Darwin

Theory Development

Charles Darwin and Alfred Wallace independently proposed a theory of evolution whilst collecting a range of evidence towards it (they separately came up with the same idea at a similar time).

20 years after their independent work, they collaborated and published their scientific ideas in 1858.

They proposed the idea that all species of living things have evolved from simple life forms over a long period of time. There is a lot of scientific research to suggest that living things existed, billions of years ago.

Theory of Evolution

The theory of evolution __suggests that it happens through __natural selection:

1. There is a lot of variation within a single species, and that is due to genetic variation and mutations (which can also be inherited).
2. Species__ compete__, and only the strongest, or the one with the most desirable characteristics will survive.
3. Their genes have allowed them to be successful in their environment - and this would be__ passed onto their offspring__.
4. Through time, the species with the more ideal characteristics will evolve, and the species with the less ideal characteristics will die off.

Resistant Organisms

The theory of natural selection is demonstrated through bacteria.

Bacteria reproduces rapidly, therefore allowing them to evolve rapidly too. When there are mutations of bacteria, new strains are created.

When certain bacteria become resistant to antibiotics, they are cannot be destroyed by the antibiotic as they are __resistant __towards it. The bacteria that is resistant to the antibiotics will reproduce rapidly, as the bacteria without the mutation will die off.

This means that the person that is taking the antibiotics will become even more poorly as they have more bacteria that is stronger and does not respond to the first round of antibiotics.

Fossils

Fossils are the remains of organisms that were alive millions of years ago. This supports the theory of evolution as we can see how organisms have developed through the years.

1. Ardi is a female human-like fossilised skeleton from 4.4 million years ago. She has bones that suggest that she was able to walk upright, but she had long arms and long big toes.
2. Lucy is a female human-like fossilised skeleton from 3.2 million years ago. She has bones that suggest that she was able to walk upright, and had a small skull like an ape. Her foot was similar to the modern foot, but her toes were curved.
3. Mary and Louis Leakey found fossils from around__ 1.6 million years ago__, and they were thought to resemble a modern human more than Ardi and Lucy. This suggests that human evolution has taken place through the years.

Stone Tools

Tools that were used by the humans in the past also supports the idea of evolution.

1. Flint hand axes were found, and it is predicted that they were used around 10,000 to 2.5 million years ago.
2. Arrowheads, which are more advanced have been found, and it is thought that they were used around 6,000 __to __10,000 years ago.

It is helpful to look at the__ development of stone tools over time__, as it shows that humans have evolved to create better tools using their skills.

Dating of these objects can be done by looking at the layers of sediment around the tool. Archaeologists can also use radiocarbon dating or other specialised techniques to look at elements such as iron and potassium. They assume that the found tools are approximately as old as the rock which surrounds it.

Pentadactyl Limbs

Although different species of vertebrates look different, their bone structure is actually quite similar.

Vertebrates have a pentadactyl limb - this means that they are five fingered.

This suggests that many vertebrates may have descended from the same common ancestor. This is evidence towards the theory of evolution.

Back in the day, horses with smaller feet were usually faster in marshy grounds. They would be the ones to escape from predators. This allowed them to evolve, therefore creating offspring that had small feet. Nowadays, horses have evolved to be much smaller as they no longer need to run from predators, as they have now become taller and stronger.

What does it mean if a vertebrate has pentadactyl limbs?

Your answer should include: 5 / five / fingers

Give two examples of stone tools that were used in the past:

Your answer should include: Flint hand axes / arrowheads

Which two famous scientists worked together to create the theory of evolution?

Your answer should include: Charles Darwin / Alfred Wallace