The first episode explores the most violent event in the history of the Earth when, four and half billion years ago, it collided with another planet, Theia, helping create the unique circumstances for life on Earth.

It includes contributions from Bill K. Hartmann who first convinced the scientific mainstream that the Giant impact created both the Moon and the Earth's 23° tilt.

[2] This episode considers the events over the last 75,000 years that wiped out many of present-day humans ancestors.

Super-volcanoes, ice ages and cosmic impacts have all had a malign effect on the development of the human race and the evidence is that such events will continue to be a threat in the future.

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