ريتشارد دوكنز's Blog, page 688

Patient Receives 3D Printed Titanium Ribs and Sternum

Anatomics

By Jason Dorrier

It’s a bit like a Marvel superhero comic or a 70s sci-fi TV show—only it actually just happened. After having his sternum and several ribs surgically removed, a Spanish cancer patient took delivery of one titanium 3D printed rib cage—strong, light, and custom fit to his body.

It’s just the latest example of how 3D printing and medicine are a perfect fit.

The list of 3D printed body parts now includes dental, ankle, spinal, trachea, and even skull implants (among others). Because each body is unique, customization is critical. Medical imaging, digital modeling, and 3D printers allow doctors to fit prosthetics and implants to each person’s anatomy as snugly and comfortably as a well tailored suit.

Titanium chest implants aren’t new, but the complicated geometry of the bone structure makes it difficult to build them. To date, the typically used flat plate implants tend to come loose and raise the risk of complications down the road.In this case, the 54-year-old patient suffered from chest wall sarcoma, a cancer of the rib cage. His doctors determined they would need to remove his sternum and part of several ribs and replace them with a prosthetic sternum and rib cage.

Now, we can do better. We have the technology.

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Early warning gene signature for Alzheimer’s

NHGRI

By Genome Biology and BioMed Central

A ‘gene signature’ that could be used to predict the onset of diseases, such as Alzheimer’s, years in advance has been developed in research published in the open access journal Genome Biology.

The study aimed to define a set of genes associated with ‘healthy ageing’ in 65 year olds. Such a molecular profile could be useful for distinguishing people at earlier risk of age-related diseases. This could improve upon the use of chronological age and complement traditional indicators of disease, such as blood pressure.

Lead author James Timmons, from King’s College London, UK, said: “We use birth year, or chronological age, to judge everything from insurance premiums to whether you get a medical procedure or not. Most people accept that all 60 year olds are not the same, but there has been no reliable test for underlying ‘biological age’.

“Our discovery provides the first robust molecular ‘signature’ of biological age in humans and should be able to transform the way that ‘age’ is used to make medical decisions. This includes identifying those more likely to be at risk of Alzheimer’s, as catching those at ‘early’ risk is key to evaluating potential treatments.”

The researchers analyzed the RNA of healthy 65 year old subjects, and used the information to develop a signature of 150 RNA genes that indicated ‘healthy ageing’. The signature was found to be a reliable predictor for risk of age-related disease when studying RNA from tissues including human muscle, brain and skin.

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Epic Climate Change Textbook #FAIL

Climate change educationAlabama

Is our children learning science?

If those children are being taught about climate from Florida’s 5th grade science textbook from publisher Scott Foresman (Pearson), then those children are learning from a text so riddled with glaring and obvious errors that it’s hard to know how such a book could see the light of day, much less be adopted by Florida public schools.

NCSE recently heard that a Florida parent was concerned about this particular section of the Scott Foresman Science: See Learning in a Whole New Light book:

How Climates Change

There are many events that might cool a climate. The Little Ice Age may have occurred because the Sun produced less energy. Volcanic eruptions and asteroid or meteorite impacts may have quickly caused cooler climate in the distant past. They could have done this by putting dust and other materials into the upper atmosphere. These materials can cool the climate by blocking sunlight or reflecting sunlight back into space.

Carbon dioxide, methane, and water vapor also can make climates warmer. They can be produced by human activities, such as burning coal and gasoline. These gases can also enter the atmosphere naturally, such as through decaying matter, forest fires, volcanoes, and the water cycle.

Many different events help to form a climate. Because of this, it is hard to determine why a climate has changed. Scientists have had debates on these changes and will probably have more in the future.

 

Wow. Let’s parse the blunders here:

1. “The Little Ice Age may have occurred because the Sun produced less energy.”

In a very basic sense, decreased solar energy was one of several factors causing the Little Ice Age (~1450-1850). But mentioning the Little Ice Age at all, without any other context, is problematic because of the way the Little Ice Age has been used by climate denialists. Their false claims about the Little Ice Age, dissected in devastating detail by SkepticalScience, argue that modern warming is simply “coming out” of the Little Ice Age, rather than a unique worldwide phenomenon caused by anthropogenic activities.

