Science & Nature Archive

Tuesday, September 20, 2016

Is Evolution Falsifiable?

Is the March of Progress InevitableI came across the following Quora question, Is the theory of evolution unfalsifiable?. Although I'm not sure the question was asked in good faith, it's still an interesting question to think about. Here was my response.

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All good science should in principle be falsifiable. The problem is that some fields become so well backed up by evidence, it's hard to conceive how they could be falsified short of ludicrous conspiracy theories or Matrix like scenarios.

For example, take the roughly spherical shape of the Earth. For all intents and purposes, this is a concept that has been proven beyond a shadow of a doubt. You can find multiple Quora threads dealing with flat earth 'theories', such as this one, Let's say I don't believe the world is round. How can one prove the world is round to me?, which lists some of this overwhelming evidence in support of the Earth's true shape. It's really hard to conceive how this concept could be falsified given all that we know. It would take a conspiracy on par with The Truman Show, where everyone we thought we knew was an actor, and we had been misled our entire lives, or an equally ludicrous scenario like the Matrix, where we were living in a simulated reality not at all like the reality outside the simulation. In short, falsifying the roughly spherical shape of the Earth would entail a shake up so huge that we couldn't trust anything we thought we knew about the world.

Evolution in broad stroke approaches that level of certainty. Between biochemistry, biogeography, comparative anatomy, comparative embryology, molecular biology, paleontology, genetics, observed instances, and other lines of evidence, it's really hard to conceive of how the concept could be falsified.

One of the flip answers you'll often hear is rabbits in the Precambrian, supposedly a response from J.B.S. Haldane when asked what evidence he thought would falsify evolutionary theory. But to return temporarily to the flat Earth example, that's like saying that a photograph of a disc world from space would be evidence to falsify round world theory. But honestly, would the image below be enough to convince you that the world was flat? Or would you suspect Photoshop or some other type of hoax?

Flat Earth Illustration

So even if fossil rabbits were claimed to be found in Precambrian deposits, they would be investigated and considered very extensively before being taken as evidence overturning evolution. Could they be hoaxes? Some type of disturbance to the geological column in that locale? A section of Precambrian deposits that were temporarily exposed long enough for some poor ancient rabbit to die and become fossilized there? To be honest, given the vast other data in support of evolution, a single Precambrian fossil rabbit would probably be chalked up to an unexplainable anomaly.

But, supposing more out of place fossils were found than just a single anomaly, or you could find evidence of huge conspiracies among all the world's biologists past and present lying about the evidence for evolution, or you could find evidence for the Matrix and that the real world is far different from this simulation that we're living in, then you might have something in the way of falsifying evolution.

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More Info - I included a link to a Quora thread in the original answer, and I've written about the topic numerous times, myself. So, here are links to that Quora thread and a few of entries I've written.

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

Image Source 2: Pinterest - It's actually all over the place without attribution, so I doubt that I've actually found the original. If anyone knows the actual original source, please let me know.

Friday, April 22, 2016

Answering Quora on the Safety of Organic Foods and Microwaves

Organics, Just Say NoI recently came across a question on Quora, Will it be okay if I eat healthy organic food, twice a day, with the stipulations that they be microwaved?. This is related to a previous entry of mine, Why I Oppose Organic Food, so I decided to repost my answer here, with a few edits.

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It depends on what context you mean by 'okay'.

Let's start with the organic food. If you mean okay as far as your own health, then sure, organic food can be healthy. Here's a good summary from a previous Quora question, Jae Won Joh's answer to Is organic food a better option?. For the most part, organically grown food is about the same nutrition-wise as conventionally grown crops. Organic had slightly higher risks for some bacterial infections, but not by a huge amount. Organic tended to have less pesticide residue than conventional, but according to another study (see this Quora answer - Richard Muller's answer to What are some mind-blowing facts about food?) organic crops tend to be higher in carcinogens. This makes sense because varieties used for organic crops have to have higher natural resistance to pests, meaning the chemicals conferring this resistance will be present throughout the food, not just on the surface like sprayed pesticides which can be washed off.

But me, I tend to be a bit of a tree hugger. So when I think of 'okay', I think in terms of the whole environment. And this is the main reason I try to avoid organic foods. Habitat loss is perhaps the biggest threat to biodiversity in the world - even more of a threat than global warming. And studies show that organic crops on average give yields 20-25% lower than conventional techniques (with a lot of variation depending on the particular crop). That's huge. If all crops were grown organically, we'd need roughly 1/3 more cropland! And that means a whole lot more habitat destruction, and hence a lot more loss to biodiversity. And the thing is, 'conventional' farming will always be at least as good as organic, and most likely better, because conventional farms can use every technique available to organic farms plus some. (More info - Why I Oppose Organic Food).

