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

I'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.

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.

Posted by Jeff on Friday, Oct 9 | Permalink | Comments (25) | TrackBacks (0)

I'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.

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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.

Posted by Jeff on Friday, Oct 2 | Permalink | Comments (0) | TrackBacks (0)

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

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?

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.

Posted by Jeff on Friday, Aug 28 | Permalink | Comments (24) | TrackBacks (0)

Organic food is becoming increasingly popular. The Market Analysis page of the Organic Trade Association describes how organic food sales were $39.1 billion in 2014, nearly 5% of total food sales in the U.S., and up 11.3% from the previous year. It seems that nearly every grocery store now carries organic foods. I can't even find non-organic fresh herbs in my local grocery store.

There are a lot of hyped up claims about the health benefits of organic foods without a whole lot of data to back up those claims. There's also a lot of misunderstanding about what it actually takes to get classified as 'organic' from the USDA. For example, many organic farmers till use pesticides - they're just naturally occurring chemicals as opposed to synthetic ones. You can read about a lot of these issues in a Scientific American article, Mythbusting 101: Organic Farming > Conventional Agriculture.

But most of that is just hype, and if people are willing to pay extra money for a product that doesn't live up to all its claims, I believe P.T. Barnum may have had something to say about that*. My major problem with organic foods is where they actively cause harm to the environment. A good discussion on organic and conventional crop yields can be found in the entry on the Jayson Lusk blog, Organic vs Conventional Crop Yields. As Lusk points out, most large scale literature reviews find that organic crops on average give yields around 20-25% lower than conventional techniques (there's a lot of variability in that discrepancy depending on the particular crop). And as Lusk further went on to point out, conventional farming will always have an upper hand on organic, because even if some organic techniques are found to be beneficial, conventional farming can always adopt those particular techniques while still having other options that aren't available to organic**.

So, 20-25% lower yieds means that roughly 20-25% more cropland is required. Or to put that a different way, it means 20-25% more habitat destruction. And that's a big deal. Here's an excerpt from the World Wildlife Fund page on Impact of habitat loss on species.

Habitat loss is probably the greatest threat to the variety of life on this planet today.

It is identified as a main threat to 85% of all species described in the IUCN's Red List (those species officially classified as "Threatened" and "Endangered").

Increasing food production is a major agent for the conversion of natural habitat into agricultural land.

I know global warming gets most of the attention now as far as environmental disasters, but habitat loss is arguably worse. There are 7 billion people on this planet right now, and that's likely to increase to around 10 billion in the future, if not more. All those people need food, and most of that food has to be grown on farms. We should be doing everything we can to make those farms as productive as possible, minimizing habitat destruction as much as possible. We shouldn't be pushing for farming techniques that make that production 25% worse.

Most people buy organic foods because they want to eat healthy or because they are concerned about the environment and think organics reduce environmental problems. But they've been misled. The health claims aren't backed up, and the environmental impact is far more negative than most people realize.

*Actually, I still do have a problem with it, the same way I do with all false advertising. Organic proponents are pushing claims that aren't backed up by evidence, which is pretty misleading, though they probably believe the claims themselves so it's not exactly dishonest. And the saying about a sucker born every minute wasn't actually made by PT Barnum, but I'm sure he still had something to say about making money off of suckers.

**It reminds me of the passage from Tim Minchin's poem, Storm, "You know what they call “alternative medicine” / That's been proved to work? / Medicine.”"

Posted by Jeff on Friday, Aug 21 | Permalink | Comments (22) | TrackBacks (0)

I've seen quite a few people who seem to think that evolution implies that the meaning or purpose of life is to reproduce. Just Google the phrase, the purpose of life is to reproduce, and you'll find plenty of examples of people proposing or debating this interpretation. Even Scientific American has a blog entry, Is the Meaning of Your Life to Make Babies?, which partially supports this view. While that article does recognize that we can have other meanings besides evolutionary ones, it still implies that this evolutionary meaning is real:

So is making babies -- and having genes survive through the generations -- the meaning of life? The answer is yes -- from an evolutionary gene's eye view. Making babies, and also other actions and social structures that result in the survival and reproduction of one's gene, such as protecting one's relatives. Differential reproduction is a process which, in conjunction with environmental interactions, has led to all life as we know it, with all its diversity and grandeur, including conscious experience itself. This is modern knowledge that is not to be taken lightly, and has impact on how we view our own meaning.

But from almost every other perspective -- individual, group, moral, environmental, or concern for life as a whole -- the answer to the question is no. Meaning from these perspectives -- from life as it is actually experienced -- is up to us. Reproduction and genetic survival may be the meaning of Life, but it is not inescapably the meaning of your life.

However, I think any interpretation that says the meaning of life is to reproduce is misguided, since it's an answer to a misguided question. Other than meanings we ascribe to ourselves, life has no meaning. Reproducing and leaving copies of our genetics isn't meaning, it's just a description of what happens. When a boulder falls off a cliff, gravity means it will fall. Does that mean the meaning of the boulder was to fall, or is it just that the act of falling is what happens due to gravity?

Or consider a river. Do rivers have a meaning? Do they have a purpose? Sure, they return water to oceans, but that's simply what happens due to water flowing downhill and collecting in the lowest regions. There's no meaning to it. It's just the result of physics.

That's how it is with evolution. Organisms that are more 'fit' in whatever sense that means for their environment have more offspring, which means their genes become more prevalent. But that's no more a meaning or purpose than a river flowing downhill. It's just a description of what happens.

Meaning and purpose only make sense in relation to a conscious entity. Genes are not conscious entities. Nature is not a conscious entity. Evolution is not a conscious entity. So it makes no sense to describe the results of evolutionary processes as having any meaning or purpose. They're simply results.

Image Source: I made it myself. And if you don't get the reference - 42.

Posted by Jeff on Thursday, Jul 23 | Permalink | Comments (25) | TrackBacks (0)