BEFORE I was elected to Congress, I was a physiologist at the Navy’s School of Aviation Medicine. For our successful missions to transport men to the moon and return them safely to Earth, I invented a series of respiratory support devices, which we tested on primates, including Baker, a squirrel monkey. Before humans were rocketed into space, Baker was the first primate to survive a trip into space and back; Able, her counterpart on the flight, died from an allergic reaction to an anesthetic during a procedure shortly after the landing.

At the time, I believed such research was worth the pain inflicted on the animals. But in the years since, our understanding of its effect on primates, as well as alternatives to it, have made great strides, to the point where I no longer believe such experiments make sense — scientifically, financially or ethically. That’s why I have introduced bipartisan legislation to phase out invasive research on great apes in the United States.

Today is the start of a two-day public hearing convened by the Institute of Medicine, which is examining whether there is still a need for invasive chimpanzee research. Meanwhile, nine countries, as well as the European Union, already forbid or restrict invasive research on great apes. Americans have to decide if the benefits to humans of research using chimpanzees outweigh the ethical, financial and scientific costs.

The evidence is mounting that they do not. For one thing, many new techniques are cheaper, faster and more effective, including computer modeling and the testing of very small doses on human volunteers. In vitro methods now grow human cells and tissues for human biomedical studies, bypassing the need for whole animals.

Such advances have led to a drop in primate research. Many federally owned chimpanzees were bred to support AIDS research, but later proved inferior to more modern technologies. As a result, most of the 500 federally owned chimpanzees are idling in warehouses. Ending chimpanzee research and retiring the animals to sanctuaries would save taxpayers about $30 million a year.

We also know more about the consequences of invasive research on the animals themselves. Biomedical procedures that are simple when performed on humans often require traumatizing restraint of chimpanzees to protect human researchers from injury, as chimpanzees are five times stronger than humans. For instance, acquiring a blood sample from a chimp can require a “knockdown,” or shooting it with a tranquilizer gun. If you’ve seen video of a knockdown, you know it is clearly frightening and stressful.

Moreover, even the mere confinement in laboratory cages deprives chimpanzees of basic physical, social and emotional sustenance. Numerous peer-reviewed studies of chimpanzees in sanctuaries who had previously been confined in laboratories have documented behavioral symptoms associated with post-traumatic stress disorder. Chronic and traumatic stress harms chimpanzees’ health and compromises the results of experiments conducted on them.

There is no question that chimpanzees experience pain, stress and social isolation in ways strikingly similar to the way humans do. James Marsh’s recent documentary, “Project Nim,” chronicles the 27-year life of Nim Chimpsky, a chimpanzee who was the subject of a controversial research project that involved raising him as though he were a human. Nim was taught sign language — and he used those signs to tell his human interlocutors that he was traumatized by his living conditions.

Nim isn’t alone. In his book “Next of Kin,” Dr. Roger S. Fouts recounted his reunion with a chimp named Booee. After 13 years of separation, and after Booee was deliberately infected with hepatitis C, Booee recognized, signed and played with Dr. Fouts, to whom he had given the signed nickname of “Rodg.” Other visitors reported that Booee used the American Sign Language gesture for “keys,” indicating that he wanted to get out of his cage.

Stories like these, as well as my understanding of the state of biomedical research, persuaded me to sponsor the Great Ape Protection and Cost Savings Act with Senator Maria Cantwell, Democrat of Washington. The bill would phase out invasive research on great apes and retire the 500 federally owned chimpanzees from laboratories to sanctuaries.

Continuing innovations in alternatives to the use of invasive research on great apes is the civilized way forward in the 21st century. Past civilizations were measured by how they treated their elderly and disabled. I believe that we will be measured, in part, by how we treat animals, particularly great apes.

Americans can no longer justify confining these magnificent and innocent animals to traumatic invasive research and life imprisonment.

Roscoe G. Bartlett is a Republican representative from Maryland.