Friday, April 27, 2012

Murdering Animals is Bad, Children, Mmm'kay?

Here's a screen shot of a new vegan propaganda book:


From the blurb:
In Vegan Is Love, author-illustrator Ruby Roth introduces young readers to veganism as a lifestyle of compassion and action. Broadening the scope of her popular first book That’s Why We Don’t Eat Animals, Roth illustrates how our daily choices ripple out locally and globally, conveying what we can do to protect animals, the environment, and people across the world. Roth explores the many opportunities we have to make ethical decisions: refusing products tested on or made from animals; avoiding sea parks, circuses, animal races, and zoos; choosing to buy organic food; and more. Roth’s message is direct but sensitive, bringing into sharp focus what it means to “put our love into action.” Featuring empowering back-of-the-book resources on action children can take themselves, this is the next step for adults and kids alike to create a more sustainable and compassionate world.
If you really want to empower your kid, make sure they get plenty of meat in their diet. They might get empowered enough kick ass on the climbing wall.

And here's a newspaper article about the apparently somewhat controversial book. The article ends with helpful tips from 'experts' for helping your kid go vegan. Is there anything more useless than an expert in child veganism? Well, perhaps a reporter who quotes them.

Saturday, April 21, 2012

Is String Theory Just Waiting For Empirical Evidence To Catch Up?

I was reading a science article by Paul Doherty and Pat Murphy in Fantasy & Sci-Fi, that compared string theory to atomic theory in around 1900. I've long been skeptical of string theory because it hasn't been able to make any sort of testable prediction. But the authors make an interesting point when they argue that atomic theory was in the same situation roughly 2000 years after it was first proposed by Democritus.

And how can one bring up Democritus without linking to this? Sorry, Sagan doesn't actually say billions and billions in this clip:



Until Einstein came up with a proper solution to Brownian motion (and it was validated experimentally), there was no firm foothold for atomic theory, or so the authors argue.
When you think about all this research and speculation, keep in mind that no one could see the tiny particles these scientists were speculating about. At that time observations were made with light waves. Since a wavelength of green light is about 5000 times bigger than an atom, light waves were much too big to reveal atoms.

To get an idea of the size disparity, consider ocean waves with a wavelength of ten meters rolling past and hitting the side of a cylindrical lighthouse with a diameter of twenty meters. The waves will bounce off the lighthouse, making circular waves. Looking at these reflected waves, you could find the shape of the lighthouse. Now suppose those same ocean waves crashed into a stick just one centimeter in diameter. Any ripples bouncing off the stick are lost in the ocean wave, useless for revealing anything about the stick. Seeing an atom with light waves was hopeless.

So those scientists in 1900 were making up stories (logically consistent, reasonable stories, but stories nevertheless) about stuff no one had ever seen.
The article goes into the history of atomic theory along with the empirical evidence. I thought this was especially cool:
If you have a laser pointer, equipment not available back in Brown's day, you can also see Brownian motion by shining the laser light into a dilute solution of milk and looking at the scattered laser light on a white card after the light passes through the milk. The bright central dot of laser light will be surrounded by twinkling dots of light. These twinkling dots are produced by the interference pattern of all the light scattered by the fat globules in the milk. The pattern changes because the fat globules are in constant motion as they are bombarded with collisions with invisible particles. Those invisible particles are (according to the story of atomic theory) molecules of water in the milk. 
So by shining a laser pointer through diluted milk, one can observe the underlying random motion of molecules, is that cool or what? And let's not forget that a laser itself is based on the quantization of photons, so this simple experiment is seeing evidence of some of the most profound theories of the Universe that were barely accepted or even known of 100 years ago (Max Planck proposed quantization of energy in 1900 as a fix to the black-body radiation problem).

