Evidence from multiple fields of study points
to all life on Earth having a universal common
ancestor - a single-celled organism that lived
roughly 3.5 billion years ago.
The theory of evolution explains how the great
diversity of life developed  from that one organism.
When living things reproduce they create offspring
that inherit a mix of their traits as well
as developing traits of their own.
Small changes can add up over multiple generations
to create dramatic changes and animals may
even evolve into different species.
These changes happen via DNA mutation and recombination.
DNA is a chain like set of chemicals present
in every cell of a living organism.
It is the building block of life and has coded information
that tells the cell how to grow and function.
DNA mutations occur as a result of copying errors.
The change brought about by a mutation is
either beneficial, harmful or neutral.
An example of a neutral DNA mutation is blue
eyes in humans.
During sexual reproduction, the father’s
sperm cell - which contains a copy of half
his DNA - and the mother’s egg cell - which
contains a copy of half her DNA - fuse.
The resulting cell has a complete set of DNA,
which is a unique recombination of the parental DNA.
All the dogs that we have today were descended
from one group of grey wolves.
Breeders selected the wolves with the most
desirable physical and behavioural traits
and allowed them to mate, so over time those
desirable traits became more and more pronounced.
More and more specialised breeding lead to
all the breeds of dogs we see today,
from labradors to pugs.
When nature creates new species it acts like
the dog breeders albeit over a longer period of time.
Animals that have less desirable characteristics
to survive in their environment are selected
out by nature, leaving only the most suitably
adapted to survive.
These survivors then pass on their desirable
traits to their offspring and the process
repeats over millions of years until a species
becomes uniquely adapted to survive and thrive
in their environment.
Predators, parasites, excessive competition,
toxins, climate change are just some of the
things in nature that weed out the weaker
members of a population from the rest.
The consequence of natural selection is neatly
expressed by the phrase
‘Survival of the fittest.’
And that, in a nutshell, is evolution. This
is a brief overview, covering the basics of
the theory and this video is designed to be
a springboard for further study.
As always, I hope you enjoyed this video and
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