BBC Four schedule

4/6. Ben Garrod delves into the surprising ways in which bone has evolved to help vertebrates sense the world around them, from wolves and sheep to the great grey owl. [S] [HD]

4/4. Timothy and his wife Shane encounter several Scottish ports and islands in the misty drizzle, and venture up the Caledonian Canal. [S,AD]

7/12. Documentary which looks at why the most inhospitable place on the planet has exerted such a powerful hold on the imagination of explorers, scientists, writers and photographers. [S]

1/5. The rocky planets Mercury, Venus, Earth, and Mars were born at the same time from the same material, yet they have lived radically different lives. What immense forces are at play? [S,AD,SL] [HD]

Programmes start at 7.00pm. [HD]

Programmes start at 7.00pm. [HD]

5/6. Ben Garrod uncovers the secrets of how vertebrates capture and devour their food using extreme jaws, bizarre teeth and specialised bony tools. [S] [HD]

1/5. Rugby legend Gareth Edwards and wife Maureen try steam trains and rallying in Machynlleth. [S] [HD]

During the Second World War, a group of Allied prisoners of war mount a daring breakout from a supposedly inescapable Nazi prison camp. Based on a true story. [1963] [S]

Acclaimed mystery about a couple grieving the loss of their daughter in a tragic accident. Contains some strong language, explicit sexual content, some violence... [1973] [S,AD] [HD]

Donald Sutherland talks with Mark Cousins about his life and work. Contains some strong language, some sexual content and disturbing scenes. [S]