All chickens are not born equal. If a few more philosophers had had a little more empirical interaction with chickens, John Locke may have reconsidered his notion of tabula rasa, the idea of the incipient individual as a blank slate embarking on a course of self-authorship. Chickens are born with certain personality traits, and these endure in a remarkably stable fashion throughout their lifespans (which can be as long as 15 years).

Of course, chickens are not born fully mentally formed - you can watch them learn by discovery, doing, copying and sometimes even adapting and improving. Eventually, older ones end up teaching younger ones. You don't see that in the battery farm, but put some in the garden and you soon do.

Watching chickens is a very old human pastime, and the forerunner of psychology, sociology and management theory. Sometimes understanding yourself can be made easier by projection on to others. Watching chickens helps us understand human motivations and interactions, which is doubtless why so many words and phrases in common parlance are redolent of the hen yard: "pecking order", "cockiness", "ruffling somebody's feathers", "taking somebody under your wing", "fussing like a mother hen", "strutting", a "bantamweight fighter", "clipping someone's wings", "beady eyes", "chicks", "to crow", "to flock", "get in a flap", "coming home to roost", "don't count your chickens before they're hatched", "nest eggs" and "preening".

You'll even see that the boss cockerel tends to take possession of the highest point - the top of the heap. And the longer you watch chickens, the more you think of them as people rather than some strange alien species with feathers, beady eyes and a strange language. Squint a little as you watch them enact their various roles and you can see a brood of Sainsbury's retail managers jockeying to maintain position.

Keeping chickens may not be the most efficient way to source eggs, of course, but then it depends on what is being measured. I benefit from eggs, mobile garden ornaments, endless amusement and companionship; I even learn from them. My nine-year-old budding evil-scientist son has learnt that evolution can go down as well as up, and that ground-feeding birds can, over generations, get larger and lose the ability to fly. He also discovered that rigging up a chicken catapult baited with corn can improve individuals' flying skills, but is not likely to reverse the evolutionary trend and is very likely to get you into trouble. Fair enough: he also learnt to take care of them and understand their preferences and behaviour; he teaches them things, and they patiently go along with it as long as some tasty titbit is part of the deal.

Put that way, keeping chickens is a lot more efficient than driving to the supermarket for eggs of unknown heritage. Ours are great eggs with big golden-orange yolks that sit like perfect hemispheres in the pan. Hardly surprising, as these are gourmand chickens: they eat what we eat (chicken excepted, of course). They like sweetcorn, peas, pasta and rice. They love steak and cooked bacon rind. In the course of evolution, I don't know where chickens developed a taste for cooked pig. Maybe a freak accident: a bolt of lightning; a forest fire; an unfortunate pig ... They also like prawns, salmon, cake and bread, and ironically are rather partial to sage and onion stuffing. They are also fans of strawberries, raspberries, blackberries, gooseberries, carrot tops, cabbage leaves, grass, shoots - especially the ones you've just planted. And they turn all this rather efficiently into eggs and excrement.

Chickens don't spend a lot of time theorising about efficiency, or devising best-practice feeding strategies to maximise resource utilisation, nutrition uptake and product throughput. But if you think humans invented fast food, you should watch chickens demolish a plate of cooked vegetable peelings. Are they silly, fussy, defenceless creatures? For a worm, woodlouse or a small frog, they are huge, fast and efficient predators. It all depends on your point of view.

What's life like to a chicken? Does their world look similar to mine? Is their green, with apologies to Richard Gregory, the same as mine? Is a chicken's life simpler than mine? More fun? More or less fulfilling?

It depends which chicken. For a chicken "in the wild" (are there any now?), life may be interesting, exciting and quite short. For a battery hen, it's stressful yet boring, and definitely short: a year of gainful employment as an egg factory, then redundancy (death). A chicken bred for eating would have an uninteresting life of 12 to 20 weeks.

For a free-range hen, it's probably quite nice, peaceful, interesting even. For a pet hen, complete with a name, it's a cosseted life: guaranteed food and water, protection from predators, plenty of space, time to relax, the opportunity to spread your wings, take a dust bath, sunbathe a little, explore a bit, look for a hole in the fence, raid the vegetable garden, go and watch the funny humans with their endless activity for activity's sake.

