"Extremophiles" is a bit of a parochial term - this is the name for organisms that live happily in environments that we consider extreme. Too cold, too hot, too acid, too something to support life, in our terms. Studying the lifeforms that disagree with us on what is a good place to live has started a new field of astrobiology and a new appreciation of the possibility of life existing in the wider universe.
Secrets of Bones was a 6 part series of half hour programmes about skeletons, presented by Ben Garrod. Each episode covered a different aspect of the way that skeletons are vital to vertebrates. The series looked at both the commonalities between the vertebrate skeletal structure, and also the ways that skeletons are adapted to the life style of the particularly organism.
Mud Sweat and Tractors is a four part series about the changes in farming in Britain over the last century or so. It split it up into four areas - milk, horticulture, wheat and beef - and treated each as a separate story, so each episode seemed quite self-contained. Each time there were two or three farming families chosen who had photographs and video footage stretching back to the 1930s. So they made good case studies and could talk about why they or their Dad or Grandad had made particular decisions at particular points.
The Necessary War and The Pity of War were a pair of programmes from the BBC about the First World War that aired a couple of months ago. In The Necessary War Max Hastings put the case for WW1 being, ultimately, necessary despite the loss of life etc. And in The Pity of War Niall Ferguson argued that it was all a terrible and costly (in terms of lives) mistake - this programme finished with a debate.
In the end nearly all life on Earth depends on sunlight for its energy source. Heterotrophs like ourselves are a step or two away from the sunlight, but ultimately it's the process of photosynthesis that fuels our food and thus ourselves. Photosynthesis also, as a byproduct, provides the air we breathe. The three experts who talked about it on In Our Time were Nick Lane (University College London), Sandra Knapp (Natural History Museum) and John Allen (Queen Mary, University of London).
Monkey Planet was a three part series presented by George McGavin about primates - monkeys, apes and lemurs. The first episode in was primarily a survey of just how wide-ranging and varied a group the primates are. The other two looked at aspects of primate behaviour that we tend to think of as particularly human, and showed both how it's actually primate-wide and more varied than our narrow perspective suggests.
Pilgrimage with Simon Reeve was a three part series that was partly a travelogue and partly about the history of Christian pilgrimage across Europe and the Holy Land from medieval times through to the modern day. Reeve made it pretty clear several times that he's not a Christian himself, so this was an outsider's view on the subject. He did, however, talk to several people who do pilgrimages for religious purposes today, so we got both sides of the subject represented.
The second episode of Alastair Sooke's series about the art of Ancient Egypt covered the Middle Kingdom (briefly) and most of the New Kingdom. He only picked a couple of objects from the Middle Kingdom - both from Senusret III's reign. He gave the impression that this is because the New Kingdom was the Golden Age, which is true in some ways, but the Egyptians themselves looked back at the Middle Kingdom as their "classical age" where art and culture first achieved great heights.