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Platypus: A Darwinian Cautionary Tale Print E-mail

The platypus is an evolutionary enigma and we encourage you to read the new technical article that has just been posted on the Truth in Science Website. For according to Professor Tom Kemp:

The greatest mystery of all concerning mammalian evolution stretches back for 200 years: the question of what exactly the monotreme mammals are, and how they relate phylogenetically to therians [from T.S. Kemp (2007) The Origin and Evolution of Mammals Oxford University Press pages 173-174].

Mammals comprise three major groups. The therians [theria] include all placental mammals [eutheria] and marsupials [metatheria] which have the characteristic pouch in which the immature foetus is nurtured after birth. The third group of mammals are the monotremes or egg-laying mammals. These are the prototheria [as distinct from the theria] and there are only three species of monotremes living today, only found in Australia. These are the platypus [Ornithorhyncus], the short beaked echidna [Tachyglossus] and the long-beaked echidna [Zaglossus].

Is it a reptile?

At one time, it was believed that the monotremes were transitional between reptiles and mammals. It is easy to see why. The prototheria [Gk: first beast] lay small round eggs and have some other reptilian features. For example, the male platypus possesses a spur on its hind limbs through which it delivers a venomous cocktail which contains proteins that are similar to those found in snakes. Nevertheless, the main reason that monotremes cannot be considered intermediate between reptiles and mammals is the current Darwinian consensus that reptiles and mammals have evolved independently from a putative common ancestral amniote either via the synapsid [leading to mammals] or sauropsid [leading to reptiles and birds] lineages. We refer you also to the article “Synapsids and the Evolution of Mammals” which can be found here.

Since the recent publication [May 2008] of the platypus genome in the journal Nature there has been a great deal of activity in the academic press and in the popular media including the BBC.

Is it a bird?

All this activity, however, has not brought any resolution to the evolutionary enigma that is the platypus. If anything, the situation has become even more confused. Even though there is no doubt that the platypus is a mammal, there are many genetic features that are more like birds. For example, since the platypus lays eggs, there is an ongoing requirement for active yolk production and this is reflected in its genes. Perhaps the most remarkable feature of the platypus genome, however, is the structure and number of sex chromosomes. Typically, all male mammals have one X and one Y chromosome whereas females possess two X chromosomes. The male platypus has five X and five Y chromosomes and the female platypus five pairs of X chromosomes. In most mammals, the Y chromosome possesses a gene called SRY which is a major sex determining factor but this appears to be absent in the platypus. Sex determination in the platypus is therefore something of a mystery and a great deal of research is continuing in order to discover its mechanism. Elizabeth Finkel has written a recent review of this research entitled “Genome speaks to Transitional Nature of Monotremes” in the prestigious American journal Science in which she states:

The genome sequence now shows that one of the platypus X chromosomes [X5] has more than just that one bird gene: It's almost entirely equivalent to the chicken Z chromosome.

Of course, there are also other genetic features that are unique to the platypus. These include the possession of all the biology required for the exquisitely sensitive chemical and electrical detection systems in its leathery bill. In particular, researchers have discovered numerous genes coding for odour receptors. Similar genes are found in many other mammals that rely on a sense of smell, the dog being a classic example. The platypus, however, requires this sensitivity underwater.

Thus, the platypus remains an enigma. Is it from a sauropsid lineage which includes reptiles and birds? Is it from a synapsid lineage which supposedly led to the emergence of the mammals? Or is it derived independently from some unknown ancestral amniote? Or could it be that the Darwinian hypothesis, cladistic analysis or any other classification system for that matter is just far too restrictive? The platypus is a Darwinian cautionary tale. Is it a bird or is it a plain … old platypus?

To read the full article on the platypus – go here.

 
Cambridge Professor writes History of Intelligent Design Print E-mail

The Laurence Professor of Ancient Philosophy at the University of Cambridge, David Sedley, has published a scholarly account of the debate over intelligent design among classical philosophers.

“David Sedley’s treatment of ancient views on intelligent design will transform our current thinking”, writes Oxford University’s Dr Thomas Johansen on the book’s cover.

