The Great Summer Snake-Hunt
by JoyWell, the Great Snake Hunt of 2006 began today here at the homestead, a little later than usual. He was a Big Daddy pit viper of the copperhead variety, whose presence within the tended parameters of our carved-out living space demanded attention after he bit my visiting nephew last night. Which required a not-convenient trip to the emergency room even though the boys reported him to be a Big Daddy and the bite through high-top and sock wasn't deep. Today it looks more like he stepped on a wasp for the minimal amount of redness and swelling, so he didn't need antivenin. Two years ago my visiting grandson required not one but two doses of antivenin (at $5,000 a pop), which kills more people than snakebites do. But that was just a little copperhead, and they tend to be more liberal with their venom than the Big Daddies are. Life experience, no doubt. Less venom to waste when you're older, and there's no reason to waste it on something you're not going to eat.
I dispatched the serpent and hung his head on the fence. A friend from Texas told me years ago that would keep other snakes away, but in my experience that doesn't work. What it does do is make you feel tough, sort of like collecting rattles as my brother-in-law does out in Oklahoma, and as his great-grandmother did back when it was still Indian Territory and she was the local Medicine Woman. A sort of macho display I can easily imagine to be related to the snake-primate evolutionary wars. If only the storytellers could get their stories straight, that is…
While out browsing the net for info, I encountered yet another new Neodarwinian just-so story I thought was quite humorous. This one attributes the color vision and acute eyesight in primates directly to this snake-primate evolutionary struggle:
Seeing the Serpent: Ability to Spot Venomous Snakes May Have Played Major Role in Primate Evolution
"There's an evolutionary arms race between the predators and prey. Primates get better at spotting and avoiding snakes, so the snakes get better at concealment, or more venomous, and the primates respond," Isbell said.
[...] Having evolved for one purpose, a good eye for color, detail and movement later became useful for other purposes, such as social interactions in groups.
Some time ago there were discussions over at ARN about other just-so stories purporting to explain primate visual acuity and tricolor perception. One had it evolving for the purpose of finding ripe fruit, though a contradictory finding had primates trading olfactory sensors for visual sensors. Since ripe fruit smells ripe, why would old world primates need to see red if new world primates don't, and why would either give up reliable olfactory sensibilities for the privilege?
Another just-so story had tricolor vision evolving so primates could see potential mates blush. However relatively difficult it may be to perceive a black-skinned gorilla turn red, we know that mandrills and baboons and such have developed very showy faces and butts, making some use of reds. But which came first? The showy skin or the ability to see the show? …and if nobody knows, why say the ability to see the colors evolved for the purpose of perceiving the display?
So now we know (yes, I'm kidding) that the color perception and close-up acuity of primate vision – and all associated brain development – evolved for the purpose of spotting snakes. Except in prosimians (like lemurs and such) that live in places without snakes, thus have bichromatic and not very acute vision instead. Unless you consider those that do have tricolor vision (despite being nocturnal), in which case it must have nothing to do with snakes.
However, there are some red snakes out there, and some of them are venomous. But they're more often green or brown or black or grey. Which is camoflauge the authors of this piece of work say evolved for the purpose of defeating primates' ability to spot serpents! Luckily, primates found other uses for their visual skills, snakes never developed color vision, and pit vipers evolved heat sensors to hunt mammals at night despite their daytime camoflauge.
You might wonder what snakes make a steady diet of primates, whether they were ever venomous (since it's not cobras or rattlesnakes or copperheads that eat monkeys, it's constrictors), and why this supposed two-sided evolutionary arms race between primates and serpents didn't lead primate-eating serpents to evolve venom. Though snake venom can kill primates effectively, so there's reason for primates to avoid 'em, many primates do eat snakes…
It's a vicious chicken-egg circle, and the plot line changes every time a researcher manages to get funding for another piece of work on the subject. Which causes me to suspect that it's more about funding than about what's real out in snake-ville or primate-land. And it occurs to me that if researchers get research grants to come up with just-so stories explaining the purpose for the evolution of any trait, why in the world are we fighting about the subject of purpose in evolution?
I know, I know. Neodarwinists will say blind selection directed the purpose, so it's not purposeful. People reading the public releases about these researches will come away with an entirely different impression, since they're being told about the competition and reasons for traits in the overall context of evolution, not the mechanistic details. Think about that for a moment. The interested public is as likely as not to accept the context – evolution – even if they aren't convinced by the claim that directed results don't have directed causes.
For the interested, here's the abstract on the actual piece of work. Anybody have the rest of it? The snake war isn't done here until late fall, so I'm interested!
