As we enter our teenage years, many of us feel like life is just getting started. But for dogs, celebrating a ‘teen’ birthday is a sign of old age, entering a phase when things start slowing down. Listener Susan was besotted with her beloved corgi Copper John and wants to know why our furry companions rarely live as long as us. We investigate what accounts for the huge differences in lifespans across animal species. From fish that live a few weeks, to sharks who can survive for 500 years, what are the factors that affect the ticking on our biological clocks? Central to this field is the idea of ‘live fast, die young’, with some animals burning more quickly through their ‘life fuel’. But is this rate set in stone?

Presenter Anand Jagatia find out how animals’ growth, reproduction and anti-ageing methods contribute to the length of their survival. Dr Kevin Healy, a macroecologist at the University of Galway, discusses some of these theories, explaining how the dangers and luxuries faced by animals during their evolution shape their speed of life.

One example of extreme slow living is the Greenland Shark. John Fleng Steffensen, Professor of Marine Biology at the University of Copenhagen, describes how he helped figure out how old they really are, and how their cold living quarters increase their lifespan. Alessandro Cellerino, physiologist at the Scuola Normale Superiore in Pisa, finds the key to the sharks’ longevity in their DNA.

Anand also goes on a hunt on the west coast of Ireland for a creature that lives fast but surprisingly, dies old. Noel Fahy, research student at the University of Galway, is his guide, while Dr Nicole Foley, Associate Research Scientist at Texas A&M University, reveals the life-extending secrets of this creature.

And geneticist Trey Ideker, Professor at the University of California San Diego, busts the myth that one dog year is seven human years. But how much is this misconception off by?

Presenter: Anand Jagatia Producer: Julia Ravey Content Editor: Cathy Edwards Studio Manager: Sarah Hockley Production Coordinator: Ishmael Soriano

(Photo: Copper John the Welsh Pembrokeshire Corgi, by listener Susan)