HUMAN EVOLUTION 26 AUGUST 2015 Section A: Summary … · 2018. 5. 1. · HUMAN EVOLUTION 26 AUGUST...
Transcript of HUMAN EVOLUTION 26 AUGUST 2015 Section A: Summary … · 2018. 5. 1. · HUMAN EVOLUTION 26 AUGUST...
HUMAN EVOLUTION 26 AUGUST 2015
Section A: Summary Content Notes
Evidence of common ancestors for living primates, including humans
We looked at the use of fossils as evidence for evolution in the previous chapters.
We can now use that knowledge to explain the origin of modern humans
Humans share a common ancestor with two closely related groups of African apes, namely
chimpanzee and bonobos. This common ancestor lived about seven million years ago and
gave rise to humans and their direct ancestors (homnins)
A common ancestor is an ancient species that gives rise to two or more new species. The
new species are descended from the common ancestor.
The phylogenetic tree below shows that gibbons, gorillas , orang-utans, chimpanzees and
humans descended from a common ancestor that lived 35 million years ago
Scientists use different kinds of evidence to construct a phylogenetic tree.
One kind of evidence is to compare anatomy of two closely-related living species.
Similarities in the anatomy were probably present in the ancestor
Differences have evolved since the common ancestor divided into two new species
A phylogenetic tree for apes
and humans
Anatomical similarities between African apes and Humans
Enlarged and more complex brain relative to body size
Reduced snout with reduced sense of smell
Eyes in front of skull- stereoscopic vision
Eyes have cones
Two hands – five digits
Mobile opposable thumbs
Digits with flat nails
Long, slender limbs that rotate freely at shoulders and hips
Sexual dimorphism –male and female clearly distinguished
Have molars and premolars with rounded cusps
Anatomical differences between African apes and Humans
When we look at the differences you must be able to compare the following:
o Bipedalism (foramen magnum, spine and pelvic girdle)
o Brain size
o Teeth (dentition)
o Prognathism
o Palate shape
o Cranial ridges
o Brow ridges
o
There are three main lines of evidence that that indicate hominids have a shared common
Fossil evidence
Genetic evidence
Cultural evidence
1. Fossil evidence Palaeontologists study fossils to provide more information about structure,
movement, lifestyle, and environment
In search for a common ancestor for hominids , palaeontologists look at the
following features
Bipedalism
Dentition (teeth)
Palate shape
Brain size
Prognathism
AFRICAN APES HUMANS TYPE OF MOVEMENT
Quadrupedal – knuckle-walkers/
walk on all fours
Bipedal – walk upright on two legs
Foramen magnum at back of skull Foramen magnum closer to front of
the skull
C-shaped vertebral column S-shaped vertebra column
Long and narrow pelvis Short and wide pelvis
BRAIN SIZE
Smaller less developed brain Large well developed brain
TEETH (dentition)
Large prominent canines Smaller canine
Thin tooth enamel Thick tooth enamel
PROGNATISM
Large prominent jaw bone with no
chin (prognathism)
Rounded jaw with developed chin
Wider, sloping face Narrow flat face
PALATE SHAPE
Narrow rectangular palate Wider more curved palate
CRANIAL and BROWRIDGES
Prominent cranial and brow ridges Reduced cranial and brow ridge
2. Genetic evidence
DNA comparisons are made between living hominids , as DNA breaks
down in dead cells and its very rare to extract DNA from a fossil
Organisms have two types DNA
o Chromosomal DNA – in the nucleus
o Mitochondrial DNA (mt DNA in the mitochondria)
3. Cultural evidence Tools – Oldowan, Acheulian, Mousterian
Fire-making, burial rites, art and hunting techniques
Development of speech and language
MAJOR PHASES IN HOMINID EVOLUTION Humans and their fossil ancestors between the common ancestor and modern
humans are classified as hominids
The three main genera (phases) of human evolution are:
Ardipithecus
Australopithecus
Homo
Section B Practice Questions
Question 1 (Taken from DBE Feb-March 2013 Paper 1)
Professor Lee Berger and his colleagues studied the fossils they found in a cave at the Cradle
of Humankind. The skeletons from the cave are ranked amongst the most complete finds to
date. The adult female, Australopithecus sediba, was remarkably well preserved and some
of the following characteristics were identified:
Images showing the structure of the skull and bones of the palm of A sediba
1.1. Write down THREE characteristics from the list above that also apply to the Homo
species. (3)
1.2. State TWO advantages of A. sediba being bipedal. (2)
1.3. Professor Berger called Australopithecus sediba a transitional fossil. Using the
information in the list above, explain why he called A. sediba a species in transition. (2)
Question 2 (Taken from KZN Prelim Paper 1 2012) The diagrams below show the skull capacity of extinct hominid species and the time they
occurred
2.1. Draw a bar graph to compare the skull capacity of the above hominid species (6)
2.2. What trend can be observed from the graph above? (3)
2.3. Describe TWO visible differences between A. Afarensis and H. Sapiens. (4)
2.4. List FOUR characteristics that humans share with other primates. (4)
2.5. Homo sapiens are considered to be the most developed species. Although
Homo neantherthalensis has a brain capacity of 1 500cc Homo neantherthalensis
is extinct but Homo sapiens are still in existence. Explain how this is possible. (3)
Question 3 (Taken from DBE Exemplar Paper 1 2011)
Diagrams A and B below illustrate the skulls of Homo sapiens and Homo erectus. The diagrams are drawn to scale.
