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Page 1: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

EvolutionEvolutionYear 10 Topic 4Year 10 Topic 4

Page 2: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

EvolutionEvolution

Nearly two million different kinds of plants, animals and micro-organisms are known to be currently living on Earth. More are being found each year. The average time that a species lasts on Earth is about four million years. Which means that, like the dinosaurs, many species are long extinct.

Nearly two million different kinds of plants, animals and micro-organisms are known to be currently living on Earth. More are being found each year. The average time that a species lasts on Earth is about four million years. Which means that, like the dinosaurs, many species are long extinct.

Page 3: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Evolution suggests that all forms of life stem from the same remote beginnings and that the different species we now know have developed gradually over millions of years. The fossil record clearly shows that through time, life became more complex.

Evolution suggests that all forms of life stem from the same remote beginnings and that the different species we now know have developed gradually over millions of years. The fossil record clearly shows that through time, life became more complex.

Page 4: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Surviving in different environments

Surviving in different environments

In order to evolve, a species must survive.

In order to evolve, a species must survive.

Page 5: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

AdaptationsAdaptations

Organisms survive and breed in their environments because they have characteristics suited to that environment. Specific structures, functions and behaviours increase their chances of surviving, at least until the organism is able to reproduce. These characteristics are called adaptations. They are inherited and are passed from parents to offspring. Adaptations take many forms and can be classified as either structural (where the adaptation is physical), behavioural (where the adaptation controls the way they act).

Organisms survive and breed in their environments because they have characteristics suited to that environment. Specific structures, functions and behaviours increase their chances of surviving, at least until the organism is able to reproduce. These characteristics are called adaptations. They are inherited and are passed from parents to offspring. Adaptations take many forms and can be classified as either structural (where the adaptation is physical), behavioural (where the adaptation controls the way they act).

Page 6: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Structural adaptationsStructural adaptations

Many animals blend with their background, now invisible to predators.

Many animals blend with their background, now invisible to predators.

Page 7: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

A few can change colour to blend with changing backgrounds

A few can change colour to blend with changing backgrounds

Page 8: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Others resemble non-living objects such as leaves, twigs etc

Others resemble non-living objects such as leaves, twigs etc

Page 9: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

With some animals it is difficult for a predator to tell which end is which. The predator attacks the wrong end, giving the prey a chance to escape.

With some animals it is difficult for a predator to tell which end is which. The predator attacks the wrong end, giving the prey a chance to escape.

Page 10: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Some extremely colourful animals warn predators to stay away, because they taste bad or are poisonous.

Some extremely colourful animals warn predators to stay away, because they taste bad or are poisonous.

Page 11: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

A tricky variation on this is the ‘mimic’. The mimic is not dangerous to predators, but has copied the colourings and shape of another animal, so predators avoid it.

A tricky variation on this is the ‘mimic’. The mimic is not dangerous to predators, but has copied the colourings and shape of another animal, so predators avoid it.

Page 12: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Some animals have features that make them look larger and more frightening to predators. For example, the neck frills of some lizards can be opened to make the head seem like that of a much larger lizard.

Some animals have features that make them look larger and more frightening to predators. For example, the neck frills of some lizards can be opened to make the head seem like that of a much larger lizard.

Page 13: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Behavioural adaptationsBehavioural adaptations

Some animals have learned to sit very still or move slowly to avoid predators.

Some animals have learned to sit very still or move slowly to avoid predators.

Page 14: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Others are active only at certain times of the day or year to avoid unfavourable conditions such as extremes of heat or cold.

Others are active only at certain times of the day or year to avoid unfavourable conditions such as extremes of heat or cold.

Page 15: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Some have learnt to use tools to access difficult food. For example, chimpanzees commonly use broken twigs to extract termites.

Some have learnt to use tools to access difficult food. For example, chimpanzees commonly use broken twigs to extract termites.

Page 16: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Some collect and store food for future use.

Some collect and store food for future use.

Page 17: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Many larger animals form herds to provide protection from predators.

Many larger animals form herds to provide protection from predators.

Page 18: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Adaptations serve many purposes. Arctic fish contain a kind of antifreeze in their blood, allowing them to survive in waters that would freeze the blood of other

Adaptations serve many purposes. Arctic fish contain a kind of antifreeze in their blood, allowing them to survive in waters that would freeze the blood of otherfish. The long mane of a male fish. The long mane of a male lion makes it appear larger to lion makes it appear larger to opponents. This kind of opponents. This kind of adaptation for intimidation is adaptation for intimidation is common. Intimidation also common. Intimidation also involves behaviours such as involves behaviours such as puffing out the chest and puffing out the chest and standing up as tall as standing up as tall as possible.possible.

Page 19: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Plants also have adaptationsPlants also have adaptations

One orchid achieves pollination by imitating the shape, colour and smell of a female bee. When a male bee attempts to mate with the orchid, pollen is transferred from flower to flower.

One orchid achieves pollination by imitating the shape, colour and smell of a female bee. When a male bee attempts to mate with the orchid, pollen is transferred from flower to flower.

Page 20: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The silvery coloured, narrow-shaped leaves of the wattle tree help reduce water loss by evaporation. All organisms have adaptations that assist their survival in their environment.

The silvery coloured, narrow-shaped leaves of the wattle tree help reduce water loss by evaporation. All organisms have adaptations that assist their survival in their environment.

Page 21: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

VariationVariation

Although individuals within a species are very similar, they are not identical. Variation occurs within all species. Much of this variation comes from the differences in genes each individual inherits from their parents.

Although individuals within a species are very similar, they are not identical. Variation occurs within all species. Much of this variation comes from the differences in genes each individual inherits from their parents.

These differences are the result of the random assortment of chromosomes during meiosis, and the combination of gametes (sex cells) during fertilisation. Further genetic variation occurs as a result of mutations. Other variations come from environmental factors such as the amount of exposure to the Sun and differences in diet.

