ELi5: Rats seem to be the gold standard for behavioral lab experiments – why? Other than quantity, what makes rats good test subjects in relation to humans?
In: Biology
Size, quick gestation period, ease of maintenance, but mainly their physiology is close to ours.
Objectively, testing on primates would be better and more accurate to the effect a drug would have on humans. The problem is mostly logistics.
However, if you want to test say 10 different drug mixtures, each with 10 different dose sizes, and you want to have a sample size of 100 individuals, suddenly you need 10,000 individuals.
It’s far easier to house and maintain 10,000 rats than it is to maintain 10,000 monkeys.
One of the big factors is that we can reliably clone them, allowing us to remove genetic factors almost entirely from study results. This massively simplifies the design and interpretation of the experiment.
If you look into it, rats are a terrible way to test things that are made for humans. There have been a ton of situations where something works on rats but not humans or had no effect on the rats while being super harmful to human beings.
If you want to truly test something, you gotta test on human beings.
They’re small, don’t require a ton of space, they breed quickly, and they’re also really smart, trainable, and sociable, which makes some tests much easier to conduct.
There’s also some PR in play as well. People don’t care as much about rodents, so find it more acceptable to test on them compared to something like say a cat or a dog.
they recently started switching to lawyers for lab experiments instead of rats.
2 reasons: the lab techs get less attached and there’s some things you can’t even get a rat to do
but to answer your question rats are surprisingly similar to humans in a lot of ways and they breed quickly and are easy to take care of in a laboratory setting
Interesting thing I found out is a common blood thinner is also used for rat poison.
Only in much larger doses
Unfortunately, while they are very tractable test subjects and very smart and social animals, there is a lot of evidence that they aren’t ideal test environments for human health questions. Coming from a long time rodent researcher, many very promising drugs in rodents have failed to work as expected in human trials.
Behavioural experiments need a subject that is smart and mice are very smart for their size. They are also cheap to maintain due to their small size – requires very small space and small amount of food to maintain. Their life cycle is relatively fast, so you can observe generations of behaviour on a reasonable time line.
Other popular test subjects (not necessarily for behavioural experiments) are fish and flies, because they are cheap to maintain in large quantities and life cycle is very fast. These are good for drug tests, but not necessarily good for behavioural tests as they are not as smart and doesn’t behave in a way that mammals would, and usually we are doing experiments to extrapolate to humans.
Another reason is that the mice you use in labs are highly standardised and their genetics have been bred to be a specific way. You buy from special suppliers who maintain specific genetic lineages of mice and they are basically all clones. This means you reduce any variance of genetics from your test results. I believe there’s specific lineages with desirable characters and you pick one that helps with whatever research you’re doing, such as more docile or more aggressive in their personalities etc.
Cheap to obtain and house, relatively smart, quick to grow/reproduce, mammals, nobody really gives a shit about them so there’s less legal stuff to jump through compared to like dogs or monkeys or other charismatic species
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