Hominid Studies (5.7)

210

Define evolution.

Evolution is the gradual change in the inherited characteristics of populations over many generations, resulting in new species from pre-existing species.

Define biological evolution.

Biological evolution is the change in the genetic composition of populations over time through mechanisms such as natural selection.

Define a hominid.

A hominid is a member of the family Hominidae, which includes modern humans, extinct human ancestors, chimpanzees, gorillas and orangutans.

Define a hominin.

A hominin is a member of the human lineage after the split from the common ancestor shared with chimpanzees. It includes Australopithecus and all species of Homo.

What is the difference between a hominid and a hominin?

Hominids include humans, extinct human ancestors and the great apes. Hominins include only humans and their extinct ancestors after the split from the common ancestor with chimpanzees.

Define fossil.

A fossil is the preserved remains, impression or trace of an organism from the past.

Define palaeontology.

Palaeontology is the scientific study of fossils.

Define palaeoanthropology.

Palaeoanthropology is the study of human evolution using fossil evidence.

Define bipedalism.

Bipedalism is the ability to walk upright on two legs as the primary method of movement.

What is the foramen magnum?

The foramen magnum is the large opening at the base of the skull through which the spinal cord passes.

Why is the position of the foramen magnum important?

It indicates posture and locomotion: More backward → quadrupedal movement. More forward → upright walking (bipedalism).

Define cranial capacity.

Cranial capacity is the internal volume of the skull that houses the brain, measured in cubic centimetres (cm³).

What does an increase in cranial capacity generally indicate?

Larger brain. Greater intelligence. Improved reasoning and planning abilities.

Define prognathism.

Prognathism is the forward projection of the jaws and face.

What is a prognathous jaw?

A jaw that projects forward beyond the upper face.

What is a non-prognathous jaw?

A flatter face with little or no forward projection of the jaws.

Define brow ridge (supraorbital ridge).

The brow ridge is the bony ridge located above the eye sockets.

What is the sagittal crest (cranial ridge)?

A ridge of bone running along the top of the skull where large chewing muscles attach.

Define palate.

The palate is the roof of the mouth.

What is a U-shaped palate?

A narrow, almost rectangular palate commonly found in apes and early hominins.

What is a parabolic palate?

A rounded palate that widens towards the back, characteristic of modern humans.

Define diastema.

A diastema is the gap between the canine and adjacent teeth.

Why did early hominins have a diastema?

To accommodate large canine teeth when the jaws closed.

What is a canine tooth?

A pointed tooth adapted mainly for tearing food.

Define transitional species.

A transitional species possesses characteristics of both ancestral and descendant groups.

Define genus.

A genus is a taxonomic category above species that groups together closely related species.

Which two genera are studied in Grade 12 Hominid Studies?

Australopithecus and Homo.

Define species.

A species is a group of organisms capable of interbreeding naturally to produce fertile offspring.

What is mitochondrial DNA (mtDNA)?

DNA found in mitochondria that is inherited only from the mother.

Why is mtDNA useful in human evolution studies?

Changes slowly over time. Passed from mother to offspring. Used to trace maternal ancestry.

What is Y-chromosome DNA (Y-DNA)?

DNA found on the Y chromosome that is inherited only from father to son.

Why is Y-DNA useful in evolution studies?

Used to trace paternal ancestry. Shows relationships between human populations.

Define genetic diversity.

Genetic diversity is the variety of genes and alleles within a population.

Why is high genetic diversity important in human evolution?

Populations with the highest genetic diversity are generally the oldest because mutations accumulate over long periods.

State the Out of Africa hypothesis.

Modern Homo sapiens evolved in Africa and later migrated to other continents, replacing earlier Homo species.

During what time period did Australopithecus live?

Approximately 4.5–1.4 million years ago.

During what time period did the genus Homo first appear?

Approximately 2.2 million years ago.

Which genus first showed clear evidence of habitual bipedalism?

Australopithecus.

Which genus is characterised by larger brains, improved tool use and culture?

Homo.

Which famous fossils must IEB learners know?

Lucy (Australopithecus afarensis), Taung Child (Australopithecus africanus), Mrs Ples (Australopithecus africanus), Turkana Boy (Homo erectus).