Page 22: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Variation and survivalVariation and survival

The organisms best adapted to their environment are the most likely to produce offspring. Their offspring will inherit these characteristics. Over several generations, individuals with favourable characteristics will become the most common. In contrast, those with less favourable characteristics will find the environment inhospitable. They will be more likely to die before they get a chance to reproduce and so will become less common. We can say that favourable characteristics are ‘selected’.

The organisms best adapted to their environment are the most likely to produce offspring. Their offspring will inherit these characteristics. Over several generations, individuals with favourable characteristics will become the most common. In contrast, those with less favourable characteristics will find the environment inhospitable. They will be more likely to die before they get a chance to reproduce and so will become less common. We can say that favourable characteristics are ‘selected’.

Page 23: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Variation in a species is important if environmental conditions change. Some individuals will have characteristics that are favourable, allowing the species to survive the change.

Variation in a species is important if environmental conditions change. Some individuals will have characteristics that are favourable, allowing the species to survive the change.

Page 24: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The Theory of EvolutionThe Theory of Evolution

The theory of biological evolution states that life on Earth has changed over time. This gradual development of different species from a common ancestor is called evolution.

It basically states that a species has natural variation which allows it to adapt to a wider range of environments. The best suited to their environment will survive and breed the next generation, this eventually gives rise to new species.

The theory of biological evolution states that life on Earth has changed over time. This gradual development of different species from a common ancestor is called evolution.

It basically states that a species has natural variation which allows it to adapt to a wider range of environments. The best suited to their environment will survive and breed the next generation, this eventually gives rise to new species.

Page 25: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Alternatives to Evolution

Alternatives to Evolution

Most societies have stories about the origin and diversity of life. Creation is the view that regards the world and everything in it as having been made by supernatural means, by a god or gods. The ancient Greeks suggested that the world grew out of Chaos, a dark mass where everything was hidden. From Chaos emerged a god and/or a goddess. The ancient world was peopled by them, producing other gods and goddesses, and then mortal men and women. The Biblical account includes stories of the creation of the Earth and all life on it in six days.

Most societies have stories about the origin and diversity of life. Creation is the view that regards the world and everything in it as having been made by supernatural means, by a god or gods. The ancient Greeks suggested that the world grew out of Chaos, a dark mass where everything was hidden. From Chaos emerged a god and/or a goddess. The ancient world was peopled by them, producing other gods and goddesses, and then mortal men and women. The Biblical account includes stories of the creation of the Earth and all life on it in six days.

Page 26: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

There is also an account of the first man, Adam, being created from clay and the first woman, Eve, being created from his rib. Some people believe the events happened exactly as stated. Other people interpret these as stories with symbolic meaning, as teachings about the relationships between God or gods, the universe and humans. The whole question of the origin of life then becomes bound to religious belief.

There is also an account of the first man, Adam, being created from clay and the first woman, Eve, being created from his rib. Some people believe the events happened exactly as stated. Other people interpret these as stories with symbolic meaning, as teachings about the relationships between God or gods, the universe and humans. The whole question of the origin of life then becomes bound to religious belief.

Page 27: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Early Theories of EvolutionEarly Theories of Evolution

Until the late 1700s most scientists believed that the different types of organisms and their characteristics had been fixed for all time. This idea of the ‘fixity of species’ was questioned by the French naturalist Georges Buffon (1707–88) and. Erasmus Darwin (1731–1802), who both suggested that one species could change to another.

Until the late 1700s most scientists believed that the different types of organisms and their characteristics had been fixed for all time. This idea of the ‘fixity of species’ was questioned by the French naturalist Georges Buffon (1707–88) and. Erasmus Darwin (1731–1802), who both suggested that one species could change to another.

Page 28: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Jean Baptiste Lamarck (1744–1829). believed that organisms were guided through their lives by a creative force that enabled them to overcome adverse environmental conditions. Organisms adapted through a struggle to survive.

Jean Baptiste Lamarck (1744–1829). believed that organisms were guided through their lives by a creative force that enabled them to overcome adverse environmental conditions. Organisms adapted through a struggle to survive.

Page 29: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

In 1809 he stated:‘Organs are improved with repeated use and weakened by disuse. Any changes to organs due to the environment ‘are preserved by reproduction [and pass] to the new individuals which arise’.

These changes are acquired characteristics, which Lamarck thought were then passed on to the offspring.

In 1809 he stated:‘Organs are improved with repeated use and weakened by disuse. Any changes to organs due to the environment ‘are preserved by reproduction [and pass] to the new individuals which arise’.

These changes are acquired characteristics, which Lamarck thought were then passed on to the offspring.

Page 30: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Giraffes, for example, stretched their necks to reach food high in the trees. This acquired characteristic (a longer neck) was passed on, so that offspring inherited the characteristic of a longer neck.

Giraffes, for example, stretched their necks to reach food high in the trees. This acquired characteristic (a longer neck) was passed on, so that offspring inherited the characteristic of a longer neck.

Page 31: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Charles Darwin aged 22, took a position as naturalist on the HMS Beagle, a ship commissioned to survey and chart the coast of South America.

For the next five years Darwin observed the geographical distribution of plants, animals, fossils and rocks in various parts of the world. He became convinced that species could develop from a common ancestral type.

Charles Darwin aged 22, took a position as naturalist on the HMS Beagle, a ship commissioned to survey and chart the coast of South America.

For the next five years Darwin observed the geographical distribution of plants, animals, fossils and rocks in various parts of the world. He became convinced that species could develop from a common ancestral type.

Page 32: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Darwin’s FinchesDarwin’s Finches

The Galapagos Islands are about 1000 km off the coast of Ecuador. The islands were effectively isolated from one another by strong ocean currents and a lack of winds blowing from one island to another.

The Galapagos Islands are about 1000 km off the coast of Ecuador. The islands were effectively isolated from one another by strong ocean currents and a lack of winds blowing from one island to another.

Darwin marvelled at the diversity of forms on Darwin marvelled at the diversity of forms on these islands. He also noted some similarity these islands. He also noted some similarity between island organisms and mainland between island organisms and mainland organisms.organisms.

