Top 10 Human Origins Discoveries in 2015
In 2015, DNA analysis provided deeper insight into the lives of our ancient ancestors. Studies of their appearance, diet, living conditions, and the human family tree, were all hot topics. Research suggesting new species and the concept of human de-evolution also made waves. Each of the following investigations into human origins demonstrate that human evolution is not as simple as many people think, and that technology is a tool that is of great advantage in advancing our knowledge of the past.
The living quarters of Neanderthals also made the news this year. Archaeologists in Spain made a number of discoveries inside an ancient cave in Abric Romaní, Catalonia which suggest that Neanderthals had hot water and separate living quarters around 60,000 years ago. The finding adds to the mounting evidence that Neanderthals were a lot more sophisticated than previously thought and were at least as advanced, if not more so, than early Homo sapiens.
More than 10,000 fossil remains and artifacts were retrieved from the cave, enabling scientists to confirm long-term occupation of the site by Neanderthals. Among the more significant discoveries was a concave hole, which was found enclosed by a large number of hearths with evidence of fire use. Archaeologists believe the Neanderthals used the hole to heat water by placing heated stones from the hearth. Archaeologists also determined that Neanderthals used different parts of the cave for different activities, including making tools, butchering meat and preparing food, throwing out rubbish, and sleeping.
A fossilized lower jaw, with five small teeth, began to connect the dots between primitive ancestors and modern humans. The specimen, discovered in Ethiopia, is the bone of one of the very first humans and comes from a time when humans split from the more ape-like ancestors, Australopithecus. The find is more than 400,000 years older than the oldest fossils belonging to the early humans who eventually gave rise to Homo sapiens, our modern species.
Field work is being done in the Ledi-Geraru site to see if more fossils can be recovered. More information could help determine if the jaw belongs to a known early species of Homo, or an entirely new species, and researchers are putting off definitively naming it for the time being.
People who came from prehistoric Germany, Belgium and France beginning about 11,000 years ago seem to have contributed the most genetic material to modern Caucasian Britons, according to a new study. People may have gone to the islands from those areas long ago via a land bridge. Also, some came from what is now France by boat.
The genetic study analyzed genes of 2,039 white people from England, Scotland, Wales and Northern Ireland. The results show their dominant ancestry pre-dates the most recent invaders – the Anglo-Saxons, Vikings, Normans and Romans. But of those four, the group that contributed the most genes was the Anglo-Saxons, who invaded in the fifth century AD.
As for the distribution of genes: The Orkney Islands are the only area where the people have significant Viking ancestry, with about 25 percent of the Orkney people’s genes being Viking. The modern people of Wales most closely hew genetically to Stone Age peoples. A bit less than half of modern Britons have Anglo-Saxon ancestry, most of whom are in England proper.
In a third study on Neanderthals, a 55,000-year-old skull found at Manot Cave in northern Israel may be the earliest evidence of modern man meeting and mating with Neanderthals found to date. The partial skull “provides evidence that both modern humans and Neanderthals inhabited the southern Levant during the late Pleistocene, close in time to the likely interbreeding event between modern humans and Neanderthals.” This challenges the theory that two species connected 10,000 years later in Europe.
(Image of reconstructed faces of three early humans in profile view. Credit: Smithsonian Institution's Human Origins Program/Smithsonian National Museum of Natural History)
A recent analysis by anthropologists suggests that the light skin color and the tallness associated with European genetics are relatively recent traits to the continent. The evidence suggests modern Europeans do not appear as their ancient ancestors did. Their study was based on 83 human samples from Holocene Europe and shows that for the majority of the time that humans have lived in Europe, the people had dark skin, and the genes signifying light skin only appear within the past 8,000 years. This recent and relatively quick process of natural selection suggests to researchers that the traits which spread rapidly were advantageous within that environment – especially those necessary for Vitamin D absorption. People in less sunny climates required different skin pigmentations in order to absorb and synthesize Vitamin D. Thus, pale skin was advantageous in the region.
