The answer is the smoking of crack cocaine. This drug is more simply known as<span> '</span>crack'<span>, and is widely considered the most addictive form of cocaine. Crack is widely used as a recreational drug, and was first widely used in US cities during the mid 1980s. The term 'crack epidemic' describes the rapid increase in its use and the resulting socio-economic problems that resulted.</span>
When pigments are mixed together, more colors are being absorbed which results to few colors that will be reflected. Each pigment absorbs and reflects light which results to the "color" or hue that we see. When these pigments are to be mixed, then more wavelengths would be absorbed which results to lesser reflection.
This is because if we strictly only allow people or things of our type to mingle, there are not enough of us to keep the population going, because then reproducing would be slower and we'd die out, and it would happen that some people who insist on finding "soulmates" that are perfect for them wouldn't find it in their group and refuse to reproduce, therefore making the population even lower.