Although they are incapable of discerning certain colours, colour-blind people can nevertheless distinguish a wide range of shades of khaki.
They would thus make excellent soldiers or hunters, since they are not fooled by camouflage or mimicry.
Biologists from the universities of Cambridge and Newcastle upon Tyne, in England, have hypothesized that colour-blindness may be a holdover from previous ages when humans had to identify predators or find food among the branches and leaves of trees.
Following on the heels of rollerskates and scooters, unicycles have now found their way onto the streets of Europe.
A fun, sporty and ecological means of transport, unicycles have also been the object of serious study in Asia, where researchers have found that they have significant benefits for physical and mental development.
In Japan, the National Ministry of Education has even included unicycling into physical education programs in schools.
Those little grooves at the end of your fingers are very useful.
If you didn't have fingerprints, your fingers couldn't grip objects and you would have trouble holding on to them!
Fingerprints are unique : even identical twins have different ones.
They are useful in identifying criminals.
And fingerprints can remain for a long time at a crime scene : up to 40 years on paper and wood, and several years on glass, metal or plastic.
Fingerprints can also be found on paintings, like those of Leonardo da Vinci: he used his fingers to mix colours with his saliva.
By seeking out fingerprints on his work, he can be shown to be the real artist.