There are more than a few hokey moments in Horses (World, 10pm), the documentary that fills this evening's National Geographic slot. It sometimes feels as though house-style demands a large dollop of sentimentality be added to the script. The only reason why this time it is remotely bearable is because Gillian Anderson (above) does the voice-over, and she is capable of making the most saccharine words sound sensible. The programme explores the relationship between man and horse, but does not get around to the most interesting point until we are introduced to a horse whisperer called Brian towards the end. Brian manages to tame a wild two-year-old in about two hours using a mixture of calm, kindness and carefully chosen body language. What Brian still cannot figure out after all these years is why big, strong, smart animals like horses allow puny animals like human beings to get on their backs (just the way a smart predator would do, as Brian points out) and stay there for hours. The programme begins in the Mongolian grasslands at a massive horse race featuring 500 riders all under 12. These young riders have no time for such philosophical questions: to them, these animals are beloved friends. It is hard to judge which is the more pathetic shot: the sight of a broken horse being hoisted into the air by a bulldozer and dumped in the back of a lorry, or the six-year-old boy wiping away tears as his animal is taken away. Not all the animals on view are the servants of human masters. In one of the most interesting sections, Anderson talks us through the social lives of a herd of wild horses in Montana. The usual practice is one stallion, lots of mares, and when roving stallions approach the herd, that stallion is usually on hand to see off the competition with several vicious but well-aimed kicks. More of this would have been better than the inevitable Black Beauty-style ending about a good-natured old horse called Carousel who has enjoyed a late second career as a medal-winning mount for disabled riders. Carousel retired last August and now lives out his final years cantering contentedly around a sun-filled paddock. These images inspired someone to get Anderson to end with a line even Anna Sewell, author of Black Beauty, would have been embarrassed to write: 'For all that they are, may they always have green pastures, each and everyone.'