A new study of ancient DNA has completely changed our understanding of the peoples who lived in Stone Age and Bronze Age Europe. It was only about 1000 BC, well into the Iron Age, that we first saw light skinned individuals emerge on the continent. The study, published in BiorXiv, concludes that lighter skin and associated features such as green or blue eyes probably evolved several times over the course of human history, in response to migration from African into areas with lower UV radiation such as Europe. The study reaches back as far as 45,000 years ago and concludes that, for the vast majority of that time, this evolutionary change had not occurred and Europeans shared the same skin tone as their African ancestors. Absorption of UV radiation is essential for the production of Vitamin D and, all things being equal, paler skin is better at absorbing it. This would suggest that paler skins in more northern regions with less UV radiation would be a key advantage. The previous theoretical consensus was that lightening pigmentation would evolve gradually and in a linear fashion in response to the different conditions in Europe, but this was not the case. However there were other changes during the period which shed an interesting light on the evolution of Europeans. While the skin remained dark, eye color changed in a less predictable fashion. Eyes got paler until the Mesolithic, the middle Stone Age between roughly 15,000 and 5,000 years ago. At this point Europeans were predominantly dark skinned and blue eyed (as were the Neanderthals of the region, an interesting bit of convergent evolution). However from this point the number of dark eyes in the population began to increase again, for an unknown reason. Similarly, the team also saw evidence of localized variations suggesting that specific circumstances (and smaller, more isolated gene pools) could result in faster or more radical changes. Take for example the Neolithic farmers of Western Eurasia. These populations were faced with a wildly different lifestyle to their ancestors, and the pace of change for these peoples was accordingly a swift one. Gone were the semi-nocturnal hunter gatherer communities of forests and grasslands, adapted to long distance aerobic exercise and with their diet of meats and wild vegetables. In their place there was a people used to long daylight hours spent on heavy labor in a single place, tied to the land they cultivated. These farmers, in isolated communities, slowly developed paler skin at varying rates, but all generally faster than the Stone Age predecessors. This suggests a change in behavioral habits was also key to developing lighter skin, and that the environment alone was not a genetic disadvantage of darker skinned Neolithic humans. The changes to the diet of the Neolithic farmer resulted in less Vitamin D being taken in from foodstuffs. This meant that a paler skin was necessary for such communities to survive in health, and this is indeed what appears to have happened. And of course the study is far from conclusive. There may well have been isolated populations in the early Stone Age with paler skin, but only more research can tell us for sure. Header Image: Reconstruction of an early (between 37,000 and 42,000 years old) European Homo sapiens based on bones found in the cave Peştera cu Oase (Romania). Source: Daniela Hitzemann (photograph) / CC BY-SA 4.0.
The Origin of the Huns: Revealing the Truth Behind a Legend
The Huns, according to ancient sources, came out of nowhere. But then, these ancient sources were largely Roman and, as far as the Romans were concerned, the Huns really did. They first appear around the middle of the 4th century AD, harassing the northeastern frontiers of the Roman Empire. In 370 AD they suddenly appeared on the banks of the Volga in vast numbers, and over the next 50 years they established a huge empire, a new eastern front for Rome. They reached their peak under their great and feared leader Attila, who led enormous war parties on raids first into Roman Gaul (modern France) and then the Italian peninsula itself. It was only the sudden and unexpected death of Attila the Hun on his wedding night that stopped them. There are several competing theories as to where the Huns came from, even today. The Romans and Greeks had no idea, but over the years something like a “best guess” consensus has emerged based on an 18th century theory. The Huns are thought to be the same people as the Xiongnu mentioned in Chinese sources. These nomadic peoples had for centuries lived in the eastern Eurasian steppe on the Mongolian plateau, before suffering a devastating defeat by the Chinese Han dynasty in the 4th century. It is thought the retreating remnants of these people formed the Huns of European history. The problem is a 300 year gap between the defeat of the Xiongnu and the rise of the Huns. And now a genetic analysis of Hunnish remains published in PNAS may throw new light on whether this gap can be bridged. In the study a team of archaeologists, geneticists and historians led by Guido Alberto Gnecchi-Ruscone from the Max Planck Institute for Evolutionary Anthropology looked at hundreds of ancient genomes spanning an 800 year period from 200 BC to 600 AD. The genomes