The 8th blog in the Explaining evolution series aimed at those studying, or interested in studying, GCSE Science looks at the evidence for evolution.
At the time of the formulation of evolutionary theory, scientific evidence supporting it was sparse but since that time there has been a continual feed of ideas and evidence in various branches of science to support, explain and add increasing detail to evolution.
Astronomical evidence has produced theories that explain the formation of the solar system in the context of our galaxy, the Milky Way and the universe over 13 billion years. Study of astronomy gives a timeline for the development of Earth and shows that our planet’s environment has been subject to many ongoing external influences such as radiation, gravitation, dust and meteorites.
Geological evidence has also produced theories that explain the way rocks have formed over billions of years, how continents and mountains have been fashioned according to tectonic plates shifting, and, importantly, how fossils can be dated according to their position in the rock layers.
Study of the fossil evidence gives support to a ‘tree of life’ structure, a simple framework that links the development and demise of all species from the start of life 3.5 billion years ago. One startling consequence of the ‘tree of life’ is that every living organism on the planet is descended from the initial life form. We can trace the development of this initial life form over billions of years into eucaryota, then animals, mammals, apes and finally humans.
There is evidence to suggets that there have been several cataclysmic events on planet Earth which have removed a large number of species, including the seemingly fittest of species, in a very short space of geological time. The cause and time scales of these events is still a matter of debate, but it shows how a planet’s environment can change far faster than a species of an organism can mutate and adjust to a changing environment.
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