Laughing is totally natural and, apparently, the average adult laughs 17 times a day.
Laughter has nothing to do with language. A giggle or guffaw crosses those boundaries and bonds us together. It seems to be more in common with animal calls than speech.
The Study of Laughter
Gelotology is the study of laughter. Professor Sophie Scott, and The Laughter Lab, has been conducting interesting studies over the last few years even though sometimes the academic world doesn't want to take the research seriously.
Laughter is Social
We are certainly more likely to laugh with others than alone so it is a social reaction. These studies showed laughter is 30% more likely in a social situation rather than a solitary one. Laughter seems to offer a signal to others. It can be encouraging and a sign we enjoy the company of who we are with.
Most of our laughter is actually not in response to jokes and instead seems to punctuate a conversation. It can be awkward laughter when something cringeworthy or embarrassing is said, or we might add it to the end of our sentences such as, "I told him I wasn't like that! [hee hee]"
Laughter is Contagious
Our unconscious social mimicry will often lead us to copy without realising it and laughter is a fine example. It's hard to remain stoney-faced in a room where someone is laughing uncontrollably.
In 1962, in Tanzania, three schoolgirls started laughing and soon the whole school was affected and had to shut. The laughter spread across villages and took months to recede. (See more.) Omuneepo is the Swahili word for the laughing disease.
Back to the original question we don't all laugh at the same things. Age seems to play a large part in our 'sense of humour' but, of course, there are lots of other influencing factors.
For me, those autocorrect text message conversations get me every time. I know many of them are made up but they get me guffawing whenever I see them. And seeing a photo of a small dog dressed as Yoda will generally raise a snigger from me.
So, come on, it's your turn. What makes you laugh?