Ancestry of Organisms.
The theory of common
decent states all organisms on Earth descend from a common ancestor or ancestral gene pool
Evidence from common
descent is viewed by the similar traits in all organisms. Also every living organism has nucleic acids and also has the 20
amino acids of proteins. The generation of non-living matte rheas never been observed.
The evolution process
is very slow in most cases but it is possible for it to be fast as well. We know from geology the Earth is 4.6 million years
old Fossil evidence states the Earth was also very diverse back then as well.
A National Science
Foundation found that evolution in the wild can be 10 thousand to 10 million times faster than the educated guess. Study of
planets can also give us evidence about the age of our Earth and its changes throughout the millions of years.
Fossils can estimate
different characteristics in a once living organism. Fossil evidence without hard body parts exists in microfossils and in
burrows of soft bodied organisms.
of pre-historic life can be found throughout the Earth. It can lead to important clues like. Why are there fossil shells on
the Himalayas? Radiometric Dating can determine their age. Fossils we find can either be radically different or either similar.
Evolution clues and evidence can help back the theory.
Looking for key
features in fossils can give information that leads to what type of animal lived here at the time. Fossils can also be used
as evidence to find missing links within the chains and ancestry of animals.
Origin of life
Whilst we know
little about the early development of life. Organisms do share similar traits. These include the type of cell they have and
similarities and differences in their DNA structure. The current theory proposed by scientists is that all organisms share
a common ancestor, who had the origin of life or the tree domains. Archea, Bacteria and Eukaryota.
History of life
It is probable
that oxygen was introduced to our atmosphere around 3 billion years ago. This was a major milestone because it gave way to
the ability of cellular respiration. In the past billion years there was the emergence of the first animals. There was a lot
of diversity in the ecosystem that existed then if any. This was the first formations in the planning and production of the
first modern animals. 500 million years ago plants and fungi lived on the land giving clues to the moisture in the air. These
are the first ecosystems we will be familiar to.
Mutations are permanent
genetic changes in the form of DNA and RNA. This is caused by copying errors in the process of reproduction. This can occur
in 3 ways: radiation, chemicals or viruses.
Mutations can be
either good or bad. It may affect different levels in the body depending like the rate of reproduction.
Mechanisms of inheritance
are traced through the genes which are encoded in molecular molecules which are known as DNA. From mutation DNA can be
changed slightly and it always changes. We know this because no organism is the same. For example; I am much different to
another person in my street.
There are factors
in frequency of existing alleles. This means some traits will live on whilst other slowly die out or become extinct. Natural
selection, gene flow and genetic drift affect the survival of a gene.
Gene flow is the
process of populations becoming similar of closely genetically related whilst building gene pools. Migration from one population
to another can result in a gene flow. This will only occur when the environment and culture don't change.
Genetic drift is
the change in an allele frequency from one generation to another. Genetic drift can also change when the size of the population
is smaller or larger. Differences in the frequency in successful generations can result in alleles dying out in a population.
There can be a drift when separate populations start to become different in the characteristics of their genes. So alleles
can be existent in one whilst not in the other.
is efficient in big populations because alleles are common in that population. But a genetic drift is stronger in smaller
populations. The amount of people in a population that share those same alleles depends on the size of that population. So
a smaller population would be quicker at acquiring that common allele.
By natural selection
organisms become more adapted to their surroundings. An adaptation occurs over a long amount of time but it is usually
shorter. It is the environment forcing them to change a characteristic in order to survive. So if the world started cooling
over a long period of time a mammal like a human will be adapting to grow more body hair.
that an adaptation occurs when there are a string of small mutations. But, a macro mutation can involve one very large change
in a mutation.
Extinction is the
disappearance of a species or gene pool. Extinction occurs at the death of the last of its species. In a geological time the
real threat of extinction is humans as there have been no major environmental changes. Species are created through speciation
but die-out through extinction.