Archive for the 'General Science' Category

May 26 2017

Pyramid Homology vs Analogy

Pyramid nonsenseI saw this post on the Credible Hulk Facebook page today. It refers to an old claim by proponents of ancient astronaut theories that the fact that there are similar looking pyramids from different locations on Earth proves cultural contamination from an extraterrestrial source.

While this is a silly argument, it is interesting to explore exactly why it is silly. The underlying principles have to do with homology and analogy, and are exactly the same as they are applied in evolutionary theory. The displayed meme implies that because there are step pyramids in Mexico, Egypt, and Indonesia – countries too far removed to have had direct contact with each other – the idea of a step pyramid therefore had a common source.

This is similar to the evolutionary argument that because two structures look similar or serve a similar function, they must have had a common source, which means the feature was derived from a common ancestor. But we know that this is not always true. The wings of bats, birds, and pterydactyls have similar features, but not a common evolutionary origin. The eyes of vertebrates and cephalopods also have features in common, but evolved independently. But giraffes and humans both have seven cervical vertebrae.

So how do evolutionary biologists tell the difference? They try to determine if the features are homologous (derive from a common ancestor) or analogous (independent origins but similar structure). They can do this in a number of ways, either based on direct evidence or inference. Direct evidence would be finding a fossil of a common ancestor with the feature.

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10 responses so far

May 25 2017

Organic Farming is Bad for the Environment

Published by under General Science

land useMarketing sometimes involves the science of making you believe something that is not true, with the specific goal of selling you something (a product, service, or even ideology). The organic lobby, for example, has done a great job of creating a health halo and environmentally friendly halo for organic produce, while simultaneously demonizing their competition (recently focusing on GMOs).

These claims are all demonstrably wrong, however. Organic food is no more healthful or nutritious than conventional food. Further, GMO technology is safe and there are no health concerns with the GMO products currently on the market.

There is an even more stark difference, however, between beliefs about the effects of organic farming on the environment and reality.  In fact organic farming is worse for the environment than conventional farming in terms of the impact vs the amount of food produced.

First, organic farming may use pesticides. They just have to be “natural” pesticides, which means the ones they use are not chosen based upon their properties. Ideally choice of pesticide and the strategy in using them would be evidence-based and optimized for best effect, minimal impact on health and the environment, cost effectiveness, and convenience.   Organic farming, however, does not make evidence-based outcome choices. Their primary criterion is that the pesticides must be “natural”, even if they are worse in every material aspect. This represents ideology trumping evidence. It is based on the “appeal to nature” fallacy, an unwarranted assumption that something “natural” will be magically better than anything manufactured.

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64 responses so far

May 16 2017

The Impact That Killed the Dinosaurs

Published by under General Science

asteroid impactI have loved science as long as I can remember, partly because scientists have the best stories to tell. The stuff that actually happened is usually far more interesting than any fantasy, and has the added bonus of being real. Reality is complex, dramatic, and interesting. Reality is also endlessly surprising.

Lucas wanted to evolve Star Wars. I always thought that was an interesting idea, adding a new layer to the film medium. It would love to see a great director do that well, not only updating special effects, but evolving the story as the culture evolves. Unfortunately, most of the changes Lucas made were crap, watering down character arcs and adding blandness. Some of the extra CG was OK.

Science stories, however, seem to always just get more interesting. That is because the universe has already written the entire script from the beginning, and we are just peeling back the narrative layers one by one. As the story gets deeper, it all makes sense because it has to. Plot twists are never contrived, because they were baked in from the beginning.  Continue Reading »

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Apr 28 2017

Shaky Evidence for Humans In Americas 130,000 Years Ago

Published by under General Science

mastodon bonesScientists like to be really sure. That is pretty much what the scientific method is all about – systematically controlling for all possibilities, all confounding factors, all variables and all alternative interpretations. We feel more confident when multiple lines of evidence converge on one explanation, and when rigorous attempts to disprove that explanation fail.

I like seeing that process in action over specific claims, especially when the claim itself is interesting.

One such interesting question is, what was the earliest human presence in the Americas? Any question about first or earliest is always tentative in paleontology. It simply refers to our current evidence, but it is statistically unlikely that we will have found the literal earliest example of a species or an occupation. So conclusions about “earliest” are always changing, moving back as more evidence is found.

There is solid archaeological evidence for human occupation near the  Bering Strait 14,000 years ago. There is strong but not universally accepted evidence for this occupation going back 24,000 years. So that is the current range of possible dates for the earliest presence of humans in North America.

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25 responses so far

Apr 20 2017

Retreat of the Cryosphere

glacier-retreatPatrick Burkhart and his colleagues recently published a review of their research on the cryosphere, which is a collective term for all the ice on the surface of the Earth. In addition to their review of the science, the new information they add is a photographic project documenting the retreat of glaciers around the globe.

The retreat of the cryosphere is one of the many lines of evidence supporting the idea that the earth has been warming over the last half-century. There are several different ways to look at this. You can look at each pole to see the extent of ice coverage at their peak in winter and minimum in summer. You can look at specific ice sheets, like Greenland. You can look at glaciers. And you can look at total global ice, the cryosphere, which of course is the best single measure.

With regard to glaciers, the authors point out that there are many variables affecting the current size of any individual glacier. It is possible but difficult to account for all these variables and isolate one as a primary cause of melting. However, you can survey glaciers from around the world, which is a good way to control for local variables. When we do this we find there is a significant trend toward glacial retreat.

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178 responses so far

Mar 20 2017

The Need for Publicly Funded Science

Trump-ScienceThe American scientific community is in a bit of a panic over Trump’s first proposed budget. The budget calls for an 18% decrease ($5.8 billion) for the National Institutes of Health (NIH). There are deep cuts in energy research and Earth science as well.