As far as using a microwave, the health considerations are minuscule. Cooking only with a microwave can be slightly more nutritious, as described in this article, Microwave cooking and nutrition - Harvard Health. The shorter cooking time means less breakdown of nutrients, and less liquid means less nutrients are leached out to be dumped down the drain (like if you boil veggies). But if you're going to be cooking your food conventionally at home first and then using a microwave to re-heat it, then this nutrient loss will have already occurred when you initially cook the food. But as that article stated, "let's not get too lost in the details. Vegetables, pretty much any way you prepare them, are good for you, and most of us don't eat enough of them."

As far as the environmental impact, here's another article, Stove versus Microwave: Which Uses Less Energy to Make Tea?. Basically, the difference is tiny. Stove tops are slightly more efficient at boiling water than microwaves, while microwaves are slightly more efficient than full size ovens at heating food. But to put those slight differences in perspective, the article quotes a consumer advocate as saying "You'd save more energy over the year by replacing one light bulb with a CFL or turning off the air conditioner for an hour--not an hour a day, one hour at some point over the whole year." So the differences are hardly worth worrying about.

So to summarize, as far as health, organic has about the same nutritional value as conventionally grown food, only slightly higher risks as far as bacterial infection, and a bit more risk regarding cancer due to the higher carcinogen levels. Microwaves don't make much difference at all regarding health, especially if you're using them to reheat food, not for the initial cooking. On the environmental side, organic has a much higher negative impact due to lower crop yields and associated habitat destruction. Microwaves make hardly any environmental difference compared to conventional cooking techniques.

So all in all, while it's not super risky, I'd recommend against organics because of the higher levels of carcinogens and the bigger environmental impact. Using a microwave to reheat food is fine.

Wednesday, April 13, 2016

New Book - Future Humans

A friend of mine, Scott Solomon, has just finished writing his first book, Future Humans: Inside the Science of Our Continuing Evolution.

Future Humans book cover
Publisher's Page
Buy from Amazon

Here's the description from the publisher's website:

In this intriguing book, evolutionary biologist Scott Solomon draws on the explosion of discoveries in recent years to examine the future evolution of our species. Combining knowledge of our past with current trends, Solomon offers convincing evidence that evolutionary forces still affect us today. But how will modernization--including longer lifespans, changing diets, global travel, and widespread use of medicine and contraceptives--affect our evolutionary future?

Solomon presents an entertaining and accessible review of the latest research on human evolution in modern times, drawing on fields from genomics to medicine and the study of our microbiome. Surprising insights, ranging from the rise of online dating and Cesarean sections to the spread of diseases such as HIV and Ebola, suggest that we are entering a new phase in human evolutionary history--one that makes the future less predictable and more interesting than ever before.


Scott Solomon is an evolutionary biologist and science writer. He teaches ecology, evolutionary biology, and scientific communication at Rice University, where he is a Professor in the Practice in the Department of BioSciences. He lives in Houston, TX.

I read one of the draft manuscripts, and so can say that it really was an interesting, engaging read. And while you might worry that a book about future human evolution might be hokey or too speculative, you can rest assured that this book is well grounded and sticks to reasonable inferences.

You can pre-order the book from Amazon right now. It will be shipped in October.

Friday, April 8, 2016

Answering Quora - Is technology replacing spirituality?

In keeping with the spirit of my recent entry, Does spirituality provide anything that science cannot provide?, this week I'm answering a related question that was recently posted on Quora, Is technology replacing spirituality?. Here is my answer.

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Below is perhaps my favorite photograph of all time, the The Chandra Deep Field South*:

Deep Look Into Space

That's only a very low-res version. Go visit the ESO page, A Pool of Distant Galaxies, download the full image, and take some time to look at it and marvel (really, I mean it, you won't be disappointed). Practically every point and smudge of light in that image is an entire galaxy, not just a single star. And that image covers a portion of the sky smaller than the full moon. The image is awe-inspiring, humbling, and marvelous all at the same time. Thousands of years ago when people looked up at the night sky, they thought the stars were shiny objects embedded in a firmament, or mythological beings. There was no conception at all of how unimaginably vast the universe really is. It's only technology that makes images like this one possible, and that reveal to us our place in the universe.

And how did I come to find this image personally? The Internet - a vast collection of networked computers sharing practically all of human knowledge. And this image is but just one example. There's a whole vast array of mind-blowing lessons to be found online, from understanding evolution and our place in the vast tree of life, to the tiniest known portions of nature, subatomic particles, that are only known about because of technologies like the LHC at CERN. And the Internet itself is only possible because of humanity's understanding of semiconductors, electronics, logic, etc. Without that type of technology, I'd be stuck with magazines and other print sources for whatever scraps of information I could find. And even those 'old' information sources rely on printing technology. Before the printing press, my only information sources would have been hand written manuscripts or word of mouth.

Science and technology have revealed so much that would have been impossible to know before. Sure, it's given us distractions, as well. But for those willing to look, it's provided us with a far deeper understanding of nature and the universe and our place in it than any ancient culture could have dreamt of.


