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I am a politically-progressive, ethically-herbivorous anthropoid pursuing a paleontology education in the Los Angeles Basin. I am largely nocturnal, have rarely been photographed, and cannot thrive in captivity.

16 March 2013

Cannibalism: Another Missing Link In The Paleo Diet

Look, there's Science!TM to back up my month of cannibalism:

Homo habilis used stone tools to de-flesh one another's skulls.
So did archaic Homo sapiens.
And there's lots more right here.

There are some pretty good, if imprecise, recipes available with a quick Google search, too. Though I'd appreciate some reader recipes, as well. That can mean either "recipes sent in by readers" or "recipes featuring readers as the main course," by the way.

My ancestors did it, and my genes crave it. There must be some deficiency in my vegan diet that's making me crave human flesh. I'm glad to report that my skin has cleared up, my energy levels have improved, and my LDL has gone WAY down since killing and eating my own free-range human in the backyard last week.

Y'all should try some of this "bacon."

09 March 2013

Cannibal For A Month

In honor of Alex Jamieson's recent conversion, I have decided to listen to my body, too. Starting tomorrow, I will be cannibal for a month.

I mean, I appreciate the compassionate motives of all those wonderful people in the world who just can't bring themselves to eat other people. But I can't live a lie anymore. I've craved this for years.

And really, I'm surrounded every day free-range people who have led good lives. It's not like it'll be hard to find affordable, decent cannibal food. Heck, it's free! I won't even have to invest in any weapons, since as a geology student I'm already equipped with a collection of hammers, picks, knives and other implements that could help me quickly dispense my prey.

And for them, it's only one bad day at the end, right?

I've heard we taste like pork. I wonder if that's true. Cuz let me tell you, I've really been craving bacon lately.

03 March 2013

Farewell, Anonymi

In an attempt to cut down on the number of Anonymi posting here, I have changed the comments settings to require a registered Google or OpenID avatar.

I know it's not foolproof, but I want to hold people to a modicum of accountability for their comments.

01 January 2013

Paleo Parasite Profile 1: Giardia lamblia

It's been nearly a year now, so I'm no longer sure whether it was Plant Positive or me who first brought to light the connection between parasitic infection and low lipid profiles in primitive human populations (I mentioned it briefly in my post about grain blamers). But if there was ever a contest between us, he won it last week by posting an excellent video on the subject in his latest epic series.

What I'd like to do is zoom in and examine some of these amazing lifeforms in closer detail. Parasites are widely reviled, and for many good reasons. But people tend to overlook the fact that parasites also often grant their host a small benefit, thus maximizing their own fitness.

There is a strong tendency among fancy-pants Global Northers, sheltered as we are in the most hygienic environment that has ever existed for our species, to unconsciously project our relatively parasite-free daily existence backwards into the past, by failing to account at all for the role of parasites in our evolution. It's this blindness to parasitic co-evolution, I'd argue, that lies at the root of the grain-blamers' obsession with grass-fed animal flesh, cholesterol denialism, and other expressions of low-carber paleofantasy. After all, they see the evidence of low LDL in extant hunter-gatherers who eat lots of meat, and can't make sense of the apparent paradox in light of what current health science tells us about the effects of saturated fat and cholesterol. How can these kinds of foods be bad for us, they wonder, when they're obviously not bad for the !Kung? Maybe the secret lies, they speculate, in the nutrient profile of the prey animal. Maybe there's some esoteric "optimal" macronutrient ratio in hunter-gatherer diets that modern man has lost knowledge of. Or maybe cholesterol and saturated fat aren't really bad for anyone, and the truth is being suppressed by a powerful grain lobby.

I submit there's a simpler answer to resolve this paradox: lipid-eating parasites have been hitching rides inside hominid bodies since before we were hominids in the first place.

That's what this little half-tribute series will be about. I'm calling it the Paleo Parasite Profiles, and each installment will focus on a particular clade of the hidden passengers who helped give our paleo ancestors good heart health by keeping their serum lipids low. And I say "half-tribute" because I don't want you to forget that many of these pugnacious little buggers impose a high cost on us for their fat-munching services. Nor do I want you to get the impression that there's anything altruistic or mutualistic in the relationship; it's almost purely exploitative (in the parasite's favor) from our point of view. There's no spiritual kindness motivating the parasites; they're entirely self-serving. From their point of view, we are just walking bags of nutrients. They sneak their way inside us, take root somewhere dark and safe, and gorge on fat and cholesterol to their little organelle's content.

They're nature's ultimate low-carbers.

So, let's start with the spooky-cutest parasite of the bunch.

