Human Origins: Not That Simple
Recent discoveries have radically changed our view of human evolution. In 2014, genome sequences harvested from Neanderthal bones confirmed that around 40.000 years ago Homo Neanderthalis not only came in contact with Homo Sapiens (modern humans), but also mated with them to produce fertile offspring.
Fossil and genetic evidence indicate that Neanderthals and modern humans evolved from a common ancestor between 350.000 and 400.000 years ago. As a result of a period of crossbreeding that may have taken some 10.000 years, nowadays Neanderthal-derived DNA accounts for an estimated 1–4% of the Eurasian genome, but it is significantly absent or uncommon in the genome of most Sub-Saharan African people. In Oceanian and Southeast Asian populations, there is a relative increase of Denisovan-derived DNA. An estimated 4–6% of the Melanesian genome is derived from Denisovans.
The Neanderthal contributions are peppered across the genome, and different people have different Neanderthal genes. Some of these genes are involved in functions such as battling infections and coping with a lack of sunlight. No evidence of Neanderthal mitochondrial DNA has been found. This form of DNA is located outside the cell nucleus and is therefore transmitted by the mother only.
The question is how the interactions took place: Were they hostile in nature? Did they steal women and murder the men, like some tribes living in very remote areas still do today, as well as primates like gorilla's and chimpansees? Or did intercourse happen peacefully as a result of mutual attraction and curiosity?
In 2015, extensive research of human fossils that were unearthed years earlier in the Fuyan Caves in Daoxian in Southern China showed that modern humans already lived there 100.000 years ago. This indicates that Homo Sapiens presented itself in Asia much earlier than previously thought.
Although some were guessing this already, it was still a big surprise for many others. It's a fairly revolutionary idea because the 'common opinion' until recently was that Homo Sapiens evolved from about 200.000 to 150.000 years ago in Africa and traveled through the Middle East to colonize the world only about 50.000 to 60.000 years ago. This is called the Out of Africa (OOA) theory.
Part of this theory is also that Homo Sapiens was able to wipe out another human species (Neanderthals) because of his supposed superior mind and dominant technologies. In this view, an uninterrupted and undisturbed genetic line runs from the African 'Adam and Eve' to us. However, our origin is much more complex than that and this 'romantic' OOA-image is no longer tenable.
The last few years, strong evidence has emerged that there was a previous emigration wave (or even waves), which may explain the presence of a prior Homo Sapiens in China. The view now gaining ground is that Asia played a prominent role in the history of human species even though archaeological finds from this continent are still very scarce.
Another discovery made in 2015 is a hitherto unknown tiny human species that has survived until at least 14.000 years ago in caves in South China. This means that until recently, different species of humans were living together as contemporaries for several hundred thousand years.There is increasing evidence that they learned techniques from each other and exchanged DNA through sexual contact. This further illustrates that a simplistic theory of our descent is inadequate.
Moreover, research published in 2015 showed that it's very likely that Homo Floresiensis, the little man from the island of Flores, was its own kind of people, and not a degenerate Homo Sapiens. Homo Denisova was also found in the Ural mountains in Asia and it is now increasingly believed that Neanderthals spread from the Asian continent to Europe and North Africa.
Africa has a larger archaic human variety than previously thought as well, as was shown by the discovery of Homo Naledi in 2013. Homo Naledi is a puzzling mishmash: researchers concluded that he walked upright like us and buried his dead, but had very small brains.
Rather than a straight line, our evolution is more like a web or a winding road with many branches, dead ends and even declining roads. Perhaps the most astonishing is the fact that there is now only one human species about: Homo Sapiens in all its colorful diversity. Although even today there is the occasional strong belief that a big monkey man, best known under names such as Yeti, Bigfoot or Sasquatch, is sneaking around in the mountains.
(February 2016 )