Page 33: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Darwin found 14 species of finches, all with similar colourings, calls, nests, eggs and courtship displays. They differed, however, in habitat, diet, body size and beak shape. Darwin believed these 14 species had come from a common ancestor. He suggested that a few finches had arrived on the islands at some time in the past. These finches showed natural variation in their beak shape. On one island, those with beaks of one shape were better able to feed on the cacti found there. Finches with other beak shapes found it difficult to survive. On other islands, other beak shapes gave some finches a feeding advantage.

Darwin found 14 species of finches, all with similar colourings, calls, nests, eggs and courtship displays. They differed, however, in habitat, diet, body size and beak shape. Darwin believed these 14 species had come from a common ancestor. He suggested that a few finches had arrived on the islands at some time in the past. These finches showed natural variation in their beak shape. On one island, those with beaks of one shape were better able to feed on the cacti found there. Finches with other beak shapes found it difficult to survive. On other islands, other beak shapes gave some finches a feeding advantage.

Page 34: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The birds most suited to their island survived to produce offspring, which inherited that beak shape. This is called ‘survival of the fittest’. The ‘fittest’ were the birds that were able to feed and reach breeding age. The characteristic that gave some beak types an advantage were ‘selected

The birds most suited to their island survived to produce offspring, which inherited that beak shape. This is called ‘survival of the fittest’. The ‘fittest’ were the birds that were able to feed and reach breeding age. The characteristic that gave some beak types an advantage were ‘selectedfor’. Over many generations, the birds on different islands for’. Over many generations, the birds on different islands became sufficiently different from each other to be became sufficiently different from each other to be recognised as a different species.recognised as a different species.

Page 35: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

This shows how different beaks might have been ‘selected’ for the food available on each particular island.

This shows how different beaks might have been ‘selected’ for the food available on each particular island.

Page 36: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Darwins explaination of Giraffes

Darwins explaination of Giraffes

Page 37: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Challenging DarwinChallenging Darwin

Darwin spent 20 years collecting and sorting evidence for his natural selection theory of evolution. It was 1858 that Darwin presented his ideas to the scientific world. He was prompted to publish his work by the publication of a paper by another naturalist, Alfred Russel Wallace (1823–1913).

Wallace had reached a conclusion similar to Darwin’s—that evolution occurs by natural selection. His second paper on evolutionwas presented jointly with Darwin’s in 1858.

Darwin spent 20 years collecting and sorting evidence for his natural selection theory of evolution. It was 1858 that Darwin presented his ideas to the scientific world. He was prompted to publish his work by the publication of a paper by another naturalist, Alfred Russel Wallace (1823–1913).

Wallace had reached a conclusion similar to Darwin’s—that evolution occurs by natural selection. His second paper on evolutionwas presented jointly with Darwin’s in 1858.

Page 38: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Darwin’s major work, titled On the Origin of Species by Natural Selection or Preservation of Favoured Races in the Struggle for Life, was published in 1859. Although all 1250 copies of the first edition sold out within a day, much of the reaction did not support him or his theory.

Darwin’s major work, titled On the Origin of Species by Natural Selection or Preservation of Favoured Races in the Struggle for Life, was published in 1859. Although all 1250 copies of the first edition sold out within a day, much of the reaction did not support him or his theory.

Page 39: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Throughout England, religious leaders denounced his work as heretical or against the word of God. The biblical account held that man was formed in the image of God. How then could he have apes as ancestors?

Although the Church opposed his theory, Darwin was given a state funeral in Westminster Abbey in 1882.

Throughout England, religious leaders denounced his work as heretical or against the word of God. The biblical account held that man was formed in the image of God. How then could he have apes as ancestors?

Although the Church opposed his theory, Darwin was given a state funeral in Westminster Abbey in 1882.

Page 40: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Neo-DarwinismNeo-Darwinism

Darwin’s explanation that evolution occurs through natural selection is one of the most important theories of science and is still regarded as being essentially correct. Darwin’s theory can be restated in terms of modern genetics. This is sometimes called neo-Darwinism.

Evolution is natural selection based upon the natural genetic variation that appears in all populations.

Darwin’s explanation that evolution occurs through natural selection is one of the most important theories of science and is still regarded as being essentially correct. Darwin’s theory can be restated in terms of modern genetics. This is sometimes called neo-Darwinism.

Evolution is natural selection based upon the natural genetic variation that appears in all populations.

Page 41: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Natural selectionNatural selection

Is the process in which the environment ‘selects’ favourable characteristics, reducing the frequency of unfavourable characteristics. This means that after many generations of selection, a species will become better adapted to its environment. Individuals will become highly adapted if their environment doesn’t change. Except for mutations, each individual will be very similar, because the amount of variation will have declined.

Is the process in which the environment ‘selects’ favourable characteristics, reducing the frequency of unfavourable characteristics. This means that after many generations of selection, a species will become better adapted to its environment. Individuals will become highly adapted if their environment doesn’t change. Except for mutations, each individual will be very similar, because the amount of variation will have declined.

Page 42: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Environments are rarely constant, however!Suppose the environment suddenly got colder for a couple of generations of a particular animal. Some individuals within the species may naturally be better able to tolerate the cold, having thicker coats or some other favourable characteristic. They are better suited to the new, colder conditions than the rest of their species. Over time, natural selection would increase the proportion of individuals with this tolerance of the cold and decrease the proportion of those who don’t.

Environments are rarely constant, however!Suppose the environment suddenly got colder for a couple of generations of a particular animal. Some individuals within the species may naturally be better able to tolerate the cold, having thicker coats or some other favourable characteristic. They are better suited to the new, colder conditions than the rest of their species. Over time, natural selection would increase the proportion of individuals with this tolerance of the cold and decrease the proportion of those who don’t.

Page 43: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Natural selection takes several generations to become obvious and so it is extremely difficult to observe in large plants and animals. It is more obvious in organisms that reproduce quickly. Bacteria and insects are two organisms in which natural selection can occur quickly enough to be observed.

Natural selection takes several generations to become obvious and so it is extremely difficult to observe in large plants and animals. It is more obvious in organisms that reproduce quickly. Bacteria and insects are two organisms in which natural selection can occur quickly enough to be observed.

