Theory Of Evolution - EXPLAINED

THEORY OF EVOLUTION NEW SCIENTIST

The In Depth Explanation of the Theory of Evolution

Theory of Evolution

Contents:

Biological Evolution

> Biological Evolution

> Biological Evolution is the process through which the characteristics of organisms change over successive generations, due to natural selection and genetic variation. It is also referred to as “Changes in gene frequencies in Populations”.

> Fossil Record

- Relation to the Age of the Earth - Relation to how long the Earth has been Evolving - Dating Methods - What and How

> Natural Selection

- What it is - How it Changes Populations

> Speciation - What it is

- How Genes and environment factors affect the survival of Organisms

> Accuracy of Evolution Theory > Case Study - The Evolution of the Horse

> Charles Darwin, an English Naturalist and Geologist, hypothesised the Theory of Evolution. He hypothesised that ‘all species of life come from a common ancestor”. > To put it simply, Biological Evolution is how we homo sapiens evolved from apes. Although that is just a small part of our evolution from apes to humans, animals have been Biologically evolving since the first creatures were born on our planet. > An Example of Evolution is shown through the Case Study on the Evolution of Horses on the final page of this issue.

Theory of Evolution Fossil Record > The Fossil Record is the record that

Biological Evolution occurred through the fossils (Bones of animals) that existed from a past geological time. It can also be referred to as the ‘evidence’ that supports the Evolution theory.

Dating Methods that scientists use and how they work

Relation to the Age of the Earth

> Dating is the act of figuring out the time pe-

> The Fossil Record definitely does relate

riod of which an object existed in, for this case, its the dating method’s of fossils. Scientists use many unique ways to date fossils, but there are only really 3 methods accepted by most geologists. The methods are dendrochronology, the molecular clock and Radiometric Dating, also known as Carbon 14. For early fossils (No Older than 70,000 years) Radiometric dating is the most widely used by many Archeologists.

However Radiometric dating is the most reliable for dating fossils that go back to millions, even billions of years.

> Radiometric dating is very complex, but is

very well understood by most geologists/archeologists. It involves finding the date of a fossil by using radioactivity. They do this by separating the Carbon 12 and Carbon 14 in the object and creating a ratio. This ratio is calculated and turned into an age. This method only works for fossils before 70,000 years

> Dendrochronology however is used mainly to

date trees but has been used to date fossils.

This is done by ‘counting the rings’ inside the tree and can be used to find the age of fossils.

This is the least used method of the 3 but is still effective.

> The Molecular Clock is a useful technique

Relation to how long life has been evolving >

The Oldest living fossil is believed to be our earliest descendant cell, although the comb jelly being the first complex organism. This shows us how much this small cell organism evolved into complex organisms such as ourselves, over the course of 3.5 billions years. You can now imagine how many different species were created from this simple organism, as there are almost 9 million different species. The large amount of species shown in fossils gives us a clear indication that many evolutions took place over a long period of time.

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that calculates the time in geographic history when two or more life forms diverged. This special technique uses mutation rate of biomolecules to show the reveal time period in which the fossil existed.

to the Age of the Earth as it gives us a relative time period in which animals/life existed. This then gives us an estimate into how old our planet is, as the fossils can be dated to a particular time period, with the oldest giving the better picture.

Fossils of bacteria and small creatures were the oldest fossils known, so estimates can be made further than the life span of these creatures. So far, the estimated existence of our planet is around 4 Billion years. Although being estimated using the age of rock formations, the oldest living creature was believed to live around 3.5 billion years ago, close to the 4.6 billion year old estimate.

Natural Selection > Natural Selection is the process in which the better-adapted species survive, more commonly known as ‘survival of the fittest’.

It is drawn from Darwin’s theory of Evolution, as he describes how some animals adapt and flourish while others don’t adapt and perish.

Relation to changes in a population > Natural Selection relates to changes

in a population because each individual organism that doesn’t adapt to the natural changes die out while the ones who have adapted survives and reproduces. These chains of events do change the population of each species, as the well suited have evolved. This shows how Nature acts as a filter for all living organisms, by disposing the organisms that don’t adapt.

Theory of Evolution Speciation > Speciation is a ‘lineage splitting event that

produces two or more separate species”.

Speciation events however can be compared to branches on a tree. Every branch splits into 2, as do most species. Although some branches are longer and don’t split and can be prehistoric. Animals such as the Crocodile are considered to be a ‘long branch’ of the tree, as it hasn’t gone through speciation in a very long time. The reasons why animals go through speciation are to do with the factors of isolation.

lived in a lush green paddock and the other in a cold deadly forest. The horse in the cold climate would grow more fur for the cold climate and would have sharper hooves to protect it from predators. And if one horse tried to cross the mountain they would perish, as they can’t adapt to each other’s climate. This allopatric isolation caused the 2 species to split from the lineage and become almost different species, thus causing speciation.

