Production values: Protect an endangered species

Last week saw a rare conjunction. Two landmark series running at the same time: The Life of Birds (BBC1, Wednesdays) and Earth Story (BBC2, Sundays). Landmarks are series that claim direct descent from Lord Clark's Civilisation and Jacob Bronowski's The Ascent of Man, the twins who founded factual television. Their common format involves a single eminent presenter developing an argument over a number of weeks. The aim is identifiably lofty: to familiarise the viewer with one or other of the structural elements of the edifice of human knowledge.

It is not so obvious nowadays that knowledge is an edifice and, for this reason, the genre makes some people feel uncomfortable. All theoretical doubts disappear, however, in the face of the affable self-assurance of a presenter such as David Attenborough. The Life of Birds takes his pieces to camera and puts them with wildlife footage with the kind of confidence (and money) that takes a crane to a remote Scottish location for a single establisher. The commentary never jars or irritates. Special effects, when they are used, enter as unobtrusively as Jeeves the butler.

Fledgling landmark presenter, Aubrey Manning, also made a creditable start with Earth Story. As a biologist who is interested in geology, he manages to be expert and amateur at one and the same time. Geology does pose a problem, though: rocks peck not, neither do they flap, so what do you put on the screen while you are talking about them?

Although series producer David Sington was sometimes thrown back on staples like time-lapses of clouds, waves breaking on the shore, and a rather half-hearted reconstruction, only very occasionally did they bear the tell-tale marks of desperation. The programme's main assets were human. We met a succession of enthusiasts: a fossil collector with an encyclopaedic knowledge of ammonites, the keeper of the world's oldest pebble, and a geologist in South Africa who read the land like an ancient seer. Manning combined all this into a coherent account of the discovery of geological time, and I for one ended up more interested in rocks than I was before.

The landmark series is, so far as I am aware, uniquely British, yet it has always relied on foreign money. The Life of Birds was co-produced with theold, established Public Broadcasting Service, known to disgruntled Americans as the particularly British system. Earth Story has got into bed with the new source of mega-bucks, the Discovery Channel, via its subsidiary, the Learning Channel.

The ways of Discovery are not our ways and I confess that I have been disquieted ever since an executive of the channel told me that a script I had written had too many black people in it. What worried me most about this remark was that the film in question was about Martin Luther King. Discovery relies on a narrowly defined advertising audience and it will never risk anything that they might get puzzled or upset by (a cynic might say that it didn't want them to learn or discover anything).

Apart from the music, which made a misguided attempt to generate spurious tension, Earth Story showed few signs of its co-producer's influence. A series about rocks is the least likely to provoke ideological conflict, and, as a landmark, it had the whole force of the corporation behind it.

Others are not so able to protect their virtue. There is now a genre of factual programme that substitutes any attempt at large-scale understanding with an escalation of ever-more fiery volcanoes, more terrible weapons, or more devastating storms. The danger is that eventually these disasters may completely erode the landmarks of informed and intelligent wonder at the natural world which are shown to us by the likes of Attenborough and Manning.