Happy rat/sad rat news

So Ratatouille was a kind of documentary?   I didn't realise Paris has a rat problem.   Probably because there's too much nice food there.  And how's this for a pest control manager who can still admire his prey (as well as making a dubious sounding claim):

Listening to Mr. Demodice, who has spent much of life observing rats, it is almost possible to feel affection for them.

“A rat is a very intelligent and athletic animal,” he said.

“Rats play a very useful role for us because what they eat we do not need to dispose of, so it’s very economical for us, and when rats are underground they also clean the pipes with their fur when they run through them.

“So we need to keep them. They’re sort of our friends, but they need to stay below. That’s all we ask: that they stay below.”

And in happier rat news, here's how to tell if your rat is happy:

Wondering if your pet rat is feeling happy? You should check its ears, researchers say.
A team of scientists in Switzerland found that a rat's ears are more pinkish and are positioned at a more relaxed angle when it is experiencing positive emotions. The researchers recently published their findings in the journal PLOS ONE.
Previous studies have focused on negative emotions –- for example, identifying how rats indicate that they are feeling pain, with the aim of learning how to avoid those situations.
Now, the research team led by Kathryn Finlayson is focused on promoting positive emotions in rats – rather than simply aiming for the absence of a negative state. As animal behavior researcher Luca Melotti tells The Two-Way, this is centered on the question of "what does it mean to have a life worth living?"

Actually, now that I read the article fully, couldn't the pink ears just be a result of the physical activity of tickling?   The controls should have had physical activity too, surely, before you could read much into pink ears.