If the textbook never intended to explain that the Little Ice Age was caused by a combination of solar energy, ocean circulation, and increased volcanic activity, then why mention this climate denialist trope at all?

2. “Volcanic eruptions and asteroid or meteorite impacts may have quickly caused cooler climate in the distant past.”

I can hear the teeth gnashing of astronomers around the world, especially Bad Astronomer Phil Plait, who explains it this way:

...while something is orbiting the sun it’s called an asteroid. As it’s entering the Earth’s atmosphere, the bit of it that’s actually solid—whatever it is, the rock, the metal—we call it a meteoroid. As it’s burning up in the Earth’s atmosphere and is very bright, we call it a meteor. And if it hits the ground, we call it a meteorite.

Given these definitions, “asteroid impact” doesn’t make a lot of sense. No wonder children don’t understand the proper terminology when their textbook gets it wrong.

Now, it is certainly true that volcanoes can affect climate. The 1815 eruption of Tambora, 1883 eruption of Krakatoa, and the 1991 eruption of Mt. Pinatubo all created measurable climate effects. But these are hardly “in the distant past,” and the textbook lost an opportunity here to convey to students the specifics of how volcanoes can temporarily influence worldwide climate. It is also a lost opportunity to clarify that what humans are doing to the atmosphere is much more significant and long-lasting.

3. “Carbon dioxide, methane, and water vapor also can make climates warmer. They can be produced by human activities, such as burning coal and gasoline.”

Okay, let’s get something straight: water vapor is a greenhouse gas, but it’s not one humans produce directly. If a nefarious villain were to establish giant humidifier plants to increase the water vapor content and create runaway global warming (unless, of course, the government paid him one million dollars!), this evil plan would fail when that extra humidity immediately rained out of the atmosphere. If the villain decided to desiccate the atmosphere instead (where do all those silica gel packets go, anyway?), evaporation would quickly reestablish normal humidity. (“Curses! Foiled again!”)

Water vapor is a favorite dodge of climate denialists, who like to talk about it instead of the much more urgent issue: manmade carbon dioxide. Water vapor we can’t do anything about, carbon dioxide we can, so of course it is more comforting to assert that it’s all water vapor’s fault. So for this textbook to report that water vapor is “produced by human activities” and is just like other greenhouse gases is inaccurate and supports climate denialist claims.

4. “... it is hard to determine why a climate has changed. Scientists have had debates on these changes and will probably have more in the future.”

This is the worst of the lot. Fifth grade students reading this section in Scott Foresman’s Science are left with the impression that climate scientists are uncertain about their results, that they have “debates” about the issues, and that climate may just be too hard to understand fully. Nothing could be further from the truth. There is a growing wealth of research supporting the reality of climate change. Because of the quality of this evidence, there is remarkable, overwhelming consensus about the reality of human-caused climate change; there is far more agreement among scientists that climate change is real and human-caused than there is agreement about the details of quantum mechanics or dark matter. 

The Florida edition of Scott Foresman’s Science textbook is not unique in being inaccurate and sloppily written. The truth is, subject experts rarely write textbooks—staff at educational publishing houses do most of that work to ensure the texts align with standards. Content accuracy and quality are further diminished by adjusting textbook language to fit the philosophy of whatever pedagogical fad currently reigns. Most textbooks are not written by single authors in a coherent, sustained narrative, but by non-expert committees attempting to meet the minimum requirements of flawed educational standards.

The poor quality of textbooks emphasizes the importance of teachers. A good teacher can draw on his or her education to recognize when the content of the textbook is inaccurate and bring to students a meaningful educational experience despite the book. A good teacher knows when to check off the required boxes, and then teach the kids what the subject is really about.

Great teachers know when to stand on the desk—like Robin Williams’ character in Dead Poets Society—and tell students which pages to rip out of their textbooks. For this textbook, I recommend giving the climate page the Dead Poets treatment. 