Genus & species: Giardia lamblia
Giardia lamblia, spooky-cutest low-carber of them all.

Sources of infection: water or food contaminated by fecal matter of carriers; unprotected anal sex. G. lamblia is one of the leading causes of water-borne diarrhea in the U.S. He's a particular problem for hikers and campers taking their water from rivers, and to children in under-developed countries. Giardia is the most common water-borne disease in humans. In the ancestral environment, he'd have run rampant through a small band of hunter-gatherers.

Manner of infection: Giardia has two life-stages: the cyst, which exists in a protective shell outside of a host; and the trophozoite (pictured at left), which lives inside a host. Giardia cysts most commonly enter a host by getting ingested in contaminated food or water. They weather the acid storm of the stomach and make their way to the small intestine where, in the duodenum, the cysts open up and each release two bi-nucleated trophozoites (this process is called excystation). Each trophozoite is equipped with a large adhesive disc made of cytoskeletal proteins on its ventral side, which it uses to attach to the epithelial walls of the duodenum and the jejunum. They reproduce asexually through binary fission, then eventually grow a new cyst, detach from the intestine wall and move out of the host's body through its feces.

Symptoms of infection: Giardia infection can be asymptomatic and/or chronic, but often runs its course in a matter of weeks. When symptomatic, it usually presents through either chronic or intermittent foul-smelling diarrhea that's light colored, greasy and mixed with mucous. Other common symptoms are weight loss (especially in the context of good appetite and adequate food intake), listlessness, vomiting, nutrient malabsorption, and retarded growth in immature animals.

Lipid service: G. lamblia trophozoites do not have the capacity of de novo fatty acid synthesis, and have to obtain their cholesterol and phosphatidylcholine from an external medium. In layman's terms, that means they can't make their own cholesterol, and have to get it from their environment. And their environment is us.

When a G. lamblia cyst enters an environment that's rich in LDL or VLDL cholesterol (like, say, the duodenum of a hunter-gather who eats a lot of meat), it releases its trophozoites. The trophozoites then start to absorb various kinds of lipids from the host medium, and use them to synthesize the lipids they need for their own purposes (chiefly, the building and maintenance of cell membranes). When and if they pass into a lipid-poor environment (like, say, the ilium or large intestine of a hunter-gatherer who eats a lot of meat), cyst formation is stimulated, and Giardia gets the heck out of there. The drop in environmental lipids acts like a signal telling him, "no more food here, time to move on."

Humans infected with G. lamblia have been found to possess lower lipid parameters (LDLc, HDLc, and total cholesterol) than uninfected control groups.

All of this, taken together, means that a Giardia-infected hunter-gatherer population that eats a lot of meat can be expected to have a comparatively low lipid profile compared to the fancy-pants (and largely parasite-free) Global North low-carbers who are trying to mimic them. And remember that since Giardia infection can be both chronic and asymptomatic, it wouldn't necessarily be obvious to an outside observer that parasitic infection was playing a role here.

Obviously, we fancy-pants Global Northers would like to avoid parasitic infections, even by spooky-cute Giardia here. But, we'd also like to maintain a "primitive" lipid profile below about 150 or so. We can't do that by eating lots of fat and cholesterol, unless we're infected with Giardia or some other lipid-eating parasite. But we can do it by eating a whole-foods, plant-based diet.

Or by using statins.

Which do you prefer?

More on Giardia lamblia:
Mechanisms of Giardia lamblia Differentiation into Cysts (Lujan, Mowat, & Nash, 1997)
Lipid metabolism in Giardia: a post-genomic perspective (Yichoy, et al., 2011)

28 December 2012

Plant Positive Is Back

After a long hiatus, the infamous slayer of paleo dragons has returned. This time, be begins by focusing his keen intellect and talent for attention to detail on Gary Taubes, the 800-lb. gorilla of paleo- and low-carb world. (By the way, does Taubes actually weight 800 lbs. yet?)

It's 44 videos totaling about 16 hours, and it's not just all about Taubes. Plant Positive also goes into great detail about the co-evolution of hominids with lipid-eating parasites, a topic no paleo-dieter should ever be allowed to ignore. I haven't gotten through the whole series yet, but it looks to be as good and comprehensive as his previous two efforts.

On a personal note, I'd  like to say I find this fellow to be a great inspiration. The amount of time and effort he dedicated to this project -- for free -- is truly awe-inspiring. He's gotten me to think about producing some videos of my own, though I'm not sure what's left for me to cover.

Anyway, Part 1 is below. Watch the whole thing, enjoy it, and spread the whole series far and wide.