But it's really out of your hands (claws) which kind of chicken you are - miserable and short-lived or lucky and long-lived. In the lottery of evolutionary niches, some species got to be fast, powerful and sharp. Humans got the mental wherewithal to try to control everything; the chicken's future rested on being tasty. Chickens are thus relieved of an enormous responsibility, making their lives simpler. They don't have to organise the whole world, or attend meetings to discuss policies "going forward"; they don't have to invent the future continually - it just comes when it comes.

Chickens have hierarchies, of course, but not as high as Mount Everest, with the top cockerel sitting up in the stratosphere. They form small, manageable hierarchies and politics is a simple matter: "When I come into contact with another chicken, what is our relative status?" The lower-status chicken moves away, ceding the morsel of food or best perching place. If they are of a similar status, they have to fight it out. The chicken at the bottom of the pecking order always has to let everyone else eat first, or must run in to steal and risk being viciously pecked. (Even the nice, docile, mild-mannered, fat old brown hen will throw a jab at the poor bottom-of-the-ladder chicken; bullying isn't just the property of a single bully.)

As a chicken, you don't have to better yourself; you just need to find your place. A chicken doesn't have to be ambitious or worry about realising its potential and getting on in life.

Is a chicken's life somehow less fulfilling, then? Is it anthropomorphic to say that hens find life more or less interesting? I'm told that battery farming isn't too bad because the chickens don't know any better (and it's not for long, anyhow); you can't miss what you never knew existed - the convenient concept of tabula rasa again. I'm sorry, but I can spot a happy chicken a mile off. Anyone who ever lived with chickens about the place wouldn't spout such rubbish.

From close, if hardly scientific, observation, I can report:

Chickens' environmental preferences and territoriality

They complain if I don't get up and let them out of the hen-house soon after dawn. They come and nag vociferously, even tapping on the back door, if they don't have enough water. Chickens are quite good at manipulating humans.

They spend a lot of time wandering around in the undergrowth, good for scratching up moss. They like a little sunbathing in the afternoon, weather permitting. They shelter from the rain and really, really don't like snow on the ground, standing on one leg by the back door and plaintively calling to be let into the house.

They like a handful of corn in the food hopper, but prefer to wander around pecking it. If I throw bread out, they spend a lot of time chasing each other, stealing bits from each other's beaks. Then they run off to try to consume it in peace. If they see another hen pick up a nice piece, they'll drop their own and chase after that one.

Sometimes a truce emerges; they compete vigorously until they've each got a decent piece, whereupon they scatter, going off a little way to consume it without having to defend it at every instant. But the truce can be upset by the arrival of a very competitive bird. Like uncooperative drivers in a traffic jam, they all dash for the advantage and end up worse off; the whole activity takes more effort and time.

Economic and management theorists subscribing to the view that unbridled competition offers the greatest efficiency should be made to watch chickens.

They have clear attitudes to territory (that's what a pecking order is all about, after all). They chase away pigeons; they also sometimes gang up on our collie dog. If a cat comes into the garden, they complain vehemently until I arrive to shoo it away; it's the same if a fox calls by at night to test my security arrangements.

Sometimes, if there's no cockerel, a bossier hen will assume the role, even being the first to leap to the defence of the brood at great personal risk. If a cockerel is subsequently introduced, a period of adjustment to the pecking order follows. A good cockerel enjoys droit de seigneur (frequently) but is a fierce and brave protector of the flock, putting himself between the threat and the hens, defending to the death if necessary. When tasty food is served he waits courteously for the hens to have their fill. A diffident cockerel is cold-shouldered by the hens.

Personality traits and behaviour

Some little groups stick together quite closely, while other individuals are more independent and go off by themselves.

Some breeds are flighty and nervous while others are calm, placid even. Some are aggressive and stroppy, yet occasionally the placid ones gang up on them and see them off. Smaller breeds like to roost and fly more often. Some breeds are more adventurous than others, some are less intelligent, some can be very tame, and others will never quite be. When we have several breeds, they tend to hang out with their own kind.

