General characteristics of order Primates

Mammals in the order Primate have the following characteristics:

Structural:

• Prehensile (grasping) hands and feet - allows them to grip/manipulate objects.

• Sometimes a prehensile trail - used for balance.

• Nails instead of claws, sensitive finger pads - helps with manipulating objects.

• 5 functional digits on each foot

• Forward facing eyes/overlapping visual field. Allows them to easily see the world in 3D

• Good hand-eye coordination

• Bony ridges to protect eyes

• Tendency toward having an erect upper body - associated with sitting, standing, leaping, and in some, walking.

Physiological:

• Oestrus/reproductive cycle of female, 2 nipples

• Gestation (pregnancy period) is longer than most other mammals.

• Typically have one young per pregnancy

Behavioural:

• Longer periods of infant dependency, and large parental investment. This nurturing increases survival rate and allows cultural development.

• Highly sociable, greater dependency on highly flexible learned behaviour.

Hominin: the group of modern humans, extinct human species, and all our immediate ancestors (including members of the genera Homo, Australopithecus, Paranthropus, and Ardipithecus.

Hominid: the group of all modern and extinct Great Apes (e.g. modern humans, chimpanzees, gorillas, and orangutans, plus all their immediate ancestors).

Bipedalism is the main trait that separates hominins from all other hominids.

You must be familiar with the following species involved in human phylogeny:

• Australopithecus afarensis

• Paranthropus sp.

• Homo habilis

• H. erectus

• H.heidelbergensis

• H. neanderthalensis

• H. sapiens

• H.floresiensis

• Denisovans

Hominins include living humans, our ancestors (pre-humans) and the bipedal apes with whom we share our evolutionary history.

About 6-7 mya, the ancestor of living humans and chimpanzees diverged into two geographically isolated populations. One of those groups eventually evolved into us, the other evolved into chimps. Thus, we and the living chimps share a common evolutionary ancestor who lived about 6-7 mya in Africa. This is demonstrated by the fact that we share about 99% of our DNA.

The most defining characteristics of hominins is our bipedal (two footed) locomotion and upright posture. It is a form of locomotion found 6-7 Mya. The earliest hominins also show changes in tooth form that mark a change in diet and social organisation.

Dozens of hominin species lived on earth. Most of the evidence on hominin lineage is from fossils and as more and more fossils are found; the hominin lineage is refined.