The quality of most of these comments makes me sad. I see snark, refusal to consider new hypothesis in light of previously held beliefs, and rejection of the idea of entertaining other hypothesis (let's dismiss them as speculation). Here's a hint--coming up with new hypotheses is speculating. Then you test. As long as you don't hang your hat on the hypothesis as a new truth without testing it, speculating is great.
Is there some subconscious need to make fat people's fatness a character flaw? I'm trying to understand the intransigence against considering what looks like a great area for research. I'm wondering if this is a case of cognitive dissonance. The reductionist calories in/calories out approach seems disingenuous to me. If large portions of the population began breathing 10% more over a long period, I wouldn't assume they were greedy-breathers, I'd look for a medical cause.
This is an intriguing finding. Particularly that animals on controlled diets are gaining weight. (even if the control is simply what is available). Forgetting the reductionist view, hunger is a drive, and depends on a self-regulating system. If something is interrupting the equilibrium in animals, either type of food, type of calories, environment (not necessarily the global environment, it could be local, like room temperature or something else), or foreign agents, isn't that pretty interesting, especially if it is happening to animals on controlled diets with exceedingly similar environments?
Is there some subconscious need to make fat people's fatness a character flaw?
As someone that was fat my whole life, then lost over 50bs to visual abs, I noticed that people aren't fat or skinny, they have fat or they don't. In other words rather than describing someone as fat, its more accurate to describe them as having a lot of fat.
The problem is that extraordinary claims require extraordinary evidence.
There are broadly two possibilities:
1. Some unknown phenomenon is defying everything we know about physics. Matter and energy are being created, apparently from nothing. Or perhaps transmutation is occurring without emitting lethal doses of gamma and X-ray radiation.
2. There has been uncontrolled variance due to faulty or incomplete record keeping, unobserved changes in activity, genetic drift affecting the appetite and activity of the population, changes in environment affecting the appetite and activity of the population (eg cage size change, lighting changes, temperature changes), unannounced changes in food supply composition (the food is a commercial product) etc etc et bloody cetera.
In human subjects, when placed in controlled situations, weight loss or gain very closely aligns to the simplest model of calories in - calories out, modulo fluctuations in water weight and personal variations in digestion and activity.
Furthermore, when zoomed out to a population level, BMI tracks calories consumed per capita very closely[1]. The increase in wealthy country population obesity reflects that food is cheaper, easier to get and more calorically dense that at any time in history[2].
Calories in/out is reductionist. But it's all you need to control weight.
> 1. Some unknown phenomenon is defying everything we know about physics.
You have entirely missed the point if you are arguing about physics when discussing this. It is like stating tornadoes occur because the wind moves faster.
When one has data a theory doesn't explain, you hypothesize, and re-test. That's science. Regardless of whether you have convenient correlations like your 1 and 2, you don't assume those correlations are causation and stop researching. What you don't do is dismiss the outlying data and call it a day.
But that's the point: when people or animals are placed under controlled conditions specifically to measure changes in mass vs caloric balance, it all averages out as expected. The samples in this study come from a mix of uncontrolled wild populations living in contact with humans and from captive populations who were not subject to a long term control.
In science you don't get to declare any old thing you like and then everyone else has to immediately agree to test it. Everyone else is free to propose other hypotheses that fit the facts and it is generally accepted that the simplest hypothesis consistent with the evidence is more likely to be correct.
The concept of a viral or epigenetic effect on either the efficiency of digestion or the efficiency of metabolism is worth investigating. However it would require a complicated mechanism to explain how and why it happened simultaneously across a mix of populations. Another explanation, given that all these populations are in contact with the human food supply, is that the human food supply has changed to be more calorifically dense. And, of course, it may be some combination of the above.
A simple way to examine the mystery would be to look at animal populations in other countries. If the wild animal populations of places where people are starving to death are becoming obese, there might be something to it.
> But that's the point: when people or animals are placed under controlled conditions specifically to measure changes in mass vs caloric balance, it all averages out as expected.
No, that's not the point at all. Whether something is causing a greater appetite is the point.
