Science & Nature Archive

Tuesday, November 17, 2015

Weird Engineering Unit - The Slinch

Standard MassTechnical fields are full of units that most non-technical people have never heard of. It gets even weirder with customary U.S. units, given the history of how these units came about. The most obscure unit I've ever actually used for real practical applications is the slinch.

If you're not involved in a technical field, you may not be familiar with the idea of coherent or consistent units. Basically, it's the idea that you shouldn't need any fudge factors in an equation because of the units you're using. For example, power can be calculated as a force times a speed, or P=F*V. Using consistent U.S. units gives an answer in ft-lb/sec, while using metric units gives an answer in N-m/sec (also known as Watts). A non-consistent unit of power that most people are familiar with is horsepower. If you multiply force times speed, you then have to divide by a fudge factor of 550 to get your answer in horsepower, or HP=F*V/550. And the fudge factors only work if the inputs are the units you're expecting. If people wanted to use mph instead of ft/s for the velocity, then you'd need another fudge factor on top of that, HP=F*Vmph*(5280/3600)/550. Equations can get pretty messy if you're not using consistent units, having to multiply all those fudge factors together.

In the standard units used for engineering in the U.S., pounds are a measure of force, not mass (this is already a distinction some people are unfamiliar with, confusing weight and mass). The unit for mass, which most non-technical people would already consider an obscure unit, is the slug. But trust me, I use slugs on a nearly daily basis as an engineer. On Earth, a slug weighs approximately 32 lbs (i.e. F=mg). Or for you metric people, it's equivalent to about 14.6 kg (which measure mass, not weight).

But the engineers who do stress calculations don't always use the normal FPS (foot-pound-second) system, because everyone's used to seeing stresses reported in lbs/in², or psi. And if you were using the normal FPS system, your stresses would come out in lb/ft², and you'd have to do a conversion at the end of your calculations to put the results in the psi that most people are used to seeing*. That's not a huge deal for spreadsheets or hand calcs, but it does make it more difficult for certain finite element programs. So, the stress guys sometimes use a different set of units based on pounds and inches, with the mass unit being the slinch. A slinch is 1/12 of a slug (i.e. the ratio between feet and inches). On Earth, a slinch weighs approximately 32/12 lbs, or 2.7 lbs.

Of course, a lot of these weird units could be simplified if all the engineers in the U.S. started using the metric system like the rest of the world, but that's not the way it is right now, so I've got to use units that other U.S. engineers are familiar with. And if Wikipedia is to be trusted, the metric stress guys have their own weird mass unit of glugs in the centimeter-gram-second system.

* Speaking of weird stress units, I remember working with a foreign engineer one time who gave me her results in Pascals, which is the normal metric way to do it. When I asked her to convert her results to U.S. units, she gave them to me in N/ft².

Image Source: Wikimedia Commons, slightly Photoshopped to remove a dead fly

Note that this entry was adapted from a response I left on Quora.

Saturday, October 31, 2015

A Response to Ben Carson's Creation vs. Evolution Video

Note: for a list of all my Carson related entries, go here.

Ben CarsonThis is my third entry inspired by a speech Carson gave a few years ago, but was just posted to YouTube in June of this year. The first entry was Ben Carson Being Noticed by Popular Science Writers, where I mostly described popular science writers' reactions to the video. Then next entry was Yet Another Look at Ben Carson's Views on Evolution - His Creation vs. Evolution Speech, where I mostly explained why this speech made Carson unfit for the presidency. But I didn't really rebut Carson's misinformation in either of those entries. I merely stated how wrong he was, without demonstrating it. That actually was on purpose, since as I wrote in that second entry, "I'm tempted to go into a point by point refutation of Carson, but there are so many falsehoods and misunderstandings, it would make this post extremely long." But, since I know not everybody studies evolution as much as I like to, I realize that not everybody might understand just how wrong Carson is in this video, so I have decided to do a more detailed rebuttal to his claims. Even ignoring politics, this is an opportunity to educate people on some common creationist misconceptions. Like I expected, this has made for a very long post.

First, just to repeat a theme I've written in both of those previous entries, the aspect of this video that's so damning of Carson isn't merely his ignorance of evolutionary theory, but that he was unable to recognize his own ignorance on the issue, and that despite this ignorance, he was arrogant enough to give a prepared lecture to a crowd of people. As I wrote in the second entry, "Most of us are ignorant about a whole range of issues, but we don't go around giving speeches about those issues." How can we trust Carson to recognize his own limitations?

