It is permitted, and even a mitzva, to conduct scientific experiments on animals in order to understand diseases and develop cures for human beings. Even when these experiments cause animals great suffering, they are not prohibited, because they are done for human benefit and not out of cruelty. Nor should one refrain from them as an act of piety. Through such research, cures may be found for many illnesses, and the highest moral duty is to protect human life and health (see Shevut Yaakov 3:71; Seridei Esh 3:7). Indeed, people are prepared to suffer and even risk their lives in order to save and heal their children or friends. The more lives are at stake, the more willing people are to endure severe suffering and danger to save others. All the more so, one may cause animals under human control to suffer in the search for cures for human disease.
Nevertheless, each proposed experiment must first be evaluated to determine whether it is truly necessary. When the research can be done equally well on different species, one should choose the species with the lower capacity for suffering. For example, if the same experiment can be done on either monkeys or mice, it is better to use mice, whose brains and nervous systems are less complex and whose experience of pain and suffering is more limited. Monkeys, by contrast, are cognitively complex enough that one can tell when they are happy and content or sad and in pain, and one must therefore be especially careful not to cause them to suffer (above, note 1, principle 2). Even when animal research is necessary, every effort should be made to minimize the animals’ suffering. Surgery, for example, should be performed with anesthesia when possible. If the research leaves the animals physically damaged, they should be put down painlessly in order to spare them further suffering (Tzitz Eliezer 14:68).
Strictly speaking, high school students may experiment on insects, such as testing the temperatures at which they can survive, whether extreme heat or extreme cold. True, these experiments have already been performed by others. Still, students gain something by learning how experiments are conducted and by practicing scientific observation. In addition, the main prohibition of tza’ar ba’alei ḥayim applies to animals that serve human beings or have a meaningful level of awareness; it does not apply in the same way to insects, whose nervous systems are far simpler. Nevertheless, since these classroom experiments do not add to scientific knowledge, and it is far from clear that the students will become scientists who need this kind of training, it is better for them to perform experiments that do not cause living creatures to suffer. It is proper to have compassion for all creatures, as it is stated (Tehilim 145:9): “His compassion extends to all His works.”
