Archaeology Excavation

A team of scientists has announced the discovery of a 3.4 million-year-old partial foot from the Woranso-Mille area of the Afar region of Ethiopia. The fossil foot did not belong to a member of “Lucy’s” species, Australopithecus afarensis, the famous early human ancestor. Research on this new specimen indicates that more than one species of early human ancestor existed between 3 and 4 million years ago with different methods of locomotion.

The analysis will be published in the March 29, 2012 issue of the journal Nature.

The partial foot was found in February 2009 in an area locally known as Burtele.
“The Burtele partial foot clearly shows that at 3.4 million years ago, Lucy’s species, which walked upright on two legs, was not the only hominin species living in this region of Ethiopia,” said lead author and project leader Dr. Yohannes Haile-Selassie, curator of physical anthropology at The Cleveland Museum of Natural History. “Her species co-existed with close relatives who were more adept at climbing trees, like ‘Ardi’s’ species, Ardipithecus ramidus, which lived 4.4 million years ago.”
The partial foot is the first evidence for the presence of at least two pre-human species with different modes of locomotion contemporaneously living in eastern Africa around 3.4 million years ago. While the big toe of the foot in Lucy’s species was aligned with the other four toes for human-like bipedal walking, the Burtele foot has an opposable big toe like the earlier Ardi.

“This discovery was quite shocking,” said co-author and project co-leader Dr. Bruce Latimer of Case Western Reserve University. “These fossil elements represent bones we’ve never seen before. While the grasping big toe could move from side to side, there was no expansion on top of the joint that would allow for expanded range of movement required for pushing off the ground for upright walking. This individual would have likely had a somewhat awkward gait when on the ground.”
The new partial foot specimen has not yet been assigned to a species due to the lack of associated skull or dental elements.
The fossils were found below a sandstone layer. Using the argon-argon radioactive dating method, their age was determined to be younger than 3.46 million years, said co-author Dr. Beverly Saylor of Case Western Reserve University. “Nearby fossils of fish, crocodiles and turtles, and physical and chemical characteristics of sediments show the environment was a mosaic of river and delta channels adjacent to an open woodland of trees and bushes,” said Saylor. “This fits with the fossil, which strongly indicates a hominin adapted to living in trees, at the same time ‘Lucy’ was living on land.”

Following questions about the validity of using a genetic sample from a modern day relative of Richard III to help identify his remains, Dr Turi King of the University of Leicester guides us through the process she used.

I’m afraid I must start with a quick DNA primer! I promise to keep it short. Our DNA can be divided into two different sorts: nuclear DNA (which is so called because it’s found in the nucleus of our cells) which is made up of 23 pairs of chromosomes, and mitochondrial DNA (which is found outside the nucleus of the cell).

The DNA being used in this analysis is primarily (more about that later!) mitochondrial DNA. Indeed this is the DNA of choice for two reasons. The first of these is that after death the usual mechanisms which keep our DNA molecules long and healthy (and easy to analyze) no longer work. Our DNA begins to break down into tiny fragments and it becomes increasingly difficult, if not impossible, to retrieve any DNA to analyze. While there is only one copy of our nuclear DNA in each cell, there are many hundreds of copies of our mitochondrial DNA, so if any DNA has survived that is sufficient to be analyzed, it will be mtDNA. The other reason that mitochondrial DNA is so useful in this case is that it’s passed down the female line: from mothers to children – but only daughters pass it on. Richard III would have inherited his mitochondrial DNA from his mother – as would any of his siblings – and his sisters would have passed it on too, down through the generations to any of their female-line descendants.

We are fortunate to have a female-line relative of Richard III in the form of Michael Ibsen. Some years ago,
the historian John Ashdown-Hill was researching Richard III’s family tree and he discovered an unbroken female line from Anne of York to Joy Ibsen – Michael’s mum. Within weeks of the remains being found, Professor Kevin Schürer, Pro Vice Chancellor for Research at the University, who is also an expert in surnames and genealogy, managed to find another female-line relative of Richard III, who wishes to remain anonymous. Anne of York and Richard will both have inherited their mtDNA from their mum Cecily, who passed her mtDNA type down through the maternal line to Michael and this second lineage. So essentially I was able to compare the mitochondrial DNA from the skeletal remains with that of his two female-line relatives and see if there is a match consistent with them being related – which there was.

Now, I say primarily mitochondrial DNA was being used as there is one of our chromosomes (found in the nucleus) which could be used to help identify the remains as well. Our 23rd pair of chromosomes is our sex chromosome pair. Women have two copies of the X chromosome (XX) and men have an X chromosome but also a Y chromosome (XY). The Y chromosome has the gene for maleness it can only be passed down the male line. As part of this project, genealogical evidence has been used to identify putative modern-day male-line only relatives, a number of whom have been kind enough to take part in our study. Should it be possible to retrieve Y chromosome DNA from the skeletal remains, this will be analyzed and compared with the modern relatives to see if there is a match down the male line as well.