The leopard and the jaguar are renowned for their lovely spotted
coats, and tigers for their stripes. Math and genetics show us
how we can get the same things for our own offspring — along
with why no striped animals have spotted tails. As weird as it
may seem, one model describes almost all mammal coloration
patterns. All it takes to make an animal a certain color is the
interaction of a couple of chemicals with the skin. One chemical
stimulates melanin, causing darker coloration in the skin and
fur of mammals, while another keeps melanin from being produced.
These spread outwards through the body of the animal in the same
way in every mammal. Clearly, though, every mammal doesn't end
up having the same coloration. The key to the differences in
coloration is the fact that the chemicals spread outward in
waves at different phases during the gestation period. Some
start their move when the embryo is still tiny. Some start when
it's nearly fully grown. If the animal is tiny, no pattern will
form, which is why t