Archive for the 'General Science' Category

Nov 12 2015

Nutrient Density of Crops Over Time

Published by under General Science

A new video is making the rounds on social media making the incredible claim that you would have to eat five grocery store apples today to equal the nutrient density (not calories, but other nutrients) of a grocery store apple from 1936. The video makes a second claim, that the decrease in nutrient density is due to poor soil. The video is little more that pro-organic propaganda, and neither claim is sourced – because they are not true.

However, the story of nutrient density of fruits and vegetables is a complex and interesting one. It is interesting to compare food plants from thousands of years ago (prior to any cultivation), 100 years ago, and today. First we need to ask – what are the differences? Then we can try to explain them.

Let’s compare first fruits and vegetable from today to 50 and 100 years ago. ¬†A systematic review by Donald David found:

Recent studies of historical nutrient content data for fruits and vegetables spanning 50 to 70 years show apparent median declines of 5% to 40% or more in minerals, vitamins, and protein in groups of foods, especially in vegetables.

So there does appear to be a real decline, although not the 80% across the board suggested by the pro-organic video. The declines are significant for vegetables, and less so in fruits (so apples was a poor example to use). Averaging out all the declines, you get about a 20% decline in nutrient density for produce.

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144 responses so far

Sep 15 2015

Solar Hydrogen and our Energy Infrastructure

Published by under General Science

We are at an interesting point in our civilization. It seems pretty clear that the fossil fuel infrastructure on which our technology is largely built is not sustainable. Pulling massive amounts of conveniently stored energy out of the ground fueled the industrial revolution, and continues to be the primary source of our energy. Currently fossil fuels produce 82% of the worlds energy.

However, putting all that sequestered carbon back into the atmosphere is having unintended consequences on the climate. A recent estimate indicates that if we burn all the remaining known fossil fuel reserves the Antarctic ice sheet will essentially melt raising the oceans by 60 meters. Even if they are off by an order of magnitude, a 6 meter rise in sea level will dramatically alter the coastlines of the world.

Even if we put aside climate change, burning fossil fuels produces pollution. Beijing’s atmosphere is a good example of what happens when you try to fuel an industrial revolution with coal. Further, fossil fuels are finite. We can argue about how much there is available in the world, but it’s not infinite.

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39 responses so far

Sep 10 2015

The Arctic Sea Ice Hubbub

Published by under General Science

Those who accept the consensus that the Earth is warming due to human activity (anthropogenic global warming or AGW) point to declining Arctic sea ice as one line of evidence to support this conclusion. Those who do not accept the AGW consensus claim that Arctic sea ice is not declining, or at least we have insufficient data to reach such a conclusion.

What I like about this controversy is that it is about data. It is a fake controversy, driven by political ideology, but none-the-less we can sink our teeth into the data and see which side has the better position.

Arctic sea ice varies throughout the year, growing in the winter and melting in the summer. Therefore any year-to-year comparisons need to take this seasonal variation into account. Scientists use the summer minimum as one measure of the extent of Arctic sea ice for that year. You can also look at the winter maximum.

Sea ice can be measured in square miles, essentially the amount of area covered by ice. It can also be measured in thickness, and the two measures can be combined to calculate the overall volume of ice.

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55 responses so far

Aug 31 2015

The Reproducibility Problem

Published by under General Science

A recent massive study attempting to replicate 100 published studies in psychology has been getting a lot of attention, deservedly so. Much of the coverage has been fairly good, actually – probably because the results are rather wonky. Many have been quick to point out that “science isn’t broken” while others ask, “is science broken?”

While many, including the authors, express surprise at the results of the study, I was not surprised at all. The results support what I have been saying in this blog and at SBM for years – we need to take replication more seriously.

Here are the results of the study:

We conducted replications of 100 experimental and correlational studies published in three psychology journals using high-powered designs and original materials when available. Replication effects (Mr = .197, SD = .257) were half the magnitude of original effects (Mr = .403, SD = .188), representing a substantial decline. Ninety-seven percent of original studies had significant results (p < .05). Thirty-six percent of replications had significant results; 47% of original effect sizes were in the 95% confidence interval of the replication effect size; 39% of effects were subjectively rated to have replicated the original result; and, if no bias in original results is assumed, combining original and replication results left 68% with significant effects. Correlational tests suggest that replication success was better predicted by the strength of original evidence than by characteristics of the original and replication teams.

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31 responses so far

Aug 07 2015

Industry Conflicts of Interest

Published by under General Science

This is an old issue but seems to have been heating up in the last decade – concern over ties between academia and industry. The concern is legitimate, but often overblown, and can easily be abused to justify an unfair witch hunt.

A Nature article published yesterday discusses a recent round of accusations against scientists who support the technology of genetic modification. Before I discuss this article directly, let me give some background.

There is the potential for useful and productive collaboration between industry and academia. Academics are the experts and they have knowledge and resources that could benefit industry. Meanwhile, to put it simply, industry has the money. They can fund research, labs, and educational programs. Academics often survive on meager pay, living grant to grant.

