15.+Hominin+evolution

Have you ever wondered what makes us different from other animals? Why//Homo sapiens// appear to dominate the earth, altering the landscape and using vast amounts of energy compared to other species? The story might have began around six million years ago, when the primate lineage between humans and chimpanzees branched; in other words, we didn’t evolve from chimpanzees, they are like distant cousins, with a common ancestor six million years ago. A recent non-fiction book by psychologist Thomas Suddendorf, “The Gap – The science of what separates us from other animals” distills two traits that appear to account for most of the ways in which our minds appear quite different from other animals – the ability to cast our mind back and forward, imagining different scenarios and our drive to communicate with others, linking our minds together. I have only just started it, but so far it is fascinating and easy to read. On Monday we had another terrific Polycom session with Tony and Frazer from the Gene Technology Access Centre. The session focussed on the characteristics of seven fossil skulls – in fact, half-scale models of skulls, including:
 * //Homo sapiens (human)//
 * //Homo habilis//
 * //Homo erectus//
 * //Homo neanderthalensis//
 * //Australopithecus afarensis (also known as ‘Lucy’)//
 * //Gorilla gorilla//
 * //Pan troglodytes (chimpanzee)//

You can see some of these skulls at the African Fossils site, a virtual lab which showcases a spectacular collection of fossils and artifacts found mostly at Lake Turkana in East Africa.

We looked carefully at the models and tried to order and classify them based on the following characteristics:
 * Presence or absence of pronounced canine teeth
 * Presence or absence of a sagittal crest (presence indicates exceptionally strong jaw muscles)
 * Protruding jaw
 * Brow ridges (subtle or pronounced)
 * Presence of temporal lines
 * Cranium capacity (an indication of brain size – measured in millilitres)
 * Location of the foramen magnum – where the spinal cord passes through the skull to attach to the brain (using a ratio) – this indicates if the specimen is quadrupedal or bipedal.

If we consider the //Homo sapien// skull to be most advanced, it appears that the brain case has increased in size and become smoother, with a more rounded forehead and the face has become flattened, with a less pronounced jaw. More Human Evolution Resources here:


 * Human evolution interactives from the Natural History Museum
 * Human Evolution 101 from Berkeley
 * “What does it mean to be human?” from the Smithsonian National Museum of Natural History including the Mystery Skull Interactive
 * Human Family Tree and the “Skulls Lab”
 * Hominids – including good photographs of fossil skulls.
 * Neanderthal – the first human (YouTube video)