Sunday, 7.30pm, SBS One Castles aren’t everyone’s cup of hemlock. On tour in Scotland recently I suffered castle fatigue and chose to sit by the water or in a nearby green meadow while my companions exhausted their infinite interest in these crumbling old joints. However, I must say that in this series presenter Dan Snow’s enthusiasm, as he unravels the stories of six of the world’s most famous medieval castles, is infectious. Snow also presents fascinating back stories not normally found on the tourist trail. In tonight’s debut he is not in Scotland or France but in Syria, at Crac des Chevaliers, possibly the mightiest castle built. The castle was built by the Knights Hospitaller, an elite order of Christian warrior monks in the 12th and 13th centuries, who designed it to guard against Muslim attacks during the Crusades. The series also features particularly gory reenactments of beheadings, impalings and the other atrocities that went on as medieval castles were raided and defended, surely a value add. Next week we are off to France to visit Chateau Gaillard in Paris. just a chemical, it’s an epic poem about life on Earth. Since the human genome was decoded 10 years ago, the codes of hundreds of other species have been unravelled, including creatures from nearly every branch of the tree of life. It all begins in thermal pools east of Reykjavik, Iceland. Here we join Jacob Kristjansson as he digs about in what looks like mud that is apparently also full of bacteria and archaea — the latter being recognised as the oldest organisms on the planet. These little guys were all there was to life on Earth for the first billion years, along with other singlecell organisms known as bacteria. And wouldn’t you know, when scientists compared archaea DNA with human DNA they found that we share about 200 genes. We are so truly of this Earth.