In the September 5th New York Times, James Gorman writes that "dogs may
laugh, but only cats get the joke". The article reads:

"The last time I wrote about cats and humour was 20 years ago. It did
not turn out well. I was happy with the column, which appeared in a
science magazine, but many readers were not. The mail was unfriendly,
to say the least. One letter writer (this was back in the days of
actual letters) wanted to see me eaten by a Doberman. Another suggested
I should be in a mental hospital.

What prompted their ire was that I had argued, with support from Darwin
and other luminaries, that cats have no sense of humour.

My idea was simple and based on evolution. I argued - and I did not
invent this idea - that animals like wolves and primates that live in
hierarchical social groups need a sense of humour to survive. Wolf pack
or newsroom, when the big dog growls, the beta, gamma, delta, epsilon,
lambda, mu, nu and omega dogs had better be able to laugh it off, so
they can live to reproduce another day. Thus, laugh-it-off genes are
preserved. If they were not needed, they would probably be lost.

We know that this happens. Last summer, scientists figured out how cats
long ago in the course of evolution lost the ability to detect
sweetness. Dogs can taste sweet things, as can many other mammals, like
rodents. But neither alley cats nor lions have a sweet tooth. They do
have sweet receptors. But sometime after cats and dogs diverged, a gene
was turned off in cats, so that they no longer make one of the proteins
necessary for the receptors to work.

This may be why they seem so independent. The desire for sweets can
certainly make people do foolish things.

Humour genes could have been lost. Or, the capacity for humour may not
have evolved in animals like dogs and primates until long after they
diverged from cats. But this was not the reason I decided to tackle the
cat/humour issue again. A colleague and friend who had a dry, slightly
wicked sense of humour and who loved and identified with his cats -
he was known to meow on occasion - died unexpectedly. I thought, how
could he have been enamoured of an animal that does not have a sense of
humour?

So I began to rethink the issue, and I have concluded that I may have
actually been thinking about laughter rather than humour.

Laughter is not always about what's funny, as Robert R. Provine, a
professor of psychology at the University of Maryland, Baltimore
County, who has studied laughter, has noted in books and articles. It
is frequently a social behaviour unrelated to jokes or wit. It can
serve different purposes. It can be friendly or submissive, hostile or
dominant. Witness the old distinction between laughing with and
laughing at someone.

This makes sense when you think that some of the people who laugh all
the time are actually not funny, or even appreciative of a good joke.
They just laugh to punctuate conversation, or sometimes to seem
unthreatening. Or threatening - I know those people, too.

Perhaps, I thought, this is what dogs and other social creatures have,
not a sense of humour, but an "I'm just happy to be part of the
pack/team/company" sense of laughter. You know when your dog lies on
its back, looking goofy, with the tongue falling out one side of its
mouth? Just think of that as laughing.

I love dogs. But if I think about dog humour honestly, it's really a
kind of goofy, good-natured submissiveness.

Dogs amuse us. Cats, I suspect, amuse themselves, as a creature
unconcerned about its place in the corporation might well do. With a
mouse, or a ball of yarn, a cat may play and be amused, whether we are
watching or not.

Obviously, this can be solved only by mining the genomes of dogs, cats
and people. Most of the detailed DNA research on humour so far has to
do with the aqueous humour or the vitreous humour. Those are in the eye
and, from my brief survey of the literature, are not at all funny.

There is, of course, a school of thought that a sense of humour in
humans is not genetic, but depends on one's upbringing. This may be
true within species, but I'm thinking it doesn't apply in
cross-species studies. However, if cats or dogs have a true capacity
for humour, as opposed to some version of social laughing, they may
well acquire their taste in humour from their owners.

So, I'm now prepared to acknowledge that some cats may have a sense
of humour. Very dry and slightly wicked, I'll bet."