This leads to the idea that strings, should they be the underlying phoenoma that explain everthing, would exist at a very small scale:
To find the size of a string, scientists need to find the scale at which both quantum mechanics and general relativity apply. To do this, they must consider the size of a quantum black hole. Normal black holes have the mass of a large star or of many thousands of stars, and form by gravitational collapse. They are larger across than a small city. The gravity of a black hole is so great that even light cannot escape across the surface of the black hole, a surface known as the event horizon.
[...]
So here's the math. The radius of a black hole is proportional to its mass (R = 2GM/c2 where R is the radius, G is the universal gravitational constant, M is the mass, and c is the speed of light.) The wavelength is inversely proportional to its mass (L = h/Mc where L is the wavelength, M is the mass, h is Planck's constant, and c is the speed of light). These equations can be solved to find the mass of a black hole with a radius equal to its wavelength. (We'll do the calculation to within an order of magnitude so we can ignore factors of 2 or pi (π).) The quantum black hole is found to have a mass of 10-8 Kg or 10 micrograms. If you were to take a strand of hair that's 0.1 mm in diameter and snip off a piece that was as long as one diameter, it would have a mass of about 10 micrograms. If this piece of hair were compressed to 10-35 m in diameter, it would become a black hole with a wavelength of 10-35 m.
[...]
These calculations show that the length scale at which both gravity and quantum mechanics are important is 10-35 m. This is an estimate for the size of the loops of string in string theory, the string loops that encircle and bind quantum mechanics and general relativity. This length scale is called the Planck length. The Planck length is 1.6 * 10-35 m.
The Planck length is pretty important in physics, it pops up a lot (including theological debates). To say that 10-35 meters is small is something of an understatement.

Another understatement is this sentence:
Several major difficulties complicate efforts to test string theory. The most significant is the extremely small size of the Planck length, which is expected to be close to the string length (the characteristic size of a string, where strings become easily distinguishable from particles). 
Wikipedia goes on to list some of the ways string theory could be tested.  There's not a lot of promising stuff there, but it does show that string theory is not lacking a null hypothesis. Is string theory simply a victim of the lack of empirical evidence that atomic theory lacked in 1900, or perhaps back when Democritus first proposed it (since we are possibly 2000 years away from measuring things at the Planck length). Yes, perhaps. I'll just note that two of my favorite physicists, Richard Feynman and Roger Penrose, are (were) very skeptical of string theory, on the grounds of its lack of testability. Admittedly, Feynman died in 1988 so perhaps he'd be less skeptical of string theory today. Somehow I doubt it, though.

Wednesday, April 18, 2012

Buckminsterfullerene and Immortality


Via Gizmodo, comes a new study by Tarek Baati et al in which rats were given buckyballs, which doubled their lifespan.

Wait, what?!?! Apparently the researcher set out to test the toxicity of buckyballs, and found an anti-toxicity instead.

Here's the abstract:
Countless studies showed that [60]fullerene (C60) and derivatives could have many potential biomedical applications. However, while several independent research groups showed that C60 has no acute or sub-acute toxicity in various experimental models, more than 25 years after its discovery the in vivo fate and the chronic effects of this fullerene remain unknown. If the potential of C60 and derivatives in the biomedical field have to be fulfilled these issues must be addressed. Here we show that oral administration of C60 dissolved in olive oil (0.8 mg/ml) at reiterated doses (1.7 mg/kg of body weight) to rats not only does not entail chronic toxicity but it almost doubles their lifespan. The effects of C60-olive oil solutions in an experimental model of CCl4 intoxication in rat strongly suggest that the effect on lifespan is mainly due to the attenuation of age-associated increases in oxidative stress. Pharmacokinetic studies show that dissolved C60 is absorbed by the gastro-intestinal tract and eliminated in a few tens of hours. These results of importance in the fields of medicine and toxicology should open the way for the many possible -and waited for- biomedical applications of C60 including cancer therapy, neurodegenerative disorders, and ageing.
And the results summed up in Gizmodo:
The results, which appear in Biomaterials, took the researchers by surprise. The control group had a median lifespan of 22 months, and the olive oil group one of 26 months. But the Bucky ball group? They stuck it out for 42 months. That's almost double the control group.