Inquisitiveness, teaching and learning

If I'm working in the garden, the chickens come, sit on the wall and watch. If I'm chopping logs, the tamer ones have a disconcerting tendency to hop on to the chopping block looking for tasty woodlice. They follow me into the shed and back out into the garage, through the side gate, tripping me up every time I turn, all the while murmuring and clucking softly. I think they may be reassuring me so I don't get spooked.

I've not heard of a functional magnetic resonance imaging study of mirror neurons in hens, but they do learn by copying each other. One hen makes a special, ungainly jump to get at the out-of-reach juicy berries - very comical. By the end of the week, they're all at it until the berries are gone. Next year, the technique is deployed straight away.

It's the same with finding out how to get over the fence in stages; a low wall, then on to the shed roof, along a bit then a short flight and a crash-landing in next door's garden. Once one does it, most of them can; the escape route will have to be sealed.

If you allow a mother hen to hatch some chicks (and not all hens are equally good at this - some just forget the eggs!), they suddenly develop a whole new vocabulary, teaching the chicks how to peck, scratch the ground and so on. Mother hens fuss endlessly; the chicks, initially clueless, learn rapidly. Chicks that have been reared in an incubator without a mother hen seem a lot more clueless, for a lot longer.

Hens that have lived the first year of their life in commercial intensive-farm environments are amazingly clueless when introduced to my garden. Sometimes they won't come out of the hen-house for the first day or two, even with the open door right in front of them. They don't know how to roost, and instead sit all night (and day) on the floor. Once they do get out, they don't know how to scratch and peck. However, once hens have become used to the outdoor life and the freedom of the garden, if they are left shut in the compartment (which is outdoors, with plenty of food and water), they insistently march up and down the fence or try repeatedly to fly over.

Now, I've hardly done much to refute charges of anthropomorphism - but am I bovvered? I'm not projecting human characteristics on to dumb animals - I'm saying I really don't see that much difference in their hopes and fears, behaviour and petty foibles. If one actually lives with chickens, it's a lot harder to treat them as mere objects.

Their preferences are astoundingly obvious, so what possible excuse could there be for giving them any less? If they like greens, why give them pellets? If they like sunbathing, why pack them into a tiny, noisy, smelly place with no natural light? If, as I suspect, the answer is something to do with the "efficiency" of food production, then the notion of efficiency is horrible, incompetent, brutalised and brutalising, and it's certainly not in the interests of chickens at all. And I'm not sure that our ethical notions are all that more advanced than chickens'.

All right, we could argue that they're only chickens, not people, and frankly, we're the top species so we call the shots - that's evolution, we're the winners and might makes right. So our notions of ethics extend only to "like me"? But how like is "like"? In the grand scheme of things, if we stand back and consider all the matter and energy we know of in the universe, we're a lot more similar to chickens than we are to almost everything else - all that rock and water, those suns, the endlessness of space and dark matter. Chickens are positively family.

In today's economic climate, efficiency and competitiveness are the guiding principles of business, of life; more product faster, while taking up less space. But are these concepts in our interests at all? Efficiency without ethics is psychopathic. And how much cleverer than chickens are we, ultimately?

So what do I get from chickens? Simple lessons like these: competition without co-operation is nonsense; you can't win by simply eradicating all the opposition - that's a pyrrhic victory. In life, winning really isn't everything - it isn't even anything. Taking part is all.

Reward and risk go hand in hand. The top cockerel has to take the biggest share of both. A flock can manage without a cockerel, but a cockerel without a flock is nothing.

A flock can keep you warm, inform you about dangers and advantages, and provide you with companionship; but you have to work at it.

Everyone should have a place in the pecking order. Strive for your place in life, not someone else's. Someone else's bread isn't necessarily tastier than your own. Envy will cost you dearly.

Don't let "flock-think" smother your own opinions; give yourself space to be an individual. Common sense is useful, but it's not always right. The society you're in may prompt you to behave badly, but only you can change that.

One could spend years on a moral philosophical quest, or keep chickens and treat them with courtesy and common sense. One doesn't just keep chickens, one lives with them. All chickens are not born equal, but they deserve equal respect.