2. Hominin Evolution
Your learning has been successful if you can do the following:
Learn these so you can communicate this concept well.
Your group has been given a picture of a hominin skull.
Use your SciPAD pg 276-275 to identify the species name of your skull.
Go around the room and find the species name and real-life skull that matches your picture.
(We don't have real-life skulls for some species, so don't worry if you can't find your one).
Hominins and Hominids
Hominin: all the species belonging to the human lineage. This includes 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:
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.
Timeline of Hominin Evolution
Overview of Trends in Hominin Evolution
Zoom in on parts of the diagram below, which shows the trends in hominin evolution over time. Only the five species representative of the general trends are shown here.
Australopithecus afarensis - The early australopithecines were ancestral to Homo habilis.
Homo habilis - Ancestral to modern humans.
Homo erectus - Some populations of Homo erectus migrated out of Africa, evantually giving rise to populations of Homo in the Middle East and Europe.
Homo neanderthalensis - Eventually evolved in Western Europe
Homo sapiens - Evolved in Africa
The hominin fossil record shows clear evolutionary trends towards bipedalism, increased brain size, increased height, and increased technical ability.
Trends seen in skull fossils:
Increased cranial capacity.
Trends in brain volume, height and dentition.
Trends in other skeletal features: pelvis, foot, foramen magnum, spine and valgus angle.