An Example of Why Understanding Evolution Matters
September 28th, 2009
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I’ve said before that if a school does not teach evolution, they may as well not teach biology. It would be better to spend another year on physics or chemistry than to teach biology without evolution, because without evolution, biology makes no sense – it would be like trying to teach chemistry without acknowledging the existence of elements or electrical charges. It’s too fundamental to leave out!
Recent news from China has shown an example of how a little understanding of evolution and developmental biology can shed light on what otherwise seems damn near supernatural. Organisms evolve and as they evolve they gain and lose certain traits. The various traits of an organism are controlled by its genetics, but it’s not as simple as one gene making one trait. Many traits and structures are controlled by multiple genes, including control genes, which regulate how and when a gene is expressed. This is a nifty feature because it makes it possible for genes to be used in multiple ways. For example, the genes that build arms and hands can be used to produce legs and feet, either through a recombinant mutation or by changing how and where they are expressed.
Since we all have evolved from previous species, we carry all kinds of genes for traits that they had, even if we ourselves do not manifest the traits associated with these genes. It may simply be that the gene is “switched off” or that it has mutated in a way that makes it no longer effective at producing a given trait. This is very helpful for evolution because these genes are like a library that can produce complex traits without having to completely reinvent them from the ground up. A single mutation can switch back on one of these genes, inherited from previous ancestors and usually not useful. However, on the rare occasion that it is, it can reemerge, sometimes being used in a totally different way.
Thus, our understanding of genetics has shed light on evolution and vice-versa.
Okay, it’s still weird, but the basic explanation is pretty simple: a mutation of some sort has caused the snake to manifest traits associated with a genes that have been long dormant and were inherited from the past ancestors of the snake which did have legs. If we didn’t accept evolution we’d be left scratching out heads and looking at this saying “what the…”
So what the hell is a gene for a leg doing in a snake? Did God put it there? What for? Did Satan do it? Is this snake really Satan? No. The answer is much more straight forward than that. It’s there because the snake evolved from legged reptiles.
This entry was posted on Monday, September 28th, 2009 at 12:54 am and is filed under Bad Science, Education, Good Science, Misc. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.
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September 28th, 2009 at 1:59 am
Richard Dawkins believes that there are a substantial number of people who are closet Atheists. I disagree. There are a substantial number of people who don’t even know what they are. They honestly don’t care, or want to care. Religion has lost its point.
History shows us that all religions die, though the great ones die more slowly, and can linger in a moribund state for centuries. They can die in several ways. They can die when the cosmology supporting them collapses. They can die when they no longer inspire passion or affection in people’s hearts. — And they can die when their stories and symbols are more easily hijacked by preachers and politicians of low and mean purpose.
Religion has failed because it was not updated with time. The stories you read in the Bible or any of the main 7 religions, are all from 2,000 years ago to 8,000 years ago. Vague, mystical, irrational. Remember the people who told you that Jesus was the son of God were also the same people who told us that the world was flat and the sun revolves around the Earth.
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September 28th, 2009 at 8:32 am
Isn’t creationism bad for religion as well as for science? Check out why the Slacktivist has a bee in his bonnet about creationism…
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September 28th, 2009 at 9:14 am
Isn’t an even simpler explanation for the snake, “Someone painted up a chicken foot and stuck it on there?” Because that’s been the explanation for crap like this about 100% of the time. Aside from the platypus.
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September 28th, 2009 at 10:10 am
proscriptus said:
I believe this one has been verified.
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September 28th, 2009 at 10:18 am
drbuzz0 said:
By whom? The foot is difficult enough to swallow, but this thing making it to maturity? No effing’ way.
And speaking of not understanding evolution, genes don’t work that way. Snakes are tens of millions of years removed from footed ancestors. Those genes would have to survive intact in every single snake for this to be plausible. I honestly don’t understand how any adult could possibly take this seriously.
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September 28th, 2009 at 12:49 pm
I’m inclined towards the “fake” theory myself; that foot is suspiciously well developed on an animal that would find the foot to be a serious impediment. It does not look like a chicken foot, though. More like a lizard foot.
That said, you’d be surprised how many genes *do* survive remarkably intact. This is because there aren’t actually genes for hands/feet/etc. The genes produce hands/feet/etc based on how they interact with the genes of neighboring embryonic stem cells, so in some cases it can take very little push to cause a whole slew of cells to go off down the wrong track. For instance, footed snakes *have* been found before, outside of the few species of snake which retain pelvises and hind claws. I think the feet tend to be much more deformed, however.
