Category Archives: nature

The redder the male, the more successful it is.


According to Joseph Corbo, an associate professor of pathology and immunology at Washington University, the genes affecting red coloration belong to a wider family of genes involved in detoxification. Redness may be a sign of a robust, quality mate who can easily cleanse harmful substances from his body.

“In many bird species, the redder the male, the more successful it is at finding mates,” – Joseph Corbo.

For more see

green light may cure your headache

I get migraines. Not often. Just a few times each year. But when I get one I have been known to turn off the lights and go to sleep in my office. I have found that taking a pain killer and then going to sleep is the only way to relieve my symptoms. But a study in the journal Brain suggests that exposure to green light actually has a beneficial effect.


In the study 80 percent of subjects reported intensification of headache with exposure to high intensity of light, except green. Surprisingly, the researchers found that exposure to green light reduced pain 20 percent. They also found that the signals generated in the retina for green light are smaller than those signals generated for red and blue light. Researchers are now trying to develop a more affordable light bulb that emits pure narrow-band wavelength of green light and sunglasses that can block out all colours of light except narrow-band green light.

non-visual effects of light

Most people know that the ear system has two functions: hearing and balance. It is less well known that the visual system also has two functions. The first is seeing. The second is a set of non-visual functions including circadian rhythm. Mechanisms are being discovered that are particularly sensitive to blue light. So short-wavelength, or blue, light inhibits melatonin which is a chemical that makes you drowsy. So looking at bright lights late at night, especially blue ones, can contribute to a poor night’s sleep. So put your smart tablet away now and go to sleep!

In all seriousness though, I knew there was a reason why I do not like watching Chelsea on Match of the Day.


Studying these functional effects of colour and how they can be used in design is a major theme of the research I lead at the University of Leeds in the School of Design. If you have interest in these areas please contact me.

colour helps you sleep


Light in our natural environment tends to be bluer first thing in the morning and redder at dusk.

Researchers from the University of Manchester looked at the change in light around dawn and dusk to analyse whether colour could be used to determine time of day. They constructed an artificial sky beneath which they placed mice and they then measured the body temperature of the mice for several days and their body temperature was recorded. The highest body temperatures occurred just after night fell when the sky turned a darker blue – indicating that their body clock was working optimally. When just the brightness of the sky was changed, with no change in the colour, the mice became more active before dusk, demonstrating that their body clock wasn’t properly aligned to the day night cycle.

According to Dr Timothy Brown: “This is the first time that we’ve been able to test the theory that colour affects the body clock in mammals. It has always been very hard to separate the change in colour to the change in brightness but using new experimental tools and a psychophysics approach we were successful. What’s exciting about our research is that the same findings can be applied to humans. So in theory colour could be used to manipulate our clock, which could be useful for shift workers or travellers wanting to minimise jet lag.”

What colour is the sky on mars?


The cameras never lies. Or does it? Recently I had to take a photo for a medical case and before submitting it I had to sign to say that the photo had not been modified. I did this – but it was ridiculous of course. Many people have this idea that the cameras faithfully captures what the scene looks like and that, unless we intentionally manipulate the images (in photoshop, for example), then we have captured the truth. Nothing could be further from the truth – as the recent image of #TheDress showed.

The top photo above was taken and released by NASA in 1976 and shows a Martian landscape. The sky is blue. However, at the time, Carl Sagan said “Despite the impression on these images, the sky is not blue…The sky is in fact pink.”

You see the original image had not been colour corrected. Colour correction is a process that takes place on most cameras these days without the user being aware of it but in 1976 was not automatic. The process can compensate for the spectral sensitivities of the camera sensors (which may differ from one camera to another) or for the colour of the light source. The second picture (above) shows the colour-corrected image. Some people are now arguing, however, that the amount of colour correction applied by NASA is wrong and that the sky should not be as red as it appears on the second photograph. For the full story including some other nice images of Mars see here.

black plants can save the world

About three years ago I posted about the question of why leaves are green. In this I postulated as to why chlorophyll (the green stuff in leaves) should be green; after all, this means that it only absorbing some of the wavelengths in the visible spectrum. In fact, I argued that it would be better if plants were black, absorbing all of the wavelengths in the visible spectrum. Now, someone on is suggesting just that – that green plants absorb only about 2% of the possible energy and that scientists are thinking of turning them black. Presumably this would save the world because plants would be more efficient at converting harmful greenhouse gasses into oxygen. There’s catch though, apparently. If you make the plants black they get too hot and overheat resulting in cell damage. Actually, I also suggested this might be the case in my original article in 2011. Looks like black plants won’t save the world. They won’t even save themselves.

There’s nothing wrong with black carrots though – see here.

Structural colours


Most colours around result from light being absorbed (electronic transitions) and scattered by dyes and/or pigments. However, there was an interesting article in The Guardian today about structural colour. Structural colour is quite common in nature; it occurs when light is scattered because of a regularity in packing or structure; the wavelength of the light that is most strongly scattered is determined by the repeat distance of this packing, which has to be comparable to the wavelength of the light.