years these fossils persisted? We know the fossilization process is a time intensive process, and many different weathering affects affect how surfaces of bone are preserved. Furthermore, many fossils are formed by being deposited in or around water sources. Water moves things, like rocks, wood, and bones. The abrasive edges of rocks are buffed down to smooth river stones over time. Couldn't this have happened on a microscopic scale?

Yeah, I think it is certainly possible, even if the entire specimen, like OH 5, don't show signs of massive weathering, we are talking about teeth that are very old. Teeth that were exposed could have been buffed out by other elements like wind, too. Suffice to say, many different things coulda happened to them to affect the degree of the abrasions. Comparing them to modern primate teeth is somewhat flawed because modern primate teeth haven't been affected by the forces of nature for millions of years.

Ungar, P.S., Grine, F.E., Teaford, M.F., Petraglia, M. (2008). Dental Microwear and Diet of the Plio-Pleistocene Hominin Paranthropus boisei. PLoS ONE, 3(4), e2044. DOI: 10.1371/journal.pone.0002044

What is dental plaque? Much to the chargin of dentists out there, the composition and origin of dental plaque isn't known to most. We may know it simply as something we work so diligently every morning and evening to brush away. Plaques are a type of biofilm. Bioflims are an amalgamation of microorganisms, who excrete a goo to protect themselves and allow them to stick together. Inside this gooey microecosystem, these crafty microorganisms also trap food particles to use as energy sources for themselves. If left untreated on teeth, these plagues of microorganisms grow and the amount of anaerobic respiration increases reciprocally. One of the byproducts of anaerobic respiration are acids which consequently demineralize adjacent tooth surface, and form cavities. That's why you should brush and floss twice a day.

In September of last year, I shared news of how Neandertals may have also been aware of their dental hygiene. We saw how they may have used toothpicks. But, they didn't have Sonicare toothbrushes and dental hygenists scraping away plaques every six months. Inevitably, some plaques persisted and in the teeth of a 35,000 year old Neandertal (Shanidar III). Amanda Henry was able to recover plant material. Henry gets into a discussion on how this showed evidence that Neandertals ate plants.

Not too novel, but definitely important to finally confirm. Much like the conclusion that Neandertals were mobile, plant consumption among them is one of those things we knew was most likely the case. How? Based upon the dental anatomy and morphology of the teeth, we knew they had very robust molars to grind down plant materials. Comparison to extant apes, like chimpanzees and humans, confers that Neandertals may have also been omnivorous. Furthermore, the results of a 2006 Science paper, an isotopic analysis of hominid teeth revealed that hominids ate a variety of foods.

I was gonna get into a discussion on how this one finding doesn't mean all Neandertals died without brushing after a nice yummy salad meal. Nor does it elucidate how many times this Shanny-3 ate his greens. But, Henry acknowledges that and cautions that Shanidar III is only one fossil and does not provide enough evidence to make conclusive statements about the entirety of the Neandertal diet. I commend her on that. Even with this disclaimer, Matt Sponheimer, lead author of the 2006 isotopic analysis still wanted to have the last word, rehashing that,

"...[this study] does not indicate whether an individual Neandertal ate plants once or a thousand times.

It also doesn't show the relative proportions of a food type in the individual's diet.

"Thus it is but one flawed technique of paleodietary reconstruction among many," he said."

While we consider Matt's critiques, let's also consider one I thought of -- The most simple explanation of the presence of plant material in plaques on the teeth means that this Neandertal chewed plants. Without an isotopic comparison of the recovered plant material to Shanidar 3's teeth, we don't know if this guy was really digesting the plant. Maybe Amanda Henry is looking into that...

One last thing, if Shanidar 3 really was eating plants, did his foot injury have anything to do with this? See, Shanidar III has a degenerative joint disorder in his foot. That woulda caused a lot of pain and limited his mobility. Would that have anything to do with why he was chewing on sedentary food sources?

Trinkaus, E. (1982). The Shanidar 3 Neandertal. American Journal of Physical Anthropology, 57(1), 37-60. DOI: 10.1002/ajpa.1330570107

Sponheimer, M., Passey, B.H., de Ruiter, D.J., Guatelli-Steinberg, D., Cerling, T.E., Lee-Thorp, J.A. (2006). Isotopic Evidence for Dietary Variability in the Early Hominin Paranthropus robustus. Science, 314(5801), 980-982. DOI: 10.1126/science.1133827

The basic principles of his diet are to

• Eat lean meat and high fiber, non-starchy fruits and vegetables.
• Grain, tubers (potatoes, yams, etc.), beans and sugar are not allowed
• Fat intake should be moderate
• Saturated fats are to be avoided. Equal amounts of omega-3 and omega-6 fats should be eaten
• Sodium intake should be kept low and potassium.
• The diet should have a net alkaline load.
• Focus should be on meat and nutrient rich plant foods.

Dr. Cordain feels that this is the way we are genetically programmed to eat. The diet he recommends is most likely healthier than what the average American eats in a day. In fact, there is a chart in the books comparing the nutrients in a sample standard American diet versus a sample Pale Diet menu. The levels of nutrients in thePaleo Diet are many times higher that the typical American diet. One thing I'm not sure about is the high amount of meat he recommends people eat in his sample menus. A high meat diet is contrary to many of the recommendations of other diet experts. He might be right, but it hard to accept his advice because it is so contrary an ideas to what most people have been taught about healthy diets over the years.

One of the factors I liked about this book is that many of his suggestions seem to be based on hard science. I've read some of the other books available on alkaline balance and few, if any, refer to any research papers. Many of the other books have a lot of claims about alkaline diets that are unsupported and unverifiable. While other health experts I'm sure would take issue with many of the suggestions in the book, at least Dr. Cordain does attempt to provide scientific backing and supporting studies for most of his recommendations.

I tend to agree with him about avoiding grains. I can't say I always follow the advice to limit grains, but I do feel better when I do minimize them in my diet. I think most grains tend to be too high in carbs and too low in nutrition for the amount of calories they provide.

However, I don't understand why Dr. Cordain doesn't want people to eat tubers, though. They are a completely natural food and it seems like they are a staple for many primitive tribes. I'd be very surprised if Paleolithic people didn't in reality eat tubers. I also like to eat beans. They are very high in magnesium, which is a good anti-stress mineral. I always feel better after eating lots of beans, so I wouldn't stop just because of this book.

Overall the book has some good points, but I'm not sure it is really for perfect diet for everyone. It seems like a high meat diet would not be healthy for all body types, especially people who are overweight since meat is a very high calorie food.