10,000 BC

The first 12 volunteers arrive and appoint a leader. As the scouting party sets out, they discover a abandoned camp and convince the other tribespeople to move, unaware that this is in fact the allotted camp for the second tribe arriving in 24 hours time.

The second tribe arrives and finds that the first tribe have settled in their allotted camp.

A member of Wood camp receives bad news from home. The two tribes decide to share the fishing gear and catch 50-50. The Crays want to poach Dan, but he isn't sure whether to defect or not.

John orders Snake tribe to move to Hunt camp, but the Cray tribe has already been and cleared all the useful tools and taken all the fruits and nuts off the trees. Tempers flare as hunger and hardship take their toll, health detoriates and a divide emerges in one tribe.

The Crays are not happy when the Snake tribe moves in with them whilst their camp is rebuilt.

The Cray and Wood camp's join together to form a joint hunting party. John moves his remaining tribe across the lake to their new home. A member of the Snake camp defects and both camps lose members due to illness.

Jay flies home to be with his pregnant girlfriend. The Crays contend with receding water, whilst the Snakes begin to fall out with one another.

The food sharing pact is broken when the tribes take a lot for themselves. Dan brings down a small deer and the tribes eat meat for the first time in weeks.

The Crays are unsure what to do with the three goats they have in their possession. Teri confronts Dave over accusations of laziness.

With only five original members of the twenty camp-mates left, Mel begins to feel the strain. Before the experiment ends, will anyone else throw in the towel?