Thank you to all who have posted thoughtful, helpful responses.
Now, one last question: most of the fatalities people have documented involved either unqualified people trying to keep large constrictors as pets or kids who were attacked by escaped pets.
But how often are people attacked and/or killed in the wild by pythons or anacondas? Are there any reliable numbers out there?
A lot of random stories like these…
http://worldnewsdailyreport.com/22-foot-anaconda-captured-and-killed-in-amazon-river/
…but they seem suspicious. A Brazilian would be handy right now.
I wish I could find it now, but I read about a farmer in the developing world who was attacked by a constrictor. I believe it got him such that one of his arms was free and the other was pinned to his torso. Anyway, he was able to escape by biting through the snake until it died.
I apologise if this is too much of a hijack, but what is the appeal of keeping snakes as pets? I have nothing against them, and appreciate their beauty, but I wouldn’t want one as a pet. Is it a rewarding experience? Do they recognise you or form an attachment of any sort?
When a snake bites a man that’s not news, but when a man bites a snake, that’s news.
I’m going to WAG that it is a vanishingly small number. Every part of the world that has giant constricting snakes also seems to have a local legend or two about people being killed, or killed and eaten. But there are rarely any personal observations offered and it’s the “my cousin’s friend knew a cab driver who talked with the guy who visited the village where…” story. Or it’s a modern, too well documented story that screams FAKE! – FAKE for MONEY!! Given the numbers of developing-world people living in places where giant snakes are also found, I’m sure it has happened. But probably at a frequency as to make death by meteorite seem commonplace in comparison.
Most predators exhibit caution as a normal part of their predatory behavior and snakes are no different. Humans are at, or exceed, the upper limit of appropriate size prey for even the largest snakes. Recall, snakes cannot chew their food nor bite off smaller pieces. All food is swallowed whole. Thus attacking an animal (human or not) that cannot be swallowed is wasted, and dangerous, effort.
Plus, wild snake populations have experienced “selective pressure” against messing with upright bipeds that can carry clubs or blades. Captive snakes (and other animals) can become acclimated to human presence. Couple that with a feeding response that comes to be triggered when a human approaches and opens the lid to the cage and you understand why keepers are in greater danger.
May as well answer this, while I’m expounding :D.
Some people claim that their snakes are pleasant and affectionate pets, but I’ve never had that experience. Snakes either do not exhibit any attachment at all, or such is so slight as to be virtually invisible to an outside observer. It’s hard to determine if the snake is just comfortable with the temperature given off by a human hand, or is actually “happy” to be held. Snakes in my experience don’t respond to handling, petting, or cuddling like a mammal or many birds would respond.
The appeal is different.
Snakes can be beautiful, and their habits and life history can be fascinating. Finding ways to maintain them successfully in captivity can be a rewarding quest. Sharing such new knowledge about these reptiles with other interested parties is no different than dog lovers’ conversations at the dog park.
But the very word “pet” has connotations that I think are inappropriate, or raise inappropriate expectations, for most wild animals including snakes. That’s why I prefer the term “personal possession animals” instead. Dogs are pets, cats are pets, even horses are pets. But snakes, hyenas, blackbuck, and owls may be ‘personal possession animals’. Not pets. 
Second the above. Snakes are wild animals and incapable of domestication. Keeping them can be a rewarding experience, but not because they love you.
My take on “people claim that their snakes are pleasant and affectionate pets” is they have learned when it’s safe to handle the snake and when it’s not, even if that knowledge is subconscious.
When snakes are hungry and they sense food, they get excited. The common expression would be “they get their blood up.” In that situation, you had better know what you’re doing, because your “friend” won’t hesitate to strike quickly at movement, even if that movement is you.
The first link is from a satirical website much like the Onion.
It’s the same website that had that news story about chimps in the Congo discovering how to make fire.
Mulder’s World specializes in stories about the paranormal, UFOs, and Bigfoot.
Not very reliable sources, either of them.
Thanks- and this is SORT of what I was getting at in my original post. I never really doubted that a large wild python or anaconda COULD attack or kill people in the wild (as the simulated scenes in the “documentary” showed)… I just found it unlikely that they would UNLESS you had a VERY large, VERY hungry snake and a fairly small person. In the same way, a VERY hungry puma might attack and try to kill me if he thought he had the element of surprise (he certainly wouldn’t have any moral compunctions!), but I suspect he’d rather go after something smaller and easier to kill, if it’s available.
IF a huge anaconda who hadn’t eaten in a long time saw me, and THOUGHT he had the drop on me, I wouldn’t put it past him to take a chance and attack me. But I don’t think I’d be his first choice.
And it sounds as if he couldn’t swallow me even if he managed to suffocate me.
If you’re a normal sized adult human, there isn’t a snake in the world that could swallow you. It’s those shoulders. But there are untold numbers of snakes that could kill you. I recall in my wasted youth, many sawgrass seasons ago, several of us were cleaning our snake cages in the back yard. One guy put a 6 foot yellow rat snake across his shoulders while he worked on its cage. The snake decided, for reasons only a dimwitted snake could know, to constrict his neck. He went running around the yard, face red, eyes popping, plucking ineffectually at his throat, unable to draw a breath, while the rest of us laughed ourselves sick. At the point where he was collapsing onto the ground, a couple of us finally uncoiled the snake. Had we not been present, this small, quite unremarkable and otherwise inoffensive snake could have killed all 6’2” and 190 pounds of him.
In the wild the giant snakes are pretty much ambush predators, waiting under cover (or under water) for prey to approach closely enough for a strike. If you blundered into a vulnerable position, one might – just might – make an investment in you. But again, this would be a vanishingly rare event. Smaller prey animals are more common, easier to overcome, pose less danger of injury to the snake (bites, kicks, hoof or claw lacerations), and more certain to be of swallow-able size. There are lots of other things in the jungles of the world that pose far, far greater danger to you or me than giant snakes.