Which diagrams are commonly examined by IEB?

Skull comparison, Foramen magnum position, Cranial capacity, Brow ridge, Prognathism, Palate shape, Canine size, Diastema, Pelvis comparison, Evolution timeline, Phylogenetic tree, Out of Africa migration map.

Define Australopithecus.

Australopithecus is an extinct genus of bipedal hominins that lived in Africa approximately 4.5–1.4 million years ago and showed both ape-like and human-like characteristics.

List the general characteristics of Australopithecus.

Lived only in Africa. Lived approximately 4.5–1.4 million years ago. Walked upright (bipedal). Small brain (≈380–500 cm³). Long arms and relatively short legs. Smaller canines than apes. Slight or no diastema (species dependent). Prognathous jaw. U-shaped palate. Could climb trees as well as walk upright.

What evidence shows that Australopithecus was bipedal?

Foramen magnum positioned more forward underneath the skull. Pelvis became shorter and broader than that of apes. Big toe aligned with the other toes. Lower limbs adapted for upright walking.

Which characteristics of Australopithecus remained ape-like?

Small cranial capacity. Long arms. Curved fingers. Prognathous jaw. U-shaped palate. Brow ridges. Tree-climbing ability.

Which characteristics of Australopithecus were more human-like?

Habitual bipedalism. More forward foramen magnum. Reduced canine teeth. Reduced diastema. More efficient upright walking.

Where have Australopithecus fossils been found?

Ethiopia, Kenya, Tanzania, South Africa.

Which famous Australopithecus fossils must be known for IEB?

Lucy, Taung Child, Mrs Ples, Australopithecus sediba.

Define Australopithecus afarensis.

Australopithecus afarensis is an early hominin species that lived approximately 3.5 million years ago in East Africa and showed clear evidence of bipedalism while retaining many ape-like features.

Where was Australopithecus afarensis found?

Ethiopia, Kenya, Tanzania.

Approximately when did Australopithecus afarensis live?

Approximately 3.5 million years ago.

What was the cranial capacity of Australopithecus afarensis?

Approximately 400–435 cm³.

List the skull characteristics of Australopithecus afarensis.

Small cranium. Low forehead. Prominent brow ridge. Prognathous face. Large canines. Diastema present. U-shaped palate.

Describe the skeleton of Australopithecus afarensis.

Long arms. Short legs. Curved fingers. Pelvis adapted for upright walking. Could climb trees and walk upright.

Which famous fossil belongs to Australopithecus afarensis?

Lucy.

Why is Lucy important?

One of the most complete Australopithecus skeletons discovered. Provided strong evidence for bipedalism. Showed a combination of ape-like and human-like characteristics.

What evidence from Lucy indicates bipedalism?

Pelvis adapted for upright walking. Femur angled towards the body's centre. Foramen magnum positioned more forward.

Where was Lucy discovered?

Ethiopia.

Which famous fossil footprints are associated with Australopithecus afarensis?

The Laetoli footprints.

Why are the Laetoli footprints important?

They provide direct evidence of habitual bipedalism. The footprints show a human-like walking pattern. The big toe is aligned with the other toes.

What type of evidence are the Laetoli footprints?

Fossil trace evidence.

Define Australopithecus africanus.

Australopithecus africanus is a South African hominin species that lived approximately 2–3 million years ago and is considered a possible ancestor of the genus Homo.

Where was Australopithecus africanus found?

South Africa.

Approximately when did Australopithecus africanus live?

Approximately 2–3 million years ago.

What was the cranial capacity of Australopithecus africanus?

Approximately 450 cm³.

List the skull characteristics of Australopithecus africanus.

Larger cranium than A. afarensis. Smaller brow ridges. Shorter face. Reduced prognathism. Smaller canines. Usually no diastema.

Why is Australopithecus africanus considered evolutionarily important?

It possesses more human-like characteristics and is regarded as a possible ancestor of the genus Homo.

Which famous fossils belong to Australopithecus africanus?

Taung Child, Mrs Ples.

Why is the Taung Child important?

