When the U.S. Air Force was designing its first supersonic jet bomber in the 1950s, it turns out bears were an essential part of the process, helping to test the plane’s new ejection seats during the Cold War, according to i09.com.

The website has put together a summary of the role bears played in testing the supersonic Convair B-58 Hustler. Apparently, because Himalayan and American black bears are reasonably close in size to humans, they were deemed acceptable substitutes, after a team of humans died in an early ejection test.

So, while Chief Warrant Officer E.J. Murray became the first human to successfully eject from a B-58 at nonsupersonic speeds on Feb. 28, 1962, it was a 2-year-old, female black bear that made it into the history books for the first successful supersonic ejection from the aircraft. That occurred about a month later, on March 21.

The bear was ejected from the plane at 35,000 feet above Edwards Air Force Base at a speed of Mach 1.3. It took nearly eight minutes for the capsule containing the bear to reach the ground safely.

Io9 describes the ejection system: “In the new system, a pre-ejection handle yanked the pilot's legs in close and closed a scalloped shell that enclosed him while still allowing rudimentary control of the plane. The actual ejection handle sent the capsule up with a rocket burst, automatically deploying a parachute. The capsule was designed to float, and contained food and survival supplies.”

Statistically, the bears actually fared better than their human counterparts: While a team of humans died in an early ejection test of the B-58, no bears died during the later test runs. However, in an extremely unsettling twist, the bears were euthanized so their bodies could be examined after the ejection tests.

You can watch a lengthy U.S. Air Force video, which discusses the B-58 testing in great detail and includes shots of the bears and chimpanzees after their flights:

It seems unlikely that such measures would be used today. Bears and chimpanzees were undoubtedly subjected to a painful and terrifying process. Still, the report sheds light on a truly unusual bit of aviation history and the role animals have played in helping to advance science and technology.