July 21st, 2006 at 2:16 am
Why didn't somebody tell me we were at war with the snake heads? Did Congress declared war yet?
OK, maybe this is an unlikely hypothesis, but if you add this with the thousand other improbable hypotheses, then it becomes probable, right? I mean, isn't this cumulative evolution?
Joy, you are a fascinating woman.
I've never even heard of synesthesia until you mentioned it. Now I find out you are the Clampett lady (absolutely NO denigration intended), living without A/C? In truth, I can use some advice. There have been reports of copperheads and cottonmouths near where I live. What is the best way to dispatch these vipers? How fast do they move? Will I be able to sever it with a thrust of my shovel? 
Comment by teleologist — July 21, 2006 @ 2:16 am
July 21st, 2006 at 9:26 am
Joy,
I'm glad to hear that your grandson didn't need the antivenin. IIRC, the main problem with antivenin is allergic reaction to the horse(?) serum, and that is likely to be more pronounced if one has been sensitized by a previous dosage.
I've only seen one copperhead on our property, but we have kingsnakes, so hopefully they'll keep the population down. I tend to live and let live, but I may have to re-evaluate that position once my son starts toddling outside.
You might wonder what snakes make a steady diet of primates, whether they were ever venomous (since it's not cobras or rattlesnakes or copperheads that eat monkeys, it's constrictors)
You're right that constrictors are more likely than venomous snakes to eat primates (though some of the very large vipers might be capable of eating a monkey). However, venomous snakes can be a threat to primates, even if they don't eat monkeys. Last time I visited the Duke Primate Center, the docent mentioned that the lemurs that live in pens out in Duke Forest sometimes encounter copperheads. After several were bitten, the lemurs developed a unique warning call for copperheads. I thought that was a nice example of learning and cultural transmission, since lemurs in Madagascar don't encounter venomous snakes. Upon further consideration, they do encounter at least one large constrictor, so field work would probably be required to make sure the lemurs haven't just adapted a pre-existing constrictor warning call.
For the interested, here's the abstract on the actual piece of work. Anybody have the rest of it?
The full paper is here
If that requires a subscription that you don't have, the author's email is listed as laisbell-at-ucdavis-dot-edu. She would probably be willing to send a reprint.
Comment by Nick — July 21, 2006 @ 9:26 am
July 21st, 2006 at 9:45 am
Joy:
[you might wander] why this supposed two-sided evolutionary arms race between primates and serpents didn't lead primate-eating serpents to evolve venom.
Yeah, an arms race/co-evolution seems unlikely in this situation, and it doesn't seem necessary for Isbell's hypothesis.
on the other hand…
Though snake venom can kill primates effectively, so there's reason for primates to avoid 'em, many primates do eat snakes"¦
That could be the basis for an evolutionary arms race, if there were evidence that snake venom is required to defend the reptiles against predatory primates. Alas, it's pretty clear that the primary function of snake venom is for subduing prey, and most venomous snakes prefer not to use it for defense unless absolutely necessary.
And also…
The Isbell paper closes with a quote from some 100-year old observations of different primates encountering snakes. Only the lemurs showed any interest in eating the snakes. The old world monkeys and apes were panic stricken, so I wonder how often primates actually eat snakes.
Comment by Nick — July 21, 2006 @ 9:45 am
July 21st, 2006 at 9:58 am
OK, one last comment and then I'll shut up.
Isbell's paper has a section on "testing the hypothesis," including 9 core predictions which are essential to her hypothesis and if shown to be incorrect would lead one to reject it. She also lists 25 corollary predictions which "are not essential to the core hypothesis if refuted, but would support the core hypothesis if they are confirmed."
Of the core predictions, she argues that 5 are supported by existing evidence and 4 are novel predictions that require new research.
Comment by Nick — July 21, 2006 @ 9:58 am
July 21st, 2006 at 11:11 am
LOL! Hi, teleologist. I don't have AC mostly because this old cabin is way too 'open' to allow for a convenience that requires tight seals. I call it "healthy flow-through ventilation."
Shovels are good beheading devices. We also have an old bank-cutter that looks impressive but is too heavy for me to wield. Then there's machetes, flat-hoes and my grandson's sword collection. It's generally a 2-person job, with one pinning the snake with a staff or tri-fork so the beheading can be quick and clean. Our policy is that if you see one you stay right where you are (at least 3 feet away) and don't take your eyes off it – just yell "SNAKE!" and someone else will bring the tools. He'll stay coiled in defensive mode so long as you're there, but if you don't stay there he'll disappear right quick, only to strike again another day.
