Hominid Evolution: Top 10 Discoveries of 2012
Diversity of Human Ancestors
2012 has been a banner year for hominid evolution research, with discoveries shedding light on the remarkable diversity and adaptability of our ancient relatives. Over the past 12 months, researchers have found evidence that throughout most of hominids’ seven-million-year history, numerous species with a range of adaptations coexisted.
Multiple Species of Early Homo in Africa
One of the most significant discoveries of the year is the confirmation that multiple species of Homo lived in Africa around two million years ago. This finding challenges the long-held belief that there was only one species of Homo, Homo habilis, during this time period.
In August, researchers working in Kenya announced they had found a lower jaw that fits with the previously found partial skull of Homo rudolfensis. The new jaw does not match the jaws of Homo habilis, suggesting that there must have been at least two species of Homo present in Africa two million years ago.
New 11,500-Year-Old Species of Homo from China
Another major discovery of 2012 is the identification of a new species of Homo that lived in China between 11,500 and 14,300 years ago. The fossils, which were found in a cave in southern China, have a mix of traits not seen in modern humans or other known populations of Homo sapiens. This suggests that the fossils may represent a newly discovered species of Homo that lived alongside humans during the late Pleistocene epoch.
Shoulder Blades Indicate A. afarensis Climbed Trees
Another hotly debated question in human evolution is whether early hominids still climbed trees even though they were built for upright walking on the ground. Fossilized shoulder blades of a 3.3-million-year-old A. afarensis child suggest that the answer is yes.
Scientists compared the shoulders of the child to those of adult A. afarensis specimens, as well as those of modern humans and apes. They found that the A. afarensis shoulder underwent developmental changes during childhood that resemble those of chimps, whose shoulder growth is affected by the act of climbing. This suggests that A. afarensis, at least the youngsters, spent part of their time in trees.
Earliest Projectile Weapons Unearthed
Archaeologists made two significant discoveries related to projectile technology in 2012. At the Kathu Pan 1 site in South Africa, archaeologists recovered 500,000-year-old stone points that hominids used to make the earliest known spears. Some 300,000 years later, humans had started making spear-throwers and possibly even bow and arrows.
At another South African site called Pinnacle Point, researchers uncovered tiny stone tips dated to 71,000 years ago that were likely used to make projectile weapons. The geological record indicates that early humans made these small tips over thousands of years, suggesting that they had the cognitive and linguistic abilities to pass on instructions for making complex tools over hundreds of generations.
Oldest Evidence of Modern Culture
The timing and pattern of the emergence of modern human culture is another area of intense debate in paleoanthropology. Some researchers believe that the development of modern behavior was a gradual process, while others see it as progressing in fits and starts.
In August, archaeologists contributed new evidence to the debate by uncovering a collection of 44,000-year-old artifacts at South Africa’s Border Cave. The artifacts, which include bone awls, beads, digging sticks, and hafting resin, resemble tools used by modern San culture today. The archaeologists argue that this is the oldest known instance of modern culture, as it is the oldest set of tools that match those used by living people.
Earliest Example of Hominid Fire
Studying the origins of fire is a difficult task because it is often hard to differentiate between natural fires that hominids may have taken advantage of and fires that our ancestors actually ignited. However, in April 2012, researchers announced that they had established the most “secure” evidence of hominids starting fires: one-million-year-old charred bones and plant remains from a cave in South Africa. Because the fire occurred in a cave, the researchers believe that hominids were the most likely cause of the inferno.
Human-Neanderthal Matings Dated
It is well-established that Neanderthals and Homo sapiens mated with each other, as Neanderthal DNA makes up a small portion of the human genome. In 2012, scientists estimated when these trysts took place: between 47,000 and 65,000 years ago. This timing coincides with the period when humans are thought to have left Africa and spread into Asia and Europe.
Australopithecus sediba Dined on Wood
Food particles stuck on the teeth of a fossil of Australopithecus sediba revealed that the nearly two-million-year-old hominid ate wood—something not yet found in any other hominid species. Australopithecus sediba was discovered in South Africa in 2010 and is a candidate for the ancestor of the genus Homo.
Earliest H. sapiens Fossils from Southeast Asia
Scientists working in a cave in Laos dug up fossils dating to between 46,000 and 63,000 years ago. Several aspects of the bones, including a widening of the skull behind the eyes, indicate that the bones belonged to Homo sapiens. Although other potential modern human fossils in Southeast Asia are older than this find, the researchers claim that the remains from Laos are the most conclusive evidence of early humans in the region.