Dr Alice Roberts re-traces the greatest ever journey taken by our ancestors. Thousands of years ago one small group of our species, Homo sapiens, crossed out of Africa and into the unknown. Their descendants faced baking deserts, sweat-soaked jungles and frozen wildernesses and risked everything on the vast empty ocean. Within 60,000 years they colonised the whole world... How did they do it? Why do we, their descendants all look so different?

Of all the objects in the cosmos, planets, stars, galaxies, none are as strange, mysterious, or powerful as black holes. Black holes are the most mind-blowing things in the universe. They can swallow a star completely intact. Black holes have these powerful jets that just spew matter out.
First discovered on paper, on the back of an envelope, some squiggles of the pen. The bizarre solution to a seemingly unsolvable equation, a mathematical enigma. Einstein himself could not accept black holes as real. People didn't even believe for many years that they existed. Nature doesn't work that way. Yet slowly, as scientists investigate black holes by observing the effect they have on their surroundings, evidence begins to mount.

In recent years, close study of the aging process has opened up new ways that could help us all live healthier for longer. Can we move beyond treating individual diseases, and instead treat the aging process itself? But would a longer life necessarily be a better life? A loose-knit group of researchers believe the real breakthrough is extending our health span - the period of life spent free of disease". Hear from Laura Deming, who dropped out of M.I.T. at the age of 14 and committed herself to finding and funding projects that can expand the human health span, and Dr. Brian Kennedy, whose work in the basic biology of aging has been crucial to the development of countless other researchers' work.

This episode explores the nature of the greenhouse effect (discovered by Joseph Fourier and Svante Arrhenius), and the evidence demonstrating the existence of global warming from humanity's influence. Tyson begins by describing the long-term history of the planet Venus; based on readings from the Venera series of probes to the planet, the planet had once had an ocean and an atmosphere, but due to the release of carbon dioxide from volcanic eruptions, the runaway greenhouse effect on Venus caused the surface temperatures to increase and boiled away the oceans. Tyson then notes the delicate nature of the amount of carbon dioxide in the atmosphere can influence Earth's climate due to the greenhouse effect, and that levels of carbon dioxide have been increasing since the start of the 20th century. Evidence has shown this to be from mankind's consumption of oil, coal, and gas instead of from volcanic eruptions due to the isotopic signature of the carbon dioxide. The increase in carbon dioxide has led to an increase in temperatures, in turn leading to positive feedback loops of the melting polar ice caps and dethawing of the permafrost to increase carbon dioxide levels. Tyson then notes that humans have discovered means of harvesting solar power, such as Augustin Mouchot's solar-driven motor in the 19th century, and Frank Shuman's solar-based steam generator in the 1910's. Tyson points out that in both cases, the economics and ease of using cheap coal and oil caused these inventions to be overlooked at the time. Today, solar and wind-power systems would be able to collect enough solar energy from the sun easily. Tyson then compares the motivation for switching to these cleaner forms of energy to the efforts of the Space race and emphasizes that it is not too late for humanity to correct its course.

Memory is the glue that binds our mental lives. Without it, we’d be prisoners of the present, unable to use the lessons of the past to change our future. From our first kiss to where we put our keys, memory represents who we are and how we learn and navigate the world. But how does it work? Neuroscientists using cutting-edge techniques are exploring the precise molecular mechanisms of memory". By studying a range of individuals ranging —from an 11-year-old whiz-kid who remembers every detail of his life to a woman who had memories implanted— scientists have uncovered a provocative idea. For much of human history, memory has been seen as a tape recorder that faithfully registers information and replays intact. But now, researchers are discovering that memory is far more malleable, always being written and rewritten, not just by us but by others. We are discovering the precise mechanisms that can explain and even control our memories. The question is— are we ready?

'In Search of Beethoven': takes a comprehensive look at the composer's life through historical research and Beethoven's biography and letters, but with the emphasis always on the performance -- and interpretation -- of Beethoven's music. From his early piano concertos through the "Moonlight Sonata," "Für Elise," and the immortal notes of the Fifth and Ninth Symphonies, Beethoven's music remains as beloved, popular, and relevant as any work of art has ever been. "In Search of Beethoven" brings together the world's leading performers and experts on Beethoven to reveal new insights into this celebrated composer.