Dr. Carlos Wesley cues up some Carole King on his laptop and positions a head squarely in front of him. It’s been thawing for 24 hours, ever since arriving by UPS from a cadaver lab in Arizona that sells bodies donated to science. It’s now tender and looks frostbitten, with hair buzzed to a gray stubble.

“This was a 59-year-old woman,” says Dr. Wesley, looking down at the head. “I don’t know what the cause of death was, it should say somewhere on the box.” That box is only big enough to fit a head and packing materials: unlike most scientists and surgeons, Wesley isn’t interested in a cadaver’s internal organs or ligaments and bones. He’s only interested in the scalp.

It’s two in the afternoon, and a cloudless sky is beaming down over the Rocky Mountains south of Salt Lake City, Utah. Inside the sparse laboratory, the doctor’s blue scrubs are the only color amid the dull gleam of stainless steel tables. The air is odorless and artificially chilled. A Kevlar poster that reads “CoorsTek” — the name of the medical-device company whose lab we’re using for the day — has been hastily affixed to the wall prior to my arrival, for branding purposes.

As footloose folk-pop melodies fill the room, Wesley extends two fingers towards a small incision in the cadaver’s head and gently lifts a flap of skin. With his other hand, he picks up the piloscope, the invention he’s here to test: the device looks like a piece of AV equipment, a cross between a mic stand and a camera, with an Xbox-style controller of metal knobs and gears. He inserts its rodlike arm several inches into the cadaver’s scalp through the incision, and taps his foot on an attached floor pedal, like a sewing machine. A motor, located on the table beside him, makes a whirring sound.

After 10 minutes of intermittent whirring, Wesley lays down the device and unscrews the top of a closed Petri dish connected to the machine with a rubber tube. Pink, larval-looking hair follicles, sucked from inside the cadaver’s scalp, bob in saline solution. Wesley examines the specimens closely and looks up, triumphant. “These,” he exhorts, “are the shape we want!”