Are rats good guinea pigs?

Anyone who doubted the idiocy of animal experimentation for medical purposes might ponder the following test which sets out to show if exercise can improve the mind.

While studies have shown an association between exercise and higher mental function in older people, scientists say this does not prove that exercise is the cause. It could be that smarter people exercise, anyway.

So, assuming that stupid people don't exercise, a team from the University of California decided to get to the truth on a team of rats. They wanted to test the effects of exercise on rats' levels of brain derived neurotrophic factor (BDNF), a molecule that apparently supports the survival and function of many neurons.

The rats were exercised on a running wheel for two, four and seven nights and then compared with rats that hadn't exercised. Levels of BDNF increased with exercise, although the rats were not subjected to any memory tests or puzzle-solving during the experiments.

Quite what this proves is a mystery to everyone, including the researchers themselves, we imagine. A simple before-and-after test among humans might have told us more, and saved a group of rats from running for seven nights.