Download Australopithecus

Australopithecus
Around ten million years ago, the climate was slowly changing on the continent of Africa. In turn, the vegetation and
wildlife also changed to adapt to the climate. Grassland was replacing dense forests, and a new species was evolving
that was able to spend more time hunting and foraging on the land than in the trees. The members of this new species
were hominids. A hominid is an early human ancestor. They were different from other ape-like species because they
were able to walk upright. In addition, their teeth and jaw structures looked different and their brains were larger. An
early group to show these features was the australopithecines. Fossilized remains of this species date back to around
3-4 million years ago. The remains of australopithecines have been found in eastern and southern Africa. Due to the
lack of extensive evidence, scientists still disagree about the exact relationship between the australopithecines and
modern humans. Most scientists suggest they are an early relative of humans, but that they are not human themselves.
Australopithecines ranged in size from about 47"-67" (120 cm-170 cm) tall, the smallest of the species being about
the size of an upright chimpanzee and the largest equaling the heights of modern humans today. By comparing bones
from an Australopithecus to that of a gorilla, it was discovered that they walked upright. The spinal column on an
Australopithecus, like a human, perpendicularly met the skull. This means the head was balanced on the top of the
backbone. On a gorilla, the backbone meets the head at an angle, making it better suited for walking on all fours. The
pelvis on an Australopithecus, also like that of a human, was short and broad, helping it to walk upright. A gorilla has
a long, narrow pelvis. The feet of an Australopithecus also show human-like tendencies. A gorilla's big toe sticks out
at an angle, much like the thumb on a hand, and is used for grasping. However, the foot of an Australopithecus was
more like a human's, the big toe aligned with the others.
The Australopithecus' skull was similar to that of an ape because it had a low forehead, large protruding eyebrow
ridge, flat nose, and jutting jaw. In contrast, its muzzle was much shorter than that of an ape's, and its teeth were
arranged more like a human's, with the sides of the jaws sloping outwards. Although the Australopithecus' jaw was
shaped like that of a modern human, it was far more powerful and held larger teeth which could be used for chewing
tough plants.
The brains of the australopithecines ranged from 28-31 cubic inches (450-500 cc) in volume. This is less than half the
size of a modern human brain, which is approximately 85 cubic inches (1400 cc) but much larger than the brain-tobody size ratio of an ape. The larger brain sizes meant that the australopithecines had greater intelligence and the
ability to work cooperatively. Although no evidence has been found showing that they made tools, scientists believe
the australopithecines probably used branches or stones to defend themselves. In addition to eating small animals,
these early humans, scientists believe, mostly ate birds' eggs, insects, and such plants as berries, leaves, fruits, and
roots.
Ape Skull
Australopithecus Skull