First Australopithecus fossil discovered. Showed evidence of bipedalism. Demonstrated that early hominins lived in Africa.

What evidence from the Taung Child suggests upright walking?

The foramen magnum is positioned more forward beneath the skull.

What was the cranial capacity of the Taung Child?

Approximately 450 cm³.

Why is Mrs Ples important?

One of the best-preserved Australopithecus africanus skulls. Shows many human-like dental characteristics. Supports evidence for human evolution in Africa.

What human-like characteristics are seen in Mrs Ples?

Reduced canines. No diastema. Smaller brow ridges. More forward foramen magnum.

What was the approximate cranial capacity of Mrs Ples?

Approximately 340 cm³.

Define Australopithecus sediba.

Australopithecus sediba is a South African hominin species that lived approximately 1.8–1.95 million years ago and possessed both Australopithecus and Homo characteristics.

Approximately when did Australopithecus sediba live?

Approximately 1.8–1.95 million years ago.

Where was Australopithecus sediba discovered?

South Africa.

Why is Australopithecus sediba regarded as a transitional species?

It possesses both Australopithecus and Homo characteristics. It demonstrates the gradual evolutionary transition between the two genera.

Which Australopithecus characteristics are present in Australopithecus sediba?

Long arms. Ability to climb trees. Some primitive skeletal features.

Which Homo-like characteristics are present in Australopithecus sediba?

Longer legs. Smaller teeth. More human-like lower limbs. More efficient bipedal walking.

Arrange the Australopithecus species from oldest to youngest.

Australopithecus afarensis, Australopithecus africanus, Australopithecus sediba.

Define the genus Homo.

Homo is the genus of hominins characterised by larger brains, improved bipedalism, smaller teeth, advanced tool use, culture, and increasingly complex behaviour.

When did the genus Homo first appear?

Approximately 2.2 million years ago.

List the general characteristics of the genus Homo.

Fully bipedal. Larger brain (≈600–1 400 cm³). Smaller canines. No diastema. Less prognathism. Smaller jaws. More rounded skull. Increased intelligence. Tool manufacture and use. Cultural development. Language (especially Homo sapiens). Controlled use of fire (from Homo erectus).

How does Homo differ from Australopithecus?

Larger cranial capacity. Smaller teeth. Reduced prognathism. More efficient bipedalism. More advanced tool use. Greater intelligence. More complex social behaviour.

Which Homo species are examinable in IEB Grade 12?

Homo habilis, Homo erectus, Homo naledi, Homo neanderthalensis, Homo sapiens.

Define Homo habilis.

Homo habilis was an early Homo species that lived in Africa approximately 2.2–1.6 million years ago and is regarded as the first maker of simple stone tools.

Why is Homo habilis called the "Handy Man"?

Because it was the first hominin known to manufacture and use simple stone tools.

Approximately when did Homo habilis live?

Approximately 2.2–1.6 million years ago.

Where did Homo habilis live?

Africa.

What was the cranial capacity of Homo habilis?

Approximately 640 cm³.

Describe the physical characteristics of Homo habilis.

Larger brain than Australopithecus. Long arms. Small body. Slightly sloping face. No true forehead. Fully bipedal.

Why is Homo habilis evolutionarily important?

First known maker of stone tools. Larger brain than Australopithecus. Represents increased intelligence and manual dexterity.

Which type of tools did Homo habilis make?

Simple stone tools (Oldowan tools).

Define Homo erectus.

Homo erectus was a hominin species that lived approximately 1.8 million–300 000 years ago and was the first to migrate out of Africa.

Approximately when did Homo erectus live?

Approximately 1.8 million–300 000 years ago.

Where did Homo erectus live?

Africa, Asia, Europe.

What was the cranial capacity of Homo erectus?

Approximately 900–1 100 cm³ (about 1 000 cm³ in many IEB resources).

Why is Homo erectus considered evolutionarily important?

First hominin to migrate out of Africa. First controlled use of fire. Hunted cooperatively. Manufactured more advanced stone tools. Body proportions similar to modern humans.

What advantages did the controlled use of fire provide Homo erectus?

Warmth. Protection from predators. Cooking food. Improved digestion. Hunting. Social interaction.