I know this is a long entry. In fact, some individual answers could stand as their own entries. But I decided to address Carson's mistakes on evolution comprehensively, and he had so many mistakes. On the plus side, many of these mistakes are common creationist mistakes not limited to Carson, so addressing them comprehensively does offer an opportunity to educate others. But, if you want to just skim over this entry and only read the portions that catch your eye, that's understandable.

To keep this entry from growing even longer than it is, I mostly limited myself to discussing evolution, even though Carson discussed a few more topics. However, a few of his statements on those other topics were just too tempting to pass up, so they're discussed here, too.

Continue reading "A Response to Ben Carson's Creation vs. Evolution Video" »

Friday, October 9, 2015

If Humans Went Extinct, Would Something Like Us Evolve Again

This entry is part of a collection on Understanding Evolution. For other entries in this collection, follow that link.


Is the March of Progress InevitableI've seen the question that's the title of this entry many times, most recently on Quora (If all humans died, would we evolve again from apes? and in a comment thread to Aaron Weyenberg's answer to If humans evolved from apes, why are there still apes?. I wrote a response for Quora that I figured I'd adapt for the blog.

It's certainly possible that some lineage of modern ape or monkey could eventually evolve into something like humans (though definitely not exactly the same as us), or given an even longer time, some other lineage not particularly closely related to humans could as well, but it seems extremely unlikely.

The first issue with the question is an assumption I've pointed out before (such as in the entry, Local Church Misunderstands Evolution - Why Are There Still Apes?). This assumption goes back to the Great Chain of Being, that there's a hierarchy of life, with humans at the pinnacle being the most perfectly evolved of all creatures. That's simply not the case. Evolution adapts organisms to their environments. The raw material for this is random mutations, with natural selection acting like a filter to ensure that only beneficial and neutral mutations persist (though that's not the only mechanism in evolution). There's no intention behind the mutations, guiding organisms towards some end goal. It simply adapts them to their current environments, with no foresight to some future species.

Moving on, there is a concept in biology known as convergent evolution. This refers to two separate lineages that didn't originally have the same features both evolving those features independently, 'converging' on the same solution. And it is true that convergent evolution happens quite a bit. Here are a few examples showing how different marsupial and placental mammals have independently evolved similar body types.

Placental Marsupial Convergent Evolution

But convergent evolution is almost always in cases of 'easy' solutions. Let's look at an example separate from those above or from humans - powered flight. Powered flight has only evolved three times in vertebrates (each time by a different path - pterosaurs, birds, and bats), because powered flight is a difficult to achieve strategy. It takes a very specific set of adaptations, and the likelihood of all of these adaptations occurring simultaneously in a single organism is rather small. If birds and bats were to suddenly go extinct, it might be quite some time before another lineage evolved to fill that flying vertebrate niche.

Just focusing on the intelligence aspect of humans, when you look around at other animals, the type of extreme intelligence seen in humans just isn't very common. On land, there are the other apes and elephants that are nearly as smart as us. In the water, some dolphins and whales also approach human intelligence. But none seem to be as smart as us, or at least not in a technologically inclined way.

There's a reason for that. Brains take a lot of energy. Even though your brain is only around 2% of your weight, somewhere around 20% of the calories you eat go to supporting your brain (one source: University World News: The brain - Our most energy-consuming organ). That's a lot of extra food you need to survive compared to a similarly sized animal with a smaller brain. And yes, being clever can help individuals exploit more resources than less intelligent animals, but just by looking at the distribution of intelligence of all the species out there, it doesn't seem like a strategy that natural selection often favors.

Even us humans, who are now so dominant on this planet, wouldn't have looked particularly noteworthy a few tens of thousands of years ago. Genetic studies show that the effective population got all the way down to around 10,000 - 30,000 individuals at some point in the past (more info: Why Evolution Is True: How big was the human population bottleneck? Another staple of theology refuted). That's not a very successful species. Our ancestors were on the brink of extinction, and barely managed to survive.

If some modern lineage of apes or monkeys went down the evolutionary path to extreme intelligence with the high energy requirements of large brains, they might not be lucky enough to survive a similar situation to what caused the bottleneck in our ancestors, and might end up going extinct before their culture advanced to the point where technology made them as successful as us.

Once you start considering the other specializations of humans (bipedalism, long distance running, object manipulation, etc.), the possibility of another lineage evolving into something closely resembling us seems even more unlikely.

Image Source 1: Wikipedia, with further editing by me.

Image Source 2: The Roaming Naturalist, who herself doesn't know where the original came from. Let me know if you recognize it.


Want to learn more about evolution? Find more at Understanding Evolution.