Page 44: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Selection of peppered moths

Selection of peppered moths

Scientists noticed that populations of the peppered moth, were changing from mostly light-coloured to mostly dark-coloured forms

Scientists noticed that populations of the peppered moth, were changing from mostly light-coloured to mostly dark-coloured forms

Page 45: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The change occurred during the Industrial Revolution, when coal-burning factories produced a lot of pollution in the form of soot. When on the soot-darkened trees, the light-coloured form of the moth was easily seen by birds, their main predator. The dark-coloured moth blended with the blackened background,

The change occurred during the Industrial Revolution, when coal-burning factories produced a lot of pollution in the form of soot. When on the soot-darkened trees, the light-coloured form of the moth was easily seen by birds, their main predator. The dark-coloured moth blended with the blackened background, increasing its chances of

survival. The dark colour is an inherited characteristic. Hence, more dark-coloured moths survived to produce dark-coloured offspring.

Page 46: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

After clean-air regulations were implemented, lichen began to regrow on tree trunks and the trees returned to their original paler colouring.

After clean-air regulations were implemented, lichen began to regrow on tree trunks and the trees returned to their original paler colouring.

Moth populations in many of these areas have shifted back towards the light-coloured forms

Page 47: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Selection and rabbit control

Selection and rabbit control

In Australia, rabbits overran the land for many years. The myxoma virus, carried by fleas and mosquitoes, was released in Australia in December 1950 to control the rabbit population. Within two months, 90% of rabbits in certain areas had died. Ten years later over 99% of infected rabbits were dead. This means less than 1% of

In Australia, rabbits overran the land for many years. The myxoma virus, carried by fleas and mosquitoes, was released in Australia in December 1950 to control the rabbit population. Within two months, 90% of rabbits in certain areas had died. Ten years later over 99% of infected rabbits were dead. This means less than 1% ofrabbits infected with the virus survived. Ten years later,

only 25% of rabbits in those same areas would die as a result of the virus, and around 40% of those infected with the virus would survive.

Page 48: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

These dramatic changes were the result of natural selection acting on the rabbits. The resistant rabbits would have survived the initial myxoma spread, and produced offspring with an inherited resistance. A healthy rabbit may produce seven or more litters of

These dramatic changes were the result of natural selection acting on the rabbits. The resistant rabbits would have survived the initial myxoma spread, and produced offspring with an inherited resistance. A healthy rabbit may produce seven or more litters ofyoung per year, and therefore young per year, and therefore

within a few years the number of within a few years the number of resistant rabbits would have resistant rabbits would have increased dramatically.increased dramatically.

Page 49: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Selection and diseasesSelection and diseases

There have also been several well documented cases of populations acquiring resistance to introduced chemicals. Mosquitoes, which carry the diseases yellow fever and malaria, were treated with

chemical pesticides.

There have also been several well documented cases of populations acquiring resistance to introduced chemicals. Mosquitoes, which carry the diseases yellow fever and malaria, were treated with

chemical pesticides. By natural selection, populations of mosquitoes with a natural By natural selection, populations of mosquitoes with a natural resistance to the pesticides developed over the 20-year period resistance to the pesticides developed over the 20-year period following the introduction of the pesticides into their environment. following the introduction of the pesticides into their environment. Similarly, many bacteria are now resistant to certain types of Similarly, many bacteria are now resistant to certain types of antibiotics.antibiotics.

Page 50: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

SuperbugsSuperbugs

When penicillin was first introduced it was very effective in treating infections caused by golden staph. Now, a new stain of Staph is resistant to it as well as around twenty other substances, including antibiotics, antiseptics and disinfectants. Recently, several strains of Staph have become resistant to the drug of last resort—vancomycin. If vancomycin fails, the death rate from Staph will rise dramatically.

When penicillin was first introduced it was very effective in treating infections caused by golden staph. Now, a new stain of Staph is resistant to it as well as around twenty other substances, including antibiotics, antiseptics and disinfectants. Recently, several strains of Staph have become resistant to the drug of last resort—vancomycin. If vancomycin fails, the death rate from Staph will rise dramatically.

Page 51: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

SpeciationSpeciation

A species is defined as a group of organisms that normally interbreed in nature to produce fertile offspring. The formation of a new species is called speciation. Natural selection over long periods of time, combined with other factors such as isolation and mutations, can lead to new species forming.

A species is defined as a group of organisms that normally interbreed in nature to produce fertile offspring. The formation of a new species is called speciation. Natural selection over long periods of time, combined with other factors such as isolation and mutations, can lead to new species forming.

Page 52: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Geographic isolationGeographic isolation The first step in speciation is

geographic isolation of the populations. Suppose a particular population of rabbits. If the environments differed on each side of the river, each population would change through natural selection and the occasional genetic mutation. Eventually the two rabbit populations would have their own characteristics, sufficiently different from each other to be called a variety, or subspecies. Subspecies appear different but are still capable of interbreeding.

The first step in speciation is geographic isolation of the populations. Suppose a particular population of rabbits. If the environments differed on each side of the river, each population would change through natural selection and the occasional genetic mutation. Eventually the two rabbit populations would have their own characteristics, sufficiently different from each other to be called a variety, or subspecies. Subspecies appear different but are still capable of interbreeding.

Page 53: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Reproductive isolationReproductive isolation

If the isolation of the populations was long enough, the change might be sufficient to make them incapable of interbreeding.

If the isolation of the populations was long enough, the change might be sufficient to make them incapable of interbreeding.

They would then have reproductive isolation. At this point a new species has emerged.

They would then have reproductive isolation. At this point a new species has emerged.

Page 54: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Factors that might cause reproductive isolation are:

• a change in colour patterns so that mates are no longer recognised

• seasonal differences in mating times

• a changed chromosome which prevents the sperm of one group from fertilising eggs of the other.

Factors that might cause reproductive isolation are:

• a change in colour patterns so that mates are no longer recognised

• seasonal differences in mating times

• a changed chromosome which prevents the sperm of one group from fertilising eggs of the other.

