Down with CreationismDown with Creationism

• In the early 18th century the commonly held belief of Creationism was being questioned

• Extinctions such as the dodo led them to produce alternative theories

LamarkLamark

• Lamark proposed that aquired characteristics were in inherited

• He used the example of the giraffe stretching its neck

• This is now know to be wrong but it was the first attempt to explain how species change over time

Darwin’s Tree of LifeDarwin’s Tree of Life

‘‘‘‘I think’’I think’’

• This is alleged to be Charles Darwin's first sketch of an evolutionary tree of life (circa 1837), taken from his First Notebook on Transmutation of Species

• Darwin hypothesised that all living things descended from our Last Universal Common Ancestor

The Tree of LifeThe Tree of Life

From LUCA the different species

branch out

The biological ‘holy grail’ was to build up an image of this tree in its

entirety

It started off so well…It started off so well…

• Early RNA sequencing compared RNA in various organisms

• Some species were not as closely related as was previously thought

• Tree highly biased to species that are alive today

HybridsHybrids and and HGTHGT• Darwin’s model does not take into account

HYBRIDIZATION or HORIZONTAL GENE TRANSFER

– The 'Tree of Life' starts to resemble a 'Web of Life

Web of lifeWeb of life

• This tangled mass is more representative as it illustrates that species can exchange genetic information with each other

• A ‘web of life’ is a more accurate way to depict the way species are interrelated

"If there is a tree of life it's a small irregular structure growing out of the web of life." Dr John Dupré

‘‘‘‘The tree of life was useful’’The tree of life was useful’’The concept of the Tree of Life gave rise to

the theory of evolution

It is time to adapt Darwin’s original theory as modern scientific techniques have changed

"The tree of life was useful. It helped us to understand evolution was real. But now we know more about evolution it's time to move on.’’ Dr

Eric Bapteste

ReferencesReferences• Darwin’s notebook: www.fossilmuseum.net/Evolution/darwin/darwintree

• Lamark’s giraffes: www.princessleia.com/images/essays/giraffe_lamark.jpg

• Darwin image: www.darwin-online.org.uk

• Lawton, G; 2009; ‘Uprooting Darwin’s Tree’; New Scientist; 24th January; page 34

• LUCA tree: www.nature.com/nature/journal

• www.telegraph.co.uk/scienceandtechnology

• www.physorg.com/news

• www.biologymad.com

• www.biomedcentral.com/

• Open University ‘Tree of Life’

• Web of Life: http://sandwalk.blogspot.com/2009/01/darwin-was-wrong

• Mule image: http://www.ruralmissouri.org/04pages/04SeptKahoka.html

• Ligre image: http://news.nationalgeographic.com/news/2005/08/photogalleries/ligers_dynamite