We think of comets as beautiful glowing balls of light streaking across our skies with their long sweeping tails, yet comets are so much more than just a cosmic firework display. Comets have a uniquely important place in modern science. As time machines from the early universe, they could hold the key to unlock the secrets of the cosmos. Comets could even be the origin of life itself. We follow the incredible odyssey of a comet as it sails through the solar system, watching it's every move as it evolves from a dormant chunk of ice and rock into a tumbling, violently active nucleus engulfed in a gaseous haze. What we learn is a revelation; comets are even more mysterious and fascinating than we had ever imagined.

At 11 o'clock on New Year's Eve of the Cosmic Calendar, Homo erectus stood up for the first time, freeing its hands and earning the species its name. They began to move around, to explore, daring to risk everything to get to unknown places. Our Neanderthal relatives lived much as we did and did many of the things we consider to be 'human.' More restless than their cousins the Neanderthals and Denisovans, our Homo sapiens ancestors crossed seas and unforgiving landscapes, changing the land, ocean and atmosphere, leading to mass extinction. The scientific community gave our age a new name, 'Anthropocene.'
Since the first civilizations we've wondered if there's something about human nature that contains the seeds of our destruction. Syukuro Manabe was born in rural Japan and took an intense interest in Earth's average global temperature. In the 1960's, he would assemble the evidence he needed to predict the increase of Earth's temperature due to greenhouse gases until it becomes an uninhabitable and toxic environment, leading to our extinction. 'This doesn't have to be,' says Neil deGrasse Tyson, 'it's not too late. There's another hallway, another future we can still have; we'll find a way.'

What If we could talk to animals? For as long as we've shared our lives with pets, we've been seeking better ways to communicate with them. In Washington state, Alexis Devine and her sheepadoodle Bunny think they've found a way of making communication a reality. Alexis went further than most, with a set of communication buttons, each programmed with a pre-recorded word to help humans and animals speak the same language. She has 90 buttons with which to express herself and even seems to combine them into simple sentences. Bunny is paving the way in pet communication.
The undisputed masters of verbal communication are our pet parrots. They have mastered the art of vocal expression. Some parrots have even learned to fool devices designed to recognize human voices.

Human society is incredibly complex, and the duelling forces pushing us to conform and also to express our individuality are both necessary. Other people can influence us in good ways and in not-so-good ways.
Michael Stevens takes a look into the human urge to conform and just how strong it is against our own beliefs and sense of selves.

Cabeza de Vaca was shipwrecked off the coast of Texas in 1528 and lived with Indians for eight years. Upon his return to Spain, he wrote a book based on his experiences. His tale is one of empathy and respect for the Indians. Follow along as Michael Wood traces his journey.

Francisco de Orellana failed to find El Dorado, but discovered the Amazon. Early in 1541, a rumor swept Quito that beyond the mountains, there lay a land richer than Mexico, or even Peru - a land of gold. The ruler of this land was so rich that he covered himself with gold dust every day and washed it off every evening. He was "the golden man", El Dorado. They had tree goals: to find La Canela, the land of cinnamon: to assess new lands for colonization; and to find El Dorado. On march 1541, They marched eastwards with more that 200 Spanish troops and thousands of native servants.