Page 55: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Types of evolutionTypes of evolution

Page 56: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Divergent evolutionDivergent evolution

The Galapagos Island finches and the geographically isolated rabbits illustrate the idea that many new forms can evolve from a single ancestor. This is known as divergent evolution.

The Galapagos Island finches and the geographically isolated rabbits illustrate the idea that many new forms can evolve from a single ancestor. This is known as divergent evolution.

Page 57: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The idea is that new environments are inhabited, causing the evolution of new species. Divergent evolution results in a phenomenon known as adaptive radiation. As the ancestral organisms adapt and evolve in their different environments, they take on new forms. Australia’s marsupial ancestors have evolved and radiated into many different forms, from tree-dwelling, fruit-eating possums to blind, meat-eating underground moles, and the more familiar kangaroos and koalas.

The idea is that new environments are inhabited, causing the evolution of new species. Divergent evolution results in a phenomenon known as adaptive radiation. As the ancestral organisms adapt and evolve in their different environments, they take on new forms. Australia’s marsupial ancestors have evolved and radiated into many different forms, from tree-dwelling, fruit-eating possums to blind, meat-eating underground moles, and the more familiar kangaroos and koalas.

Page 58: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Convergent evolutionConvergent evolution

Or convergence, occurs when organisms evolve and end up having similar adaptations. This is due to:

• living in similar environments, and• having similar habitats and lifestyles.In similar habitats the same types of characteristics are ‘selected for’,

resulting in organisms that look similar despite having very different genes. These organisms may have analogous structures, structures that look similar but which have come from different ancestors. One example is the gliding membrane found between the limbs of Australia’s gliding possums and also found in the flying squirrels of North America, Europe and Asia.

Or convergence, occurs when organisms evolve and end up having similar adaptations. This is due to:

• living in similar environments, and• having similar habitats and lifestyles.In similar habitats the same types of characteristics are ‘selected for’,

resulting in organisms that look similar despite having very different genes. These organisms may have analogous structures, structures that look similar but which have come from different ancestors. One example is the gliding membrane found between the limbs of Australia’s gliding possums and also found in the flying squirrels of North America, Europe and Asia.

Page 59: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Parallel evolutionParallel evolution

A third type of evolution is parallel evolution, which occurs where related species evolve similar features while separated from each other. The result is organisms that look alike and have common ancestry, but are found in different locations.

Old and New World monkeys share many features. New World monkeys like the vervet (bottom left) have prehensile tails to hold onto branches, whereas Old World monkeys lack prehensile tails since they have evolved to live on the ground.

A third type of evolution is parallel evolution, which occurs where related species evolve similar features while separated from each other. The result is organisms that look alike and have common ancestry, but are found in different locations.

Old and New World monkeys share many features. New World monkeys like the vervet (bottom left) have prehensile tails to hold onto branches, whereas Old World monkeys lack prehensile tails since they have evolved to live on the ground.

Page 60: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Evidence for Evolution Evidence for Evolution

Page 61: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The fossil recordThe fossil record

Direct evidence for evolution comes from palaeontology, the study of fossils. The fossil record from all over the world provides evidence of continual changes in life forms from over 3500 million years ago until the present. Fossils are the preserved evidence of past life usually found in sedimentary rocks.

Direct evidence for evolution comes from palaeontology, the study of fossils. The fossil record from all over the world provides evidence of continual changes in life forms from over 3500 million years ago until the present. Fossils are the preserved evidence of past life usually found in sedimentary rocks.

Page 62: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Fossils may be the:

• actual remains of organisms (e.g. mammoths frozen in ice, insects trapped in a type of sap called amber)

Fossils may be the:

• actual remains of organisms (e.g. mammoths frozen in ice, insects trapped in a type of sap called amber)

Page 63: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

hard parts of organisms (e.g. shells, teeth and bones)

hard parts of organisms (e.g. shells, teeth and bones)

Page 64: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

impressions of organisms (e.g. hollowed casts, moulds where substances have replaced the organism)

impressions of organisms (e.g. hollowed casts, moulds where substances have replaced the organism)

Page 65: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

evidence of the presence of organisms (e.g. footprints).

evidence of the presence of organisms (e.g. footprints).

Page 66: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The ages of fossils, and the rocks in which they are found, can be estimated using radioisotope-dating techniques. These techniques have enabled scientists to devise a geological time scale, dividing the history of the Earth into eras. These eras are subdivided into periods, which are further subdivided into epochs.

The ages of fossils, and the rocks in which they are found, can be estimated using radioisotope-dating techniques. These techniques have enabled scientists to devise a geological time scale, dividing the history of the Earth into eras. These eras are subdivided into periods, which are further subdivided into epochs.

Page 67: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Using the fossil recordUsing the fossil record

The fossil record allows us to trace major events in the history of life on Earth. Life seems to have begun around 3500 million years ago. The first organisms were probably simple, single-celled, anaerobic (no oxygen was available) bacteria which fed on organic compounds in the primitive seas. Later, photosynthetic bacteria and blue-green algae appeared, releasing oxygen into the atmosphere. This oxygen release allowed ozone (O3) to form and accumulate, screening out some of the ultraviolet (UV) radiation. This gave some safety to the newly evolving organisms.

The fossil record allows us to trace major events in the history of life on Earth. Life seems to have begun around 3500 million years ago. The first organisms were probably simple, single-celled, anaerobic (no oxygen was available) bacteria which fed on organic compounds in the primitive seas. Later, photosynthetic bacteria and blue-green algae appeared, releasing oxygen into the atmosphere. This oxygen release allowed ozone (O3) to form and accumulate, screening out some of the ultraviolet (UV) radiation. This gave some safety to the newly evolving organisms.

Page 68: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

An explanation for the appearance of life?

An explanation for the appearance of life?

to create complex organic molecules, which collected in pools to form an ‘organic soup’. Over millions of years this ‘organic soup’ became concentrated, more complex molecules formed and the first cells appeared.

to create complex organic molecules, which collected in pools to form an ‘organic soup’. Over millions of years this ‘organic soup’ became concentrated, more complex molecules formed and the first cells appeared.

