Not such a dirty rat

Here's a question : if there was a machine which had emotions but no intelligence at all, would it be ethical to experiment on it ? Another one : is it ethical for us to eat animals, and if not, is it ethical for animals to other animals ?

I have no idea. Anyway, I'd heard of rats showing empathy before, but I wasn't aware this was known in the 1950's. See original article for links to individual studies.

We now know that rats don’t live merely in the present, but are capable of reliving memories of past experiences and mentally planning ahead the navigation route they will later follow. They reciprocally trade different kinds of goods with each other – and understand not only when they owe a favour to another rat, but also that the favour can be paid back in a different currency. When they make a wrong choice, they display something that appears very close to regret. Despite having brains that are much simpler than humans’, there are some learning tasks in which they’ll likely outperform you. Rats can be taught cognitively demanding skills, such as driving a vehicle to reach a desired goal, playing hide-and-seek with a human, and using the appropriate tool to access out-of-reach food.

The most unexpected discovery, however, was that rats are capable of empathy.It all began with a study in which the rats refused to press a lever to obtain food when that lever also delivered a shock to a fellow rat in an adjacent cage. The rats would rather starve than witness a rat suffering. Follow-up studies found that rats would press a lever to lower a rat who was suspended from a harness; that they would refuse to walk down a path in a maze if it resulted in a shock delivered to another rat; and that rats who had been shocked themselves were less likely to allow other rats to be shocked, having been through the discomfort themselves. Rats care for one another.

Most scientists were not convinced, suggesting instead that the rats probably just wanted someone to hang out with, or that they found it annoying that the trapped rat was making such irritating noises and wanted it to stop. The rats, according to these scientists, were not acting out of concern for the other, but out of pure egoism. What else could one expect from a rat?

The obvious question here being : what's the difference between humans and rats in these scenarios. The answer is easy : nothing. We have no grounds for assuming that humans are empathic beyond their own protestations that they have possess emotions and sentience, which might simply be a lie. So when it comes to other animals displaying emotional behaviour, we have only the behaviour itself on which to judge. And it's no more valid to attribute rat behaviour to irritation than it is to empathy. Given that the behaviour shown is far, far more similar to what we know about empathy than annoyance, assuming it's due to irritation because we don't like rats is just plain stupid. When it comes to analysing inner mental lives, we have no choice but to make assumptions.

But the sort of people who experiment on rats, one suspects, aren't capable of understanding this. If you're looking for the stereotypical evil scientist, your search is at an end.

For decades, Harlow created psychologically damaged primates in order to better understand human psychopathologies. Monkey babies were separated from their mothers for six to 12 months so that he could study the effects of breaking the maternal bond. Juveniles were isolated in what Harlow called the ‘pit of despair’: a tiny metal cage meant to induce depression in otherwise healthy and happy monkeys. It worked all too well. 

Scientists are now tinkering with rats’ empathy in order to find ways of treating human psychopathologies. In some cases, rats are given treatments that temporarily disable their empathic capabilities, such as anxiolytics, paracetamol, heroin or electric shocks. In other cases, the harm is permanent. Rats are separated from their mothers at birth and raised in social isolation. In some studies, their amygdalae (the brain area responsible for emotion and affiliation) are permanently damaged. The explicit goal of this research is to create populations of mentally ill, traumatised, emotionally suffering rats.

I don't know if its ethically justifiable to experiment on animals to develop new medicines for humans or not. But I'm damn sure that deliberately turning animals into psychopaths is an grotesque, purposeless act. I won't try and see what sorts of experiments are ethical or not, but I will say very firmly that these ones are wrong.

Why don't rats get the same ethical protections as primates? - Kristin Andrews & Susana Monsó | Aeon Essays

In the late 1990s, Jaak Panksepp, the father of affective neuroscience, discovered that rats laugh. This fact had remained hidden because rats laugh in ultrasonic chirps that we can't hear. It was only when Brian Knutson, a member of Panksepp's lab, started to monitor their vocalisations during social play that he realised there was something that appeared unexpectedly similar to human laughter.