EvolutionEvolution Year 10 Semester 2. Introduction 1.How old is the universe? About 15 billion...

EvolutioEvolutionn

EvolutioEvolutionn

Year 10 Year 10 Semester 2Semester 2

Introduction1. How old is the universe?

About 15 billion years since Big Bang.

2. How old is the Earth? About 4.5 billion years.

3. How long has there been life on the Earth? About 3.5 - 4 billion years

4. When did the separation of man and ape from a common unnamed ancestor occur? Between 5 and 10 million years ago.

5. How old is the human species (Homo sapiens)? 100,000 to 200,000 years old.

6. Evolutionary theory teaches that humans evolved from monkeys. True or False? False - humans and modern monkeys had a common ancestor.

7. Pope John Paul II does not approve of the theory of evolution. True or False? False, according to book Voices for Evolution.

8. Major Protestant Churches have no problem with the theory of evolution. True or False? True, according to Voices for Evolution.

Introduction

What do you notice about

living things?

Describe each of the

environments in each

era.

Common Idea……

•Life, both plants and animals, have changed over time to meet the conditions of the environments they live in.

Adaptations• Three main types:

– Physiological: ?– Structural: ?– Behavioural: ?

• An adaptation is a characteristic of a living thing which allows it to survive in the conditions provided by its environment.

Evolution• The modern day theory of

evolution states that all living organisms share a common origin dating back more than 4 billion years.

• Over this period, new species have arisen and others have disappeared.

EVOLUTIONEVOLUTION is a process of change.

Charles Darwin• The Theory of Natural Selection1. Variation exists within a population of

organisms2. All organisms face a daily struggle to

survive3. Those organisms with adaptations

that best suit their environment have the best chance of survival & reproduction

4. Those organisms survive & reproduce to pass on their characteristics

5. Over time, the population changes to be best suited to their environment.

Jean Baptist Lamarck• Stated that animals have some

structures that they use frequently & others they do not use.

• The ones that are used frequently are strengthened & passed on.

• He also states that animals can acquire characteristics if they need them

How Does Evolution Work?

•Evolution occurs because of Natural Selection

Natural Selection• Within a particular species, there

is variation between individuals.• As a result, some individuals are

better adapted to their environment and are more likely to survive and reproduce.

• These adaptations are then passed onto the next generation.

SURVIVAL OF THE FITTEST

Artificial Selection• For thousands of years, humans

have made use of two very important facts:

1. There is variation within a species2. Offspring resemble their parents

• Knowing this, humans have selectively bred animals and plants for desired characteristics

• This is artificial selection

Genetic Variation• Three main sources of genetic

variation:1. Meiosis2. Sexual Reproduction3. Mutations

• Genetic variation is important to the process of natural selection.

Remember:

• Chromosomes are made of DNA & DNA consists of genes. The genes control the physical characteristics of an organism. A change in gene can lead to a change in characteristic.

An Example …• The English Peppered Moth

Speciation• Species: organisms that interbreed to

produce fertile, healthy offspring.

• Over time, the process of natural selection can cause such changes in characteristics that it leads to the formation of an entire new species. This is speciation.

• It is most often caused by geographical

isolation.

Different characteristics arise through genetic drift, mutation and

environmental pressures

Variation of characteristics

is present in population

The environment

changes

Those best suited to the environment

survive

Favourable characteristics are passed on

Frequency of new

characteristics increases

The breeding

population becomes isolated

The isolated

population is now quite

different

New Species =

SPECIATION

Selection occurs

Types of Evolution• Divergent Evolution

– one common ancestor evolves into two species, which continue to evolve and become less and less alike over time.

Types of Evolution• Parallel Evolution

– Two related species arise from a common ancestor. The two species then evolve in much the same way over time, probably in response to similar environmental selection pressures.

Types of Evolution• Convergent Evolution

– Occurs when two or more groups that are not closely related come to resemble each other more and more as time passes. This is usually the result of occupation of similar habitats and the adoption of similar environmental roles.