Double lifespan. Sounds too good to be true, which means it probably is, but what if it's not?

What could possibly be the mechanism here that would double a rat's lifespan? The paper suggests it is "attenuation of age-associated increases in oxidative stress", so the old anti-oxidants and disease and aging hypothesis.

However, there's been a lot of backlash against anti-oxidants lately. Once touted as the wonder solution, they been shown to actually have negative effects, especially when take in isolation like beta-carotene was shown to do in regard to lung cancer in the CARET and ATBC studies.

The Tarek Baati et al study also used carbon tetrachloride (CCl4), as a stressor and compared the effects with or without buckyballs. CCl4 causes liver damage (among other things) in higher doses, and the rats that had been pretreated with buckyballs for a week showed significantly less liver damage than the other groups.

So perhaps buckyballs act as some sort of universal anti-oxidants. Another possible explanation could be a reduction in inflammation. I don't have access to the full paper, but I noticed this:
The arrows indicate C60 crystals-containing macrophages with specific brown colour. Transmission electron microscopy: compared to (e) spleen macrophages, TEM micrographs show only a few C60 crystals inside (f) lung and (g) kidney macrophages.
Chronic inflammation (possibly caused by chronic infection) is another hypothesized cause of aging and diseases of civilization. Could buckyballs be regulating M1 (inflammatory) macrophages somehow? I'm just speculating here. 

Anyway, who wants to live forever?


Monday, April 16, 2012

Rockin' The Climbing Wall

The kid went to the climbing center over the weekend. It was only his second time, and he's only five, but he totally kicked ass. I'd like to think that diet plays some part in this (obviously my awesome genes are the main factor). Here he is racing his best friend:


And here he is at the top of the intermediate wall.


Dinner was meatballs cooked in ghee (not strictly paleo, added some semola di grano duro as a binder)


And potatoes roasted in Easter duck fat


I just hope he survives to six with all that artery-clogging food.

Saturday, April 14, 2012

Elephant Brain Soup

A little while back I was talking about a recent paper that allegedly debunks the expensive tissue hypothesis (ETH). Another recent paper by Miki Ben-Dor et al does just the opposite, specifically in regard to human encephalization and dietary animal fat. And not just any animal fat, ELEPHANT FAT! Paul Jaminet mentioned the paper back in December in a positive light, and everyone's favorite paleo apostate Don Matesz talks about the paper in a much more negative fashion, not surprisingly.

Man the hunter of elephants, are we awesome or what? Sorry, I mean allegedly awesome. And actually it wasn't we homo sapiens but pre-we homo erectus (childish snigger) that would've been doing the alleged hunting.

The elephant in question is the now extinct Elephas antiquus which roamed Europe and the Levant up until about 115,000 (Wikipedia) or 400,000 years ago (Ben-Dor et al and references for the Levant) when the coming ice age and predation by humans led to its demise. Now there's plenty of evidence that elephants were hunted by humans (or pre-humans depending on your definition), even up in perfidious Albion:
The elephant, which has been identified as a straight-tusked Palaeoloxodon antiquus, would have been twice the size of the largest modern African elephant.

The skeleton was also found with a number of flint tools surrounding it, indicating that it was probably slaughtered by humans. 
Hold on there BBC. Twice the size of the largest modern African elephant? That sounds a little off to me. To quote Wikipedia: "The largest individual [African elephant] recorded stood four metres (13 ft) to the shoulders and weighed ten tonnes." Wikipedia gives Elephas antiquus a height of 3.90 m (12 ft). Are you saying the elephant fossil found in Kent was 8 m (26 ft) tall? I'm rather skeptical. I think the largest elephant that ever existed was Mammuthus sungari, and it was just over 5 meters tall. Have I ever mentioned how much I hate lazy mainstream science journalists?