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15 responses so far

Jul 31 2015

GMOs and Making Up Your Own Science

Published by under General Science

Dedicated anti-science groups engage in a number of methods to maintain their propaganda upstream against the scientific evidence. It’s actually not difficult- people are generally very good at motivated reasoning. We can demonize or lionize anything.

Methods include dismissing scientific studies whose conclusions you don’t like, supporting low quality studies you do like, misinterpreting and distorting other studies, and of course cherry picking. Sometimes, however, dedicated activists seem to literally make up studies out of whole cloth, or ideological scientists perform dubious studies to create fodder for their side.

This week on the SGU we interview Kevin Folta (the show will be published tomorrow) about some of his experiences with anti-GMO activists who have no problem making up the science to advance their ideological agenda. The more I look into anti-GMO activism the more I realize that the anti-vaccine movement has nothing on them when it comes to pseudoscience. Their methods are identical. The only real difference is that anti-GMO propaganda is much more mainstream.

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10 responses so far

Jul 27 2015

Artificially Selected Organisms

Published by under General Science

A new petition to demands mandatory labeling for all “artificially selected organisms.” The petition says:

ASO plants or animals have had their genetic makeup altered to exhibit traits that are not naturally theirs. Artificial selection (or selective breeding) involves the selection of traits that are beneficial to humans, not what helps the organism survive in nature.

And concludes:

80% of Americans support mandatory labels on food containing DNA.

That last bit is true. A survey performed by¬†Oklahoma State University Department of Agricultural Economics found that 80.44% of Americans supported “mandatory labels on foods containing DNA.” That puts into perspective public support for mandatory labels on genetically modified organisms (GMOs).

The petition is obviously satire, and I think it represents the perfect use of satire – putting into sharp relief the illogic of a specific position or claim. This is a fight that happens almost every time a GMO supporter argues with a GMO critic. It goes something like this:

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18 responses so far

Jul 06 2015

The New Seralini Study

Published by under General Science

Seralini, author of the infamous study alleging to show increased rates of tumors in rats fed GM food, the one that was retracted by the journal and then later republished in a separate journal, has published another controversial study.

The study, published in PLOSone, looks at the feed that is fed to lab rodents, the kinds used in GM research. They found:

All diets were contaminated with pesticides (1-6 out of 262 measured), heavy metals (2-3 out of 4, mostly lead and cadmium), PCDD/Fs (1-13 out of 17) and PCBs (5-15 out of 18). Out of 22 GMOs tested for, Roundup-tolerant GMOs were the most frequently detected, constituting up to 48% of the diet.

The implication is that all prior research looking at GMO and pesticide toxicity is now called into question because the control rodents would also have been fed a diet that contains some GMO, pesticides, and also heavy metal contaminants. The concept here is valid – control groups need to be proper controls. If you are testing the effects of a pesticide on rats, and the control rats are also getting the pesticide in their food, then the comparison is compromised. This would dilute out the effects of the test substance by increasing the background rate of tumors and other negative outcomes, the “noise” in the study. This would further mean that studies would have to be more powerful (contain more subjects in each group) in order to detect the diluted signal.

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11 responses so far

Jun 30 2015

Lessons From GM Wheat Failure

Published by under General Science

So-called “whiffy wheat” was genetically modified to release a pheromone that repels aphids. The obvious purpose of this modification was to reduce pests without the need for insecticides, and thereby reduce insecticide use.

The trait worked well in the lab. The wheat released sufficient amounts of a warning pheromone that aphids release when attacked. The pheromone both warns aphids to stay away, and also attracts predators, such as a parasitic wasp. The pheromone was derived from the peppermint plant.

The laboratory success meant the wheat was ready for field trials where the GM crop is put to the test in close to real world conditions. The results of those field trials were just published, and unfortunately they showed that the new trait essentially didn’t work – the aphids were not significantly decreased compared to controls, nor was yield increased.

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9 responses so far

Jun 16 2015

The Debate over Nutrition Research

Can you recall everything you ate yesterday, including those little snacks you snuck, with reasonably accurate estimates of amounts? How about two days ago? Most people, it turns out, have a hard time recalling with good fidelity their recent food intake, or they have a hard time reporting it accurately not only because of the fallibility of memory but because of biases and denial.

Despite this, a great deal of nutrition research is based upon subjects recalling and accurately reporting what they ate. A recent article in Mayo Clinic Proceedings by Edward Archer et al challenges the legitimacy of this research. They write:

The reliance on M-BMs to inform dietary policy continues despite decades of unequivocal evidence that M-BM (memory-based dietary assessment methods ) data bear little relation to actual energy and nutrient consumption.

This is pretty damming. They charge that the current dietary guidelines are based upon fatally flawed data. They specifically state that such data is based upon fallible memory, uses data collecting techniques known to promote false recall, cannot be independently verified, and often does not contain objective data on physical activity. They go as far as to call such research an, “unscientific and major misuse of research resources.”

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16 responses so far

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