Chew On This: A Story For Your Ears Only, Part 1

Evolution

A basic understanding of evolution lets us know that we are all descended, with modifications, from a common ancestor. If we trace our lineage back far enough we will find our kinship with fish over 400 million years ago (mya). Moving forward in time from our formerly fishy selves, we find amphibian relatives (~350mya) and reptilian relatives (~300mya). The animals representing the base of the mammalian lineage start to show up ~200mya. While it is certainly interesting to consider our distant relationship to these other megagroups of organisms, what I find particularly captivating are the things in between.

rtist’s illustration of a therapsid (Pristerognathus). The first image that got me interested in this whole mess. (via Wikipedia Commons)

It was in an intro geology course that I first saw a picture of a therapsid. These animals look like a cross between reptiles and mammals. As a biology major I understood that we, as mammals, are descended from a group of reptiles. However, it had somehow never quite struck me that there must have been at some time an abundance of animals between these two groups, organisms that wouldn’t quite meet the qualifications of modern mammal or a modern reptile, but would have some of the characteristics of each. Looking at an artist’ rendition of a therapsid, it was fascination at first sight, and I have been studying organisms along this large-scale transition ever since.

What is it that really differentiates mammals from reptiles? Some of the classic mammal-defining characteristics are mammary glands (from which we derive the name of the group), a four-chambered heart (note: these are also found in birds, though people rarely confuse birds and mammals), and hair. These appear fairly straightforward and are easy to identify in living organisms. However, if we go to the geologic record, we quickly encounter a problem—none of these characteristics fossilize well (if at all). The predominant fossilized structures for vertebrates are bones and teeth. Surely there must be many skeletal differences between reptiles and mammals, right? As it turns out, there are not nearly as many as one might think.

In fact, the best indicator to differentiate between these groups is to look at the three smallest bones in your body, found in the middle ear. This may sound a bit crazy so brace yourself—the tiny bones with which we hear, are actually used by reptiles to chew their food. Yep, that’s right. We hear with our (ancient) jaw. A reptile’s jaw consists of multiple bones and there is but a single bone in the middle ear, the stapes. In contrast, the mammalian mandible is composed solely of a single bone, but a series of three bones comprise the middle ear: stapes, incus, and malleus.

Homology between the reptile jaw and the mammal middle ear. Image from Understanding Evolution, www.evolution.berkeley.edu

Two of the bones in a reptile’s jaw (the articular and quadrate) are homologous with the malleus and incus in the mammalian middle ear. Homologous structures have the same origin and were inherited by a common ancestor, but have been adapted differently in different lineages. One might reasonably inquire, how can we possibly know that these are the same bones? Amazingly, this was first discovered in 1837 by a German anatomist, Karl Reichert. Reichert came to this conclusion by dissecting pig embryos and finding that at early stages of development, pigs had what seemed like extra bones in their jaws and skulls. By tracking their development, he found that by the time of birth, these elements moved to the middle ear.

Not surprisingly, Reichert’s announcement was met with significant skepticism. One of his biggest obstacles to acceptance was the lack of fossil verification. However, since that time, there have been a plethora of fossil discoveries corroborating his theory. The evolution of the mammalian middle ear is now one of the most well documented transitions in the fossil record, and represents an excellent example of exaptation—a repurposing of previously existing elements for an entirely new function.

Fossil therapsid skull from South Africa (FunkMonkvia Wikimedia Commons)

While we now possess a wonderful record of transitional fossils, a significant difficulty still remains. Each fossil only provides a single snapshot in time, one still-frame view of where the bones stood in their evolutionary pathway. They may document and indicate the order of these changes, but how does such an amazing transition actually occur? What developmental processes must take place to fundamentally change the position and function of these elements from chewing to hearing? The only way to truly understand how this occurs would be to study the changes in living organisms. Placental mammals, like the pigs used by Reichert, are limited in what they can tell us because the changes occur so early in embryological development and only exhibit a partial reconstruction of the transition. But are there any mammals whose development traces the full jaw-to-ear transition? Turns out there are—marsupials.

I’ll tell you all about how modern marsupials are shedding light on ancient evolutionary events in Part 2.

About the author: Daniel Urban is a PhD student in the Department of Animal Biology at the University of Illinois at Urbana-Champaign. He studies development and embryology of modern mammals to better understand the changes observed in the fossil record. Stephanie Keep met Dan at ComSciCon and can tell you he’s an all around great guy.

“Air Conditioning System” May Make Hot Planets Habitable

Space





Photo credit:

ESO/L. Calçada

In the hunt for planets outside the Solar System that could be habitable, astronomers often look for exact Earth clones, which makes sense as we know our planet supports life. But what if some planets deemed inhospitable are actually friendlier than they appear?

