It’s World Week for #Animals in Laboratories (April 18th to the 26th) and today is the World Day for Laboratory Animals—the perfect time to consider what animal experimentation means for the animals themselves, and for science.

While the social movement to end the use of animals in experiments is a modern one, the notion that using animals in science and medicine is morally wrong and scientifically questionable dates back almost as far as the scientific method itself.

Charles Darwin in The Descent of Man argued: "There is no fundamental difference between man and the higher mammals in their mental faculties," attributing to animals the power of reason, decision making, memory, sympathy and imagination. We know this to be true today more than ever.

A landmark 2011 study by the U.S. Institute of Medicine found that, “most current biomedical research use of chimpanzees is unnecessary.”

A 2007 U.S. National Academies of Science report looked at standard methods of testing the safety of chemicals and concluded that, “Current [animal] tests … provide little information on modes and mechanisms of action … and little or no information for assessing variability in human susceptibility.” The government report advocated for new approach to toxicity testing based on exclusively “computational biology and a comprehensive array of in vitro tests based on human biology.”

In 2006, an article published in the prestigious Journal of the American Medical Association found that even the most highly-cited experiments on animals rarely translate to humans. The authors concluded, “patients and physicians should remain cautious about extrapolating the finding of prominent animal research to the care of human disease … poor replication of even high-quality animal studies should be expected by those who conduct clinical research.”

People justify the use of mice, rats, monkeys, dogs and other animals in harmful experiments by claiming that animals are so similar to humans biologically and psychologically, but then they ignore the ethical implications of those similarities. Animals are intelligent, sentient individuals who have lives and interests of their own, suffer immensely in laboratories, and don’t want to die. Humans may be different from other animals, but that doesn’t make us more important.

So, what is the alternative? Thanks to modern technology, we now have several alternatives to animal experimentation are in vitro tests based on human tissues, sophisticated computational models, ethical research with human participants, and humanlike patient simulators. Researchers at Harvard University developed microfluidic devices they call organs on a chip, which are effectively fully-functioning miniature human organ systems made from human cells and tissues.

For both ethical and scientific reasons, tormenting animals in experiments is unjustifiable.