Types of Evolution• Which is which?

Divergent Convergent Parallel

Evidence for Evolution• There is a variety of evidence that

supports evolution.

• This includes:– Fossil evidence– Comparative anatomy– Comparative embryology– Biogeography– DNA evidence

Fossil Evidence:• Evidence for many species that existed

in the past can be seen from fossilised remains of plants & animals that were once trapped during the process of rock formation.

• The rock strata & the fossils in them, can be dated & arranged in sequence to show how life on Earth evolved over time.

• Fossils also provided evidence about locations of continents & oceans, & the changing environments of the past.

Evidence for Evolution

Only primitive fossils are found in older sediments

New fossil types mark changes in environment

Fossil types differ in each sedimentary rock layer

Numerous extinct species

Recent fossils are found in recent sedimentsMost recent

sediments

Oldest sediments

Comparative Anatomy:• Involves looking at the structure of

limbs in birds, reptiles, amphibians & mammals.

• All show similar structures suggesting common ancestry (known as homologous structures).


Comparative Embryology• Involves comparing the embryonic

forms of different organisms.• Closely related organisms go

through similar stages in their embryonic development, often showing similarities among structures that become so altered later in development that their common origin would not be seen in the adult form.


Biogeography• Study of geographic distribution of

a species using present – day observations & the fossil record.

• The distribution & evolution of a species can be affected by geographic boundaries such as mountains, lakes, oceans & deserts.


DNA Hybridisation• Most powerful piece of evidence: an

organisms genetic code.• Fossil evidence suggests that the

earliest forms of life were bacteria, so it seems likely that bacteria developed the code shared by all living things.

• The degree to which two species differ in their genetic sequences can be measured by DNA hybridisation.


DNA HybridisationSteps:• Double – stranded DNA from each species is

heated causing the strands to separate• The single – strands of DNA are ‘cut’ into

smaller segments using enzymes• The segments from two species are mixed

and allowed to cool together in a petri dish – any complementary bases of the two species will bond and rewind to form a double – helix

• The degree to which there is there is a match between the two strands demonstrates the genetic similarity between the two species

Extract human DNA Extract chimpanzee DNA

Some of the opposing bases in the DNA sequence do not match

Mix strands toform a hybrid

Unzip the DNA using heat (both human and

chimpanzee DNA unwinds at 86°C)

Human EvolutionHuman EvolutionHuman EvolutionHuman Evolution

Primate Classification

Prosimians New World Monkeys

Apes HominidsOld World Monkeys

HominidsAnatomical features and habits:

Bipedal with modified feet, thigh bone, pelvis, and spineLarge cerebral cortex (forebrain)Reduced canines (and teeth in general)Prominent nose and chin, reduced eye ridgesBody hair short or very reduced to assist cooling Highly sensitive skinComplex social behaviour

Examples:AustralopithecusParanthropusHomoArdipithecus

Paranthropus boisei Homo neanderthalensis Homo sapiens

Orrorin tugenensisOther Name

“Millennium Man”

Known Date

6.0 million years ago

Brain Size ? cc

Height ? m

PhysiquePossibly bipedal, and a forest dweller. Little else known.

Skull Shape

?

Teeth and Jaws

?

Geographical

Distribution

Kenya, Eastern Africa

O. tugenensis, or ‘Millennium man’ was discovered in late 2000.A new hominin from Kenya, it is claimed to be the oldest hominin yet described.Thirteen pieces, consisting of teeth, fragments of the arm, thigh bone, and a finger, from at least five different individuals have been found.The size and morphology of the teeth are intermediate between those of a chimpanzee and those of a human.

Ardipithecus ramidus

Other Name

Two subspecies: A. ramidus ramidus A. ramidus kadabba

Known Date

4.4 - 5.8 million years ago

Brain Size ? cc

Height c. 1.2 m

PhysiquePossibly bipedal forest dweller.Little else known.

Skull Shape

Foramen magnum more forwardthan apes.