*I've used this image before, in the entry, The Universe Is Big. I had a little more explanation putting this image into perspective. And while I was at it, I did take some time to study that image again. It gives me butterflies in my stomach every time.

Friday, March 18, 2016

Answering Quora - Why There Were No 'First' Humans

Human Family TreeIn what has become my modus operandi here recently, I'm going to recycle a Quora answer for this post. This time, the question was, 'would the parents of the first human grandchild have been siblings?'. My response is very similar to parts of a previous answer/post, Which Came First, the Chicken or the Egg? And a Discussion of the Fuzziness of Species, but I think I did a better job this time explaining the example. So, here's my answer, with a few minor edits, and some additional footnotes.

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As many others have pointed out, there was no 'first human'. Evolution is a gradual process that occurs in populations. Trying to pinpoint the exact individual that was the first human is like trying to pinpoint the exact second when twilight becomes nighttime.

Some people have a bit of a hard time understanding this, even people who claim to accept evolution. They'll say that if we exist as humans now, while in the past there were no humans, there must be some individual that we can identify as the 'first human', even if it's an arbitrary distinction. But this still doesn't work.

For the sake of argument, let's say you want to arbitrarily define a certain set of genes as 'human', and any organism lacking those genes as not human*. It's just semantics, but let's see what would happen. Let's say that around 100,000 years ago, there was a population of hominids that was very, very close to fitting your definition of 'human', but lacking one last mutation that would give them the full set of genes to make them 'human'. And lo and behold, one day a couple has a child that acquired this last critical mutation, and now, by our semantic definition, it's fully 'human'**. How different will it look from its parents because of that one different gene? Once it grows up, how much of a problem will it have finding a mate among the rest of the population and producing children of its own. The answers are that it will look as much like its parents as any child, and it won't have a problem at all finding a mate and having children (at least, not because of that mutation). So, even though it fits our semantic definition of 'human', it's not a different species from its parents or the rest of the population using the biological species concept.

But let's take it further. Once this first 'human' finds a mate and has children, because its genes are being mixed with its mates, and because it likely only has one copy of this new gene, anyway, only around 1 in 2 of its children are going to contain this critical gene that makes them 'human', while the rest of its children are going to lack this critical mutation and be almost but not quite 'human'***. But those children will all grow up to have children of their own, and on and on. So at first, this particular gene was only present in one individual, so only one individual in the entire population was fully 'human'. Then in the next generation, the gene was present in roughly 50% of its children, so there were a handful more 'humans' in the population. Then, in the next generation, the gene was passed on to yet more children. And since we know in hindsight that this gene is necessary to be 'human', we know that the individuals with the gene will end up having slightly more surviving children than individuals without the gene, so that eventually, after many generations it will have spread throughout the entire population, and the entire population will be fully 'human'.

That's the problem with trying to define a 'first human'. Whatever genetic criteria you pick is going to be arbitrary. An individual with 99.9999% of the correct DNA wouldn't be human by this definition, but it would still be the same species and able to interbreed with an individual with 100% of the correct DNA. And at some point in time, there will be a population of organisms mixed between 99.9999% 'humans' and 100% 'humans', and a 100% 'human' could have a mix of human and non-quite-human children. But the only reason we'd be classifying these organisms any differently is because of hindsight, knowing that in their future, only one version of a specific gene is going to be dominant. In their own time, they'd look just like any other population with a mix of genetic diversity.

And even all that's using an arbitrary definition of exactly what genes are needed to be 'human'. In the example above, we could be tempted to say, alright, that 'almost-human' population of hominids is close enough - let's call them fully human. But now you've just shifted the same problem a few generations back. There will be a moment in time when their ancestral population was a mix of individuals with their same genes and very slightly different genes. Depending on which specific arbitrary traits are required for the definition of 'human', you could shift the first humans by tens or hundreds of thousands of years.

So, to answer the question, there never were only two individual parents that were the only ancestors of all of humanity. Our ancestors have always been members of large interbreeding populations. And because evolution is a gradual process, it's impossible to pinpoint any single individual as the 'first human'.

Image Source: Pinterest


* You'd probably be more focused on alleles than genes. Alleles are different variants of the same gene. But, since it's just a semantic definition, anyway, genes work for the discussion. It's also an over-simplified example. It's not as if the population was a bunch of genetic clones. Even among individuals in the population, there will be genetic diversity.

** Mutations happen regularly. Pretty much every person alive has at least some mutations differentiating them from their parents. Granted, a whole new gene is a much bigger change than just an allele, but it happens. More Info: Understanding Genetics - How new genes are made

***Remember that we have two copies of all of our genes. So, if this hypothetical individual had a mutation that created a new gene or new allele, it would have probably occurred on only one copy of the original gene, i.e. one strand of the double helix. Since reproduction involves random mixing of our genes for making sperm and eggs, since our individual only has one copy of this new gene, only around half of it's eggs/sperm will contain the new gene, while the other half will retain the old version.

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