The reaction of the scientific community has been consistent – such cuts would be disastrous.

It probably comes as no surprise that science is expensive. This is despite the fact that scientists are generally paid very little, especially when compared to their years of training. Science is a career of passion. But maintaining a lab or conductive field research can be very expensive. Research often requires expensive equipment and materials, lab space, support staff, and lots of time.

Research is not just something that scientists do – it requires extensive infrastructure. That infrastructure needs to be maintained mostly with one-off grants. The vast majority of scientific research will not directly generate profits for the researchers, the lab, or the supporting institution. Keeping a lab going is like keeping plates spinning, the researchers are constantly applying for grants and weaving together the funding they need.

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46 responses so far

Mar 16 2017

Does Glyphosate Cause Cancer?

Published by under General Science

glyphosate-effects-fbGlyphosate, the active ingredient in Roundup, is the most popular herbicide used in the world. It has gained particular attention because several of the more commonly used GMOs are glyphosate tolerant, and therefore are intended to be used with the herbicide. Glyphosate is also manufactured by Monsanto (although it is off patent and there are generic versions available).

The question of the safety of glyphosate is in the news again after the New York Times did an article about a recent court case against Monsanto and the documents revealed through discovery and made public by the judge. Unfortunately, in my opinion the NYTs article is poorly done, and reveals significant bias – anti biotech bias is nothing new for the NYTs or the author of this article, Danny Hakim.

Last year I wrote about another article that Hakim wrote in the NYTs about GMOs, concluding:

In my opinion Hakim’s article in the Times was a hack piece with a biased narrative that is nothing more than a rehash of tired anti-GMO tropes that have already been widely deconstructed. He is entering this conversation late, and isn’t up to speed.

There are essentially two questions raised by Hakim’s latest article. The first concerns the behavior of Monsanto. Hakim alleges that they ghostwrote scientific articles for academics and used political pressure to shut down EPA reviews of glyphosate’s safety. I would not assume this assessment is true, and certainly don’t trust Hakim’s journalism given his history. The academics in question deny the allegations, and Monsanto claims these e-mails are taken out of context. We have certainly seen that before.

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30 responses so far

Mar 14 2017

GM Corn To Prevent Deadly Toxin

aflatoxin-cornAflatoxin is a serious food contaminant that causes both acute and chronic illness in animals and humans. It was first discovered in 1960 when 100,000 turkeys in the UK died over the course of a few months. Their deaths were tracked to a nut-based feed that was contaminated with a newly discovered toxin, named aflatoxin.

Aflatoxin is a group of 20 toxins produced by a fungus, Aspergillus species. According to Food Safety Watch:

Aflatoxins may be present in a wide range of food commodities, particularly cereals, oilseeds, spices and tree nuts. Maize, groundnuts (peanuts), pistachios, brazils, chillies, black pepper, dried fruit and figs are all known to be high risk foods for aflatoxin contamination, but the toxins have also been detected in many other commodities. Milk, cheese and other dairy products are at risk of contamination by aflatoxin M. The highest levels are usually found in commodities from warmer regions of the world where there is a great deal of climatic variation.

Corn is perhaps the biggest source of aflatoxin contamination. It is estimated that 16 million tons of corn are disposed of each year due to aflatoxin contamination. The toxin is highly stable and can survive most types of food processing.

Acute toxicity can result in death when severe. Chronic toxicity is difficult to detect, and the most common effect is liver damage and increased risk for liver cancer.

Many techniques are used to minimize contamination, but even with these methods aflatoxin is a huge source of food waste and an important cause of human illness, especially in developing countries. Continue Reading »

8 responses so far

Mar 02 2017

Tucker Carlson vs Bill Nye on Climate Change

Published by under General Science

Nye vs CarlsonTucker Carlson of Fox News recently had Bill Nye on as a guest to discuss climate change. The entire interview is worth a listen because it nicely illustrates the strategies employed by denialists.

Here are some highlights:

Carlson pushes what is a very common denialist narrative, that they are skeptics who are just asking honest questions. Meanwhile the proponents of global warming are trying to shout them down, call them names, and are doing a disservice to science by trying to shut down debate.

The problem with this narrative (other than not being true) is that you can apply it to any position that denies established science. Flat-Earthers are just skeptics, stop shouting them down. Answer their honest questions.

The devil, of course, is in the details. Are climate change denier just asking honest questions? Ironically, Carlson himself demonstrates in the interview that he isn’t. He is playing rhetorical games to cast doubt on climate science.

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74 responses so far

Feb 28 2017


Published by under General Science

Recently Harvard University geneticist Prof George Church announced that he and his team are close to making a mammoth-elephant hybrid. They have been reconstructing mammoth DNA from frozen remains.

They will not be able to make a 100% mammoth clone, but rather they are splicing mammoth genes into Indian elephant DNA and hope to grow a hybrid. The result would have, they hope, enough mammoth traits to be adapted to a colder environment, and therefore essentially spread the range of the Indian elephant north.

Such programs raise two question – can we actually achieve de-extinction with such techniques, and should we?

The answer to the first question is – we’re not even close yet. The reporting of Church’s announcement was highly sensationalized, with many outlets reporting that we will have mammoths in two year. The reality is that Church’s team has made 45 mammoth DNA inserts into the Indian elephant genome. This is insignificant.

Estimates of the differences between mammoth and elephant DNA indicate that several thousand genes are involved. In addition, there may be even more regulatory changes in the DNA outside of genes. You can make a lot of evolutionary change by turning on or off, or up or down, the expression of genes without changing the genes themselves.

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24 responses so far

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