Very few people find themselves in a position to go look for early human fossils. It is not a job for the fickle. In fact, there are several traits shared by those who go looking for these early bones. One would have to have the proper training and education before going out in the field. Also needed is a good dose of patience and persistence, and in the end, a modicum of good luck.
Dr. Zeray Alemseged is such a lucky man. He received his doctorate from the University of Paris in 1998. A year later he started working in Ethiopia and in 2000 the remains of a three million year old baby were found. The skeleton was nicknamed Selam, the word for peace in several Ethiopian languages, was found by Tilahun Gebreselassie, a member of Zeray’s team2. Dr. Alemseged now works at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany3. Even though the discovery was made in 2000, the general public did not learn of it until 2006. During these six years, the remains were carefully extricated from the rock-like matrix in which they were found. Years of additional study will still follow.
Baby Selam was identified as being an Australopithecus afarensis, the same genus and species designation as Lucy4. She stands out for many reasons: she is a very well preserved individual, remarkable not only because of the three million years that separate us, but also because of here biological age. A CT scan of the baby showed that her first permanent molars had not erupted, suggesting her age to be about three5.
Another incredible aspect of Baby Selam is her brain’s endocast6. Luck would have it that the braincase filled up with mud, which ultimately petrified. While the bones of the skull were not preserved, the rough outline of the shape of the brain was recovered. This endocast , as it is called, gives us a very good approximation of the brain size in this individual.
With the discovery of the baby, a wealth of research opportunities has sprung up. We can compare brain development in Australopithecines. By looking at the brain size of a child and that of an adult Australopithecine, scientists can chart this development against that of a modern human. We already knew that the brain size of an adult Australopithecus is much smaller than that of ours, but in terms in relative sizes, were their babies on the same track as ours in achieving their adult brain size? Questions like these all are geared toward a better understanding of who these early hominids were, what their abilities may have been and where they fit in our family tree.
Brains are an expensive luxury to have, as we all know. With Baby Selam we may be observing evidence that brain development had started to rake longer. When that occurs, just like in modern humans, what is called a prolonged childhood sets in. We know that with young non-human primates development occurs rather fast; once they are done nursing, they are virtually independent and able to forage for themselves. This may not have been the case with Baby Selam. With what we know of Baby Selam’s brain size, she had to rely on her mother’s assistance for quite a while. Given her young age at the time of death, she may have never outgrown her mom’s care at all.
Depending on the state of preservation, specialists can also zoom in on regions in the brain7 that – in modern humans at least – control features like speech. The possibility of some form of communication among Australopithecines is supported by the presence of the hyoid bone. Apparently this is only the second one of its type ever recovered from the fossil record, the other one belonging to a Neanderthal8 found in a cave in Israel. Forensic specialists study the hyoid bone looking for clues of strangulation (resulting in this fragile bone being broken). Physical anthropologists look at the role played by the hyoid bone in human speech . Paleoanthropologists use the presence of the bone as a clue that Australopithecines were able to vocalize11. Baby Selam’s fossilized hyoid provides an important tangible clue to help us figure this out.
By enlisting the support of modern technology, paleoanthropologists are transforming what used to be a rather dusty endeavor into what is looking more and more like an episode of CSI. Consider the use of CT scanning to reveal the teeth that had not erupted yet.
Sometimes the story also starts resembling a good murder mystery. Questions about how an individual died are inevitably part of the morbid interest in the subject matter that arises at press conferences or in class room settings. In this case, the jury is still out. Given that the body is incredibly well preserved, it is very likely that it was covered up very soon after it died. This would have provided protection against scavengers disturbing her remains.
Even though she lived more that three million years ago, the story of baby Selam has just begun. This is a truly a unique discovery, one which allows us a peek in early development of a fossil hominid. Her mom would be proud of her baby’s contributions to science.