Snakes can move surprisingly fast when they want to, even the fat rattlers. The sheer decibel level of a cornered rattler will fairly deafen you, though. They don't like people or kept yards/gardens and are respectable participants in the ecosystem. We leave each other alone.
Copperheads are a version of moccasin, but smaller and more aggressive. I've not heard that moccasins or cottonmouths like living in tended yards or stalking humans and pets. Obviously, the biggest problem around here is with visiting city folk. You can warn them ten times a day to be alert for snakes, but they seem to have lost the capacity that snake-human co-evolution was supposed to have gifted them with. According to this just-so story, anyway. We've lived here 14 years, have to dispatch an average of 3 copperheads a year, and not one of us has been bitten. Go figure… §;o)
Comment by Joy — July 21, 2006 @ 11:11 am
July 21st, 2006 at 12:19 pm
Joy, thanks for the tips. I guess I am too evolved to live w/o AC.
This city slicker is just no good around reptiles.
I live in a new development that is still going through a lot of construction. They are awfully mad when you invade and occupy their land. Both copperheads and cottonmouths have been seen on the golf course and in front of people's houses.
Machetes are out for me, too close for comfort. I would imagine pinning it down would be the hard part for me. I assume that a swing with the shovel w/o pinning it down would not be effective? You are right, if I am not concerned with it nesting around my yard or getting bit by it at a later date, I would prefer to run away.
Comment by teleologist — July 21, 2006 @ 12:19 pm
July 21st, 2006 at 12:27 pm
Hi, Nick! Thanks for the link. I can't get the article so will email Isbell. Just a detail – it was Grandson #2 (I have 4, only the eldest lives here) who was bitten 2 summers ago. On his thumb – he ended up having to have skin grafts, but didn't lose the digit. 2 doses of antivenin and 3 days in the hospital. My nephew got bit the other night, but not enough venom to require antivenin or hospitalization. Older vipers just don't waste their venom like younger ones do (learned behavior), so venom as defense isn't necessarily instinctive as Isbell would have it.
The biggest venomous snakes are King Cobras (record is 24 feet, average 12). They have good eyesight – can track a human at 300 feet, and kill lots of people in India every year. But they don't eat people (or other primates) – they're cannibals. The latin name means "snake-eater."
The largest vipers in North America are the Timber Rattlers we have in these parts. They like rodents, rabbits, squirrels and such. The world's largest viper is the Central/South American Bushmaster. Average 6 feet long (record is 14), aggressive, heavy-bodied. Its primary prey are small rodents, birds, frogs, large insects and other snakes. The largest old world viper is the Gaboon Viper. His fangs can reach 2". He's well camouflaged, averages 6 feet long and is a heavy-bodied ground-dweller. Natural diet of large rodents, ground birds and even small antelopes.
Vipers simply don't naturally prey upon primates as food, though they will bite them defensively. They don't necessarily inject venom when biting critters they aren't planning to eat. According to herpetologist Harry Greene,
Primate-eaters aren't venomous, though. Snake venom has components that are neurotoxins to immobilize and kill, and others that begin the digestion process. Like spider venom. Thus the venom is geared directly toward the acquisition of food – a predator weapon for the purpose of getting and ingesting the prey, not for defense. Venomous snakes do not eat primates, but primates do eat snakes. Using venom for defense is a secondary application. Isbell's just-so tale looks pretty iffy to me.
Comment by Joy — July 21, 2006 @ 12:27 pm
July 21st, 2006 at 12:53 pm
teleologist,
This city slicker is just no good around reptiles.
In that case, the best thing to do probably is "run away! run away!" or walk, so you don't trip and break your ankle!
If you aren't confident about identifying the snakes, it is easy to confuse cottonmouth/water moccasins with large watersnakes and copperheads with species like the beneficial mole kingsnakes, milksnakes, and cornsnakes. Even if you choose to kill the venomous guys, you don't want to kill the non-venomous rodent eaters.
When I lived in PA, a lot of the local guys swore up and down that they saw dangerous "water moccasins" on the Delaware river. What they were actually seeing were northern watersnakes, bad tempered critters but non-venomous. I've also seen a baby ratsnake doing his best rattlesnake impression complete with vibrating tail. It was cute, once I was sure that he wasn't a baby massassauga – since he was on the floor of my bathroom, I wanted to be sure.
