Africans Are The Ancestors Of The Human Race; DNA Evidence Proves?This

Once upon a time, all humans of our species lived in Africa. Or to put it differently, we are all originally Africans by a long line of descent. Human life on earth started in Africa when the early humans were just content to be hunter-gatherers who roamed about collecting what food they could find abundant in nature, until some of them picked up their stuff and decided to find other lands.?

The first set left about 300,00 years ago with one group moving to the western part of Asia to become Neanderthals, and another group moved to the east and became Denisovans.?

The ones that remained in Africa evolved to become anatomically modern humans called homo sapiens we see today. Then a much larger migration happened 50,000 to 70,000 years ago when the climate changed threatening starvation and the extinction of the human race, and some of the Africans decided to up and move. This break-out fraction first moved towards what is now Asia and interbred with Neanderthals and Denisovans which contributed to a change in appearance, behaviour, and immune response. While there, they learned to make tools that could help them to farm, therefore leading to land acquisition and growing of food, before proceeding to Europe and the Americas.?

So how did we find out about all this if we were not there? Well, first because of fossil evidence, and second because of DNA evidence. According to fossil evidence, the oldest human remains ever found have only ever been found in Africa, those found elsewhere are never as old as the ones found in Africa so our ancestors must have been from Africa. But this was not convincing enough until we started analyzing irrefutable DNA evidence.

HOW DID DNA DISCOVER OUR ANCESTRAL BIRTHPLACE?

If anyone ever doubted the Out of Africa theory of human migration, DNA has now come to the rescue in 3 ways.?

1. To prove that Africa is the source of modern humankind, scientists took blood samples of thousands of men from Asian populations and looked for certain markers in their Y chromosome which are only carried by men, and they found that these men had inherited these markers that could be traced to people who live in Africa.

1. Mitochondrial DNA is only passed down from? Mother to her children. Blood samples were taken from women of different populations and their mitochondrial DNA was analysed. It showed that all humans originated from a single woman who lived in East Africa, and she has been named “Mitochondrial Eve”.

1. Another thing they did was to look at the genetic diversity. When people live in a place for very long, they acquire a lot of changes in their DNA, this is what is called genetic diversity. Because all humans initially lived in Africa for hundreds of years, there is a lot of genetic diversity there. As some groups started to migrate out, they lost some of that diversity. So in non-African populations, people are a lot more similar to each other even though they are not from the same family, than indigenous Africans who are unrelated. Think about it like this, let’s say you have a bag of M&Ms, that is Africa. If you dip your hand and take out a handful of the sweet multi-coloured chocolate tablets, that is any population of people outside of Africa who only carry a subset of the genetic variants present in the African continent.

THE GENETIC BOTTLENECK; THERE IS MORE DIVERSITY AT THE BOTTOM OF THE BOTTLE THAN AT THE NECK.

So far we have ascertained that Africa is the source of genetic diversity. As people moved out of Africa they moved away from this source and the differences between them reduced. This is a phenomenon in genetics known as the Genetic Bottleneck. This means that present-day Africans are the most genetically diverse people in the world. This is a good thing because genetic diversity means that the individuals in that population have some variants of genes that make them better able to adapt to different environmental pressures such as changes in diet, climate, and different diseases such as Malaria. Populations that live outside of Africa lack some genetic variants which can only be found in Africans. This is because those who left Africa (which for the purpose of illustration is the bottom of the bottle) went through a bottleneck and lost some genetic variants that were not necessary for survival in their new environment. The result of this bottleneck effect is that outside of Africa, 2 unrelated individuals are so genetically similar because there is less genetic diversity, whereas in Africa 2 unrelated people are more genetically different because there is more genetic diversity.

IF WE WERE ALL ONCE AFRICAN, WHY ARE OUR SKIN TONES AND OTHER PHYSICAL FEATURES VERY DIFFERENT?

When migration happens and a subset of a group breaks off to form a new colony elsewhere, the founder populations as they are called must now survive in the new environment otherwise nature will select them out in what is known as survival of the fittest, and they will die. So their body starts to undergo changes that allow them to adapt to their new environment and this involves change in complexion, growing more or less hair, change in taste to fit the available diet, etc. The changes that happen are not just physical, their genes eventually undergo changes which affect some of their outward appearance, and their immune system also changes over time to help them survive diseases that are prevalent in their new community. Think of when you go on vacation to a sunny country and get a tan, if you stay there long enough your tan might be permanent, the same as moving from areas of heavy sunlight to cold areas can cause your skin colour to become lighter.

Black skin came first. Until only 10,000 - 40,000 years ago, white skin colour did not exist. The initial Africans who came out to settle in Europe had dark skin. The dark skin contains cells that produce a pigment called Melanin which helps to protect them from UV radiation in the sun and from making too much Vitamin D. Our skin makes vitamin D from sunlight so if you live in an area of less sunlight your skin gets lighter to be able to produce more vitamin D.?

Because the settlers were now in that colder region with less sunlight, there was little need for melanin, and nature always discards what we do not need or what we do not use, therefore these settlers in Europe developed genetic variants that produced different versions of light skin depending on different factors.?

CONCLUSION

If at this point you are thinking about how fascinating this is, well join me and several other people who have been amazed at how genetics supports evolution and how one race can morph into several other races over several thousands of years. This article acknowledges that there are other social and political factors at play which define our current definition of race and ethnicity, but the narrative focused on in this piece of writing is purely from a biological and genetic point of view and does not encapsulate other nuances which are deeply studied in other fields and well written about in several articles and books.