New Research Changes Origin of Human Species

For most of human history, the Earth was like the planet of the apes. Indeed, the road to humanity was a long road. It began in Africa some seven million years ago, when our lineage split from that of our closest living relatives, the chimpanzees. Our ancestors still resembled apes nearly four million years later. At least a million years ago, a ghost ancestor walked this planet with a face similar to yours. The modern face, the one with a flat profile in which the nose stands out, appeared at least a million years ago somewhere between eastern Africa and southern Europe. The key to the statement lies in a bone from the center of the face unearthed in Spain. The bone, a maxilla, belonged to a boy who lived about 900,000 years ago in the area. His face was modern enough to go virtually unnoticed on a crowded street. Body size, height, and shape are also similar to modern humans. That ghost is the origin of modern humanity. We still don't know who it was because we are talking about a very dark time, a million years ago, with few fossil remains. This ghost with a modern face could have arisen from the African Homo Ergista or even from Eurasian Homo Georgicus, who lived in present-day Georgia 1.8 million years ago. At the moment, Homo antecessor fossils are the closest thing we know to the ghost. This is very interesting because of the mysteries and many questions that surround our ancient brothers and sisters. The biggest questions may be why and how they became extinct. We will find out the truth shortly, concerning all the mysteries surrounding our ancestors. But new fossils, tools, and analyzers of ancient and modern genomes are tearing apart that neat tale. With the dust yet fully to settle, the question now is how many, if any, of our old assumptions still hold. Everything, from the identity of our last ancestor, when our species left Africa, and what happened next, is up for revision. These are interesting times to be exploring the human story, there is no doubt there will be more plot twists. Europe is a little peninsula that happens to have a large amount of spectacular archaeology, including some almost a million years old. Homo antecessor has a unique combination of features in the cranium, teeth and lower jaw that are collectively different from other fossils, rather than any particular feature that distinguishes it from others. These features show a mix of modern and archaic traits. Brain size is approximately 1,000 cubic centimeters, compared to 1,350 cubic centimeters for humans today. Even though the Neanderthals' brains were about the same size as those of modern humans, we can learn from them that size isn't always important. The fact that separates modern human brains from our ancestors has been discovered to be the density of neurons in the brain, not only the size. Concerning the birth of the modern human, the world of anthropology considers it as an excellent evolutionary leap. But this is not the case with the Neanderthals. One of the unsolved questions surrounding the Neanderthals is this, why wasn't their leap as successful as the modern human's leap? Possibly, our ancestors in East Africa interbred with the diminutive Homo naledi, and their small brains had the gene for more dense neurons, which we inherited. It could be that Homo naledi had a small, but dense brain that would explain their apparent intelligence which defies their tiny brains. Homo naledi fossils have been found in Kenya and South Africa, suggesting that they had a wide geographic territory, and now many archaeologists are even questioning if stone tools, and other objects attributed to early modern humans in the region were actually made by Homo naledi. The researchers suspected that this protein could increase the proliferation of neural progenitor cells, which become neurons, as the brain develops, specifically in an area called the neocortex, a region involved in cognitive function. This, the scientists reasoned, could contribute to modern human's cognitive advantage. The modern human version of the gene, called TKTL1, differs from the Neanderthal version by only one of its amino acid building blocks. This substitution is found in essentially all modern-day humans, but extinct archaic humans, Neanderthals, Denisovans, and other ancient humans all lack the mutation. Specifically, in modern humans TKTL1 contains an arginine at the sequence position in question, whereas in Neanderthal TKTL1 it is the related amino acid lysine. For some, the neural mutation hypothesis is the most economical explanation of why anatomy and human behavior drifted apart. Fossilized skulls reveal little about the brain underneath, but a gene mutation may have changed critical neural processes such as speech and language. The abrupt emergence of human culture over a stunningly short period continues to be one of the great enigmas of human evolution. The skull has many modern traits, including a modern-looking face, hollowed cheekbones, and projecting nose. Archaic traits include a low forehead and double brow ridge, similar to Asian Homo erectus and Neanderthals, and a protruding occipital bun at the rear of the skull. The teeth and jaws also have primitive aspects of dentistry, including very robust teeth. The modern-like face of Homo antecessor, strikingly similar to that of modern humans, may have a considerably deep ancestry in our genus. Indeed, the modern human may have face-evolved, and disappeared, multiple times in the past, which is not unlikely, as facial anatomy is strongly influenced by diet and the environment. In other words, the modern-looking face of Homo antecessor is actually very ancient, and our species has retained it. Whereas Neanderthals are the ones whose faces changed more during their evolution. Either way, Homo antecessor is probably a better guide to what our direct ancestor looked like, compared to Homo heidelbergensis or Homo ergaster. At a minimum, we can say that the mechanisms of facial growth, and increased brain size in Homo antecessor are integrated to create at this early date a more modern human face than any we have seen, before in any other fossil species. Thus, the growth processes that produced the facial morphology of Homo antecessor were similar to those of modern humans. For millions of years, as the hominid brain was developing, our ancestors were less the hunters and more the hunted. In our present epoch, the Holocene, the Earth is essentially humanity's playground. But the Pleistocene was far more terrifying. As prey, the past was not a pleasant place for humans and our ancestors. Early humans were able to hunt prey by throwing rocks, aka stone-age missiles, with impressive skill. Long before the invention of the spear, our prehistoric ancestors were throwing rocks to take down prey on the African plains. Small chunks of rock, many the size of a tennis ball, still litter the ground at important archaeological sites. Whilst other animals have been known to throw objects on occasion, none can match the speed, accuracy and distances that a trained human can achieve. Indeed, humans are uniquely specialized for throwing, both anatomically and psychologically. One of the advantages of the modern human brain is that it allows us to see beyond our spatial and temporal confines, so we can avoid being prey. Throwing has played a vital role in our evolutionary past, enabling us both to hunt prey, and to compete with other carnivores to scavenge carcasses. The ability to damage or kill prey at a distance not only expands the range of foods available, but also reduces the risk of close confrontation with dangerous prey. The prehistoric hunters would have had to weigh up the size and mass of the stone to find those which worked best. Too light and it might not do enough damage, too heavy and it might not make the distance. Rocks like this have been found in association with Homo Georgicus in Eurasia and Homo Ergista in Africa. This perceptual task would have needed brainpower to analyze the properties of the stones, learn from mistakes and choose the right ones. The researchers believe that many of the rocks were likely picked up elsewhere and brought to the site, ready to launch. This shows that they are good hunting weapons when thrown overhand, and we know early humans could throw with power and accuracy. The ability to throw great distances was not a small thing, it was how we got our lunch. We are the only animals, and even the only primates, with that talent. Research suggests that the throwing of stones played a key role in the evolution of hunting, before the development of spears. In fact, Homo erectus had the same throwing ability as modern humans, and throwing may have been a primary driver in early human evolution. This all points to rocks being used in social hunting, working together to bring down prey or scare off carnivores from a kill. This isn't exactly news about humans, but being social is a good predictor of large brains and intelligence. However, the answers to the mysteries surrounding our ancestors are obvious. Earth was like the planet of the apes for most of human history. We coexisted, but as our genes make clear, we frequently interbred with various hominin species, including some we haven't yet identified. During that long interim, a menagerie of different human species lived, evolved, and died out, intermingling and sometimes interbreeding along the way. As time went on, their bodies changed, as did their brains and their ability to think, as seen in their tools and technologies. But they dropped off, one by one, leaving our own species to represent all humanity, and on an evolutionary timescale, some of these species vanished only very recently.