Michael McCarthy: Why are the stars of spring yellow?

What do colours mean? What's the significance of red or yellow, blue or green? Do they have inherent meanings? Why do we use red to symbolise anger and yellow for cowardice? Why do we feel blue with depression, and green with envy?

Once you start thinking about colours, and go more deeply into it, you realise that numberless people have been down this road before, including some great minds, and they have sometimes come up with very different answers. My own interest has been sparked by trying to understand what colours mean in the natural world, beginning with a simple question: why are early spring flowers yellow?

Leaving aside the snowdrop, which seems to be a special case of a winter plant, the first flowers of spring are out right now (a month late this year) and they are lesser celandines, eight-pointed yellow stars with heart-shaped leaves. They were covering all the country roadside verges of Hampshire and Dorset over the Easter weekend, while in the towns there were daffodils everywhere, municipally tamed versions of another wild yellow flower. Next there will be primroses, carrying on the yellow theme.

My own feeling is that that these flowers are probably yellow to be conspicuous to the few pollinators about at this chilly time, such as queen bumblebees, and I am encouraged in this belief by the knowledge that John D Herz founded the yellow cab company in Chicago in 1907 after reading a University of Chicago study suggesting that yellow is the colour most easily seen at a distance.

Well, that's what it may mean to pollinators. But what does it mean to us, a different question entirely? Why do we find these yellow flowers so attractive? Because they are the first? Or because of something to do with their yellowness? Does yellow carry a particular appeal? I tried to list yellow associations, other than with flowers, in order of when humans probably first encountered them, and I came up with the sun, egg yolks, jaundice, yellowhammers (birds), butter, mustard, lemons, bananas and the Liberal Democrats. I haven't worked it out yet. But I'm on the case.

Proved right by a raven

On Easter Sunday I was gobsmacked to see a raven flying around the town centre of Dorchester, Dorset. I heard it first, unmistakeable – Urg! Urg! Urg! – then saw the great black bird with its wedge-shaped tail. I'm still not sure what was the more astonishing – seeing it where I saw it (the only time I've ever seen a raven in a town before was in Jasper in the Canadian Rockies) – or, having just written about the spread of the raven out from Britain's Celtic fringe, finding out that something I had pontificated about was actually true.