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Hello in the Selkirk Mountains of British Columbia in Canada,

there's an outcrop of limestone shot through with the seam of fine dark shale.

A sudden mudslide into shallow water some 550 million years ago means that a startling

array of wonderful organisms has been preserved within it.

Wide-eyed creatures with tentacles below and spines on their backs, things like flattened rows of

carpet with a set of teeth at one end, squids with big lobster like arms.

There are thousands of them, and they seem to testify to a time when evolution took a leap and life on this

planet suddenly went from being small, simple and fairly rare to being large, complex,

numerous and dizzyingly diverse. It happened in the Cambrian period and it's known as the

Cambrian explosion. But if this is the great crucible of life on Earth, what

could have caused it? And how do the strange creatures relate to life as we see it now?

And what does the Cameron in an explosion tell us about the nature of evolution?

With me to discuss the Cameron explosion in the context of evolutionary science

is Simon Conway Morris, Professor of Evolution. in the context of evolutionary science.

Is Simon Conway Morris, Professor of Evolutionary Paleobiology at Cambridge University.

Jane Francis, Professor of Paleoclematology at the University of Leeds,

and Richard Corfield visiting lecturer at the Center for Earth

Planetary Space and Astronomical Research at the Open University.

Simon Conway Morris you were part of the team that made great discoveries in the Burgess

Shale in the 70s and 80s. Can you describe the slice of life you

...