studied came from burials stretching from the Eurasian steppe all the way west to the Carpathian basin: the route the Xiongnu must have taken if they became the Huns. Do the genes from these burials suggest a link to both the Xiongnu and the Huns? Are these the tombs of a people slowly heading westwards from China to Europe? The answer is “sort of”. There is some evidence in the more opulent burials, both from the genes and the design of the tombs, that a core of elites may have fled westwards following the Xiongnu defeat, but there is no evidence of a wider link between the Xiongnu people and the Huns. Instead it is possible this elite gathered a coalition as they went, arriving in Europe with an army they built on a road centuries long. The Hun genetic lineage is diverse and includes many different steppe peoples, suggesting that they may have travelled and arrived independently before finding common cause against the Romans. It could also explain why the Hunnish empire collapsed so quickly once its charismatic and successful leader Attila died. Furthermore it seems that the Xiongnu core lost much of their cultural individuality on the road. Very few burials were found in Europe’s Hunnish empire completed in the Xiongnu fashion: their genes may have made the journey but their traditions did not. In fact, various new traditions appear to have appeared and died out amongst the people who would become the Huns during this time. However there was something special about the Xiongnu who made the journey. Genetic analysis suggests a link with the very highest echelons of imperial society, and a connection to the finest Xiongnu burials back in China and Mongolia. So, are Attila’s people the Xiongnu? Yes, and no. It seems that a Xjongnu elite did flee Han China and make it as far as Europe hundreds of years later. But these were only one of many peoples who collectively were not the Xiongnu. They were the Hun. Header Image: The Huns, Georges Rochegrosse, 1910. Source: Georges Rochegrosse / Public Domain.
The Tasmanian Tiger: The Long Journey to Resurrect an Icon
The Tasmanian Tiger is one of the most famous extinct animals. Also known as the thylacine, it survived well into the modern era and we even have film footage of a living example. Sadly this footage was of the last tiger, which died in captivity on the 7th September 1936 in Hobart Zoo on the island of Tasmania. But perhaps this beautiful creature is not lost forever, according to a new press release from Colossal Biosciences. The company has actually announced multiple breakthroughs, all of which they believe brings the day closer when this extinct marsupial can be brought back to life. The key announcement is an almost entirely complete thylacine genome, with only 45 gaps in the sequencing which it is hoped will be closed in the near future. The key to this success was the quality of the material used to extract the genetic information. Beth Shapiro, chief science officer for Colossal, explained: “The thylacine samples used for our new reference genome are among the best preserved ancient specimens my team has worked with.” The team estimate the genetic information to be >99.9% accurate, which they consider exceptional as most extinct species do not contain anything like as much DNA. Most preserved bodies of extinct animals are far more degraded, making the extraction of DNA far harder. Even more impressively, the team have been able to extract RNA sequences from preserved tissue. RNA is far less stable than DNA and therefore it is extremely rare to have such information, but in this case it was preserved almost by accident. The RNA strands were taken from the head of a thylacine which was skinned and preserved in ethanol. This was, luckily, an almost perfect environment to prevent the head from degrading. RNA is so important because it details the genetic function of individual tissues throughout an organism. DNA is a standard code embedded in every cell, but RNA is different in different places. This new information will therefore be able to identify the genes the thylacine employed for taste, smell, vision and brain function. This will be particularly because of the unusual skull formation observed in these creatures. Tasmanian tigers had exceptionally articulated lower jaws, able to open them extremely wide. Other features are shared with extant canids such as wolves, and it is hoped that the research will allow us to understand how these skulls evolved, and which parts of the genome are responsible for these features. So far, so fascinating but none of this actually brings the tiger back. That is where the other aspect of the team’s focus lies: with inducing ovulation in a fat tailed dunnart. The dunnart is a marsupial identified as a candidate through which the tiger can be recovered. The team have successfully fertilized the eggs produced through the procedure, and although none made it to term it is seen as a major breakthrough. And once all these disparate strings are pulled together, we just might once again see the Tasmanian tiger in the flesh. Header Image: The last known Tasmanian tiger in captivity. It is hoped that this new research will be able to resurrect the extinct marsupial. Source: Unknown Author / Public Domain.