3. 1 Which of the diagrams (A or B) represents the following:
a. Homo sapiens b. Homo erectus (2)
3. 2 Tabulate TWO visible differences between the skulls in diagrams A and B that
represent changes in the structure that characterises human evolution. (5)
Question 4 (Taken from DBE Nov Paper 2 2010)
Study the diagrams below of the upper jaw, skull and the foot of two organisms A and B.
The diagrams are NOT drawn to scale.
4. 1 With regard to the drawings above:
a. Tabulate TWO visible differences between the upper jaws of organisms A and B
(5)
b. Name ONE visible difference between the feet of organisms A and B. (2)
4. 2 Which organism (A or B) is more likely to be bipedal? (1)
4. 3 Give a reason for your answer to question 4.2. (2)
Question 5 (Taken from DBE Feb-Mar Paper 1 2012)
The diagram below represents a cladogram (phylogenetic tree) showing primate evolution.
The letters, A to E, indicate the characteristics which are shared by the different species of
primates which follow the letter. The point where various species of primates differ from
each other is indicated by the branching-off/split into new species.
5.1. Which LETTER represents a common characteristic of all primates? (1)
5.2. List THREE structural characteristics represented by the LETTER named in QUESTION
(3)
5.3. Which organism is most similar to the chimpanzee? (1)
5.4. Name any TWO structural characteristics of the skull that make the organism named
in QUESTION 5.3 different from the chimpanzee. (2)
5.5. Write down the names of the organisms that display the characteristic C but not
characteristics D and E. (2)
Question 6 (Taken from DBE Nov Paper 1 2013)
Describe the structural changes to the skull that characterise the evolution of modern
humans from their ape-like ancestors, and explain the significance of these changes.
(20)
Section C: Solutions
Question 1
1.1. Projecting noseSmaller canines Bipedal
1.2. They had a wider view to spot danger
They could carry offspring/food/tools
Large surface area for thermoregulation
1.3. Have characteristics of both Homo species and Australopithecusspecies
Question 2
2.1.
2.2. The younger the skull, the larger he skull capacityOR
The older the skull, the smaller the skull capacity
2.3
2.4. Enlarged and more complex brain relative to body size
Reduced snout with reduced sense of smell
Eyes in front of skull- stereoscopic vision
Eyes have cones
Two hands – five digits
Mobile opposable thumbs
Digits with flat nails
Long, slender limbs that rotate freely at shoulders and hips
Sexual dimorphism –male and female clearly distinguished
Have molars and premolars with rounded cusps
2.5. Did not have a languagetherefore could not communicate unlike Homo sapiens
that had a lanugauge and could comminicate
Homo sapiens had the ability to inhabit different environments to suit their needs
unlike Homo neanderthalensis who could not and therefore became extinct
Question 3
3.1 a. B b. A
3.2
Diagram A Diagram B
Smaller brain capacity Larger brain capacity
Brow ridge pronounced Brow ridge not as pronounced
Lower jaw had a poorly developed chin Lower jaw has a much better developed
chin
Question 4
4.1
b Differences in Feet
In A the big toe is close to the other 4 smaller toes/faces forward
In B the big toe is apart/opposable from the other 4 smaller toes/points outwards
OR
In A the heel bone is relatively larger and in B it is relatively smaller
OR
In A the bones in the foot are straight and in B they are curved
OR
In A phalanges are relatively shorter and in B they are relatively longer
4.2 A
4.3 Foramen magnummore towards the centre of the skull in A/ more forward
OR
In B the foramen magnum more towards the back of the skull
Question 5
5.1. A
5.2. Opposable thumbswith power and precision grip
• Bare fingertipswith nails
• Long arms
• Freely rotating arms
• Eyes in front
• Stereoscopic vision
• Eyes with cones
• Large brain size compared to body mass
• Two mammary glands
• Sexual dimorphism
• Olfactory brain centre reduced
5.3. Humans
5.4. Shift in the position of foramen magnumto a forward position
• Gently curved jaws
• Flat face
• Well developed chin
• Not prognathus
• Forehead less sloping
• No pronounced brow ridges
• Smaller canines
• Spaces between teeth bigger
• Larger brain size
5.5. Rhesus monkey Gibbon
Question 6