Anyway, getting back to the Ben-Dor et al paper. Here's the abstract:
The worldwide association of H. erectus with elephants is well documented and so is the preference of humans for fat as a source of energy. We show that rather than a matter of preference, H. erectus in the Levant was dependent on both elephants and fat for his survival. The disappearance of elephants from the Levant some 400 kyr ago coincides with the appearance of a new and innovative local cultural complex – the Levantine Acheulo-Yabrudian and, as is evident from teeth recently found in the Acheulo-Yabrudian 400-200 kyr site of Qesem Cave, the replacement of H. erectus by a new hominin. We employ a bio-energetic model to present a hypothesis that the disappearance of the elephants, which created a need to hunt an increased number of smaller and faster animals while maintaining an adequate fat content in the diet, was the evolutionary drive behind the emergence of the lighter, more agile, and cognitively capable hominins. Qesem Cave thus provides a rare opportunity to study the mechanisms that underlie the emergence of our post-erectus ancestors, the fat hunters.
They are essentially arguing that it was the pressure of reduced opportunities for easy pickings like a few tons of elephant steak, that led to the changes we see between elephant gorging pre H. saps (whatever you want to call them, the taxonomy is contentious but I'll stick to H. erectus because it is way funnier than H. heidelbergensis) and the less muscular, longer-limbed and bigger-brained H. saps.

By looking at gut-size, the ability to process protein (via liver and kidney capacity), brain size and overall body weight, Ben-Dor et al came up with these tables.





So H. saps had an allegedly reduced overall energy requirement and body weight despite their increased brain size. Ever wonder why it's so hard to pack on muscle despite all that time spent in the gym? Blame your lazy ass ancestors for wiping out the elephants.

Once we got addicted to these walking supermarkets by having larger brains and especially larger daily energy expenditures (DEE) we then proceeded to exterminate them. Oops. Time to buckle down. Ben-Dor et al argue that the next step was to reduce overall DEE while increasing encephalization in order to take advantage of smaller, fleeter game such as antelopes and aurochs.

Now I'm not going to lie to you, as a paleo-ish person I see this as an extremely sexy hypothesis. But I'm also a huge contrarian. So I'm going to offer up a few counter-arguments.

To me, real hypotheses are all about making predictions and having them tested. This is why I hate string hypothesis, predict something, motherfuckers, and we'll test it, otherwise you got nothing.

What I find think is interesting about the Navarette et al paper is that they used a testable hypothesis to predict something which they then used to disprove the original hypothesis. I love that. I'm skeptical of the assumptions they used, but I love the methodology. The Devil is in the details, especially when it comes to experimental science, but it all rests on the back of predictive hypotheses.

So a problem I see with the paper from Miki Ben-Dor who has a blog entitled Paleo Style, or with archeology in general it is pretty easy to cherry-pick or insert one's biases, because it's all in retrospect and the data is so scant.

With that contrarian bitching aside, I think it's a pretty interesting paper.

Wednesday, April 11, 2012

Revenge Is a Dish Best Served Cold

Yesterday, one of our cats knocked over my five-year-old son's Lego robot, causing the inevitable shattering and scattering of a thousand Lego pieces. This morning, instead of getting ready for school, my son built this cat trap:


This resulted in a classic case of me being the stern parent on the outside ("We don't trap our kitties, and get dressed!"), whilst laughing my ass off on the inside. Also, I think he could have a bright future in engineering.

Friday, April 06, 2012

Science and the Sticky Issue of Intellectual Property

I'm not a huge fan of intellectual property (IP). Certainly not the current status it enjoys in the US and which the US is pressuring the rest of the world to follow suit on. At the same time I'm not convinced by the abolish IP crowd even if they make a strong case, although the fashion industry is a great example of a thriving artistic business which has virtually no IP.

Now we come to the openness in the arena of scientific papers. I recently came across the JSTOR controversy:
On July 19, 2011, internet activist Aaron Swartz was charged with data theft in relation to an alleged theft of academic journal articles from JSTOR. According to the indictment against him, Swartz surreptitiously attached a laptop to MIT's computer network, which allowed him to "rapidly download an extraordinary volume of articles from JSTOR". Prosecutors in the case say Swartz acted with the intention of making the papers available on P2P file-sharing sites. Swartz surrendered to authorities, pleaded not guilty to all counts and was released on $100,000 bail. Prosecution of the case is ongoing.