One hypothesis to explain the initial appearance of life was put forward by a Russian scientist, A.J. Oparin, in 1924. The early atmosphere is thought to have consisted of gaseous methane (CH4), ammonia (NH3), hydrogen (H2) and water vapour (H2O). Energy from lightning, ultraviolet rays or gamma rays split some of these gas molecules. New bonds formed

One hypothesis to explain the initial appearance of life was put forward by a Russian scientist, A.J. Oparin, in 1924. The early atmosphere is thought to have consisted of gaseous methane (CH4), ammonia (NH3), hydrogen (H2) and water vapour (H2O). Energy from lightning, ultraviolet rays or gamma rays split some of these gas molecules. New bonds formed

Page 69: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

In 1953, S. Miller and H. Urey tested the idea in a laboratory experiment at the University of Chicago. Electric sparks were passed into a gas mixture that was thought to be similar to the early atmosphere of the Earth. Organic molecules were produced! No experiments, however, produced a living cell.

In 1953, S. Miller and H. Urey tested the idea in a laboratory experiment at the University of Chicago. Electric sparks were passed into a gas mixture that was thought to be similar to the early atmosphere of the Earth. Organic molecules were produced! No experiments, however, produced a living cell.The Miller/Urey experiment. Given suitableThe Miller/Urey experiment. Given suitable conditions conditions

molecules can combine to form organic molecules.molecules can combine to form organic molecules.

Page 70: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

More complex life evolves

More complex life evolves

Around 1500 million years ago, organisms with more complex cellular structure appeared. Sexual reproduction appears to have begun at around this time. Organisms recognisable as animals appeared around 600 million years ago. Thousands of specimens of these invertebrates have been collected from sandstone deposits at Ediacara, in the hills north of Adelaide. They are possibly related to present-day jellyfish and earthworms

Around 1500 million years ago, organisms with more complex cellular structure appeared. Sexual reproduction appears to have begun at around this time. Organisms recognisable as animals appeared around 600 million years ago. Thousands of specimens of these invertebrates have been collected from sandstone deposits at Ediacara, in the hills north of Adelaide. They are possibly related to present-day jellyfish and earthworms

Page 71: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

From bacteria to humans

From bacteria to humans

An abundance of fossils from the Palaeozoic era (570 to 248 million years ago) show the existence of bacteria, algae, soft-bodied invertebrates and representatives from

An abundance of fossils from the Palaeozoic era (570 to 248 million years ago) show the existence of bacteria, algae, soft-bodied invertebrates and representatives from all the major animal

groups we know today. Characteristic organisms from the earliest Palaeozoic era were the trilobites. The earliest known land organisms (vascular plants) appeared around 400 million years ago.

all the major animal groups we know today. Characteristic organisms from the earliest Palaeozoic era were the trilobites. The earliest known land organisms (vascular plants) appeared around 400 million years ago.

Page 72: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The first land vertebrates (amphibians) appeared slightly later. At this time the greatest diversity and number of species lived in the sea. The Mesozoic era (248 to 65 million years ago) is often called the age of the reptiles because of the abundance and diversity of reptilian forms (including dinosaurs) that lived in this era. The earliest mammals, flowering plants and birds also appeared in this era.

The first land vertebrates (amphibians) appeared slightly later. At this time the greatest diversity and number of species lived in the sea. The Mesozoic era (248 to 65 million years ago) is often called the age of the reptiles because of the abundance and diversity of reptilian forms (including dinosaurs) that lived in this era. The earliest mammals, flowering plants and birds also appeared in this era.

Page 73: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Fossils from the most recent era, the Cenozoic era (from 65 million years ago), show the increasing dominance of mammals and the appearance of humans (200 000 years ago).

Fossils from the most recent era, the Cenozoic era (from 65 million years ago), show the increasing dominance of mammals and the appearance of humans (200 000 years ago).

Page 74: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

A changing recordA changing record

The fossil record provides evidence of continual change. A vast number and variety of species have emerged from the earliest life forms. Whole groups of organisms have appeared, become abundant and then disappeared.

The fossil record provides evidence of continual change. A vast number and variety of species have emerged from the earliest life forms. Whole groups of organisms have appeared, become abundant and then disappeared.

Page 75: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Some of these changes include:Dramatic climate change and altered sea levels may have caused the disappearance of 50% of all shallow-water marine invertebrates around 225 million years ago.

Some of these changes include:Dramatic climate change and altered sea levels may have caused the disappearance of 50% of all shallow-water marine invertebrates around 225 million years ago.

Page 76: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The impact of a large asteroid, and consequent dust storms, are thought to have caused the extinction of the dinosaurs around 65 million years ago.

The impact of a large asteroid, and consequent dust storms, are thought to have caused the extinction of the dinosaurs around 65 million years ago.

Page 77: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Other organisms, like club mosses and jawfish, have appeared, been abundant, but now survive in small numbers only.

Other organisms, like club mosses and jawfish, have appeared, been abundant, but now survive in small numbers only.

Page 78: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Others, like the flowering plants, insects, mammals and birds, were present in small numbers for some time, then became abundant.

Others, like the flowering plants, insects, mammals and birds, were present in small numbers for some time, then became abundant.

Page 79: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Mammals increased dramatically after the demise of the dinosaurs.

Mammals increased dramatically after the demise of the dinosaurs.

Page 80: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

An incomplete record?An incomplete record?

The fossil record is, however, far from complete. Only a small proportion of the plant and animal species thought to have existed are preserved as fossils. While the fossil history of aquatic organisms is extensive and detailed, the fossil history of land animals is far less so. Fossilisation is a rare occurrence. Organisms must ‘fall’ into conditions where decay does not occur. The soft tissues of organisms usually do not form fossils.

The fossil record is, however, far from complete. Only a small proportion of the plant and animal species thought to have existed are preserved as fossils. While the fossil history of aquatic organisms is extensive and detailed, the fossil history of land animals is far less so. Fossilisation is a rare occurrence. Organisms must ‘fall’ into conditions where decay does not occur. The soft tissues of organisms usually do not form fossils.

