Science & Nature Archive

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.

Friday, March 4, 2016

Genetic Evidence for Evolution - Vitamin C Pseudogene

Histoire et culture des orangers, A. Risso et A. Poiteau. -- Paris Henri Plon, Editeur, 1872As I've been doing a lot recently, I'm going to recycle a Quora answer for this entry. The Quora question this time was What are 3 facts that prove the biologic evolution theory?. After a bit of preamble about science not being able to 'prove' anything (for example, see my essay, Confidence in Scientific Knowledge), I got down to the answer - genetics, and the specific example of the GLO pseudogene*. Here's an edited version of that portion of my Quora answer**.

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I'm only going to look at one narrow piece of evidence for evolution in our DNA. But as an aside before getting to the meatier answer, just the general similarity in genes of all organisms is already a decent argument in support of common descent. Why else should organisms have common genes? If it was special creation, why even use DNA in all organisms, and not get a little more creative in how to store genetic material. But the similarity in DNA goes beyond just genes. It's also in the structure of our chromosomes, in regions in the DNA that don't code for genes (much of it quite frankly junk - Is Most of Our DNA Garbage?), and in regions that used to code for genes that have since become non-functional due to mutation (pseudogenes).

One particularly striking example is one of the genes involved in the synthesis of vitamin C, L-gulono-γ-lactone oxidase, or GLO. All but three lineages of mammals can synthesize their own vitamin C and don't need to get it from their diets like us. The three lineages that can't synthesize vitamin C are anthropoid primates (which includes us), guinea pigs, and bats. All three of those lineages contain a form of the GLO gene, but in each lineage, mutations to the gene have damaged it to the point of disabling vitamin C production. But the thing is, the specific mutations are different in each lineage, but common to all members of those lineages. In other words, the damage to the GLO gene is the same in all anthropoid apes, but different from the damage in either guinea pigs or bats. Similarly, all guinea pigs share the same damage, which is different from that in primates or bats. Ditto with bats.

When you think about that, that's hugely indicative of common descent. With similarities in functional genes, a creationist or Intelligent Design advocate can always say that common purpose means common design, and God (or the designer) simply used the same genes in different animals. And creationists can even sort of explain isolated pseudogenes as a result of The Fall, where mutations have damaged what was supposedly at one time a perfect creation. But having the same broken genes in closely related species, and broken in the same way, is a whole lot harder to understand from a creationist perspective. The chances of those same mutations occurring in the same manner in all of the anthropoid primates is simply too unlikely to be taken seriously (and that unlikelihood is only compounded by each of the other lineages with mutations to GLO). So, absent common descent, that would mean all those broken genes would have had to have been present in all anthropoid primates from the very beginning. Why would a god (or intelligent designer) have put broken genes into organisms in the first place, and why break them in the same way in all anthropoid primates, but then in a different way in guinea pigs and yet a different way in bats (and in yet more ways in non-mammals that I didn't discuss). From an evolutionary perspective, it makes perfect sense. The damage occurred once in the common ancestor of anthropoid primates through a particular set of mutations, and that broken gene was then passed on to all it's descendants. At another time in another place, damage of a different sort occurred in some ancestral guinea pig, which was then passed on to all the descendant guinea pigs. And the same thing for bats, and all the non-mammals that have damage to GLO.

And that's just one example of one pseudogene. There are other pseudogenes, genes, regulatory stretches of DNA, and regions of junk DNA that all make the genetic evidence for evolution one of the strongest lines of evidence there is. But it's hardly the only line. To echo something I wrote in yet another Quora answer, if you're willing to put in a little reading, there are some great books on the subject. My two favorite introductory books are Jerry Coyne's Why Evolution Is True, and Donald Prothero's Evolution: What the Fossils Say and Why It Matters, which cover topics like fossil evidence for evolution, vestigial organs, embryological evidence, evidence from poor 'design', and biogeographical evidence. Given the enormity of the evidence in support of evolution, a single book can't come close to being comprehensive, but both of those books present enough evidence to be very convincing. Why Evolution Is True is my favorite of the two, and is a little more broad in the types of evidence it covers, as well as covering a bit more of the theory and mechanisms, not just evidence. If you want to get even more on the mechanisms and theory of evolution, but still in a book aimed at non-biology majors, Carl Zimmer's The Tangled Bank: An Introduction to Evolution is very good (though a bit on the expensive side - you might look for it at a library).

Reference:
The Genetics of Vitamin C Loss in Vertebrates

Image Source: Wikimedia Commons


* GLO had previously been mentioned briefly on this site before in Ein Sophistry's Genetic Evidence of Evolution.

** This Quora answer itself was adapted from a comment I left to another Quora answer, Niall Harman's answer to What is the evidence for biological evolution and what is the evidence supporting creationism?

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