Zebras are animals we are very familiar with, and the zebra crossing with white paint on a black background on the sidewalk is also named after it, so have you ever wondered whether the zebra is white or black on the ground, and is it a black or white stripe that grows out later?
Zebra with white stripes on a black background
First of all, to tell everyone the correct answer, the zebra, in fact, is white on a black background.
Studies have shown that zebras are pure black in the early stages of embryonic development, and in the late stages of embryonic development, the production of black pigment is inhibited, and white stripes appear.
Each zebra's black and white stripe is slightly different, as if they were their own natural barcodes.
From an evolutionary perspective, white animals are difficult to survive on the African savannah. The extinct spotted donkey may also represent an early image of the genus Zebra.
Spotted donkeys only have white stripes on their heads and necks, and most of their entire body is black. If you shave off all the hair on the zebra, you will see that their skin color is somewhat different, but the overall appearance is still black.
Why evolve black and white stripes?
According to Darwin's theory of evolution, zebras evolved from the original horses to the way they are today, and the reason for this was to adapt to the environment.
There are several mainstream theories about what kind of environment it is designed to adapt to.
The first is to confuse predators. Because the main color of some jungles in Africa is off-white, zebras can hide themselves well inside; And zebras are social animals, and a large group of black and white zebras can dazzle predators when they run.
In 2015, the Royal Society Open Science published a research paper in which researchers found that the higher the temperature, the more stripes there were on the zebras.
The study speculated that the black stripes absorb more sunlight, the white reflection is more, and the air flow above the skin of the two stripes is not the same. That said, black and white stripes can help zebras dissipate heat.
Some scientists believe that the black and white vertical stripes of zebras interfere with the sight of mosquitoes at a certain angle, making it difficult for them to accurately land on zebras, so the stripes can also prevent mosquito bites.
However, more evidence is needed to support these claims.
A pattern of streaks caused by genes
The study found that the coat color of animals is mainly determined by the type and distribution of melanin produced by melanocytes.
Mammalian melanocytes produce two different types of melanin, the most important being the yellow and reddish-brown melanin and the black and brown eumelanin.
The quality and ratio of brown melanin to eumelanin determines the quantitative proportion and distribution of the final color of the hair and skin.
There are more than 100 genes that affect the coat color of animals. Among them, the MC1R gene and the Agouti gene are the key genes that were studied earlier and have been shown to regulate the coat color variation of mammals.
There are differences in the MC1R gene sequence of different organisms, and these differences are mostly caused by mutations, which cause changes in the color of animal coat and can be passed on to offspring.
In order to uncover more mysteries of biological coat color, it is also necessary for biologists, mathematicians, physicists and chemists to work together to analyze and study from multiple angles.