Page 81: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Fossilisation is more likely in seas, lakes, swamps and caves, but unlikely on land. Geological processes, and human activity, are constantly moving and destroying the sedimentary rocks that contain fossils.

Fossilisation is more likely in seas, lakes, swamps and caves, but unlikely on land. Geological processes, and human activity, are constantly moving and destroying the sedimentary rocks that contain fossils.

Page 82: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Fossil evidence shows an excellent record for the evolutionary development of some organisms such as the horse.

Fossil evidence shows an excellent record for the evolutionary development of some organisms such as the horse.

Page 83: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Transitional formsTransitional forms

Provide the links between the major groups, such as the air-breathing crossopterygian fish, and the bird-like reptile, Archaeopteryx.

For many groups of organisms there are large gaps in the fossil record, often with no transitional forms being found.

Provide the links between the major groups, such as the air-breathing crossopterygian fish, and the bird-like reptile, Archaeopteryx.

For many groups of organisms there are large gaps in the fossil record, often with no transitional forms being found.

Page 84: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Anatomical studiesAnatomical studies

Comparisons of the anatomy of various plants and animals provide indirect evidence of their evolution from common ancestors. The front flipper of a seal, a cat’s paw, a horse’s front leg, a bat’s wing and your own hand all look different and perform different functions.

Comparisons of the anatomy of various plants and animals provide indirect evidence of their evolution from common ancestors. The front flipper of a seal, a cat’s paw, a horse’s front leg, a bat’s wing and your own hand all look different and perform different functions.

Page 85: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

However, they all consist of the same number of bones, muscles, nerves and blood vessels arranged in a similar basic pattern. The basic pentadactyl limb (a limb with five digits) can be traced back to

However, they all consist of the same number of bones, muscles, nerves and blood vessels arranged in a similar basic pattern. The basic pentadactyl limb (a limb with five digits) can be traced back tothe fins of certain fish from which the first amphibians are thought the fins of certain fish from which the first amphibians are thought to have evolved. These fundamentally similar structures are to have evolved. These fundamentally similar structures are called called homologous structureshomologous structures. The differences seen in the . The differences seen in the structures may reflect adaptations to different environmental structures may reflect adaptations to different environmental conditions. Their similarity strongly suggests a common ancestor.conditions. Their similarity strongly suggests a common ancestor.

Page 86: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The distribution of plants and animals

The distribution of plants and animals

Biogeography is the study of the distribution of plants and animals, both now and in the past. As Darwin saw in the Galapagos Islands, the organisms found on oceanic islands resemble those living on the nearest mainland, yet include species found nowhere else. As oceanic islands have never been attached to the mainland, their inhabitants are thought to have somehow arrived from the mainland, to then evolve in isolation.

Biogeography is the study of the distribution of plants and animals, both now and in the past. As Darwin saw in the Galapagos Islands, the organisms found on oceanic islands resemble those living on the nearest mainland, yet include species found nowhere else. As oceanic islands have never been attached to the mainland, their inhabitants are thought to have somehow arrived from the mainland, to then evolve in isolation.

Page 87: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Genetic evidenceGenetic evidence

The structure of DNA and the genetic code provide us with more evidence for evolution. Comparisons of DNA are used to provide evidence of how closely different species are related. For example, the genetic make-up of a chimpanzee is 98.5% identical to that of a human. Gorilla DNA matches human DNA except for the last 2.6%. The genetic make-up of other primates is also similar to our own.

The structure of DNA and the genetic code provide us with more evidence for evolution. Comparisons of DNA are used to provide evidence of how closely different species are related. For example, the genetic make-up of a chimpanzee is 98.5% identical to that of a human. Gorilla DNA matches human DNA except for the last 2.6%. The genetic make-up of other primates is also similar to our own.

Page 88: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Human EvolutionHuman Evolution

Evidence from the fossil record and other studies supports the theory that modern humans evolved from a common ape-like ancestor. The evidence suggests that there have been many species of humans, some of which have become extinct, while others evolved into modern humans.

Evidence from the fossil record and other studies supports the theory that modern humans evolved from a common ape-like ancestor. The evidence suggests that there have been many species of humans, some of which have become extinct, while others evolved into modern humans.

Page 89: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Humans belong to the order Primates and have many of the features of the primate group. Primates (including us) have:

• forward-facing eyes that allow binocular vision

• pentadactyl digits (five fingers/toes on each limb)

• four upper and four lower incisor teeth

• opposable thumbs (for grasping things)

• nails (not claws) on the fingers and toes

• large brains for their body size• a flexible skeleton, with arms that

rotate in the shoulder socket to allow them to reach behind their body

Humans belong to the order Primates and have many of the features of the primate group. Primates (including us) have:

• forward-facing eyes that allow binocular vision

• pentadactyl digits (five fingers/toes on each limb)

• four upper and four lower incisor teeth

• opposable thumbs (for grasping things)

• nails (not claws) on the fingers and toes

• large brains for their body size• a flexible skeleton, with arms that

rotate in the shoulder socket to allow them to reach behind their body

Page 90: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Humans are unusual, as we also:• walk upright (are bipedal)• have fewer and smaller teeth

than the apes• have a flattened face• have a very large skull capacity,

and large brain, about three times larger than that of apes

• make and use tools• use various verbal and visual

languages to communicate• are self-aware.

Humans are unusual, as we also:• walk upright (are bipedal)• have fewer and smaller teeth

than the apes• have a flattened face• have a very large skull capacity,

and large brain, about three times larger than that of apes

• make and use tools• use various verbal and visual

languages to communicate• are self-aware.

Page 91: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Evolution of humansEvolution of humans

Our distant relatives Dryopithecus, an ape-like

animal that first appeared 25 million years ago. Ramapithecus, another ape-like animal, appeared 14–16 million years ago and lasted another 6 million years. Some believe Ramapithecus to be the ancestor of the Asian orang-utan, while others see a relationship to other apes and humans.

