Many, like Edward O. Wilson, will worry about species that face extinction; but one extinct creature, the Pyrenean ibex, may actually be revived.
If you could bring something extinct back to life, what would you choose?
The standard pop-psychology answer is that dinosaurs are big, fierce and extinct.
Within a few years, the study of French at UK universities, already severely endangered, may well become extinct.
Critics may point out some omissions, such as Rustie's Glass Swords – a Technicolor rave-pop record that won the Guardian's first album award, or Evolve or Be Extinct, the latest grime offering from Wiley.
And when we look at the bones of the extinct, non-avian dinosaurs that haunt our imagination, we're faced with a seemingly infinite number of questions about how they lived.
For one thing, there are scores of other prehistoric beasties that fit the description of "big, fierce and extinct" that aren't nearly as popular as dinosaurs.
The Japanese fear that their fishing industry is next (quite rightly: fishing blue-fin tuna is close to sending the species extinct).
She spent long vigils lying, mud-splattered in the marshes, lens poking from vegetation, in pursuit of elusive water rails, bearded tits and a juvenile bittern, and her pictures proved the latter species was not extinct in Britain after all.
In the end, we rustled up the promise of feeding wild monkeys in the island's mountainous Grand Etang Forest Reserve in exchange for a spice farm, a botanical garden, a rum distillery, an extinct volcano, a nutmeg factory and an organic chocolate producer.
"If the asteroid didn't hit, I have no reason to believe they'd have gone extinct.
