A recent study asks why dinosaurs went extinct 66 million years ago while ancient birds still exist today.

The answers look beyond the established assumptions of climate change and the impact of a giant asteroid as the reasons for the end of dinosaurs. Instead, they examine how eggs hatched.

Turns out that it took a much longer time for a baby dinosaur to pop out of an egg, compared to birds. Chickens, in particular, take just three weeks. Which would imply that a calamity might not decimate an entire population waiting to be hatched.

Of course, this may not be the only, or even real, reason for the ubiquitousness of chickens. (And we’re not even talking of theories which track the evolution of the chicken from dinosaurs, with some lack of clarity.)

But the one thing that can be established is that chickens have indeed proliferated across the world as a domestic bird, and the credit goes to humans for taking advantage of the short incubation cycle.

The video above from Sam O’Nella Academy offers a comprehensive – and quick – history of how chickens were domesticated. And it all goes way back to 5,000 BC in South-East Asia, with the red jungle fowl.

But if you’re still wondering which came first – the chicken or the egg – here’s another video that tries to crack the conundrum.