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Last weekend we had an expedition out to rural Waikato somewhere beyond Morrinsville (in torrential rain of course) to a chicken farm and bought a couple of young chickens. The idea is that they’ll give us an egg supply, and, if properly controlled (ha ha!) dig up the weeds, fertilize the garden etc. (Or, more likely, get into the vege patch and destroy it.)

Having watched their behaviour, it’s clear there isn’t much to a chicken. They basically do three things:: 1. Peck at the ground. 2. Walk 3. Make a ‘puk puk puk’ sound.  Less frequently they also wake up and sleep, drink, poo, and, just occasionally, acknowledge the existence of the cat.

And that’s the lot. The first three things seem to be automatically programmed into the chicken – they are natural cycles the chicken does. Go ‘puk’, go ‘puk’, go ‘puk’ etc, until some major input disrupts this cycle.

They are rather like the neurons I model on the computer. Neurons have a few, fairly simple modes of behaviour, depending on their situation. A common mode is simply to fire electrical pulses regularly, unless something disrupts it. How quickly they fire depends on the extent and type of the electrical signals they receive – the more of them there are, the faster the neurons fire (if the signals are of an excitatory type).

The chickens tend to keep themselves close together, and it’s interesting to note that the frequency of the ‘puk puk puk’ increases the closer they get.  (By this I mean the number of ‘puks’ per minute increases, not the pitch of the ‘puks’.) One’s noise is clearly encouraging the other to make more noise, and vice-versa. So, in physics terms, we have two coupled oscillators with a variable connection strength.  The overall puk-rate depends on the connection strength between them – the closer they are – the faster they oscillate. Just like neurons, really.

Furthermore, if there is an external event that preferentially takes their attention away from their friend (e.g. I try to grab one of them as she heads for the bok choy) their ‘pukking’ cycle is momentarily disrupted, other, less harmonic sounds appear, until the disrupting stimulus leaves and, after a time lag, the normal cycle of behaviour resumes. A set of coupled neurons can do just the same when you give it a sharp, disruptive stimulus.

Incidentally, it’s also been interesting to watch the behaviour of Mizuna the cat towards the chickens. He started, predictably for a feline, with intense curiosity coupled with a bit of sheer terror (that’s terror on the part of both the chickens and the cat), but the relationship has progressed through mutual ambivalence to what might be described as friendship. He now seems to spend time following the chickens about. Just so long as he doesn’t start thinking he is a chicken.