Two days later, on July 21, Greg Maxwell published a torrent file of a 32GB archive of 18,592 academic papers from JSTOR's Royal Society collection, via The Pirate Bay, in protest against Swartz' prosecution.
On September 7, JSTOR announced that they are releasing the public domain content of their archives (about 6% of the total) to the public. According to JSTOR, they have been working on making those archives public for some time, and the recent controversy made them "press ahead" with this initiative.
Now I think ten years in prison and $100 000 bail is pretty damn draconion. But that's really the US authorities and legal machine going full retard. Anyway, there is a 32.5 GB torrent over on Pirate Bay (that I'm not going to link to) put up by Greg Maxwell. Greg has a long, long diatribe (or manifesto) about why he put it up, a lot of which I find rather naive or just downright idiotic, although I admire him for publicly identifying himself on the torrent. Here are some excerpts:
Limited access to the documents here is typically sold for $19 USD per article, though some of the older ones are available as cheaply as $8. Purchasing access to this collection one article at a time would cost hundreds of thousands of dollars. Also included is the basic factual metadata allowing you to locate works by title, author, or publication date, and a checksum file to allow you to check for corruption.

I've had these files for a long time, but I've been afraid that if I published them I would be subject to unjust legal harassment by those who profit from controlling access to these works. I now feel that I've been making the wrong decision.
[...]
Copyright is a legal fiction representing a narrow compromise: we give up some of our natural right to exchange information in exchange for creating an economic incentive to author, so that we may all enjoy more works. When publishers abuse the system to prop up their existence, when they misrepresent the extent of copyright coverage, when they use threats of frivolous litigation to suppress the dissemination of publicly owned works, they are stealing from everyone else. 
Okay, I more or less agree with this. But I don't think publishers abuse the system to prop up their existence, I think publishers created the system, using crony capitalism, to prop up their existence. Although I suspect it was the music industry that had the biggest hand in greasing the right palms (thanks Bill Clinton and a unanimous boot-licking Senate).

Still, it didn't seem to be JSTOR's intent to charge for older papers that were in the public domain. This is from JSTOR's press release:
On a final note, I realize that some people may speculate that making the Early Journal Content free to the public today is a direct response to widely-publicized events over the summer involving an individual who was indicted for downloading a substantial portion of content from JSTOR, allegedly for the purpose of posting it to file sharing sites. While we had been working on releasing the pre-1923/pre-1870 content before the incident took place, it would be inaccurate to say that these events have had no impact on our planning. We considered whether to delay or accelerate this action, largely out of concern that people might draw incorrect conclusions about our motivations. In the end, we decided to press ahead with our plans to make the Early Journal Content available, which we believe is in the best interest of our library and publisher partners, and students, scholars, and researchers everywhere.
The thing is, it actually does cost time and money to digitize old papers and make them publicly available even if they are in the public domain. Project Gutenberg is a great project that takes advantage of hundreds of thousands of hours of volunteer work, but how many people are interested in spending their free time digitizing old scientific papers?

How much do strict IP laws affect the spread of information? Probably more than you'd think. Take a look at this rather shocking graph by Paul Heald from the blog Offsetting Behaviour:


What happened? Well, 1922 is the cutoff for public domain books in the US.

How much would more open access to scientific papers affect the general health of science these days? It's very difficult to say. There are certainly much fewer people clamoring to read dense scientific papers than the latest Stephen King novel. On the other hand, there's a lot more dissemination of information these days by non-mainstream channels such as this blog.

In my opinion, post-WWII science has suffered from the peer-review system, an entrenched academia and most of all, from the underlying source of post-WWII scientific funding--the government. This doesn't mean I'm not a big fan of the open science movement (here and here) but I don't think it gets to the root of the problem.

