Mark:

I'm not confusing my citations. Let me explain in more detail.

Since the measurements given are only accurate to within 1%, proportions of 9%/8%/2% means that a single 1% variation due to rounding, let alone multiple variations, can change the listed proportions by 12% up to 50% — depending on which number you twiddle.

Furthermore, the question remains: how were these percentages calculated in the first place? From the caption for Fig. 6: "Edible carcass fatty acid composition was calculated by multiplying tissue and organ mass by fatty acid composition (% mass) in these tissues from values for caribou or similar ruminant species."  So these relative values in Fig. 6 weren't even measured directly…they're imputed from measurements that might not even be from caribou!  

 Claiming 51%/49% and 53%/47% are significantly different than 1/2 (or each other) under these circumstances is strongly disingenuous in my opinion — as is claiming any sort of 'seasonal cyclic depletion'.

My points stand.

Moving on to the other Cordain et. al. paper you reference (full text here): based on Table 5, the muscle tissue lipids of wild game average 45% SFA, basically identical to feedlot beef…and, as is noted repeatedly, muscle tissue concentrations of SFA are substantially lower than subcutaneous fat concentrations (tissues typically eaten by hunter-gatherers but trimmed and discarded by most modern humans).

Given the inevitable measurement differences between individual animals (this independent analysis shows muscle tissue concentrations of SFA in grass-fed beef to be 51.5% SFA, 44.7% MUFA, 3.8% PUFA), I think that claiming any decreased relative concentration of SFA in wild game vs. modern feedlot beef is nonsensical.

Furthermore, the data in Table 5 includes n-6/n-3 ratio. The average of all wild game is 3.8, versus 5.2 for grain-fed beef and 2.2 for grass-fed beef. So according to this data set, wild game muscle tissue has a PUFA ratio closer to feedlot beef than to grass-fed beef! (And, again, Table 5 shows 10.3% PUFA for grain-fed muscle tissue lipids, vs. 3.8% for an independent analysis of the same…so there is substantial variation involved.) 

Please note that I don't disagree with Cordain's conclusions about n-6/n-3 ratios: I disagree with his conclusion that "Fatty domestic meats" are to blame. Seed oils are to blame, as they rarely contain any n-3 at all, and never contain EPA and DHA.  And the PUFA profile of chickens and pigs is far inferior to grain-fed beef anyway.

I will give you credit for catching one error, though: the percentages in Figure 6 are total energy, not fat percentage, so my last sentence is incorrect. I'll revise to reflect that…as well as the data below.

However, Cordain's calculations of total energy in Figure 6 are wrong, and do not reflect the animals which are actually hunted and killed.

From the paper: "Total body fat and total body protein, as a percentage of energy, were calculated from the respective mean values by weight by using the cubic regression equations developed by Cordain et al (20)."  That would be this paper, and this figure contains the cubic regression equations.

The assumption Cordain makes is that hunters would randomly choose a caribou from the herd: Figure 6 includes "mature male, immature male, and mature female caribou."  

Yet the written record of hunting cultures shows this assumption to be nonsense.  [Edit to add: I've added all this, as well as direct evidence from archaeological remains of caribou hunters, to the article.  And all my speculations below turned out to be absolutely correct.] We have direct evidence from observing Native American bison hunters: they preferentially hunted only the fattest animals (usually cows that had not borne a calf that year) and often discarded the lean meat if fattier animals were available. I quote Jack Brink, Northern Plains archeologist, and his masterwork Imagining Head Smashed In:

"Fat, not meat, was the food source most sought after by all Plains Aboriginal hunting cultures…"

"Assuming that bigger was better, he [George Carlin] aimed at a massive bull and suffered ridicule and laughter from the rest of his party 'for having aimed at an old bull, whose flesh was not suitable for food.'"

And we see quotes like "My people killed three bulls … which served for our dogs." from early explorers.

Furthermore, they killed most animals during the fattest time of the year (late fall), and preserved their flesh for consumption during the leanest times: "The Indians had certain spots where the fixed winter camps were established in the fall of the year. At this season the buffalo were fat and prime and the drives to secure a winter's food supply were usually held immediately after this fixed camp was established."

One might argue that this preservation was a more recent adaptational behavior — but so is living in a cold climate at all, as modern humans didn't leave Africa until c. 65,000 years ago, and didn't arrive in Siberia until perhaps 35,000 years ago. Game in sub-Saharan Africa, where hominins evolved, doesn't have nearly the degree of seasonal fat enrichment and depletion that Arctic animals like caribou do (or even North American game animals like deer and elk), so year-round fat content of African game hunters wouldn't have had the same radical seasonal depletion issue.

Returning to Figure 6: we've established that caribou hunters would preferentially kill the fattest animals, not a random animal. Figure 5 shows average fat concentrations for mature bulls, young bulls, and mature females. (Note that caribou hunters wouldn't kill an average animal of each type, either: they would only select the fattiest.  But let's take those percentages as written for now.) Crossing 25% bodyfat (from a mature bull in October) with the cubic regression equations Cordain uses yields…

…90% of calories from fat, not 66% as he lists in Fig. 6!

Similarly, 11% bodyfat (from a bull in July) yields 54% of calories from fat, not 30% as he lists in Fig. 6!

Crossing 5.5% fat in April (from a mature female) yields 36% of calories from fat, not 23%…and so on throughout the year.

So it appears that my original misreading of the table roughly cancels out the unrealistic selection of the numbers it contains.  How about that!

There are even more issues.  Quoting the original paper again, "Larger mammals generally maintain greater body fat percentages by weight than do smaller animals." Recall that preagricultural hominins preferentially hunted megafauna: mammoths, mastodons, giant ground sloths, giant tortoises, gomphotheres, chalicotheres, giant hartebeest, giant bison, woolly rhinoceri, and the myried other megafaunal species that our ancestors drove extinct during the Quaternary period. Even modern American bison (let alone ancestral bison) are many times larger than caribou.  

Such animals would have contained a much greater percentage of carcass fat, which would therefore have comprised a much greater percentage of the human diet.  Taking caribou as a typical representative of the hunter-gatherer diet is somewhat disingenuous, as humans didn't even reach the area where caribou lived until perhaps 35,000 years ago. (Compare this to our 2.6 million year history of butchering animal carcasses with stone tools, and the fact that meat-eating most likely dates from before our split with chimpanzees 6-7 million years ago.)

In conclusion: my points stand.  The reason Cordain harps on the SFA issue is that he apparently still believes (or believed, at the time of these papers) that SFA is bad for humans, despite the fact that neither saturated fat nor modern grain-fed red meat consumption is associated in any way with heart disease…and he seems to be willing to torture the data until it supports this long-disproven hypothesis.

This turned out to be much longer than I thought, and probably deserves an entire new article!

JS

Zoe:

Thanks for the information on Aboriginals!  All the sources I can find show that adult kangaroo meat is ridiculously lean, to the point of "Where do they get any fat in their diet?"

As far as the six-packs, I believe it.  Pretty much every picture of hunter-gatherers before domestication/enslavement shows people you really wouldn't want to mess around with.  Have you read Weston A. Price's "Nutrition And Physical Degeneration"?  (I suspect you have)

I appreciate the information and hope you'll stick around.

JS