Would a big cat (lion, tiger, leopard, jaguar) be able to decapitate a human with a swipe of a paw?
What about a grizzly bear (or a Kodiak or Polar bear)?
This is not an urgent matter – I was just curious…
Short version? No. It would take a lot of force, and a long “blade” to decapitate someone. Even using an axe, with proper leverage, and the advantage of height, it was generally unlikely that you’d decapitate people with one blow. And axes are much better than claws.
Yeah, a critter-driven paw’s not gonna decapitate anything. You’ll get blunt-force trauma and the victim will go flying sideways in one piece, possibly with a broken neck, but that’s about it.
A lion might be able to partially decapitate a person, leaving a head dangling. Lion’s are extraordinarily strong and have been known to kill people and other animals with a single swipe of a paw. If the claws were able to slice through the spine and protective tissue it’s conceivable. I smell a Mythbuster’s episode. I nominate Tory.
Tigers have been know to rip off arms. I expect they could do the same with a head, but they’d need a grip on you for it or for you to otherwise be held in place so they can apply their strength. Pure impact as said above probably wouldn’t work; too much of the force involved would go into flinging you around.
It may be a bit more than blunt-force trauma if you get swiped at by something like this. (Though I suspect it might take several swipes to actually sever a head.)
I would not be surprised at all if a grizzly bear or a brown bear could knock the head clean off a human body provided the body was braced against something and couldn’t move in the direction of the stroke and the bear put some real smoke into its swing. They are immensely powerful and much, much quicker than their bulk suggests.
A lion would be most likely to break your neck with a bite. That’s the way they generally kill.
They wouldn’t decapitate you that way, though. They only interested in snapping your spine so you can’t run.
OK, to explain my previous comments: no, a big cat or other animal can’t decapitate you instantly because they’re not designed for it. I’m not going to bother coming up with some ridiculous scenario involving perfect leverage and a dozwen other improbably factors, because even then the skin of the neck would be intact on some side.