These are sticky problems, what is wrong with science these days and what is wrong with IP these days (perhaps nothing). I don't think there are any hard and fast answers, but I think they are very much related.

Wednesday, April 04, 2012

Revisiting the Expensive Tissue Hypothesis

Or, I am bloody sick of talking about food reward.

A recently published paper in Nature is supposed to have demolished the expensive tissue hypothesis (ETH) proposed by Aiello and Wheeler. An excellent summary of why this paper supposedly demolishes ETH is given at the blog PaleoVeganology (yes, not all vegans are religious extremists). Since I don't have access to the full Nature paper, the PaleoVegan post will be my basic source of info on it.

Let's start with the original Aiello and Wheeler paper (or PDF). Here's the first paragraph of the abstract:
The brain is a very expensive organ in metabolic terms. Each unit of brain tissue requires over 22 times the amount of metabolic energy as an equivalent unit of muscle tissue. There is no correlation across mammals, however, between the relative size of the brain and the relative basal metabolic rate. The Expensive Tissue Hypothesis explains this apparent paradox by looking at the metabolic cost of the brain in the context of the costs of other metabolically expensive organs in the body. The results show that the increase in brain size in humans is balanced by an equivalent reduction in the size of the gastro-intestinal tract. In other words, the increased energetic demands of a relatively large brain are balanced by the reduced energy demands of a relatively small gastro-intestinal tract. This relationship also seems to be true in non-human primates.
And later on:
The gut is the only one of the expensive tissues that can vary in size sufficiently to offset the metabolic cost of the encephalized brain. This is because gut size is determined not only by overall body size but also by diet. Gut size is associated with both the bulk and digestibility of food. Food of low digestibility requires relatively large guts with elaborated fermenting chambers (stomach and/or small intestine) while food of high digestibility (such as sugary fruits, protein and oil rich seeds and animal material) requires relatively smaller guts characterised by simple stomachs and proportionately long small intestines.
So the crux of their hypothesis is a negative correlation between brain size and gut size.

Now let us examine the Navarrete et al paper. Here's the abstract:
The human brain stands out among mammals by being unusually large. The expensive-tissue hypothesis1 explains its evolution by proposing a trade-off between the size of the brain and that of the digestive tract, which is smaller than expected for a primate of our body size. Although this hypothesis is widely accepted, empirical support so far has been equivocal. Here we test it in a sample of 100 mammalian species, including 23 primates, by analysing brain size and organ mass data. We found that, controlling for fat-free body mass, brain size is not negatively correlated with the mass of the digestive tract or any other expensive organ, thus refuting the expensive-tissue hypothesis. Nonetheless, consistent with the existence of energy trade-offs with brain size, we find that the size of brains and adipose depots are negatively correlated in mammals, indicating that encephalization and fat storage are compensatory strategies to buffer against starvation. However, these two strategies can be combined if fat storage does not unduly hamper locomotor efficiency. We propose that human encephalization was made possible by a combination of stabilization of energy inputs and a redirection of energy from locomotion, growth and reproduction.
The heart of the matter seems to be related to fat storage and human's bipedal locomotion. To quote from PaleoVegan:
In other words, it costs chimps twice to three times as much energy to move around the same amount of body fat as a human. Further complicating the matter is that the energy cost of travel during climbing for primates is almost directly proportional to body mass. Quadrapedal terrestrial walking and briachiation as modes of transport simply impose higher costs on primates than does efficient bipedalism. This energy cost adds up over time (especially evolutionary time), and thus can constrain the total amount of BMR available for encephalization. Thus, because humans save so much energy by being bipedal, they can store relatively large amounts of adipose tissue and still grow big brains.
So a fat human can walk around much more efficiently than a fat chimp, that means that just by walking on two legs humans could put that extra energy into our big brains. For me this raises the obvious question: don't chimps spend most of their time locomoting with their arms? Again, I don't have full access to the paper but it seems like apples and oranges. The biggest advantage to a bipedal hunter-gatherer existence as far as nutrient dense foods is the hunting, not the gathering, nor the increased efficiency of being able to carry around more fat.