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September 28th, 2009 at 1:40 pm
Calli Arcale said:
Well that’s it isn’t it? This particular expression is common enough to have been seen before. Like people with six fingers on one hand, it is rare but not unique. I suppose it would be safe to assume that the loss of limbs was a evolutionary recent adaptation in snakes and thus it occasional reappearance is more likely than other recessive expressions.
In the end it not the point of the post: this phenomena and those like in are not unknown, and do point to an evolutionary past – not spontaneous appearance.
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September 28th, 2009 at 3:26 pm
proscriptus said:
It didn’t make it to maturity. If you read the article, it was less than a foot long and is believed to be a juvinile. The woman who found it killed it, but the dead snake is at the University of Nanchang. A bunch of other news outlets reported this too and I don’t hear anyone from the University or anywhere else actually debunk it.
By the way: plenty of snakes have vestigial nubs or part of a pelvis that is left over from the evolutionary past, but that’s normal for the species to have it in a much smaller or non-functional kind of way. Having a full leg with claw and everything is NOT normal, but it’s not the first time this kind of thing has been found. Note this picture: http://universe-review.ca/I10-10-snake.jpg
That shows a snake which is of a species that normally has no external evidence of vestigal legs. No bumps or spurs or anything and no noticable protruding pelvis. Yet this one individual somehow sprouted two small deformed legs.
More common mutations in snakes are albinos (which usually die in the wild) and two headed snakes. They’re not sure if all two headed snakes are mutations, because some might be just developmental issues during gestation.
But Yeah, if you don’t accept evolution, you would be very hard pressed to understand how the hell this stuff happens or how you sometimes end up with a frog with a tail, complete with bones or for that matter, a human! Also, species of non-flying insects where every once in a while an individual sprouts non-functioning wings. If you’re sticking to “intelligent design” your only recourse is that god was drunk, because those genes shouldn’t be there, right?
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September 28th, 2009 at 9:25 pm
It amazes me that in this day and age we still hear of MANY people who are in denial of the fact that evolution can and does happen. It is as mind-boggling as if there were a substantial percentage of the population who still believed the earth is flat (as the Bible clearly teaches in several places).
I wrote a song about the controversy back in 1991 that is (sadly) still relevant. Check out the link for lyrics, comments and optional free mp3 downloads.
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September 28th, 2009 at 10:15 pm
Plenty of snakes have “spurs” which are really modified hind claws and if they’re disected there’s the partial structure of a leg under there and the spur is the toenail. They can move it around and use it for different things.
http://jenny.thegreenes.org/vestigal%20hips%20cindy.jpg
There was a snake discovered in the US that looks a lot like the one above and has similar legs. It has two, and has the same bulge where they connect:
http://2.bp.blogspot.com/_SqhhJb_P3Kk/SrEqEPxyP0I/AAAAAAAAJGA/W6fjxo6isKw/s1600-h/two-legged+snake+top.jpg
http://3.bp.blogspot.com/_SqhhJb_P3Kk/SrEqDwu44iI/AAAAAAAAJF4/XXkVr3IkJ_8/s1600-h/two-legged+snake.jpg
So it might very well be real. Surely things this strange and stranger have been found.
Just another obvious piece of evidence for evolution. Not sure how a creationist would address this, but it is a snake so it could always be satan.
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September 29th, 2009 at 12:14 am
Discussing why this particular snake is like it is without seeing or examining it is rather like discussing how many angels can dance on the head of a pin
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September 29th, 2009 at 1:12 am
Dionigi said:
Yeah, there’s definitely truth to that. Although if the reports are true, and the snake does indeed have a developed foot coming out of it, it would have to be a case of a vestigial gene. It has always been in the past when this stuff happens.
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September 29th, 2009 at 1:53 am
Dionigi said:
This particular snake, no, we don’t know much about, but it is known that snakes have sprouted a leg or two before and this phenemona is attributed to old genes being expressed. That’s an assumption here, but still, it brings up the topic.
A news story like this is at least useful if it brings up the subject that can be used to help show why evolutionary science is important because that is an important issue. Evolution is what has been used to explain this and it does so pretty well. But we don’t even know for 100% if this is real, although I think there is a good chance it probably is real.
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September 29th, 2009 at 6:37 am
Notice that the leg is facing the wrong way, and that there’s a gigantic bulge in the body right where the leg sticks out. Looks to me like the snake ate something that then tried to kick its way out.
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September 29th, 2009 at 6:55 am
Aren’t things like this the result, usually, of industrial chemicals (and radiation?) causing mutations? Frogs, and other creatures, are very sensitive to the chemicals released by industry which gather in the environment.
