The Frozen Zoo How scientists are putting disappearing species on ice

Ina California laboratory, four women do the painstaking work of preserving cells amid agrowing extinction crisis

- Katharine Gammon

In a basement laboratory abutting a 730-hectare wildlife park in San Diego, California, Marlys Houck looks up to see a uniformed man holding a blue insulated lunch bag filled with small pieces of eyes, trachea, feet and feathers.

"Ah," she says, softly. "Here are today's samples."

The bag contains small bits of soft tissue from animals who have died of natural causes at the zoo. Today's samples include a leaf frog and a starling.

The man holding the bag is James Boggeln, a volunteer with the zoo, who hands it to Houck, the curator of this laboratory, known as the "Frozen Zoo". She and her team will start turning these bits of tissue into a bank of research and conservation for the future. They will put the tissue into flasks where enzymes digest them, then the lab members will slowly incubate them over a month - growing an abundance of cells that can be frozen and reanimated for future use.

At nearly 50 years old, the Frozen Zoo holds the world's oldest, largest and most diverse repository of living cell cultures more than 11,000 samples that represent 1,300 different species and subspecies, including three extinct species and more that are very close to extinction.

Today the Frozen Zoo is operated by an all-female team of four, who watch over a vast collection of hand-marked vials with labels such as "giraffe", "rhino" and "armadillo", all stored in massive circular tanks filled with liquid nitrogen. In a world suffering from a climate and biodiversity crisis, putting species on ice offers one way to be hopeful about the future.

The work done here has always felt meaningful, but an accelerating extinction crisis has put mounting pressure on Houck and her team. It's a race against time to put samples into the Frozen Zoo before they slip away from the world. The women see it as their duty to hold the future in place.