What the Navarrete et al paper did was to remove adipose tissue from the equation to take into account the efficiency variation of adipose tissue and the efficiency of terrestrial movement. Another thing they decided to do was to test the ETH hypothesis across a variety of animals instead of just primates.

Again from PaleoVegan:
Any good hypothesis can produce at least one testable prediction. And the ETH has one, right there for everyone to see (though it's been astonishingly ignored for 15 years). If the ETH is true, we should expect to find a tight negative correlation between brain mass and the mass of other expensive tissues across a range of taxa, not just among primates. And it's this prediction, not whether cavemen were meat-eaters, that Navarrete, et. al., set out to test.
I would qualify that first sentence as any real scientific hypothesis has to be able to produce a testable prediction. Otherwise we are just talking about mysticism. But the devil is in the details. I can form what I think is a testable prediction of a hypothesis that is mistaken based on my assumption.

PaleoVegan:
The key way they tested the overall hypothesis across various mammal groups was controlling for adipose tissue deposits in their calculation of a given animal's mass. In short, they omitted fat deposit mass from all specimens, eliminating it as a variable. This was an important control tactic (and one not used by Aiello & Wheeler in their original paper), because adipose mass varies by season and habitat among many species, and can thus be a major confounding variable. Only by eliminating it altogether and testing brain size against fat-free body mass, the authors reason, could a possible trade-off between tissues be reliably detected.

Under these conditions, no negative correlation between brain size and digestive tract mass was found. In fact, no negative correlation was found between brain size and the mass of any expensive tissue. The authors did, however, uncover a tight negative correlation between brain size and adipose tissue depots: the fattest species had the smallest brains.

Given Kleiber's law, this might at first look like a dilemma: fat tissue doesn't use a whole lot of energy, so why would it constrain brain size? The answer is that it costs an animal a lot of energy to lug the extra weight around, especially while climbing or running. And it's here that humans -- along with whales and seals -- have an advantage: fat stores don't significantly interfere with our ways of getting around. Bipedalism and dorso-ventral flexion (the swimming method used by cetaceans and pinnipeds) are simply more efficient ways of moving.
So humans are more efficient runners? No, humans are more efficient at running with fat. Navarrete et al believe that this is an important advantage that needs to be controlled for.

This paper, The Energetic Paradox of Human Running and Hominid Evolution has this to say about the efficiency of human running:
The energetic cost of transport (oxygen consumption per unit body mass per unit distance traveled) for running humans is relatively high in comparison with that for other mammals and running birds. Early comparative studies showed that a mammal the size of man should consume roughly 0.10 ml of oxygen per gram body mass per kilometer traveled, but the measured value for man is over twice this amount (0,212 ml) A recent analysis of 64 species of running birds and mammals confirms the initial observations that the cost of transport is relatively high for human runners.
First of all I'd like to bring up what seems to me like a glaring hole in the Navarrete et al bipedal lipid tissue efficiency argument: terrestrial birds are bipedal, and they aren't exactly famous for having large brains. What's another huge difference between ostriches and human hunter-gatherers? Diet. An ostrich consumes, according to Wikipedia, "... seeds, shrubs, grass, fruit and flowers; occasionally they also eat insects such as locusts." In other words, everything you'd expect to see at your local vegan restaurant, minus the locusts, of course. None of it famous for being nutrient dense, with the possible exception of fruit.

Navarette et al go on to re-test Aiello and Wheelers original paper with updated data, which PaleoVegan considers to be the knock-out punch for ETH. PaleoVegan writes:
As detailed in the Supplemental Material, Aiello & Wheeler were working with a data set that had a couple of problems. Namely, it was biased towards catarrhine primates over platyrrhines; it didn't control for sex differences between members of species with marked sexual dimorphism (sexual size dimorphism affects body mass more than brain size), or for differences in the body mass of wild vs. captive specimens of the same species; and it didn't account for phylogenetic relationships between various hominid species (a fact I have pointed out before).

