First Life is a 2010 British nature documentary series written and presented by David Attenborough, also known by the expanded titles David Attenborough's First Life (UK) and First Life with David Attenborough (USA). First Life sees Attenborough tackle the subject of the origin of life on Earth. He investigates the evidence from the earliest fossils, which suggest that complex animals first appeared in the oceans around 500 million years ago, an event known as the Cambrian Explosion. The naturalist travels around the world, using some of the latest fossil discoveries and their nearest equivalents amongst living species to reveal what life may have been like at that time. Visual effects and computer animation are used to reconstruct and animate the extinct life forms.