Darwin was wrong about tree of life, according to the front cover and feature article in New Scientist, 24 January 2009, p34-39.
Ever since Darwin drew a spiky diagram of a branching pattern in one of his notebooks, and then included a much neater tree in Origin of Species, evolutionary biologists have depicted all life on earth as one great tree beginning from a single cell which gave rise to several basic multi-cellular body plans, which then divided into more and more specialised organisms. It was a good metaphor for the basic tenet of evolution – descent from a common ancestor.
Numerous attempts have been made to draw up the definitive tree of life that shows where branches occurred, and which species gave rise to others along the branch. However, all have failed. Genome sequencing which should have been able to show clearly which organisms arose from which, has also failed to produce a tree-like pattern, but instead has produced a scattered pattern because common genes are found in organisms on widely separated branches of the tree, and other genes seem to have disappeared and reappeared as a branch grew. For example: biologist Michael Syvanen of the University of California, Davis, recently compared 2,000 genes that are common to humans, frogs, sea squirts, sea urchins, fruit flies and nematodes, with the aim of drawing up a tree. It didn’t work. Different genes gave different trees.
In 1999 biologist W. Ford Doolittle of Dalhousie University in Halifax, Nova Scotia, Canada, claimed “The history of life cannot properly be represented as a tree. The tree of life is not something that exists in nature, it’s a way that humans classify nature.” Evolutionary biologist Eric Bapteste, from the Pierre and Marie Curie University in Paris, France put it: “We have no evidence at all that the tree of life is a reality.”
However, biologists were not going to give up on the theory of evolution, so they have come up with another explanation for the patchy arrangement of genes throughout the living world – horizontal gene transfer (HGT). According to this theory, genes are transferred from one organism to another across branches, turning the tree into “an impenetrable thicket of interrelatedness, with species being closely related in some respects but not others.” Michael Rose, an evolutionary biologist at the University of California, Irvine, describes it as “a promiscuous exchange of genetic information across diverse groups.”
HGT is believed to have occurred in bacteria by a simple exchange of genes and in more complex organisms blending with one another by endosymbiosis, hybridisation and chimera formation. Endosymbiosis is the idea that a simple cell engulfed a bacterium which transferred some of its genes to the genome of the engulfing cell. This is believed to be the process by which complex cells with a separate nucleus and mitochondria (power generators) and chloroplasts (photosynthesis machines) were formed. Chimera formation is where two organisms combine to form a new one. This is believed to explain the origin of sea squirts, which are classified as chordates, in the same phylum as vertebrates, but seem to be fifty percent sea urchin. (Sea urchins are classified as echinoderms, along with starfish.)
Evolutionary biologists insist that exchanging the tree of life for something more like a web does not mean the theory of evolution is wrong. Some biologists find it “very scary” but Michael Rose issued this challenge: “The tree of life is being politely buried, we all know that. What’s less accepted is that our whole fundamental view of biology needs to change.”
Editorial Comment: Rose is right – there does need to be a change in the fundamental view of biology, but not in a way he would like. The basic misconception that inspired Darwin to draw a tree, and modern biologists a web, is that all life must be physically connected. Therefore, they have to come up with theories that move genes around in ways that have not actually been observed.
Bacteria can exchange genes – this is one way antibiotic resistance is rapidly spread, but this has not been observed to turn them into different kinds of bacteria, so no evolution has been observed. Endosymbiosis has not been seen to occur. It is only invoked because scientists cannot come up with a plausible theory for the origin of complex structures such as mitochondria and chloroplasts by slow chance random processes. Fertile hybrids do occur – Darwin’s finches are a good example. But in every known case it really indicates the species that are combining are really one, but have been artificially separated into different subgroups and classified as different species. This is not evolution, it is simply a re-mixing of genes that have been separated. Chimeras can be deliberately made in laboratories, but this is not evolution. They do occur naturally, but usually within species – not evolution either.
In fact, the patchy distribution of genes throughout the living world can easily be explained by the original creation of separate kinds, with each kind having the appropriate ‘pre-designed’ genes for its needs. Each kind is a unique combination of non-unique genes. Therefore, it is no problem if a gene is found in both sea urchins and humans.
It is high time biologists faced up to the fact Darwin’s tree of life concept has not helped the science of biology. It has resulted in biologists using much time, energy, private enterprises’ resources and tax payers’ money trying to solve a problem that doesn’t exist. The more genome sequencing that is done, the more we see that the evidence fits with the creation of fully formed organisms, (complete with mitochondria and chloroplasts where appropriate) in separate kinds, just as the Book of Genesis states.
Evidence News 4 February 2009
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