Max MunroDr Mal, I was wondering how come Mandy got kicked by a horse that knew her. He wasn't sick or frightened or anything. I was thinking what you said at the funeral and wondered if you could explain it a bit more--about how horses see, I mean. It would be useful for my project at school on horses.
Dr Malcolm Malverson
Have a look at horses' eyes--where they're placed on their head.
Max
Can we? I mean, go to the stable and have a look at Dreamy, for instance? After you've finished your drink?
Dr Mal
I can take this with me. Just one last asparagus roll. Do you want to bring something?
[walking sounds, conversation, creak of stable door, etc...]
Dr Mal
Here she is.
Max
Too old for riding school, anymore.
Dr Mal
Horses have excellent peripheral vision. With their eyes placed on the side of their head like that they can see in front and behind without having to turn their head. Of course they can't see directly behind them.
...
I bet you've seen Dreamy standing in the paddock with her head up, looking into the distance at nothing at all.
Max
Uh-huh.
Dr Mal
Well, her vision is so accurate she was probably looking at something you could only see with binoculars.
Max
Dr Mal, while Dreamy's looking at me now... She can only see me with one eye. Does that mean she can see two different things at once?
Dr Mal
Lots of animals are like that. Probably they see mainly what they're concentrating on and are vaguely aware of what they're picking up through the other eye.
Max
Can she see in colour? Or does she see like a dog, in black and white?
Dr Mal
She sees much better than a dog, which specialises in scent and sound. But a horse's retina has mostly rods and hardly any cones. Rods are little cells (shaped like rods, of course) that are sensitive to different intensities of light. Horses' eyes have lots of rods that are sensitive to very weak light--so they can see well at dusk or in twilight. But, like most mammals, they probably see very little colour. The cone-shaped cells pick up colour. And there are hardly any cones.
Max
So she just sees in black and white?
Dr Mal
No, more like greyscale on your computer screen, only a thousand times clearer.
Max
Uh-huh. Why don't animals see in colour then?
Dr Mal
I suppose it's not that useful to them. I haven't really thought about it. I mean, when horses evolved, in the wild, what sort of situation were they in?
Max
I saw on a CD-ROM that the first horses were small and lived in herds.
Dr Mal
Well, what sort of information does a herd animal like that need?
Max
To know where the other horses are.
...
To know if there's danger...
Dr Mal
Exactly. While they're browsing on the grassland...if they can see a long way and pick up any little movement in the distance then they can get good warning of danger.
Max
Especially as the first horses were small, so lots of animals could attack them.
Dr Mal
Yes, indeed. And if they were running away on in a herd they would need to have a good idea where they were in relation to the other horses. Again, good peripheral vision is a must.
Max
But what about colour?
Dr Mal
You're a good interviewer, Max&Let me think for a moment. What are the mammals that can see in colour?
Max
Humans&monkeys I suppose, apes?
Dr Mal
Yes. We're called primates. Now what sort of things do we eat that horses--grazing animals, don't.
Max
Fruit and vegies? Meat?
Dr Mal
What sort of things do we eat that carnivores (cats and dogs, whatever) don't eat?
Max
Fruit and vegies. Grains?
Dr Mal
And when you eat fruit, do you like it ripe or unripe?
Max
Ripe, of course.
Dr Mal
And how can you tell that fruit is ripe when it's hanging in a tree, whatever?
Max
Oh, I get it. By it's colour! So fruit-eating animals need to be able to see colour. Why fruit is so important, of course, is another story.
Dr Mal
Like birds, for instance. But for most mammals, they get close enough to their food (if it's vegetable matter) to be able to smell, taste, feel if it's right for them. And if they're hunters they can see their target&their prey&move. So being able to see movement and being able to see at a distance are important.