But yes, understanding evolution is important. It’s telling, that many of the same people who express against evolution, tend to support nuclear energy – they can’t think rationally about evolution and their religious faith leads them to have “faith” that nuclear power plants will be safe. I’m not arguing bout whether they are safe or not, just making an observation about this ideological overlap, in Germany its the Christian Democrats who support nuclear power, in the US its Republicans like Jeff Sessions.
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September 29th, 2009 at 6:59 am
Look, the whole point of this post is that there are examples of the expression of anatomical atavisms, which are the reappearance of a lost characteristic specific to a remote evolutionary ancestor. There have been many examples of these including, formation of extra toes in horses, similar to what is seen in the archaic horses, atavistic thigh muscles in sparrows, extra neck muscles in dogs, wings in earwigs (normally wingless), extra toes in guinea pigs and salamanders, the atavistic dew claw in many dogs, and tails in humans.
All these are evidence for macroevolution, and that is what is being illustrated here. The question of this particular example of a snake being legitimate is not germane to the discussion.
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September 29th, 2009 at 8:12 am
Bruce said:
No Bruce, Blinky the Three-eyed Fish, is a cartoon character.
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September 29th, 2009 at 10:54 am
Bruce said:
No. Ionizing radiation and some chemicals can have mutagen effects, but the most common cause of mutations (by far) is a simple copy error during DNA replication. When cells divide, DNA splits and a number of enzymes replicate the other half of the DNA, but on rare occasions the process alters one or more nucleotides. There are mechanisms to prevent this but they are not 100% The other major cause is free-radicals – oxygen mostly, they arise due to internal cellular reactions especially respiration.
Ionizing radiation does cause mutations but it’s much much less commonly the cause then the afore mentioned. On the rare occasions that it is, the probability of it being manmade is small. The majority of ionizing radiation is cosmic or geological in origin.
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September 29th, 2009 at 3:32 pm
proscriptus said:
Why is this so hard to believe? Even if this example is faked, it is still totally plausible and similar things have happened before. Snakes do still carry genes that are tens of millions of years removed as do plenty of other organisms. Birds still have dormant genes that produce a thick scally skin and a muscular long tail, even-though it has been more than 65 million years since they diverged from dinosaurs. Humans and all great apes have a tailbone despite being millions of years since losing the tail and occasionally the gene goes further and produces a full tail.
Plenty of snakes have vestigial remains of legs and some use them when they protrude from the sides into spurs. Also, snakes with malformed legs have been found before. This is not the first time I heard of this, a snake with a full clawed limb, but sorry if I can’t find the source I saw it in originally.
Bruce said:
Oh god, that burns. No, it’s bull. Complete bull. Some industrial chemicals can damage DNA, but if they are present in enough quantity to damage it, they usually cause mutations severe enough to stop it from being viable. Most mutations are caused by free radicals or maybe a gamma photon, but even more likely to be UV light. Yeah, frogs mutate fairly easily but the whole thing about them being a signal of industrial chemicals is such bull. Frogs have always been known for showing up occasional weird mutations.
Bruce said:
Oh Christ! (Who I don’t even believe of). Next time you make a strawman, make it out of straw and not complete bull****. “Many of these same people???” Sure, some religious people support it. I’m not religious and I do too. There’s no faith here. It’s science, not faith. So what if “republicans” support it? I’m sure plenty of republicans also support not putting glass shards into their eyes. Does that mean that we should all put glass shards in our eyes?
Have you ever heard of the site “pro nuclear democrats”? it exists.
You know what else? Some really great scientists supported nuclear power. How about Glenn Seaborg? He was put into office at the AEC by a democrat and kicked out by a republican! He was all for nuclear power for the enviornmental reasons.
This is not an issue of faith. There are some who have faith in renewables because the numbers say they can’t cut it, but they insist that their belief is enough to make them viable. There are many of these same people who believe that nuclear energy is dangerous and evil and that it is somehow corrupt for mankind to dare mess with the atom.
I submit that this is a religious issue with faith and demons and gods and everything that goes along with it. It isn’t called religion and it’s different than Christianity or Judism or whatever, but commitment to an idea that is held holy against all evidence and seen as some kind of universal guiding truth, beyond science or to the exclusion of science, is a religion, even if you don’t call it that. Any ideology can become a religion when it gets to that kind of level.
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September 30th, 2009 at 1:26 pm
Bruce said:
The unusual number of three legged frogs and other “mutations” were traced not to hormone similar chemicals as originally thought. But to an outbreak of parasites. It is not uncommon for parasites to deform or otherwise make their hosts less fit. I suppose that is the definition
But by making these frogs more likely to be caught by predators they were able to help their own life cycle at the expense of the frog.
