If all ofhumanity began from the land of Africa, why are there so many varieties of human forms.?

Question

Please only informed answers.Thank you.

Answer 1

There is hard evidence from variations in mitochondrial and Y-chromosome DNA sequence data that humans have changed genetically as they have migrated out of Africa over the last 50,000 years or so.
There is much more variation within african people in these sequences because that is where the original pool of humans is. As you branch out along the migratory routes out of Africa - round the Indian Ocean rim to Australia for instance, or through Asia and across the Bering Strait into the Americas, people have less and less variation in these sequences and there are fewer and fewer "types" within these populations. The same holds true for Europeans, etc... The most genetically diverse people are the bushmen, who have been in the same place since the human species evolved.
Those who say there is no hard evidence for human evolution simply haven't got an idea what they are talking about. Biology has come a long way since Darwin's time!
One more point - the idea that humans can be split into more than one species is also rubbish. We can all interbreed and produce viable offspring and therefore we are one single species. End of argument.
I would suggest people do some reading before they spout off about something they haven't studied in detail.

Answer 2

Mutation. Our genetic material doesn't copy exactly when humans mate. Little changes come about. Thus, people change over time. Which leads to...

Evolution. Genetic mutations that are favourable in a new environment mean that those new people are more likely to be successful. For example, people in northern climates who produced less melanin and had lighter skin were more successful, because there's much less sun than in Africa and they could absorb more of the sunlight they needed.

Breeding. Once people separate and move away they only interbreed with the people that are in their area. Thus, you tend to get little clusters where mutations become common.

Answer 3

Who says that there are that many different forms? Genetic variation in the human species is quite narrow. The amount of difference between a black person and a white (or any other human) is so small as to be insignificant. Especially when you compare it to the differences found amongst other species of animal.

Answer 4

Every species adapts to its environment. Africans have dark skin because it protects them from the sun etc. Also if groups of people are separated from each other for thousands of years their genes won't mix with other races, and any changes that happen genetically aren't passed between cultures. It takes ages.

Answer 5

That, for me, is were the theory falls down. There is no evidence to support an evolutionary process that resulted in us all looking so different. There can be no really informed answers as there is only theory and conjecture.

Answer 6

Evolution.

Species adapt relatively rapidly to new environments, and the various races on Earth are all evolutionary repsonses to what would otherwise be threateningly different environmental conditions.

Answer 7

Evolution is only a "THEORY". It's a good theory, but it is still only a theory.

Darwin said he actually thought that humans should be categorised into more than one species. But he did not say this in "origin of species" because of the furore it would cause.

Answer 8

Evolution, due to physical and environmental conditions in various parts of the world.

Answer 9

Because of evolution. Humans have adapted to their habitats and surroundings.

This website may help you: http://en.wikipedia.org/wiki/Human_evolution

Answer 10

In a nut shell, it's not about where it started, but how long since.