Archaeological and bone chemistry evidence
Study Questions 6
Archaeological and bone chemistry evidence indicate that Paranthropus robustus (and likely boisei as well) ate some meat. However, their huge check teeth suggest that they had evolved to depend primarily on some other dietary source. Considering that these Paranthropine species likely had similar dietary restrictions as other hominins (they likely couldn’t eat grass, for example), what sort of diet would you postulate they followed and what sort of environmental conditions would this reflect?
- robustus is believed to have a dental formula composed of enormous cheek teeth and a very thick enamel. P. robustus chewed food using the back of the jaw. Additionally, the cheekbones of P. robustus were large and this characteristic allowed the passage of food through the huge chewing muscles to the jaws. It is this vital characteristic that gave P. robustus a broad shaped -face. More so, P. robustus had an elongated sagittal crest which was useful for accommodating the huge muscles due to the large surface area needed to chew food. As a result of these large muscles, P. robustus was well adapted to its ecological environment and thus was able to chew and grind tough fibrous food. It is, therefore, accurate to say that the possible environment within which P. robustus lived would probably be covered with abundance of wood. The wooden environment in this perspective provided the dietary nutrients like nuts, seeds, roots, and other wild fruits much needed by P. robustus. It is also believed that P. robustus did not eat grass and thus heavily relied on large hard plants, but even that being the case it would be inaccurate to assume that P. robustus environment was largely grassland. It more likely that P. robustus also inhabited wet closed environment covered by vast lakes and rivers.
Don't use plagiarised sources.Get your custom essay just from $11/page
Assume for simplicity sake here, that both Sahelanthropus tchadensis and Orrorin tugenensis represent the first hominins following the hominin divergence from our ape ancestor that we shared with Panini (the Chimpanzees and Bonobos). Also assume that that ape ancestor essentially looked like a chimpanzee. Also assume, just for this exercise, that each later genus is the descendent of the previous one (Orrorin descended from Sahelanthropus, Ardipithecus descended from Orrorin, etc.). For each hominin genus we covered in lecture 6, and based on their descriptions from the lecture and textbook, list each genus’ plesiomorphic and apomorphic traits relative to their respective directly preceding genus (doing this in table form is easiest).
| Hominin Genus | Plesiomorphic Traits (Ancestral Traits) | Apomorphic Traits (Newly Evolved Traits) |
| Sahelanthropus tchandensis | Large skull A slope shaped face Smaller brain (350cc) | Short face An increased nuchal line Much smaller canine teeth Thick enamel |
| Orrorin tugunensis | Ability to climb trees Thick molar enamel Limb sized bones | Had upper femur Smaller molars Huge incisors and canines |
| Ardipithecus ramidus | Huge incisors 300-400cc brain size Molars had a rectangular shape | Small feet Toes were largely divergent Small canines |
| Australopithecus anamensis | Had a shallow palate Same cranium and dental formula Relatively huge Dominant primitive teeth and jaws | Slightly huge Tough and long canine root Much thicker enamel |
| Australopithecus afarensis | Had a flat nose Parallel shaped tooth rows 500cc brain size Projecting strong lower jaws Canine diastema | Had no wrist bone Obligate biped Gluteus maximus was attached to the femur shaft |
| Australopithecus africanus | Sloped shaped and firm face The same body size Cranial capacity 420-485cc Long arms | Thick enamel molars Small teeth Smaller molars and canines Circled shaped cranium |
| Australopithecus sediba | Small brain size 420-435cc Had the same body size Longer arms | Similar traits as H.Erectus |
| Paranthropus aethipicus | A protruded strong face Strong jaws Huge megadont teeth | Most likely walked upright Shorter pelvic blades Adducted hallux Strong nuchal muscles |
| Paranthropus boisei | Huge cheek teeth The volume of the brain was most likely small Huge nuchal pillars Flaring cheekbones | Large molar size A shortened foramen magnum Short incisors and canines Very deep mandibular fossa |
| Paranthropus robustus | Huge cheekbones Elongated sagittal crest The face was dish-shaped Huge megadont cheek Thick enamel teeth | The parietal cortex was largely expanded Large molar size A more cerebral height Most likely used bones and stones as digging tools |