Where did the different races come from?

Answer 1

Because there are different environments; humans have adapted to their environment as they spread across the world. For example, melanin in the skin acts as a shield against ultraviolet light, however if it completed blocked ultraviolet, vitamin D would not be generated in the body. In tropical areas, the sun is very strong and people have more melanin, in cooler areas the sun is less strong and people have less melanin so sufficient vitamin D is generated.

Answer 2

Scientists say that modern humans evolved in Africa, so that the very first people were African. They had very dark skin, suited to full-body exposure to the hot sun. Light coloured skin would burn too easily in this environment.

When humans migrated to Europe, with its weak sun, they also had to cover up most of their bodies in order to keep warm. Not only was it no longer necessary to have dark skin in order to prevent sunburn, people with such dark skin suffered from vitamin D deficiency, since this requires absorbsion of ultraviolet radiation. An evolutionary change was to develop lighter skins, to allow more ultraviolet radiation absorption. Ideally, very fair skin and blond or red hair predominated in the far north of Europe, with slightly darker skin and hair in the south. The cold air also caused them to develop longer noses, with narrower nostrils, in order to warm the air before it reached their lungs. These changes were really very minor and were not made consciously, but they did help offspring who inherited these traits to survive in the colder climate. Similar changes resulted in the lighter skinned Asian people.

Within continental groups, localised changes occurred among peoples who became relatively isolated from others, either because of physical barriers or religious and cultural constraints. However, over the last few thousand years, there have been several great migrations, both within continents and across continents, which have created a much more complex mixture of ethnic groups.