Well, okay, my mother and her siblings. As kids they swung on grape vines across a creek on their farm. Note that grape vines, like a lot of vines, grow up and then hang down. Thus giving a free end to swing on. A possibility not discussed in this column.
Though they are not “vines”, many species of tropical canopy trees have areial root systems that are quite capable of supporting a grown human. Most notably the ficas species, banyons et al. As kids we would play tarzan under ficas trees swinging from “vine” to “vine” under the same tree but never tree to tree. They just aren’t planted close enough together in parks for that.
Note that this activity is a really good way to remove the skin from your palms or fracture your skull, it a wonder any of us survived childhood.
Y’know, I was going to come in to mention wild grapevines, too, but I like your phrasing a lot better :).
I used to swing on vines as a kid, too. I assume they were of the type mentioned in the column (although I don’t know for sure). They grew up from the ground, tangled themselves in the tree-top somewhere, then sometimes would break near where they had started growing. This left a (dying or dead) vine a couple of inches thick hanging from the top of a tree.
There weren’t enough of them to attempt swinging from tree to tree, and as a means of locomotion they left much to be desired. (For one, they didn’t generally take you very far. And two, there was always the chance that they’d snap off in mid-swing and you’d fall, causing your friends to laugh at you. This happened to a former friend of mine.)
But as a method for, y’know, swinging, they were great fun. 
If your grapevines are wild, you had better be more strict. Try spanking, even though that is frowned upon in this day and age. Curfews help, too. 
In the cartoon accompanying the article, is that a hairy female breast hanging out ?
The thing that’s always bothered me about Tarzan swinging on lianas wasn’t mentioned in this article, although touched upon: even if they weren’t attached at the bottom, lianas hang straight down. In order to swing on one, Tarzan-style, you’d have to go down to the ground, grab its low end, climb up a tree holding it, and then swing.
Nah. Slug’s female breasts are typically narrow cones. Apparently, Slug figured Tarzan had estrogen issues.
I see just a beer belly. Figures, you gotta be a serious drinker if your idea of fun is swinging on vines, doing elephant calls and hanging out with a chimp.
In some of his more recent works, he’s had females with much more rounded gazongas, though still not particularly resembling this picture (I’m not going to go looking for examples right now). I agree, though, that that’s a gut, not a boob.
‘Swing from trees’?
I’ve known, in my time, quite a few people who gave me the impression that their ancestors peed on trees! 
I thought everyone learned this in grade school:
Tarzan swings, Tarzan falls
Cheetah grabs him by the balls.
That’s why Tarzan goes AAAAHHHIIIIEEEEEAAHHHHHIIIEEEEAHHHHHH!!