It must be.
What evolutionary advantage is there in the ability to giggle when someone touches you?
And not even the happy kind of giggling.
More the rage-inducing kind.
Apparently, it's a useful adaptation that goes back to when sabre-toothed tigers would tickle cavemen.*
The ensuing caveman rage would enable them to survive, of course, by focusing that anger into the domestication of the tigers, as seen in any reality TV show featuring cavemen.**
So if anyone ever tickles you and you get mad, just pet them and they're yours.
And that's how science works.
* Tigers would only tickle the male cavepeople, let's say, to avoid the awkward usage of the word "cavepeople" as much as possible.
** e.g. "Pangaean Idol"
"Top Chef Before Fire Existed"
"America's Next Top Caveman"
"Who Wants to Be a Guy With a Big Stone?"
(That is caveman currency equivalent to $1 million today.
In fact, given the markets, a stone might be worth even more now.)