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October 1st, 2009 at 8:39 am
How do we move forward from behavior based upon political feasibility and economic expediency to actions driven by practical requirements of biophysical reality? At least to me, it appears that the “window of opportunity” in which restoration of balance between unsustainable, distinctly human overconsumption/overproduction/overpopulation activities on one side and Earth’s finite resources and frangible ecology on the other is rapidly approaching its closing time.
Perhaps necessary change is in the offing and comes soon enough.
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October 1st, 2009 at 11:09 am
DV82XL said:
Snakes first appear in the fossil record during the Cretaceous. I’m not sure what your standard for “recent” is, but that points to them losing their limbs over 65 million years ago. (Note: they may be quite a bit older than that; this is just how far back we’ve found fossils. Consider the case of grass; originally believed to have evolved in the Cenozoic, recent sauropod coprolites have proven that it actually dates back at least to the Jurassic.) Snakes are believed to have evolved from varanids (monitor lizards and such). This limb does resemble a varanid limb. I still think it’s pretty extraordinary to find one so well-developed; most “throwback” limbs are more deformed, such as the hind flippers which occasionally appear on dolphins and whales and are almost never functional. I’d like to hear an expert pass judgment on the actual specimen; until then, I won’t rule out hoax.
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October 1st, 2009 at 11:30 am
Oops; I meant to make all my comments go into a single post. Sorry. I’ll put the rest in this one.
David Cantrell said:
It’s pretty far down; although it does indeed look like the snake has eaten recently, I don’t think something could successfully kick its way out like that. Not without the snake being split open, and there’s no sign of that. Also, snakes generally kill their prey before attempting to swallow it, whether by venom or by strangulation, because eating is a laborious process for them. My family used to have a pet snake. There’s no way it could’ve swallowed an animal which was alive and kicking. (It did try once, and got bitten by the mouse.)
JParkerKC said:
It is worth mentioning that if this snake is legit, it is NOT a mutant. No genetic change is required to produce this sort of a deformity. The change is teratogenic, not mutagenic, which means something went screwy during embryonic/fetal development. That can happen without any change whatsoever to any DNA. Seriously.
Regarding the frogs, they are also not mutated. Pollution was a factor, but indirectly — it created an environment more favorable to the nematodes (round worms) which cause the extra limb growth. The nematodes do not actually mutate the frogs. What they do is they infest tadpoles, and at each point of entry where a nematode attacked the tadpole, a chemical change happens. The nematode releases a chemical which signals limb growth. When metamorphosis begins, the adjacent cells detect that chemical and dutifully produce legs, according to the DNA they’ve already got. The number of limbs thus created is dependent on the number of nematodes that attacked the tadpole. This is favorable to the nematode — the adult frog is crippled and will quickly fall prey to animals such as egrets, which will spread the nematode’s eggs in its feces, allowing the eggs to be eaten by tadpoles, completing the cycle.
DNA isn’t a straightforward blueprint. Most traits are probably emergent — that is to say, nothing directly codes for them, but if you’ve got enough of the right genes in the right places, cued to switch on at the right times, particular traits will emerge, assuming everything goes right. The genes to make feathers, scales, and hair are virtually identical, for instance. So it is not at all improbable for the genes to make legs to exist in a snake. Even discounting the species of snake which retain pelvises, if the genes aren’t a problem, there’s no pressure on their removal — and there may be an unforseen price to their removal which we don’t know about. Maybe they also code for better skeletal systems. Because of the emergent nature of genetics, it’s quite possible for a gene to be responsible for more than one thing.
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November 20th, 2009 at 10:02 pm
When I was in college, one of my professors had a dead snake with a leg coming out of it that looked something like the one above. It was in a jar of formaldehyde and he had it in his office, apparently it was brought in about 30 years before by someone who found it. It was small, but it definitely had a puffed up section with a leg, complete with claw sticking out of it.
He also had an x-ray of it and some photos from when it was dissected. Sorry if I don’t have a reference, but I’m sure that this is real and does happen occasionally. I doubt he is still there and have no idea what would have happened to the snake, but this was the University of Maryland, if that helps at all (I don’t think it will).
It was a young snake and the professor theorized that it was caught so early in life because it didn’t do very well with the leg and probably couldn’t get around as well as if it did not have the leg. I don’t know whether it came in alive or dead, though.
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November 12th, 2010 at 8:47 am
proscriptus said:
I think he meant the platypus…
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January 30th, 2011 at 1:36 am
Actually, this is not a mutation or a hoax. What you have here is an unfortunate snake who swallowed his prey before it was fully asphyxiated. You can see the tell-tale bulge of a lizard that was eaten by the snake. The lizard managed to bust through the snake’s taught belly-skin before he finally expired. I saw this happen before during feeding time at the Albuquerque Zoo.
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