The theory of evolution states that living things have adapted and changed over time. This theory suggests that all living things developed from earlier types. All living organisms have changed from as they were millions of years ago. This is due to changes and adaptations. Organisms adapt to changing environments. This theory grew from studying living organisms and fossils. Fossils provide us with an insight into the types of animals and plants that existed many years ago. 

Charles Darwin proposed the theory of evolution. 

Is the theory of evolution true or false?

It is important to note that this is just a theory which means it is not a fact or a scientific law. Many scientists accept the theory of evolution; however, many reject it.

A common misconception is that humans evolved from apes, although this is not the case. Humans didn’t evolve from apes; however, some believe we share common ancestors that lived millions of years ago. It is also true that organisms are still evolving. Some changes take thousands of years, some take millions of years, and some take less time.

Many people believe there is a contradiction between religion and science. Contrary to this, some people believe that religion and science are compatible as evolution is not about the origins of life; rather, it is about how organisms change over time.

So how does evolution happen? 

Living things with useful adaptations survive and reproduce. The offspring inherit these adaptations and develop their own adaptations through mutations. This process continues over time, and the adaptations become focused on the needs of the environment. 

Natural selection is known as survival of the fittest. This plays an important role in evolution. It is essentially  the process in which the best-adapted organisms are able to survive and reproduce. Desirable characteristics are passed down from the parents to the offspring, so advantageous alleles are passed onto the offspring. An organism’s genes code for different traits, such as how the organism looks, its behaviour, and its structure. Genes copy themselves in order to make new cells. During the process of making new cells, mistakes can occur that changes the genetic code; these are called mutations. Mutations can either harm the organism, have no impact on the organism, or they can help the organism to survive and reproduce.  

Species that are not adapted will be at risk of becoming extinct. This can occur due to new predators, disease, destruction of habitats, change in the environment, or increased competition for resources.

What is an example of a well-adapted animal?

Camels are well-adapted animals. They live in the desert. Camels gave thick fur on the top of their body for shade, and they have thin fur everywhere else to allow easy heat loss. They are well camouflaged, and they have humps to store fat. Camels also have a large surface area to volume ratio to maximise heat loss. Their large feet help them to walk on hot sand. This helps to spread their weight on the sand so they don’t sink into the sand. Their long thick eyelashes protect their eyes from the sand. Camels have slit like nostrils which also helps keep out sand. They are able to tolerate high body temperatures. Camels can drink gallons of water in one go and they can also go a long time without water. Lastly camels lose very little water through urination and perspiration. 

What is an example of a well-adapted plant?

Cacti are well-adapted plants. They are adapted for survival in the desert. Cacti have long roots that spread over a wide area to find water. Their large stems help to store water. Cacti have thick waxy skin that helps them reduce water loss and to reflect heat. Their needle-like spines help to reduce water loss, this is because the spines minimise surface area, therefore reducing water loss by transpiration. Spines also protect the cacti from animals that might eat them. Cacti can lie dormant for many years until rain falls. 

The colour change in peppered moths is an example of natural selection. 

At first peppered moths varied in colour, some were light, and some were dark. Light moths were at an advantage because this allowed them to camouflage against the pale trees. This allowed them to survive and reproduce; however, moths with a mutant black colouring were easily spotted and eaten by birds.

During the industrial revolution, many factories were built and the burning of coal for fuel resulted in dark smoke covering the environment. This resulted in the darkening of trees, which meant that the light-coloured moths were easily spotted on the darker trees as they could no longer camouflage. So the darker-coloured moths were able to camouflage which resulted in them living longer and passing on the gene to their offspring. 

Fossils are remains of plants and animals that are imprinted in rocks. Scientists are able to identify changes that have occurred to plants and animals over time. 

Fossilisation is the process by which a fossil is formed, this process requires specific conditions. Fossils are mostly found in sedimentary rocks. 

Palaeontologists are the people who study fossils. As they study fossils from thousands of years ago, they are able to piece together the similarities and differences between organisms. This allows them to understand how the process of evolution occurred.

A common misconception is that humans evolved from apes, although this is not the case. Even though humans and apes share some common characteristics, humans didn’t evolve from apes; however, some believe we share common ancestors that lived millions of years ago. It is also true that organisms are still evolving. Some changes take thousands of years, some take millions of years, and some take less time.

The fossil record is the record in which palaeontologists document the placement of animals and plant fossils.

Many of the fossils found were marine animals because they lived in the sea. The sand and mud below the sea buried their remains quickly after they died. 

Many dinosaur fossils have been which provide evidence that dinosaurs existed a long time ago. 

How are fossils formed? 

Fossils require specific conditions in order for them to form. When an animal dies the dead remains sink to the ground and slowly get covered in mud and sand. The soft parts of its body decompose leaving the hard parts such as the skeleton. Over time more layers of sediment form on top and the sediment around the skeleton starts to compact and turn into rock. The bones then begin to dissolve in water. The minerals in the water replace the bone which leaves a print of the animal on the rock.  

Fossils provide us with evidence of extinct animals such as dinosaurs and mammoths. 

There are different ways of describing fossil preservation: 

• Compression 
• Petrification 
• Moulds and casts
• Preserved remains 

Compression is the process in which a dark imprint of the is fossil preserved in sedimentary rock that has undergone physical compression due to high-pressure forces. 

Petrification is the process in which organic matter is exposed to minerals. Over long periods of time, it is turned into a stony substance. 

Moulds are produced where the original bone or shell is dissolved, leaving a space in the shape of the original material. Over time sediment can fill the space to form a cast. 

Preserved remains are rare as it is the preservation of the original soft body or skeleton of organisms.