Teeth and Jaws

Smaller, narrow molars; thinner jaw

Geographical

Distribution

Eastern Africa

Discovered in 1994, this species was originally thought to be an early hominin, with limited evidence of bipedalism. Two subspecies have been identified:

A. ramidus ramidus (4.4 my old)A. ramidus kadabba (5.8 my old)

This species is regarded by some researchers as ‘simply an ape with some unusual characteristics’.Some individuals may have been 1.2 m tall.Other fossils found with this hominin indicate that it may have been a forest dweller.

Other Name:

None

Known Date:

4.2 – 3.9 million years ago

Brain Size: ? cc

Height: ? m

Physique:Partial leg bones strongly suggest bipedalism; humerus extremely humanlike

Skull Shape:

Primitive features in the skull, possibly apelike

Teeth and Jaws:

Very similar to those of older fossil apes, but canines vertical; teeth have thicker tooth enamel as in humans

Geographical

Distribution:

Eastern Africa

Australopithecus anamensis• Anamensis was discovered

at Kanapoi, Kenya in 1994.

• The find consists of complete upper and lower jaws, teeth, a piece of skull, and arm and leg bones.

• Anamensis had a mixture of primitive, ape-like features and advanced, human-like features.

• The teeth and jaws are similar to older fossil apes, but the lower leg bones show evidence of bipedalism and the upper arm bone is extremely human-like.

Australopithecus afarensisOther Name ‘Lucy’, ‘First Family’

Known Date3.9 – 2.5 million years ago

Brain Size 400 – 500 cc

Height 1.07 – 1.52 m

Physique

Light build. Some apelike features: relatively long arms, curved fingers and toes, sexual dimorphism

Skull ShapeApelike face, low forehead, bony brow ridge, flat nose, no chin

Teeth and Jaws

Human-like teeth, canines smaller than apes, larger than humans.Jaw shape is half way between that of an ape and a human.

Geographical Distribution

Eastern Africa

Photos courtesy of: SkullsUnlimited.com

The Primitive Features of 'Lucy'This is a reconstructed skeleton of ‘Lucy’ Australopithecus afarensis – one of the earliest known bipedal hominins.

The skeleton exhibits

features consistent with a

species adapted for walking

bipedally ....

But it also possesses many

‘primitive’ features

normally associated with an

arboreal existence.

Sexual dimorphism in the canine teeth (a primitive trait)

Shoulder joint that is orientated towards the head

Relatively long arms compared to legs

Finger bones are curved

Toes are long and curved

Jaw shape half way between V-shape of ape's and U-shape of human jaw

Chest (thorax) is funnel-shaped

Wrist has high mobility

Relatively short legs

Ankle joint is highly mobile

Redrawn from a photograph

by © David L. Brill 1985

Low forehead

Australopithecus afarensis

A Modern Human Skull(for comparison)

Brow ridge

Large, dish-shaped face

Wide midface

Flat nose

Big, ape-like incisor

Diastema (gap)

Canines largerthan in humans

Large, thicklyenameled molars

Little of the skull is behind the foramen magnum

Small brain(410cc)

Other Name None

Known Date~3.0 - 2.3 million years ago

Brain Size 400 – 500 cc

Height 1.1 – 1.4 m

Physique

Light build. Probably long arms, more ‘human’ features, probably less sexual dimorphism than A. afarensis

Skull ShapeBrow ridges less prominent; higher forehead and shorter face.

Teeth and Jaws

Teeth and jaws much larger than in humans; shape of jaw fully parabolic as in humans; canine teeth further reduced.

Geographical

DistributionSouthern Africa

Australopithecus africanus

Australopithecus africanus


Lower faceprotrudes forwardinto a snout(prognathism)

Low facial angle

Brow ridge

No sagittal crest

Small brain (450cc)same size as gorilla'sbut organization isdifferent from an ape's

Very large molars compared with modern humans (not shown here)

Paranthropus robustusOther Name Australopithecus robustus

Known Date 2.2 - 1.5 million years ago

Brain Size 530 cc

Height 1.1 - 1.3 m

PhysiqueHeavy build. Relatively long arms. Moderate sexual dimorphism.