Watch A Taser Strike Human Skin In Slow Motion

Technology





Photo credit:

Screenshot from The Slow Mo Guys / YouTube

The Slow Mo Guys are at it again – this time tasering a poor guy named Dan, all in the name of some "hard-hitting" science. 

The video was filmed at the Taser HQ in Scottsdale, Arizona. The impact of the taser striking the volunteer’s bare skin was captured at 28,000 frames per second.

Dan’s thoughts: “It feels like it’s never going to end! That’s a long freakin’ five seconds.”

 

Huge Chain Of Volcanoes Discovered In Australia

Physics





Photo credit:

The extinct volcanoes of far north Queensland are one end of a track that extends to Melbourne. Credit: Queensland Government

The Australian mainland lacks active volcanoes, but its geologic history looks very different with the identification of a 2,000-kilometer-long (1,240-mile-long) volcanic track, the longest known on any continent. The first volcanoes on the track are 33 million years old, but the forces responsible may still be having an effect on the sea floor off Tasmania.

Human-like nose can sniff out contamination in drinking water

By Elsevier

A bioelectronic nose that mimics the human nose can detect traces of bacteria in water by smelling it, without the need for complex equipment and testing. According to a study published in Biosensors and Bioelectronics the technology works by using the smell receptors in the human nose.

The sensor is simple to use and it can detect tiny amounts of contamination in water, making it more sensitive than existing detection methods. The authors of the study, from Seoul National University, say this could make the technology even more useful in the field.

There are two main problems caused by bacteria and other microbes in water: they can make the water toxic, and make it smell bad. At high concentrations, bacteria can be toxic in drinking water. But at lower levels — virtually undetectable by current culturing techniques — they can cause an “off flavor,” putting people off from drinking it.

The new study shows how technology that mimics the human nose can sniff out low levels of bacteria and other microbes by detecting the off flavor they give off.

“Water that smells bad isn’t necessarily toxic,” said Professor Tai Hyun Park, who has been leading the study. “Imagine you don’t do your laundry; it’s not that toxic but you don’t want to wear it because the smell is bad. With drinking water, if there’s off flavor, even if the water isn’t toxic, you don’t want to drink it. We wanted to develop a way to detect and remove this kind of contamination, so people are happy to drink water.”

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Vitamin D May Protect Against Cognitive Decline

The Brain





Photo credit:

Getting out in the sunlight may be the best thing for this couple's mental functioning. Credit: Ruslan Guzov/Shutterstock

People aged over 60 with vitamin D deficiencies are more prone to losing brain power, according to a new study. While the cause of the relationship remains unclear, it adds to a growing body of research indicating insufficient vitamin D could be harmful in a remarkably diverse number of ways.

Are Vitamins and ‘Natural’ Supplements Good for You?

Ben_Kerckx via Pixabay

By Alexandra Ossola

The National Institutes of Health (NIH) announced on Wednesday that it will invest a total of $35 million toward research into dietary supplements. Five research centers will spend the next five years investigating the effectiveness of some of the most popular “natural” dietary supplements in the country.

This research is important because the medical benefits of many nutritional supplements are unproven, despite the fact that about one-fifth of Americans take them. Antioxidant supplements, for example, have been found to stave off cancer, among other diseases, in some patients but worsen preexisting lung tumors in mice. Fish oil contains Omega-3 fatty acids, which may helplower your risk of heart attack, or it could increase your risk of prostate cancer, or do nothing to stop cognitive decline. If any of these chemicals contains a miracle cure—or if health-conscious people are unwittingly hastening their demise—doctors should probably know.

Paul Offit, an infectious disease specialist at Children’s Hospital of Philadelphia who has written extensively about vitamins and nutritional supplements, sees the value in these sorts of studies, even if the result is negative—in the past, similar studies have shown that taking concentrated garlic doesn’t slow bad cholesterol, or that the herb saw palmetto can’t help an enlarged prostate. “When patients want to take [these supplements] physicians can say ‘Don’t do it, take a statin instead. And don’t take garlic because it’s “natural”—it just doesn’t work,’” Offit says. The term “natural” is deceiving, he adds, since most drugs are derived from compounds found in nature.

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