My approach to  this examination of our relations with the sentient animals seeks to be loving without being sentimental, scientific without being arcane. It is based on two central pillars of good sense. The moral case lies with Albert Schweitzer: ‘the great fault of all ethics hitherto has been that they believed themselves to have to deal only with the relations of man to man. In reality, the question is’ what is his attitude to the world and all that comes within his reach?’ The scientific case rests on the irrefutable Darwinian principle that'it is not the most intellectual of species that survives; it is not the strongest that survives;   it is the one that is able best to adapt to the changing environment'. Successful adaptation  of any species to the environment is achieved by maintaining its genetic inheritance as a stable contributor to a sustainable ecosystem. According to this strict Darwinian classification, the human species has, until recently, managed reasonably well but over the last 100 years, thanks, to a large extent, to our exploitation of fossil fuels, we have broken free from the rules and constraints of ecology.  Now we are all experiencing the consequences of our failure to be a stable contributor to a sustainable ecosystem, in the form of climate change, deterioration  of soils and extinction of animal species through loss of habitat.  Our insatiable appetite for food of animal origin and its consequences for livestock farming must carry much of the blame. This is too big a subject to present in detail here: I deal with it elsewhere in ‘Animal Husbandry Regained: the place of farm animals in sustainable agriculture’ (Webster 2013). A core message from this complex story is that farmed animals were stable contributors to a sustainable system when their needs for food and sustenance were largely complementary to, rather than in competition with ours.  Ruminants grazed food we could not digest, mostly on land we did not own; pigs lived on food we discarded, poultry contributed to our nutrition, health and hygiene by scavenging for scraps and insects.  I am not simply making an emotional appeal to go back to ‘the good old days’. I have shown, for example, that the modern dairy cow (by virtue of much hard work) can produce more food energy and protein for human consumption than she eats in the form of food suitable for human diets (Feed conversions). We could support a substantial pig industry on the discard of food from our supermarkets.

 We cannot go on as we are. If we do, the most disastrous consequences in the short term will be to other life forms, as we progressively destroy them to promote our own interests. However, in the longer term, it is we who will be destroyed by the inescapable rules of Darwinian logic. This states that while it is in the primitive interests of all species to convert all matter into themselves, those that survive, consciously or otherwise, are those that achieve a stable position within the ecosystem.  If we humans can achieve this, we too shall survive. If we fail, the planet will manage without us.

The principle of Reverence for Life commands us to avoid destruction of habitat and extinction of species and, at the same time, offer 'a life worth living' to the animals (the moral patients) with whom we share the planet. This assumes greatest importance in the case of the food animals. To satisfy  our own tastes we rear approximately 500 million broiler chickens per year, fed almost entirely on food that could support ourselves. Today supermarket frozen chicken can be cheaper than dog food.  In the interests of our health, their welfare and that of the planet we need to add value to the food from farmed animals. The adage ‘Eat food, not too much, mostly plants’ is incontestable. However, ‘only plants’ is an ecological no-no.   We need to acknowledge that, in a sustainable system, plants (and the soil) need animals just as much as animals need plants. The destruction of arable land 'supported' by constant application of inorganic fertilisers is becoming critical. Extensive systems based on grass-fed  ruminants  cannot compete with factory farming when measured by short term indices of productivity and they certainly cannot meat our present demands for meat and dairy products but they can be sustainable (emergy analysis) Moreover, to my eyes, they are usually associated with good  welfare. When I travel through classic beef cow country in the west of England and observe  Ruby Red cows relaxing with their calves in 12-month green pastures, this seems to me to about as idyllic a life as any domesticated animal could ever wish for.