Skull ShapeLong, broad, flat face; crest on top of skull; moderate facial buttressing.

Teeth and Jaws

Very thick jaws; small incisors and canines; large molar-like premolars; very large molars (megadont).

Geographical

DistributionSouthern Africa

Paranthropus robustus


Small incisors

(missing in this

specimen)

Massive molars with thick enamel

are well worn suggesting a tough

vegetarian diet

Massivezygomatic archand cheek bones

Low facial angle

Heavy brow ridge

Very prominent sagittal

crest for the attachment

of powerful jaw musclesSmall brain(530cc)

Part of the rearand top of thisskull is missing

Little of the skull is behind

the foramen magnum

Homo habilisOther Name

Homo rudolfensis

Homo habilis

Known Date


2 - 1.6 million years ago

Brain Size 600 - 800 cc 500 - 650 ccHeight c. 1.5 m 1.0 m

PhysiqueRobust but ‘human’ skeleton.

Relatively long arms

Skull Shape

Larger, flatter face

Small face with developed nose

Teeth and Jaws

Large, narrow molars; robust jaw

Smaller, narrow molars; thinner jaw

Geographical

Distribution

Eastern AfricaEastern, and possibly Southern Africa

Homo habilis


Small variant

Large variant

Projecting jaw(prognathism)

Flat nose

Smaller, narrower face than the australopithecines

Brow ridge

Rounded cranium with no sagittal crest

Tooth row displays a modern curve, with narrow molars

Bigger brain(650-680cc)

Bulge in the Broca's area of the brain for speech production

More of the skull is behind the foramen magnum

Jaw is less massive than in the australopithecines

Homo erectusOther Name

Homo ergaster for older African forms

Known Date


Brain Size 750 - 1250 ccHeight 1.3 - 1.5 m

PhysiqueRobust but ‘human’ skeleton

Skull Shape

Flat, thick skull with sagittal keeland large brow ridge

Teeth and Jaws

Smaller teeth than H. habilis, robust jaw in larger individuals

Geographical

Distribution

Africa, Asia, Indonesia, and possibly Europe

Shelving forehead

Homo erectus


OlderAfrican forms

More recent

Asian forms

Projectingjaw

No chinTeeth are smaller thanH. habilis, but moremassive than our own

Flat face

Thick brow ridge

Long, flattened cranium with a distinctive keel along the top

Bigger brainEarliest: 850ccLatest: 1100cc

Bulge in the Broca'sarea of the brain forspeech production

Bulge in Wernicke's area of the brain for speech recognition

Occipital lobe(bun-like swelling)

Attachment for strong neckmuscles to stop the headfrom sagging forward

Homo heidelbergensisOther Name

Homo heidelbergensis

Known Date

400 000 - 100 000 years ago

Brain Size 1100 - 1400 ccHeight ? m

PhysiqueRobust but ‘human’ skeleton

Skull Shape

Higher cranium, less face protruding. Many regional variants with mosaics of modern and more primitive features.

Teeth and Jaws

Similar to H. erectus, but smaller teeth

Geographical

Distribution

Africa, Asia, and EuropeAtapuerca skull

Stenheim skull

Rhodesia skull

Occipital 'bun'for neck muscleattachment

Broad, uprightface

Homo heidelbergensis


Teeth are generallymodern in form

No muzzle (no prognathism)

Broad nasal opening

Large browridge

Sloping forehead

Large brain(1200 - 1430cc)

Flat, oblong shape to the cranium

Homo neanderthalensisOther Name

The Neanderthals;H. sapiens neanderthalensis

Known Date 150 000 - 28 000 years ago Brain Size 1200 - 1750 cc

Height 1.5 - 1.7 m

PhysiqueRobust but ‘human’ skeleton,adapted for cold climates

Skull Shape

Double-arched brow ridge, high rounded orbits, midface projection, weak chin, long low skull, small mastoid process,

Teeth and Jaws

Similar to Archaic H. sapiens;except for incisors, smaller teeth.