Friday, October 2, 2015

Ben Carson Being Noticed by Popular Science Writers

Ben CarsonI've been pointing out Ben Carson's anti-intellectual stances in regards to science for a while, now (you can see all my Carson entries here). But just recently, he seems to have caught the attention of many popular science writers. This seems to have a lot to do with a recent YouTube video, which I've embedded below. More specifically, it seems to have a lot to do wtih a Buzzfeed article commenting on the video, Ben Carson: Big Bang A Fairy Tale, Theory Of Evolution Encouraged By The Devil. The video is a speech Carson gave back in 2011, but which was just uploaded this year. It was posted by Adventist News Network, who pretty much agreed with everything Carson was saying. In other words - as bad as the video makes Carson look, they weren't intentionally trying to embarrass him.

I've seen a spate of articles and blog entries about Carson recently that seem to coincide with that Buzzfeed piece. The most prominent article was in The New Yorker, and was written by Lawrence Krauss, Ben Carson's Scientific Ignorance. Being a physicist and cosmologist himself, Krauss commented mostly on Carson's mangling of the Big Bang theory and the history of the universe. Here's what Krauss had to say after quoting a particularly bad series of statements by Carson.

It is hard to find a single detailed claim in his diatribe that is physically sensible or that reflects accurate knowledge about science. His central claim--that the second law of thermodynamics rules out order forming in the universe after the Big Bang--is a frequent misstatement made by creationists who want to appear scientifically literate. In reality, it is completely false.

Krauss went on to address many of Carson's erroneous statements, giving real explanations for many of Carson's misunderstandings. Towards the end of the article, Krauss moved past simply correcting Carson, and presented some commentary that I agree with completely:

It is one thing to simply assert that you don't choose to believe the science, in spite of a mountain of data supporting it. It's another to mask your ignorance in such a disingenuous way, by using pseudo-scientific, emotion-laden arguments and trading on your professional credentials. Surely this quality, which reflects either self-delusion or, worse still, a willingness to intentionally deceive others, is of great concern when someone is vying for control of the nuclear red button.


On his website, Why Evolution Is True, Jerry Coyne wrote his own entry on Carson, Ben Carson on evolution: an ignorant (or duplicitous) Presidential candidate. Coyne himself is a biologist, and so the bulk of his article was devoted to correcting Carson's untrue remarks on evolution. He did offer a bit of commentary, though such as his introductory paragraph.

I don't care how good a surgeon Ben Carson was (and he was reportedly a terrific one), he's still pig-ignorant when it comes to evolution, geology, and cosmology. And that ignorance--regardless of whether he doesn't know the facts, knows them but eludes them and is lying for Jesus, or truly believes that the facts support creation ex nihilo--makes him unqualified to be President. For the first possibility means he's uninformed (especially as a doctor); the second means he's dishonest; and the third means he's blinded to reality by his fundamentalist faith, Seventh Day Adventism.


Phil Plait of Bad Astronomy also got in on the act, writing Ben Carson: Evolution is Satanic and the Big Bang Is a Fairy Tale. Here was the introduction to his article.

At one point in time, GOP presidential candidate Ben Carson may have been best known as an excellent, even groundbreaking, neurosurgeon. In recent years, though, he's done everything he can to throw that reputation away.

Plait had references to a lot of Carson's statements, not just the 2011 speech, as well as a lot of information refuting Carson's claims. Of course, being the Bad Astronomy website, Plait focused on the Big Bang, but he also spent a bit of time on evolution. After explaining how he tries to be polite when dealing with rank and file creationists, Plait went on to say this.

I take a different stance when it's a politician who espouses these views, especially when he's running for the highest office in America. If someone wants to run this country, then he better show that he has a solid grasp on reality. Dismissing and actively denigrating strongly understood science--whether it's astronomy, biology, or climatology--is at the very least cause to dump him.


Although he can be a bit brash for many readers, I'll also mention P.Z. Myers of Pharyngula, who wrote You don't have to be smart to be an MD. He wasn't insulting medical doctors in general, but making the valid point that expertise in one field, even particularly noteworthy expertise like Carson's in pediatric neurosurgery, doesn't translate to expertise in other fields. Here were Myers' closing remarks.

Being a neurosurgeon doesn't preclude being knowledgeable, but clearly we have to overcome this bias of using an MD degree as a proxy for intelligence. / Fortunately, Ben Carson is working hard to demolish that preconception.


I know I've been writing quite a bit about Ben Carson recently. But now it seems that notable science writers are starting to pay more attention to him, as well. So, if you want to see what other people have to say about the man, as well as corrections to his mangling of science by people actually in the fields he's criticizing, go read those articles.