[...]

Nevertheless, Navarrete, et. al., were able to identify and control for these confounders in a new test using the latest phylogenetic statistical methods on the original data sample. And the results did not support Aiello's & Wheeler's hypothesis; even their own data failed the ETH in the end.
Now I don't have access to the data or even the full paper so I can't really judge this, and I frankly wouldn't be qualified to judge it even if I did.  I would simply add that if this specific expensive tissue hypothesis has been disproven (ratio of expensive tissue gut length to expensive tissue brain size) that doesn't mean that all expensive tissue hypotheses are hereby rendered invalid, or that parameters can't be changed for this one. As I pointed out in the comments over at PaleoVegan:
The Humane Hominid [in response to Anand Srivastava]:

"Also, you don't get to change the ETH's parameters in order to save it"

I'm no expert in biological science, but in physics hypotheses and theories have their parameters modified or even added and subtracted all the time. When Einstein added in the parameter of the cosmological constant in 1917 to General Relativity, GR could have been more considered a hypothesis not a theory, as its predictions had not been experimentally tested (perihelion precession of Mercury had been observed long before GR). http://en.wikipedia.org/wiki/Cosmological_constant
But beyond this quibble I think PaleoVegan did an admirable and even-handed job of summarizing the Navarette et al paper. Do I think this destroys ETH? No. I'm pretty convinced that nutrient dense food, especially animal fat, was the key to human encephalization.

Monday, April 02, 2012

Theory of the Stork: Skepticism and My N=1 Experience

The always brilliant Paul Jaminet has highlighted an interesting paper on the Theory of the Stork (ThoS) which examines the link between storks and babies.

I have to say I'm pretty skeptical of the stork/baby causation. A lot of the sciencey types decry the N=1 results that many of us lesser bloggers like to bring up, but I'm loathe to simply abandon my own empirical experience. I was present throughout the entire birthing process when my son was born and I can say with confidence (p < .05) that there were no storks present. However, adults blink, on average, ten times a minute, so I am willing to keep an open mind, because that's what science is all about, amiright?

To be fair, Mr Jaminet seems to favor a hybrid theory that encompasses both storks and the theory of sexual reproduction (ThoSR), which should really be called hypothesis of sexual reproduction, in my opinion. Although ThoSR is now considered quaint by most of the cutting edge researchers in the field, there are still many who find merit in its approach.

But where Paul goes wrong, in my opinion, is in his proposed experiment to test ThoS. I dropped a comment at PHD to highlight some of my concerns with his proposed experiment. While I applaud Mr Jaminet's proposal for a blind study, I don't think he goes far enough in isolating confounding variables.

Paul Jaminet would like to place couples on stork farms and chicken farms and fit the chickens with stork beaks to act as a blind control. As I pointed out, I don't think this experiment qualifies as real science. Paul's experiment simply doesn't take into account many of the important factors:
  • Epigenetics - what sort of epigenetic effects will a stork bill have on a chicken?
  • Genes vs Environment - Is stork behavior really 100% genetic? What about cultural/environmental influences? What's to stop chickens from acting like storks once they are equipped with stork bills? I propose a lengthy set of identical twins vs fraternal twins studies to resolve this burning question.
  • Blind? Why not double-blind? - I propose that everyone taking part in the study wear blindfolds. It's the only way to be sure.
I'm willing to do my part to help prove/disprove the sexual theory reproduction and I am currently in the process of writing up a grant proposal to that effect. Because these are troubled times for the world economy, I'm happy to cut down on expenses by putting myself in controlled experiments that involve women in their prime reproductive years. I'm also willing to wear a blindfold during the research process, or two blindfolds because double-blind is the gold standard. Currently, the biggest obstacles to my proposed attempt to help solve this scientific question are the immense lobbying powers of Big Hospital and the fact that my wife hates the self-sacrificing scientific search for truth.