Delving beneath the surface of the Earth's oceans to uncover a world of extraordinary extremes, including crushing depths, stormy coasts, vast blue deserts, and crowded reefs; how seals fend off sharks; how orcas fight to survive.
The human eye is an amazing mechanism, able to detect anywhere from a few photons to a few quadrillion, or switch focus from the screen in front of you to the distant horizon in a third of a second. How did these complex structures evolve? Joshua Harvey details the 500 million year story of the human eye.
New Zealand was one of the last land masses to be found and settled by people. Lush and fertile, almost everything brought here flourishes, often with surprising consequences. Told through the experiences of its native species - in particular, a charismatic and peculiar giant, flightless parrot - this is the moving story of the changing fortunes of New Zealand's wildlife since humans first arrived.
The final programme looks at the superorganisms formed by bees, ants and termites. Attenborough reveals that their colonies, whose individuals were once considered purely servile, are "full of conflict, power struggles and mutinies." They evolved when such creatures moved away from a solitary existence and started building nests side-by-side, which led to a collective approach to caring for their young.