Our distant relatives Dryopithecus, an ape-like

animal that first appeared 25 million years ago. Ramapithecus, another ape-like animal, appeared 14–16 million years ago and lasted another 6 million years. Some believe Ramapithecus to be the ancestor of the Asian orang-utan, while others see a relationship to other apes and humans.

Page 92: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The first true ‘human-like’ fossils belong to the genus Australopithecus (meaning ‘southern ape’, after the first fossils found in South Africa). They are around 4–5 million years old.. These species were fully bipedal, walked on two legs, and had a brain size of 400 cm3, less than one-third that of modern humans.

All fossil australopithecines have been found in Africa. One of the most famous is a 40% complete skeleton of a female named Lucy.

The first true ‘human-like’ fossils belong to the genus Australopithecus (meaning ‘southern ape’, after the first fossils found in South Africa). They are around 4–5 million years old.. These species were fully bipedal, walked on two legs, and had a brain size of 400 cm3, less than one-third that of modern humans.

All fossil australopithecines have been found in Africa. One of the most famous is a 40% complete skeleton of a female named Lucy.

Page 93: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

More recent ancestorsMore recent ancestors

The first clear representation of the Homo line is Homo habilis (‘handy man’). Fossils found in East Africa dating to 1.5–2 million years ago reveal major anatomical and behavioural changes from Australopithecus afarensis. The brain size was 50% larger, and they used tools.

The first clear representation of the Homo line is Homo habilis (‘handy man’). Fossils found in East Africa dating to 1.5–2 million years ago reveal major anatomical and behavioural changes from Australopithecus afarensis. The brain size was 50% larger, and they used tools.

Page 94: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Homo erectus (‘upright man’) came next. Although fossils have been found in Europe, China and Africa, Homo erectus is often called ‘Java man’, after the initial discovery site. The oldest fossils are 1.5 million years old. Homo erectus had an average brain size of 1000 cm3, lived in caves and used fire.

Homo erectus (‘upright man’) came next. Although fossils have been found in Europe, China and Africa, Homo erectus is often called ‘Java man’, after the initial discovery site. The oldest fossils are 1.5 million years old. Homo erectus had an average brain size of 1000 cm3, lived in caves and used fire.

Page 95: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The evolution of Homo erectus into Homo sapiens (‘intelligent man’) is the subject of considerable debate. Some maintain that Homo erectus evolved worldwide into Homo sapiens but retained local features. This gave rise to different forms in different areas, such as Asia and Africa. Others maintain that Homo sapiens evolved in Africa, and spread from there some 200 000 years ago. This would mean that all present-day variation in humans has arisen in the past 200 000 years.

The evolution of Homo erectus into Homo sapiens (‘intelligent man’) is the subject of considerable debate. Some maintain that Homo erectus evolved worldwide into Homo sapiens but retained local features. This gave rise to different forms in different areas, such as Asia and Africa. Others maintain that Homo sapiens evolved in Africa, and spread from there some 200 000 years ago. This would mean that all present-day variation in humans has arisen in the past 200 000 years.

Page 96: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Other fossil humansOther fossil humans

Homo neanderthalensis (‘Neanderthal man’), is thought to be approximately 35 000–100 000 years old. The Neanderthals were cave dwellers who used tools and buried their dead, indicating some religious beliefs. They are thought to have become extinct due to a change in climate or through competition with other human species in Europe. The common ancestor of humans and Neanderthals probably lived in Europe around 600 000 years ago.

Homo neanderthalensis (‘Neanderthal man’), is thought to be approximately 35 000–100 000 years old. The Neanderthals were cave dwellers who used tools and buried their dead, indicating some religious beliefs. They are thought to have become extinct due to a change in climate or through competition with other human species in Europe. The common ancestor of humans and Neanderthals probably lived in Europe around 600 000 years ago.

Page 97: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

‘Cro-Magnon man’ (10 000–40 000 years old) was a nomadic hunter-gatherer who used tools and developed art. Anatomically Cro-Magnons were similar to modern humans, but more robust. Cro-Magnons lived in Europe and the exact reasons for their extinction are not known.

‘Cro-Magnon man’ (10 000–40 000 years old) was a nomadic hunter-gatherer who used tools and developed art. Anatomically Cro-Magnons were similar to modern humans, but more robust. Cro-Magnons lived in Europe and the exact reasons for their extinction are not known.

Page 98: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth
Page 99: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

Cultural evolutionCultural evolution

Humans have changed in many non-physical ways. We have learned how to use tools, and have developed speech, forms of writing, artistic creativity, reasoning powers and a sense of right and wrong. It is these changes that most distinguish modern humans from their ancestors. Humans have highly complex social structures, and an accumulation of learning and knowledge. This stored experience is passed from generation to generation, and affects survival—that is, a type of cultural evolution occurs.

Humans have changed in many non-physical ways. We have learned how to use tools, and have developed speech, forms of writing, artistic creativity, reasoning powers and a sense of right and wrong. It is these changes that most distinguish modern humans from their ancestors. Humans have highly complex social structures, and an accumulation of learning and knowledge. This stored experience is passed from generation to generation, and affects survival—that is, a type of cultural evolution occurs.

Page 100: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth

The ultimate fate of most species appears to be extinction. Homo habilis lasted for around 1 million years, Homo erectus around 1.5 million. Modern humans have existed for about 200 000 years. With cultural evolution, humans continue to acquire knowledge, enabling them to exert more control over their environment than any other species ever has, but we have probably done more damage also.

The ultimate fate of most species appears to be extinction. Homo habilis lasted for around 1 million years, Homo erectus around 1.5 million. Modern humans have existed for about 200 000 years. With cultural evolution, humans continue to acquire knowledge, enabling them to exert more control over their environment than any other species ever has, but we have probably done more damage also.

It is estimated It is estimated that of all the that of all the animal species animal species that have ever that have ever existed, only 1% existed, only 1% are alive now.are alive now.

Page 101: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth
Page 102: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth
Page 103: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth
Page 104: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth
Page 105: Evolution Year 10 Topic 4. Evolution Nearly two million different kinds of plants, animals and micro- organisms are known to be currently living on Earth