9-year-old discovers new human ancestor
In August 2008, Professor Lee Berger from South Africa’s University of the Witwatersrand, his 9-year-old son Matthew and his post-doctoral research assistant Dr Job Kibii were exploring caves and holes in South Africa’s appropriately named Cradle of Humankind World Heritage Site.
The professor and a colleague from Australia’s James Cook University, Dr Paul Dirks, had earlier been exploring the area by computer using Google Earth. They identified hundreds of unknown caves in the vast area.
9-year-old Matthew Berger finds a fossilised collar bone
The team were hunting for fossils and thought that the Malapa area would be particularly promising, and so it proved to be. Young Matthew Berger picked up a rock that had a profound worldwide effect on the study of human evolution. On turning the rock over, he saw a piece of bone. He took the fossil to his father who recognised the piece as a very human-looking collar bone. They hunted around and found more human-looking fossils, including a skull.
Professor Berger and Dr Kibii immediately applied for a permit to excavate the site. Their team found 2 partial skeletons of an approximately 30-year-old female and an approximately 9-year-old boy mostly encased in cement-like sediment. They also found various animal fossils, including sabre-toothed cats, a wildcat, a brown hyena, a wild dog, antelopes and a horse. The collar bone that Matthew found belonged to the boy, as did the skull.
Scientists believe the cave pit acted like a trap – animals (including the 2 hominids) fell in and couldn’t get out again. Because there was no evidence of predation (eating each other), scientists believe that they probably all died quite quickly, possibly within hours, if not from the fall. Later, floodwater washed their remains further into the cave system where sediment settled over them. Eventually, the cave roof collapsed, and over millions of years, erosion again uncovered the remains, which were once hidden deep underground.
Dating and naming the hominid remains
Dating techniques, including uranium-lead dating and paleomagnetic dating, determined that the bones were approximately 1.9 million years old. The fossilised hominids have been called Australopithecus sediba. ‘Australopithecus’ means Southern ape and ‘sediba’ means natural spring or fountain in Sotho. The researchers believe Australopithecus sediba may be the starting point from which the genus Homo (we are Homo sapiens) arises. Some researchers thought that the genus should also have been Homo. However, Professor Berger says they decided to put the fossils in the Australopithecus category because of the hominids’ arms and brain size. The arms were longer than modern human arms, with short powerful hands, which suggests that they were still “dependent on the trees for some of their survival”. Their brains were approximately one-third the size of a Homo sapiens’ brain.
However, they had hip bones similar to that of modern humans and long legs capable of striding and possibly even running. They also had human-like faces, noses and back teeth. The pair are possibly mother and son, but the scientists are still looking at ways to confirm this. They are yet to extract some DNA, although Professor Berger says scans reveal that some organics may be preserved in various parts of the fossils. He notes that genetic analysis has never been done on hominid fossils this old “but we are trying everything possible and are exploring the possibility that there could be at least proteins and possibly DNA preserved.”
The astonishing discovery of a human ancestor was not announced until 8 April 2010 in Science magazine. It can take time to do all the research and agree on the results, and this research team, which has cemented its place in scientific history, says there are years of work still to do.
Australian scientists in the research team
Professor Berger’s research team includes 3 Australian scientists – Dr Andy Herries from the University of New South Wales, Dr Robyn Pickering from the University of Melbourne and Dr Paul Dirks from James Cook University –who helped with identifying and dating the remarkable find.
Dr Herries, an archaeological scientist, says that these fossils probably do not represent the oldest evidence for sediba. “Sediments older than 2 million years occur at the site, and only time will tell if they will reveal earlier examples of Australopithecus sediba or other species of human ancestors.”
Dr Robyn Pickering, who helped date the fossils, says it has never been clear where our own genus Homo came from. “This new discovery, Australopithecus sediba, could answer these questions. Knowing how old these early human fossils are is critical to our knowledge of where this newly found species fits into our family tree,” she said.
“We have been able date the sediba fossils to between 1.95 and 1.78 million years ago. This is the first time in South Africa that we have been able to achieve such good age control. Now we are able to fill in the gap of what happened 2 million years ago in the beginnings of our species.”
In relation to this news story, your students may like to investigate the C-14 carbon dating process using this interactive activity.
C-14 carbon dating process
Find out more about DNA analysis on the Biotech Learning Hub website.