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Have you ever wondered why we humans don't have spots or stripes?
你是否曾經好奇過為什么我們人類身上沒有斑點或條紋？
Let me think,Humans and animals get their skin color from melanin pigments, which can be either black or yellow.
讓我想想，人類和動物的皮膚顏色來自黑色素，它不是黑色就是黃色。
Together, these two pigments account for just about every color you might see on the skin of mammals: white, red, yellow, brown, and black and every shade in between.
二者混合可呈現你能見到的各種哺乳動物的皮膚顏色：白色、黃色、棕色、黑色和他們之間的過渡色。產生黑色素的皮
The skin cells that produce melanin are known as melanocytes.
膚細胞是黑素細胞，
In the embryos of mammals, the melanocytes originate from the same group of cells that produces the spinal cord and the brain.
哺乳動物的胚胎中，黑素細胞源自制造出脊髓和大腦的同組細胞。
From there, these cells migrate through the developing skin towards the belly of the animal.
這些細胞從那里出來通過皮膚的生長遷往動物的肚子。
If the melanocytes that produce dark pigments and light pigments migrate in streaks, you end up with stripes.
如果產生深淺色素的黑素細胞以條紋狀遷移，那么你身上就有條紋。
The same goes for spots, but in this case, only random patches of certain pigments survive.
斑點也是這么來的。但在這種情況下，只有隨機的某些色素斑點能夠存活。
In either case, the migration pattern is genetically determined.
不論哪種情況，其遷移方式由基因決定。
For certain species, like zebras, stripes provided an evolutionary advantage because they worked as camouflage.
對于特定物種 ，比如斑馬， 條紋因可作為偽裝對進化有利。
Those animals with stripes were more likely to survive, and to pass along the genes that produce stripes to their offspring.
身上有條紋的動物更有可能生存下來，并把能產生條紋的基因傳給后代。
For humans, this apparently wasn't the case.
對于人類來說，情況顯然不同。
However, it's likely that our overall skin color probably is a result of adaptation as well.
但是我們全身皮膚的顏色也可能是適應環境的結果。
