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Thursday
Mar152012

Big Players in the Discovery of Evolution

Today as part of our evolution week, Into the Wild is going to be looking at those scientists that were instrumental in the formation of the modern theory of evolution. Without a doubt the discoveries and musings of these individuals changed the face of modern science forever and dramatically transformed how we look at the natural world.

Photo courtesy of shehal

The Father of it all and bestowed upon every British five pound note in the land Charles Darwin paved the way for the acceptance of evolution into the mainstay of scientific theory. Undoubtedly Darwin transformed the way we think about the natural world. In 1831 Darwin left for a five year scientific expedition upon the HMS Beagle on which he developed his theory of natural selection. It was a trip which would change the face of science forever. It was during his time on the Galapagos Islands that Darwin had a breakthrough, observing that each island in the archipelago supported its own form of finch and although the finches of all the islands appeared to be closely related, they were also very different from one another in a number of important ways.

Upon his return to England in 1836 Darwin used his observations to try and work out how species evolved. He spent 20 years forming his theory of natural selection which proposed that animals or plants which are best suited to their environments are more likely to survive and reproduce and will therefore pass their advantageous characteristics to their offspring. During this time Darwin learnt of another naturalist, Alfred Russel-Wallace, who had developed similar ideas and they decided to make a joint announcement of their discoveries in 1859 with Darwin publishing his book “The Origin of Species by Natural Selection” the following year. However the theory of evolution would not be what it is without this next guy.

Photo courtesy of wikipedia

Yes, it’s none other than the grandfather of genetics - the keen gardener - Gregor Mendel. Without Mendel’s diligent work and breeding of generations upon generations of pea plants, the theory of evolution wouldn’t be where it is today. So the problem existed that Darwin had devised the theory of natural selection and he could see examples of it in action in the natural world and although he knew that advantageous characteristics must get passed down through generations he did not know how this occurred. Darwin tried unsuccessfully to explain the inheritance of characteristics through a theory called pangenesis whilst most other biologists favoured the incorrect idea of blending inheritance. The theory of evolution had come to a stumbling block. This is when Mendel entered the playing field.

Mendel’s work proved the inheritance of genetic characteristics and gave weight and backing to Darwin’s theory of natural selection. Initially published in 1866, Mendel’s work remained under the radar until it was rediscovered after his death in 1900 by Hugo de Vries and Carl Correns. Once discovered it would prove Darwin’s theory of natural selection demonstrating that advantageous characteristics are passed from parents to offspring and that it is this which enables natural selection to act upon living organisms. With that the modern theory of evolution was nearly complete.

Photo courtesy of wikipedia

All that was needed now was someone to marry together the theories of Mendelian genetics and Darwin’s theory of natural selection. Enter Ronald Aylmer Fisher. Renowned as the founder of population genetics, Fisher developed such theories as sexual selection, mimicry and the evolution of dominance. Fisher’s book “The Genetical Theory of Natural Selection” demonstrated that Mendelian genetics was consistent with natural selection and gradual evolution. So with Fisher tying up the loose ends, we’ve finally arrived at our destination – Neo Darwinism – the modern synthesis of evolutionary theory.

Photo courtesy of wikipedia

Undoubtedly Darwin, Mendel and Fisher were fundamental in forming evolutionary theory but what about the unsung heroes? Charles Lyell was the first to suggest that the fossils found in rocks were actually evidence of animals that lived many thousands or millions of years ago which he put forward in his book the “Principles of Geology”. Indeed before Lyell there were many wild theories banded around regarding what fossils might be. Some believed they were the ghosts of animals, whilst others thought that animals came out of rocks and that fossils were animals that had failed to exit and died. Without Lyell’s contribution the opening up of the study of palaeontology may not have happened.

Photo courtesy of Wikipedia

Also not to be forgotten are those fossil finders whose discoveries have revealed how evolution has shaped the world around us. In the late 19th and early 20th centuries palaeontology was a relatively new area of scientific study with one of the most controversial fields of palaeontology being the study of human fossil and hominoid evolution. Darwin’s “The Origin of Species” was hugely controversial when it was published in the mid 19th century, as by logical extension his theories suggested that Homo sapiens are simply just another form of animal and therefore have descended from the same common ancestor as all other animals. These ideas were not welcomed by many because they opposed the prevailing orthodoxy that the world and all its inhabitants were created by God. Indeed at that time it was a mean feat just trying to get people to accept that the earth was millions of years old.

Outside the scientific community Darwin’s proposal that humans evolved from another species - most likely apes - were met with outrage and there was a definite unsanitary nature and stigma attached to the idea. Despite there being a high controversy surrounding the study of human evolution in the early late 19th and early 20th century this didn’t stop Eugene Dubois, Robert Bloom, Raymond Dart (pictured above) and Mary Leakey who among others all played a huge part in defining human evolution and proving that we evolved from apes. These intrepid palaeontologists are responsible for finding some of the most important hominoid fossils in history and pinpointing the origin of human evolution in the Rift Valley in Africa. Without these discoveries our knowledge of our own evolution would not be what it is.

Photo courtesy of Denn

Indeed today scientists are still trying to piece together the evolutionary puzzle and fill in the missing links. At any point a fossil can be discovered that changes the current views on the evolution of certain kingdoms, families or species. The discovery of Archaeopteryx provided the essential proof that the earliest birds were derived and evolved from theropod dinosaurs. Whilst only today was it reported that new analyses by Professor Curnoe’s team of fossils discovered in China in 1979 to 1989 of a human species known as ‘red deer people’ indicated that this hominoid species display a mix of modern and ancient anatomical features. This discovery is set to change current thinking about the evolution of our species and may alter current theories on the migrations of hominoids out of Africa.

It is these pioneers of evolutionary theory who are to thank for the advancement of scientific understanding. So I guess all there is left to say is keep digging - as Professor Curnoe remarked - these discoveries “open the next chapter in the evolutionary story and it’s a story that’s just beginning to be told”...

By Hannah Jones

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    The Gap Year Blog - Into the Wild - Big Players in the Discovery of Evolution

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