To
the right is a recent reconstruction of the skull of Homo erectus
based on material found at Zhoukoudian cave, China. The recovered material
is highlighted in natural color, whereas the reconstructed portion is
in gray. In making a reconstruction such as this, paleoanthropologists
use the principle of bilateral symmetry to help them. All vertebrates,
and therefore all humans, are roughly symmetrical along an imaginary
plane that runs down the middle of the body, dividing left from right.
Using this as a guide, a missing portion of one side of the skull can
be reconstructed with confidence if it is preserved on the other side.
A mirror image is thus used to reconstruct both sides of the face and
braincase. For example, in this cast, the right maxilla (bone connecting
the nasal opening and the teeth of the upper jaw) is completely missing,
but large portions of the left maxilla can be seen in the photograph.
These portions are used to reconstruct the individual's right maxilla.
(By the way, the left maxilla is from the individual's point
of view, so we see it on the right side of the photograph.) Holes
in the parietal and frontal bones (the bones that make up the roof of
the skull) are dealt with in a similar way. Not all of the skull can
be so reconstructed, and this is where a good knowledge of anatomy and
experience are needed to make a hypothesis as to what the missing areas
may have looked like.
To
the right is a recent reconstruction of the skull of Homo erectus
based on material found at Zhoukoudian cave, China. The recovered material
is highlighted in natural color, whereas the reconstructed portion is
in gray. In making a reconstruction such as this, paleoanthropologists
use the principle of bilateral symmetry to help them. All vertebrates,
and therefore all humans, are roughly symmetrical along an imaginary
plane that runs down the middle of the body, dividing left from right.
Using this as a guide, a missing portion of one side of the skull can
be reconstructed with confidence if it is preserved on the other side.
A mirror image is thus used to reconstruct both sides of the face and
braincase. For example, in this cast, the right maxilla (bone connecting
the nasal opening and the teeth of the upper jaw) is completely missing,
but large portions of the left maxilla can be seen in the photograph.
These portions are used to reconstruct the individual's right maxilla.
(By the way, the left maxilla is from the individual's point
of view, so we see it on the right side of the photograph.) Holes
in the parietal and frontal bones (the bones that make up the roof of
the skull) are dealt with in a similar way. Not all of the skull can
be so reconstructed, and this is where a good knowledge of anatomy and
experience are needed to make a hypothesis as to what the missing areas
may have looked like.