---

Added 2015-10-02: I finally took the time to watch that whole video embedded in this post, and not just rely on the excerpts that other people have provided. Wow. And I do mean wow. I'd read short interviews of Carson's beliefs on evolution, and some of the comments he's made, but they don't illustrate the depth of his ignorance and arrogance like this video. This was a 40 minute speech, a prepared speech that he had time to research, where he knew the topic ahead of time. This was not an off the cuff remark, or an answer to an interview question he wasn't expecting. This was a neurosurgeon, with the respect that goes along with that profession, giving a presentation to an entire crowd of people. And this speech is what he came up with.

His misunderstandings and ignorance of evolution are absolutely appalling, worse than I would expect from a high school biology student. So many of his misconceptions could have been cleared up just by reading a popular introduction to evolution, like Jerry Coyne's Why Evolution Is True, or Donald Prothero's Evolution: What the Fossils Say and Why It Matters. If he was too cheap to buy a book, he could have gone to the Internet and sites like The TalkOrigins Archive. His misunderstandings of astronomy and cosmology were equally egregious, not to mention his mangling of a few other topics he brought up.

Now, this type of ignorance on its own is forgivable in most people (though I would expect a surgeon who had to study biology to be a bit more knowledgeable, and I'd certainly expect presidential candidates to have good enough educations to understand basic science). What makes it so bad in Carson's case is that despite his dreadful ignorance, he was still arrogant enough to give a 40 minute speech to an audience who trusted that he was knowledgeable on the topic. That attitude on Carson's part is the worst part of this. Most people are ignorant about a whole range of issues, but we don't go around giving speeches about those issues. And if we were invited to talk about something we didn't know about, we'd at least do some research on it. It just boggles the mind that Carson felt he was qualified to speak on a topic about which he is so obviously completely ignorant.

Friday, August 28, 2015

Which Came First, the Chicken or the Egg? And a Discussion of the Fuzziness of Species

This entry is part of a collection on Understanding Evolution. For other entries in this collection, follow that link.


Which Came First, the Chicken or the Egg?It's a perennial philosophical question, 'Which came first, the chicken or the egg?' Now, thanks to our understanding of evolution, we can give a better answer. But even with science, I've seen many attempts to answer this question that get details wrong. I've written my own answer before in the entry, Which Came First, the Chicken or the Egg?, but after running across this question again on the site, Quora, I've had a few more thoughts on how to better explain it. For this entry, I'll pull from both my Quora answer and my previous blog entry, to try to provide a better answer to this age old question.

Just because you can phrase a question a certain way doesn't mean the answer has to follow that form. As an example, think of another question - when does dusk become night? There's no exact answer, because it's a subtle process that changes continuously from light to dark. You can't pinpoint the exact time when it becomes night.

That's how it is with evolution. There are gradually changing populations. If you used a time machine to follow the population that evolved from proto-chickens into true chickens, there's no single individual you could pick out as sufficiently different from its ancestors to call it the first chicken. Even if you tried to set up some arbitrary qualification of requiring certain specific genetic mutations, remember that all of the animals in that population are reproducing sexually. So even if one animal pops up with the genome that fits your criteria of 'chicken', it's going to mate with another animal in that population and scramble up that genome for the next generation. Since that mate didn't fit your criteria for chicken, it's lacking at least one of your required mutations, so at least around half of that pair's offspring is going to revert back to not being chickens. If the mate was lacking several of your 'first' chicken's mutations, then potentially none of their offspring will fit your criteria as being chickens. Does it make sense to define an individual as the first chicken if all of its offspring revert back to not being chickens? Does it make any sense at all to call an animal essentially indistinguishable from its parents as a different type of animal from them? The problem is in trying to apply a precise label to a process that isn't precise.

In reality, species is a very fuzzy concept. The biological species concept is the one most used for sexually reproducing animals. Wikipedia gives a definition for it as follows.

A biological species is a group of individuals which can breed together (panmixia). However, they cannot breed with other groups. In other words, the group is reproductively isolated from other groups.

This idea of reproductive isolation is where the fuzziness comes in -- how much reproductive isolation is necessary to classify two populations as distinct species? For example, horses and donkeys can breed and produce offspring, but those offspring are sterile, so they still get classified as two species. Polar bears and grizzly bears can breed, and their offspring are fertile. But because they don't breed very often, there's very little genetic mixing between their populations, so they do get classified as different species. Dogs and wolves can breed and produce fertile offspring, and there's more mixing than with polar bears and grizzly bears, but little enough that they're still referred to as separate species.

