Charles Darwin's “tree of life” concept describing the relationships of living and extinct organisms as they relate to evolution is being disputed by several leading scientists, who claim the evolutionary metaphor is outdated and needs to be replaced.
Based on recent revelations by geneticists, dissenting scientists contend that
Darwin's use of a tree to represent evolutionary history is misleading, with an impenetrable thicket being a more accurate and realistic way to represent the origins and inter-relatedness of species, Britain's The Guardian reported.
"We have no evidence at all that the tree of life is a reality," Eric Bapteste, an evolutionary biologist at the Pierre and Marie Curie University in Paris, told New Scientist magazine.
Though he employed the imagery in his metaphor for evolution, in his writings Darwin described evolution and ecosystems as a "tangled bank."
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It is now known that different species crossbreed more than originally thought due to genetic tests on bacteria, plants and animals. Whereas it was previously believed that genes were passed down along individual branches of the tree of life, we now know that genes are also transferred between species on different evolutionary paths.
Consequently, we have a tangled "web of life" as opposed to a tree of life, The Guardian noted.
In 2012, scientists at the University of Texas at Arlington discovered unusual strands of DNA in the genetic make-up of eight animals, among which were the rat, mouse, rat and the African clawed frog. Upon further research, it became apparent that the same DNA is missing from chickens, elephants and humans.
The DNA mystery suggests that at some point the ancestor of the animals above crossbred with one another, resulting in the genomes of some animals being wedged into the genomes of others.
Swapping genetic material between species is not uncommon.
According to some estimates, 10 per cent of animals regularly form hybrids by breeding with other species, The Guardian reported.
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Such new genetic findings lead many scientists to view Darwin's tee of life as an oversimplification of evolution.
"The tree of life is being politely buried," said Michael Rose, an evolutionary biologist at the University of California, Irvine. "What's less accepted is that our whole fundamental view of biology needs to change."
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