Friday, 27 April 2012

The Evolution of Charles Darwin

Down House - The Home of Charles Darwin

Photograph Details: Nikon D7000 Focal length 24mm ISO-320 exp: 1/500 f11

Charles Darwin (12/02/1809 - 19/04/1882) is known throughout the world as the man who figured out evolution. He published his most famous work "On The Origin Of Species" in 1859. He got his inspiration from his global sea journey of 4 years onboard HMS Beagle which set sail on 27th December 183 and returned to England on 2nd October 1836.

Darwin stated that natural selection is instrumental in the creation of new species. Natural Selection is essentially survival of the fittest, stating that the weaker of a species will loose out to the stronger as a result of being able to fight for food and survival. In 1871 Darwin updated his ideas and included sexual selection.
This addendum was included to explain the presence of features in animals which could be seen to hinder survival and he used the idea of peacock's tail feathers.
Being bright and very long means that the feathers would give the birds position away to predators and would probably even be a hindrance when it came to manoeuvrability to evade a predator. As I'm sure you can see, this almost goes against the idea of natural selection and so Darwin stated that the flamboyant plumage in fact has no advantage in terms of survival, but is in fact part of a much bigger picture to help the entire species survive.

By having slight variants in the appearance of the individual meant that the females could choose their mate more selectively and in a way that they find sexually attractive. This in turn will enable certain features to be passed on genetically to their offspring, which in turn will make them more attractive to mates and therefore more likely to find a mate with which to reproduce with and so the cycle continues...

These tiny changes eventually enable a species to change and mutate, eventually making the species completely different to how it was prior to these mutations and a new species is born.

The mutations were not necessarily linked to appearance. There are several cases where the changes occurred to enable a male to gain an upper hand when it came to sparring and fighting in able to gain the courtship of a mate. This is what theorist think may have happened with the Irish Elk. Don't let the name fool you, the Irish Elk was not exclusive to Ireland, but in fact ranged across Eurasia to Lake Baikal during the late pleistocene period.

The Irish Elk stood at 6ft 9in (2.1 metres) tall at the shoulders with antlers weighing up to 40 kg with a maximum span of 3.65 metres tip to tip. It is believed that these gigantic antlers  evolved to be so vast to enable it to have an advantage over the smaller "less-evolved" Irish Elks when it came to fighting for a mate.

Whilst their extinction has been partly attributed to hunting by man, it is thought that the size of the antlers changed disproportionally to the rest of their bodies and that in fact they became prohibitive to survival by being more of a hinderence than an advantage.

So whilst both Natural and Sexual selection both sound plausible they are unable to explain evolution on their own, you clearly need one and the other to do that, for evolution it seems occurs in two ways:

  • Naturally by enabling an animal to survive (thicker fur in Arctic regions compared to that of the same animal in more temperate regions).
  • Sexually by a mate choosing "the best stock" with which to breed - it demonstrated an ability to look after the expectant mother or her eggs/spawn as well as the baby during its upbringing.

Part of the Gardens at Down House

Photograph Details: Nikon D7000 Focal length 18mm ISO-320 exp: 1/160 f22

Useful Links:
Down House on Twitter
Down House on the English Heritage Website
English Heritage on Facebook

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As ever, thanks for reading.

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