Page 3 beings and other animals to track down pre-histoirc roots and see all the stages of evolution. Through the discovery of fossils, finding the genetic make up of these pre-historic creatures would not be possible. The fact that we share genetic material with animals that look completely different to us proves that Evolution has taken place to evolve that first organism into all the living organisms alive today.

> Speciation is commonly mistaken with

species crossbreeding. Animals such as ligers and mules are actually known as hybrids. This is known as post-zygotic isolation, as the offspring produced by these separate species are infertile and not able to reproduce. The other isolation is pre-zygotic isolation, in which a species had begun to go through speciation before reproduction had occurred. This is linked to behavioral changes, for example if fish swim in a different pattern or manner to get across the ocean.

How Genes and Environmental factors interact to affect the sur vival of organisms in a population

> Genes and Environmental factors are

mainly responsible for the natural occurrence of speciation. Another way to describe how speciation occurs is by identifying the 3 main types of isolation, with the most influential one being geographic isolation. This type of isolation is created when populations of the same species are separated/isolated from each other, and are unable to mate with one another. This means that the populations would have to breed with their own. Another type of isolation is reproductive isolation.

This is where 2 populations, for some natural reason, can mate or breed successfully. Although they may be able to make an embryo, the offspring would not survive. The last type of isolation that is linked with geographic isolation is allopatric isolation. This is when populations are separated geographically, but in this instance, when the 2 geographic locations have different climates, resources and species, and they evolve differently because of it. For example, if a horse lived on the other side of a mountain, and one horse

Accuracy of the Theory of Evolution > The Theory of Evolution is considered to

be very accurate, and that is because of all the DNA evidence that has been compiled over the past 100 years. Evidence shows that species have similar features to those that lived millions of years ago. And the evidence shows that we all share the code of that of the first living multicellular organism, the comb jellyfish, believed to have existed around 600 million years ago. These discoveries made it clearer that we humans had close DNA to many other species. In the early 2000’s it was known that 99% of our DNA had been found in Chimpanzees, which makes them our closest relatives, followed by Gorillas, which is also in the Ape Family. Many different scientists and geneticists discovered this, which further supports that this Theory of Evolution is very accurate, as thousands of well known and trusted scientists had contributed evidence to help discover this phenomenon.

Fossils were very influential in this discovery as fossils were the indicator that animals, far beyond human time, had existed.

And with the dating system being extremely accurate, scientists were able to show the chronological order of how animals transitioned/evolved into brand new species. This sparked a new era in which Modern Scientists used the genetic makeup of us Human

Case Study: Evolution of the Horse > The Horse is known to have existed

around 60 million years ago. Although this horse had pretty much the same features as Modern Horses, it was much smaller and less agile due to its short and stubby legs.

> This first horse species was called

Eohippus. It also didn’t have hooves as the Modern day horses do. It actually had paws with very sharp claws and only stood 40cm tall.

Theory of Evolution The Eohippus was very lean as it lived in the harsh environments of North America which is where most of the population sat for over 59 million years.

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large amount of fossils in various places around the world. The evidence is truly evident, so why should you doubt the Theory of Evolution?

> Later on the Eohippus began to gain mus-

cular features and have more bone structure, although some bone structures did actually change, as 2 of its toes on each foot were fused together to give it 3 toes on each feet.

The Eohippus now had evolved into the Mesohippus, a longer and slightly taller creature, but still only standing at an average of 60cm. This is also when the horses started to flourish in the areas of North America. In response to the changing environment, they began developing tougher teeth and becoming slightly larger and leggier, allowing for faster running speeds in open areas, and thus for evading predators in seen areas.

> Then around 20 million years ago, it had

wider molars, which were used for crunching the hard grasses of the steppes. The hind legs, which were relatively short, had side toes equipped with small hooves, but they probably only touched the ground when running. The Mesohippus had now evolved into the Merychippus, although the environment remained the same.

> Around 10 million years ago, the Mesochip-

pus started to take the form of the Modern Horse, but was still remarkably shorter than it. The new evolved species known as the Pliohippus only stood 1 metre tall. It had two long extra toes on both sides of the hoof, externally barely visible as callused stubs. The long limbs of Pliohippus made it a very quick animal. Until recently, Pliohippus was believed to be the ancestor of Modern-day horses because of its many similarities. However, though Pliohippus was clearly a close relative of Modern Horses, its skull had deep facial fossae, whereas Modern Horses had no fossae at all. Additionally, its teeth were strongly curved, unlike the very straight teeth of modern horses.

> This then leads us to the Modern-Day

horse, which has been living for over 700,000 years. Having all the same features as horses you and I see in real life and online. Many Fossils have been found of each of these stages of evolution. Although there are over 30 stages of horse evolution, this case study only shows the important transitions/phases of the whole Evolution process. There is substantial evidence that these animals existed due to

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