A study of skull fragments and teeth discovered in 1976 in a cave in Xujiayoa, China suggests that there may well have been multiple species of primitive humans between 60,000 and 120,000 years ago – including a mysterious people who do not fall under the categories of either Neanderthals, Denisovans, or modern humans.
Dental remains were recovered from the fragments that identify to four individuals. These were examined for size, shape and surface of the teeth, as well as other defining characteristics. When the teeth were compared to a database of over 5,000 teeth of known species, they did not match any of the accepted hominids. The question is now whether the teeth represent a hybrid of Denisovans and modern humans, or whether scientists have an entirely new human species on their hands.
In May last year, archaeologists made the exciting announcement that a complete Ice Age skeleton had been found in an underwater cave in Tulum, Mexico. Since then, more than eight well-preserved skeletons, ranging in age from 9,000 to 13,000 years have been retrieved from cenotes in Mexico and now scientists have begun to unravel the secrets that they may hold about early migration in the Americas.
The differences in skull shapes between the current indigenous people of Mexico and the Ice Age samples led some experts to argue that Native Americans arrived in a later migration to the earliest inhabitants, who came from elsewhere. According to this theory, the first wave of people was an Asian group that arrived more than 15,000 years ago via the Bering Strait, at the easternmost tip of Siberia and Alaska (the Paleoamericans), while a second migration wave occurred around 8,000 – 9,000 years ago and are the ancestors of today’s Native Americans. However, until further evidence emerges, it cannot yet be determined whether the differences in skull features between Paleoamericans and later Native Americans is accounted for by evolution or by two distinct migrations.
DNA from fossils from the Sima de los Huesos (“pit of bones”) cave in Spain show that Neanderthals are almost twice as old as previously thought, having emerged up to 765,000 years ago.
The scientists sequenced DNA from a prehistoric tooth and a leg bone, dating them to between 300,000 and 400,000 years old. They also identified one million to two million base pairs of ancient nuclear DNA, which is the oldest partial genome ever sequenced.
The findings “could lead to a dramatic shake up of the current shape of the human family tree,” as it was previously believed that Homo sapiens (modern humans) only emerged in Africa 200,000 years ago before they spread across the world. Neanderthals were believed to have evolved in Eurasia from a common ancestor. The new genome results create an earlier timeline for both species, and thus an earlier split in the evolutionary tree.
A study published in August asserts that modern humans lost DNA as we evolved after our split from apes. Our ancient ancestors, early humans, possessed substantially more amounts of genetic data than we do now. This surprising discovery raises many questions, the most obvious one being: why did we lose all that genetic information? Also, what difference has the loss made? The short answer is: we don’t know yet. This is the first time scientists have documented the loss (and gain) of large chunks of DNA in ancient populations.
The geneticists sequenced the genomes of 236 individuals from 125 distinct populations. They found that Homo sapiens have shed approximately 40.7 million base pairs of DNA after breaking from our closest living relatives, chimpanzees, around 13 million years ago. Furthermore, at least 27.96 million of the base pairs lost were unique.
Scientists also announced an earlier time frame than previously estimated for the lifetime of an early proto-human dubbed Little Foot – as much as 3.67 million years ago. The nearly complete fossilized skeleton of the small Australopithecus creature was found in Sterkfontein Cave in South Africa in the 1990s.
Age estimates of the fossil have varied greatly over the years, but new dating methods have allowed a more precise estimate. ‘It was impossible to fit Little Foot into the human family tree with any certainty because “ever since its discovery, the age of Little Foot has been debated,” said lead study author Darryl Granger, a geochronologist at Purdue University in West Lafayette, Indiana. ‘If researchers can figure out when Little Foot arose, they might be able to better pinpoint which Australopithecus species and which part of Africa ultimately gave rise to Homo.’