Maybe we're all sensing at some low level that the next Ice Age is coming. We are overdue one....
This hypothesis could be tested in one way by looking to see if whatever is happening decreases as you get to the tropics. If so its strengthened, if not it doesn't necessarily say one way or another.
Why would Brazil and India being fat have to do with it? If its an evolved attribute in all humans/animals, then there hasn't been enough time for migration to play much of a role in the adaptation. It would be quite weird though, it means it would have to have come very early in our history when we basically lived in the same place, pre-human even, and somehow the adaptation has survived through multiple cycles of speciation. Highly unlikely.
And not even mine, I got it from Glenn "Instapundit" Reynolds, can't remember if he got it from someone else.
Another half test is to wait and see if we don't have an ice age, that would be evidence against it, but not absolute if e.g. the global warming crowd is partly correct.
I think this probably has to do with the sugar in our diets. Animals that live in human environments tend to eat refuse from our food, and our food has been getting more and more packed with sugar lately.
The explanation about animals having access to more food does not work. In the wild, if there is more food, you will simply get more rats. Wild animal populations tend to rise to match their food supply without giving much opportunity for animals to get fat.
Unfortunately, the sugar explanation does not quite explain the lab rat observations. It is possible that the lab rat food has been augmented by sugar without the scientists noticing. AFAIK lab rats tend to be fed commercial food mix that is purchased from various suppliers.
The other explanation fits the lab rat results much better but it is much scarier. It is possible that due to GM crops and/or cattle food supplements we may have released some new hormone in the food supply and/or the water that makes us and animals fat.
Dominated? I just checked my cat's food, and the first ingredient is chicken and the second is chicken by product, then corn and the list of supplements. The dominant ingredient is chicken.
Are you sure there's a regulation regarding listed ingredient order for pet food? And regardless, I bet manufacturers can get away with even more ingredient list manipulation there than with human food—I might be wrong though.
It depends on the type and quality. If you purchase a can, then I would hope that it is mostly animal based ingredients. If it is dry food then it will be mostly cereals.
Not in a human environment would be a challenge, but IMO somewhat double. But not in a human environment, where we _do_ have historical weight data? Forget it.
As to the control mice: my hunch would be that 'let the control animals eat at will' has changed over time. Maybe the diameter of sugar water tubes has increased slightly?
Certainly, our notion of what constitutes overweight has changed. If you look at photos of kids in the 1950s, almost all of them look extremely skinny. We may project that on lab animals, and size the 'eat at will' containers accordingly ("hm, the control mice get too fat. Let's make it a tiny bit harder for them too get their food")
Also, chances are that lab animals live at better controlled temperatures. Possibly, they used to eat less in hot summers because the temperature in their cages was higher in summer?
Of course, that's speculation, but it is the simplest explanation I can think of.
I have data here on the weight of cats trapped on Kerguelen island since 1999, and I'm no statistician but I see no trend at all (data should also exist on the feral rabbits and mice, but I don't think I have it).
Isle Royale would be a good candidate for this kind of study. It's a small island in the middle of Lake Superior that has its own isolated wolf population. They take a lot of data from the wolf and moose populations, and it wouldn't be surprising if they had some way to track/estimate weight.
I know the research facilities there were the target of severe budget cuts several years ago. It's a shame, because this is an example of where other, unrelated research would benefit from the basic research of an environment mostly untouched by humans.
Could changes in artificial lighting affect food consumption? Lab mice, pets, and people all have been exposed to similar changes in lighting types over time. Color temperature effects? The 60hz strobing effect of fluorescent bulbs? Have better lighting technologies resulted in brighter environments? Have security concerns. etc. lead to light exposure for more hours of the day?
The study authors supply plausible and completely ordinary explanations for weight gain in each of the populations. Why speculate beyond that? No reason except that it's "intriguing."
Though it is certainly not necessary that there be a single explanation for all of these population level increases nor even a single explanation for each individual population, it is intriguing to consider whether there are any factors that could conceivably account for weight increases in all of these populations.