Geographical

DistributionEurope and western Asia.

Homo neanderthalensis


Weak chin

Swept back,lightly builtcheek bones

Large prominant nose and mid-facial projection

Double-archedbrow ridge

Sloping forehead

Low, long cranium

Teeth are smallerthan H. erectus, butbigger than our own

Powerful jaw butreduced comparedto H. erectus

Skull widest at the base (unlike modern skulls which are widest near the top)

Occipital lobe(bun-likeswelling)

Large brain (1600cc)Larger than a modernbrain but organizeddifferently

Homo sapiensOther Name

Early anatomically modern humans;Homo sapiens sapiens

Known Date195 000 - 60 000 years ago(for early humans)

Brain Size 1200 - 1700 cc

Height 1.6 - 1.85 m

PhysiqueModern skeleton possibly adapted for warmth

Skull ShapeSmall or no brow ridge;shorter and higher skull

Teeth and Jaws

Teeth may be smaller; shorter jawsthan Neanderthals; chin developed

Geographical Distribution

Africa and western Asia (for early forms)

No brow ridge, just a slight swelling of the glabella

Homo sapiens


Sizable jaw withprojecting chin

No muzzle(no prognathism)

Verticalface

High, verticalforehead

Convex cranial vault

Reduced tooth sizewith thinner enamel

Sizable mastoidprocess

Low, roundedoccipital area

Skull widesthigh up

Large brain(1400cc)

Human Evolution Timeline

In 2001, the 6-7 my old remains of a nearly

complete skull with gorilla-like features

was unearthed in Chad.

Nicknamed “Toumai” and assigned to a

new genus, Sahelanthropus tchadensis,

scientists debate whether it is human or

the remains of a proto-gorilla.




Orrorin tugenensis, or

‘Millennium man’ was

discovered in late 2000 at a

site in Kenya.

It is claimed to be the

oldest hominin yet

described.

Human Evolution TimelineOriginally given the name Australopithecus ramidus,

it was reclassified under a new genus,

Ardipithecus.

Two subspecies have been identified:

A. ramidus ramidus (4.4 my old)

A. ramidus kadabba (5.8 my old)

Regarded by some researchers as ‘simply an ape

with some unusual characteristics’.


Discovered at Kanapoi, Kenya in 1994,

this earliest known species of the

genus Australopithecus had a

mixture of primitive, ape-like features

and advanced, human-like features.


Discovered in Kenya, a new

genus Kenyapithecus appears

to be an offshoot from the main

evolutionary branches


Human Evolution TimelineAs many as four species from the

genus Australopithecus emerge,

with a wide geographic distribution,

ranging from southern Africa,

through East Africa, to Chad in the

north.

Human Evolution TimelineA group of species from the genus

Paranthropus emerge in southern and

eastern Africa. Superbly adapted to

exploit low grade vegetarian diet, they

coexist with the emerging genus Homo.

Human Evolution TimelineFrom a probable Australopithecine ancestor

emerges the first species of genus Homo.

A small-brained species with fully developed

bipedal locomotion, it has a talent for shaping tools

from stone. This hominin does not venture out of

Africa.


What followed was an adaptive radiation of the

genus Homo, leading to increased body height,

brain capacity, complex social behavior, and a

geographic distribution that extended well beyond

Africa.

Human Evolution TimelineThe most recent, and perhaps most perplexing part of this

emerging story, is the discovery in 2003 of what appears

to be a ‘pygmy’ species of human that lived on the

Indonesian island of Flores between 95 000 - 13 000

years ago.

EvolutionEvolution Year 10 Semester 2. Introduction 1.How old is the universe? About 15 billion...

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Transcript of EvolutionEvolution Year 10 Semester 2. Introduction 1.How old is the universe? About 15 billion...