The family Hominidae includes only one
contemporary species, Homo sapiens, which you may recognize as the
scientific name for modern humans. It also includes all the fossil
forms of distinctly human ancestors and related species that became
clearly differentiated from the other hominoids (the various species of
apes) and evolved in a distinctly human direction. In general,
anthropologists apply the term hominid to all human and human like
forms the fall within this taxon.
Hominids characteristic be divided into two
types:
- primitive, or generalized,
characteristics, which are held in common with other species within a
more comprehensive group (primates, anthropoids, catarrhines, and
hominoids); and
- derived, or specialized,
characteristics, which are distinct to hominid lines and are not
shared with non-human primate species.
The derived characteristics are especially
important for charting and understanding what we are as humans and how we
came to differ from other primates. One key to understanding the
special features of our species is our adaptation to a special habitat,
the tropical grasslands of Africa, which represents a departure from the
dense forests that support most primate species, including our closest
relatives: the gorilla, chimpanzee, and bonobo. A second is the
development of technologies and other cultural modes of behaviour that
increasingly transformed the environments and contexts in which we
survived and developed.
Specialized hominid characteristics
- teeth: small front teeth (canines and
incisors) and very large molars relative to other primate species;
(The reduced canine size is associated with the absence of a diastema,
a gap between the canine and the premolar, which accomadates a large
canine in ape and monkey species. The large molars may be an
adaptation to a diet based on relatively hard vegetable foods such as
nuts, berries, and grains that were abundant in the grasslands.)
- posture: bipedalism, involving numerous
anatomical adaptations including:
- a fully erect stance and gait,
- shortening of the arms relative to
the legs,
- restructuring of the pelvic bones
for weight bearing,
- restructuring of the foot or weight
bearing, involving the loss of toe opposability;
- hands: increased manual dexterity
involving a lengthening of the thumb;
- brain: increase in brain size,
especially in the frontal lobes;
- face: reduction in the musculature and
bone mass of the skull and face involving a flattening of the muzzle
area.
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