In other words, just more fuel for speculation about some alien contaminant, a pathogen or pollutant, that we can blame for the obesity epidemic. We have all the explanations for human obesity that we could possibly need, but we continue to wish for some cause that does not operate through our behavior.
Could better control of feral cat/dog populations in urban areas explain the observed increases in rat weights? What if fatter rats are easier and/or more desirable prey? Why should a cat waste effort chasing after a fast, skinny rat when a fat one providing more calories is less likely to outrun it?
Wrong logic, so wrong.. rats eat what? Exactly, they eat our processed foods, including high fructose corn sirup and other metabolism altering ingredients. So much hype about animals getting fat? Prove that monkeys of different types in their unaltered natural habitat become obese or fat, then I'll start critically listening.
Why? Increased productivity of farming. Have you ever seen a modern farm? They are just as impressive as any modern sky scraper or any other engineering accomplishment, probably more so for logical reasons. Once you throw in the logistical side, even more. The technology being used for traveling salesman problem is fascinating and cutting edge.
In fact, it's well known that there is plenty of food for everyone on Earth, but the logistics aren't quite up to snuff.. The result is lots of wasted food. Logistics is not a popular science for career-minded scientists to get into, because the costs need to stay low, thus they aren't making a lot of money. But they are well funded and working with the same type of stuff you'd see in the Oil Industry. They're supporting an entire society with their contributions. This is part of the reason I hate Monsanto so much, but that topic is for another thread.
Humans get all the food they need, so they stop forging, same for our pets, so they stop hunting. So do the rats, so they stop competing. Etc, etc, cascading down to many species.
"Among mice in control groups in the National Toxicology Programme (NTP), there was a 11.8 per cent increase in body weight per decade from 1982 to 2003 in females coupled with a nearly twofold increase in the odds of obesity. In males there was a 10.5 per cent increase per decade."
Control mice are typically allowed to feed at will from a controlled diet that has not varied much over the decades, making obvious explanations less plausible.
How do they select the parents of the next generation? At random? Pick the more healthier (i.e. 0.1% more weight)? It's possible to do artificial selection by accident.
The only idea I have to solve this problem is to froze some mice embryos and defrost some of them in 20 years and compare (and some of them in 50 and 100 years).
In the comments of the source article (linked from Marginal Revolution) people working in labs claimed the ingredients in commercial food mixes had changed dramatically since the 80s, even where the supplier remained unchanged and the calories were approximately the same.
Even the bacteria are full. Seriously though, chimps probably have similar intestinal flora as we, and they're the fattest of the fattening animals. See the original paper, they're an order of a magnitude fatter than any other species. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3081766/pdf/rspb...
I propose that the increased population and access to food is accelerating the evolution of intestinal flora, causing it to become more efficient at digesting, sometimes even exceeding the hosts capacity leading to obesity, leaky gut syndrome and IBS.
That explanation may work for pets, but it does not work for wild animals in human environments. In these cases, the wild animal population simply rises to meet the food supply.
Rats stop competing? Evolution theory would predict more rats/faster rats/more muscular rats/larger brains/improved disease resistance/earlier maturity/etc, not rats that look more like couch potatoes. That could only happen in areas with colder winters or with random long periods of lack of food.
And yes, the time period is not long enough for evolution in rats, but it is more than long enough for natural selection to have a marked influence.
Is there some subconscious need to make fat people's fatness a character flaw? I'm trying to understand the intransigence against considering what looks like a great area for research. I'm wondering if this is a case of cognitive dissonance. The reductionist calories in/calories out approach seems disingenuous to me. If large portions of the population began breathing 10% more over a long period, I wouldn't assume they were greedy-breathers, I'd look for a medical cause.
This is an intriguing finding. Particularly that animals on controlled diets are gaining weight. (even if the control is simply what is available). Forgetting the reductionist view, hunger is a drive, and depends on a self-regulating system. If something is interrupting the equilibrium in animals, either type of food, type of calories, environment (not necessarily the global environment, it could be local, like room temperature or something else), or foreign agents, isn't that pretty interesting, especially if it is happening to animals on controlled diets with exceedingly similar environments?