Comment by Nick — July 21, 2006 @ 12:53 pm
July 21st, 2006 at 1:09 pm
Joy,
I just realized who Harry Greene is. If you haven't already read it, I highly recommend Greene's book Snakes: The Evolution of Mystery in Nature. Even if you are inclined to doubt Darwinian explanations, the book is worthwhile for Greene's anecdotes of his field work, the descriptions of all the major snake groups and their natural history, and the absolutely gorgeous photographs.
It's a bit pricey on Amazon, but I once found a cheap copy on the sales table at Barnes and Noble. I'm sure a lot of libraries have it, too.
Comment by Nick — July 21, 2006 @ 1:09 pm
July 21st, 2006 at 1:58 pm
Thanks again, Nick! I'll order it from one of my fave used book finders (I get lots of great stuff that way for not too much), but only after I order Mike's book. I've definitely gotta have it. It'll be my first official ID-supporter tome!
I've always been fond of snakes (and lizards, newts, efts and such), ever since I can remember. I'm also the only official Girl Scout expel-ee I've ever heard of. Got mad at the ringleader of the "Cooler-Than-Thou" crowd in my cabin at camp one year, put a black snake I'd befriended under her pillow just to see her lose it completely. The counselor who had to drive me home in the middle of the night laughed the whole way, said it was the absolute best thing she'd ever seen any scout do in all her years.
I don't have a problem with evolution. I just have problems with Neodarwinism's ridiculous version of it. As I said, I don't kill snakes unless they're venomous and in my immediate space. I don't kill non-venomous vermin-eaters or venomous ones outside my space. I think about it like I think about sic'ing the cats on mice in the house, killing mosquitoes, ticks, fleas, ants, carpenter bees, hornets, wasps and all other in-space vermin. I'm no Jain, even though I'm a vegetarian. It's my karmic duty to 'liberate' such vermin so they can come back as something more advanced next time… §;o)
Comment by Joy — July 21, 2006 @ 1:58 pm
July 22nd, 2006 at 9:18 pm
Joy,
Not all evolution advocates find this sort of story-telling useful – see, for instance, razib at GNXP.
Mesk.
Comment by Mesk — July 22, 2006 @ 9:18 pm
July 23rd, 2006 at 12:06 pm
Joy,
You seem to be pretty good with snakes. Can you offer any advice on how to handle these kind?
Comment by chunkdz — July 23, 2006 @ 12:06 pm
July 24th, 2006 at 2:33 am
Thanks, Mesk. I'm not surprised that you grasp the implications of what I'm saying about this piece of work I haven't read in its entirety. All I've got to go on are the public reports – dumbed down beyond all sensibility – and the abstract, that appears to confirm my worst suspicions.
I have had discussion in another thread about this very sort of thing, that your average liver of life (who may or may not have any actual higher education) could tell you what's what. Instead, we usually get some researcher who goes out and does it all over again, starting from scratch with an obviously faulty premise, and reaches a totally ridiculous conclusion that wouldn't convince anyone (much less your own Grandma). Then these same funded and published researchers end up arguing endlessly about their faulty starting premise as if they can convince Grandma by the sheer [non]weight of sheepskins! [Grandma sez: Junior, just eat your Wheaties and leave the venomous serpents to us grown-ups.]
I'm not afraid of snakes. Never have been, since I knew I was alive and there was a world to explore that contained snakes. I did pay attention when Grandma said there's snakes that kill. That just made me even more interested, even if I was indeed more careful. It's a little strange when others (including those who are speaking with 'authority') are afraid, but you are not.
I'm Grandma now. Matriarch of the family. I can say with some emphasis and a significant degree of confidence in my authority to say so that there are snakes that kill, along with snakes that are welcome. When I say "watch out for snakes," I expect 'em to do so, because it's snake season. The live-in grandson knows he should listen to me, and is a valuable 2nd man in the eradication process – has been since he was a single-digit midget and knows a welcome snake from a foe. He's never been bit by either variety, and spends a lot of his time in summer guarding his younger and less experienced charges (with varying degrees of success, unfortunately).
The visiting city relatives have no idea what it is they're supposed to be looking out for. They might be afraid of any snake they see, but if they don't see snakes, what good is it?
If it were some sort of inbred instinct, they would see 'em and be afraid. If spotting the snake (and triggering a fear response) were the reason for good eyesight, city kids could spot snakes as well as we can. They can't, and that's a fact.
chunkdz – Chunk, I couldn't get anything to load from your link but some little award graphic. Just like I couldn't get the link to the pdf provided by the poster "razib" at Mesk's link. Can you just tell me what kinda snake you're talking about?
Comment by Joy — July 24, 2006 @ 2:33 am