There's a trend here. Reproductive isolation isn't a black and white property. It comes in varying degrees, and that degree depends an awful lot on how long two populations have been separated. It's not like there's a single mutation and Bam! -- no more breeding. The longer two populations are separated, the more unique changes build up in each population, and the more dissimilar their genomes become. If they've only been separated for a very short while and then come back in contact, there won't be any trouble at all with interbreeding. If it's been a bit longer, maybe breeding will result in a few more miscarriages, or a few more infertile offspring, but only a small fraction of all offspring. Longer still, and maybe fertile offspring become the minority. A bit longer, and maybe even infertile offspring would be rare. Even longer still, and maybe all the matings result in miscarriages. And after enough time, mating might not even allow the sperm to fertilize the egg.

In other words, speciation isn't a specific event. It's a process. The longer two populations are separated, the more reproductively isolated they become, shading from a single species to breeds to subspecies to separate species.

There are a few more interesting examples to illustrate the fuzziness of defining species. The first is one I already brought up - mules. In fact, when I wrote up above that horses and donkeys can breed to produce sterile mules, the truth is a little more complicated than that. While there haven't been any known fertile male mules, there have been a few fertile female mules. So, where does that put them with the biological species definition? They're mating does create some, if not many, fertile offspring.

Another interesting case is what's known as a ring species (or perhaps a better term might be pseudo ring species**). These are animals that have a range that encircles some type of barrier. A classic example is the Larus gull, which lives in a band around the Arctic Ocean. If you start with the European Herring Gull which lives mainly in Great Britain, it can mate with the American Herring Gull to the west. And they do this often enough that their gene pools mix, which indicates that they're merely subspecies, not completely different species. And if you go west from there, the American Herring Gull can mate with the East Siberian Herring Gull. And you can keep going west, with the groups being able to interbreed, all the way until you get to Lesser Black-backed Gulls, which live mainly in Europe but which also stray into Great Britain. But guess what, the Lesser Black-backed Gulls in Great Britain don't mate with the European Herring Gulls on the same island. So how do these animals get classified as a species? There's one large interbreeding population right now, which would indicate one species. But what if all of the subspecies were to go extinct except for Lesser Black-backed Gulls and European Herring Gulls? Would they instantly become two new species?

Gull Range
Larus Gull Range - All adjacent populations interbreed except 1 and 7
(Image Source: Wikipedia)

Perhaps a more familiar example is dogs. Everybody knows that dogs can interbreed. That's where muts come from. But what if some super-villain were to come along and kill every breed of dog except for Chihuahuas and great Danes? Now, I know that technically you could probably give them a hand to do the deed and make puppies, and they might even be fertile. But, if left to their own devices, they'd be two pretty effectively isolated breeding populations. (I suspect this page is either a joke or an urban legend, but it still reveals the difficulties that would be involved). So, given the current dog population, chihuahuas and great Danes are part of the same species. But there's no way they would be considered the same species if they were the only dogs left in existence.

Given that species is such a fuzzy concept to begin with, it makes no sense to think of a 'first' of any species. There's no great big event mutating an entire genome that produces a 'hopeful monster'. Speciation is a process, the accumulation of countless small mutations in two separate populations until eventually those two populations have genomes that are incompatible. There's no point where you can pick one organism as being a different species from its parent.

So, the next time you hear someone ask, 'Which came first, the chicken or the egg?', you can explain why the answer is neither. Since you can't precisely define the first chicken, you can't precisely define the first chicken egg, and you certainly can't say which came first.


Image Source: Brain Pickings


*I'm assuming that the question implies it's a chicken egg. It doesn't make much sense to ask which came first, the chicken or the dinosaur egg, because then there's no conundrum at all.

**The example I described isn't exactly the definition of ring species, at least using the classic definition. Per the classic definition, a ring species is one that has gradually encircled some type of barrier, with individuals in different locations facing different selection pressures per their local environments. As the population expands its range around that barrier, it eventually meets back up with the original population, and in a ring species, the differences between the individuals at each end of the range are great enough that they don't interbreed. The classic definition also assumes that the population has remained unbroken throughout its entire history, and that the different genetics between each end occured without any geographic isolation to stop gene flow. However, pretty much every ring species that's been studied shows evidence that there have been periods of geographic isolation in the past, accounting for much of the divergence between populations. However, there are many of these pseudo ring species that still follow the pattern I described up above, where neighboring populations can all interbreed except for those at the start/end of the ring. (more info - Why Evolution Is True)

Updated 2017-03-27: Added diagram of gull range


Want to learn more about evolution? Find more at Understanding Evolution.

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