15 December 2012

Food For Thought

I'm on winter break after a semester that was much busier than I anticipated. So, I'm gonna try to get some fresh material up over the next few weeks.

To start with, here's a thought I had the other day: a great deal of the cholesterol denialism found in the paleo and low-carb communities seems informed by a fundamental misunderstanding about the nature of adaptations. Ditto for a great deal of anatomical denialism among vegans, many of whom embrace myths that humans are obligate frugivores.

Consider the following two statements.
1) Homo sapiens are more adapted to meat-eating than other primates.
2) Meat-eating is unhealthy, at least in large amounts.

There's no necessary contradiction in those two statements, but I think a lot of paleo and low-carb folks think there is.

And, to be fair, so do a lot of vegans.

I've encountered many statements on paleo blogs to the effect that natural selection wouldn't have made us better at meat-eating if meat-eating was so dangerous to our long-term health. Or, put another, slightly different way, meat-eating can't be unhealthy because we are adapted to it.

In the vegan community, sentiment tends to run in the opposite direction, taking the form of the tiresome "humans are natural herbivores" meme: because meat-eating is unhealthy, humans therefore are not really adapted to it, and we're just fooling ourselves if we think otherwise.

Both forms of denialism rest on an assumption that adaptation carries with it an obligation (in this case, on obligation to eat other animals): paleos & low-carbers embrace fossil evidence and the implied obligation but deny the health evidence about cholesterol and saturated fat; while vegans embrace the health evidence while rejecting the implied obligation, which leads them to deny the fossil evidence.

So, here's the mistake they both make: being adapted to something doesn't necessarily make it "good" from the standpoint of individual health. There are many adaptations that come with a high price, and many others that have outlived their usefulness and have thus become burdens to be overcome rather than traits to be indulged.

A few examples from modern humans illustrate the point:

  • The unique human voice box, the anatomical source of our ability to use complex language, also makes it impossible for us to breathe and swallow at the same time... which means we're much more likely to choke to death on our food than other animals are. Language comes with the inherent risk of death by choking.
  • Chronic lower back pain is a direct consequence of our upright posture; hominoid primates have a transverse lumbar process that is serially homologous with the spinous process (rather than with the styloid process, as it is in other mammals), allowing us to assume more upright postures. But this mutation puts a lot of mechanical stress on the lower vertebrae, often leading to herniated discs. This is a risk few other mammals run, because the weight of their upper bodies is distributed along a longer axis.
  • Sickle cell anemia and the various forms of thalassemia are preserved in the human genome because they provide heterozygotes with greater resistance to malaria... despite the fact that heterozygotes suffer debilitating long-term health consequences from these adaptations, and recessive homozygotes die from them. For humans no longer living in malaria-prone areas of the world, these adaptations are now useless, and have become burdens rather than boons.

So, too, can it be for meat-eating. There's enough fossil evidence to plausibly argue that the genus Homo was given an edge in fitness by being better adapted to meat-eating than other primates. This allowed them to flourish on savannahs, under the selection pressures of the Pleistocene.

But this does not imply that meat-eating became healthier, from the point-of-view of degenerative disease. We still carry within us the mechanisms of atherosclerosis inherited from 22 million years of hominoid evolution, not to mention almost 200 million years of mammal evolution. We are, like nearly all extant organisms now living on this planet, a species of Rube Goldberg devices full of jury-rigged solutions that need only be good enough. If the traits of early Homo were good enough, there'd have been no need for the underlying biochemistry of cholesterol and atherosclerosis to be changed much, if at all.

Any advantage provided by adaptations to meat-eating would have been for the purpose of reproductive success, not "optimal health." That is, it would have provided early humans with a way of obtaining calories reliably enough, for long enough, to beat their rivals in the race to die with the most kids. Evolution, as I've pointed out before, is fundamentally about sex, not food or health. If being better at meat-eating allowed our ancestors to avoid starvation long enough to see their kids grow up, then it would have been preserved despite its atherosclerotic and other effects.

And thus, it's entirely possible that said adaptations are now burdens rather than boons, since we no longer face the selection pressures of life on the Pleistocene savannah. Something that helped us in the past can now be hurting us, and thus "eating like our ancestors" might be a terrible idea.

So, there's no need for denialism from either side of this paleo-vs.-vegan debate about diet. It turns out, they might both be right.

06 September 2012

BBC Doc: How To Grow A Planet

Hat tip to Idan, a commenter who left me a link to the first part of this visually amazing BBC documentary about how plants have shaped the planet and driven the course of animal evolution.

Watch it more than once. I know I will.