Up here in the northern hemisphere spring has just started, bringing with it daffodils, sunlight and singing birds. But why do birds sing? They don’t have calendars like we humans do, so how do they know it’s time to start breeding? After all, it can’t be the weather, because where I live it’s been snowing today, but that hasn’t stopped the birds singing.
Scientists from Britain and Japan teamed up to solve this age-old problem. The result – birds sing not because of temperature changes or weather, but because of the lengthening days. As the days get longer, hormones are released which trigger the activation of a specific gene.
This gene gives the birds the urge to attract a mate and produce offspring – and just as humans gel their hair or wear make-up to attract a companion, birds are attracted to each other by singing. I suppose humans could sing to attract a mate, but somehow I don’t think it would be too likely to work. Just as giving a blackbird makeup probably wouldn’t inspire another blackbird to want to mate with it. But you never know…
Anyway, as always the big question is how on Earth did the scientists work out which gene was responsible? How did they know it was because of day lengths? Basically, they put a ‘genome chip’ in a sample of birds (Japanese Quails) to work out if any genes were activated or deactivated as the birds received varying amounts of sunlight each day.
They found that certain genes on the surface of the birds’ brains were switched on when the days were longer, and the cells with these genes then produced hormones that had already been known to give the birds the urge to mate. The result: birdsong, followed not too long afterward by baby birds.
It’s amazing to think how simple yet complicated nature can be sometimes. Interestingly, it is thought that humans may have genes affected by day lengths similar to those in the birds – these could be what causes some people to feel depressed in the winter.