The book, published by the University of California Press, is titled “Creationism and its critics in antiquity”. In the preface Professor Sedley makes clear that he has a particular definition of “creationism” in mind:

What I intend by creationism is neither [creation out of nothing or creation at some past time], but rather the thesis that the world’s structure and contents can be adequately explained only by postulating at least one intelligent designer, a creator god. This is indeed the primary issue that divides modern “creationists” from their Darwinian critics. It also divided the greatest thinkers of antiquity.

As a history from 500 to 300 BC, this book is a powerful refutation of the view that intelligent design was invented in the United States in the late 1980s.

The arguments between ancient philosophers have a surprisingly modern ring, as Dr Armand Leroi (evolutionary biologist at Imperial College London) points out in his review in Nature [Nature 452, 153 (13 March 2008)]:

Listen to Empedocles describing a time when the world was filled with a diversity of creatures with improbable combinations of features, most of which were then winnowed out, and you hear the late Stephen Jay Gould illuminating the body plans of the Burgess Shale fossils. Listen to Aristotle heaping scorn on Democritus for supposing that living things self-assemble from accidental combinations of atoms, and you hear Fred Hoyle's gambit that "a tornado sweeping through a junkyard might assemble a Boeing 747 from the materials therein". Truly it has been, as Darwin said, just "one long argument".

How did the ancients argue for intelligent design? Here are two examples.

Xenophon’s Socrates would take a statue or painting, which everyone would attribute to an artist or craftsman, and argue that the human body, with its greater complexity and functionality, must have been formed by a greater artist or craftsman.

The Stoics would take Archimedes’ mechanical model of the world’s rotations in space. Even an ignorant barbarian would not doubt that this was the work of intelligence. Yet the celestial motions of the world are a vastly more complex and superior machine, and therefore we can infer that they are the work of a greater intelligence than Archimedes.

These arguments are similar to the recent argument that complex, specified information in computer programs and in the DNA of living organisms both allow us to infer intelligent design

The arguments against intelligent design in the ancient world also have close similarities to those used today. The Atomists of 3rd-1st Century BC used the idea of infinitely many worlds as a way of explaining away highly improbably structures, just as the idea of multiple universes is used today. Lucretius also used the idea of natural selection: “that accident on a sufficiently vast scale accompanied by the systematic survival of the fittest could account for the presence of apparently purposive structures in nature” (p. 151). Sedley argues that this idea was not original even to Lucretius, but that he gained it from the earlier poet Empedocles.

Clearly, the modern debate over intelligent design is not new. Professor Sedley argues that it developed when thinkers first began to question something that had previously been taken for granted: that there is a supreme governing power present in the world.

 
When is a Mammal a Mammal? Print E-mail

The issue of New Scientist dated 27 February 2008 carried a major article on intermediate or transitional forms in nature which was entitled “What Missing Link?”. It was written by Donald Prothero who is Professor of Geology at Occidental College in Los Angeles and lecturer in Geobiology at the California Institute of Technology in Pasadena. Thus far, we have considered the first three examples of his list of ten. These are (1) Velvet worms  - see the blog item “What Missing Link?”, (2) Lancelets – see the blog item “Sounds very Fishy to Me!”, and (3) Fishibians – see our article entitled “Tiktaalik - the Fishopod from the Canadian Artic”.

The fourth item in this series concerns the emergence of mammals in the fossil record. In his New Scientist review, Professor Prothero’s suggests:

Another excellent example of a transitional sequence is the evolution of mammals from their ancestors, the synapsids. These were once called "mammal-like reptiles", but that term is no longer used because synapsids are not reptiles - the two groups evolved in parallel from a common ancestor.
There is no doubt that the so-called synapsid transition leading to the emergence of mammals is regarded by neo-Darwinists as the best evidence that the fossil record has to offer. We encourage you to read a new TiS article in the Evidence for Evolution section of this website. The article is entitled “Synapsids and the Evolution of Mammals” and is to be found here.

 

 
Nature journal retreats on evidence for evolution Print E-mail

The world’s leading science journal has today published an article 'Science teaching must evolve' that agrees with several of Truth in Science’s criticisms of current school science teaching on evolution. It calls on educators to retreat from the use of several forms of evidence critiqued by Truth in Science, and concentrate instead on DNA evidence of molecular evolution.

For over a year, Truth in Science has criticised the widespread use of similarities in form as evidence for evolution. Today, Nature writes: “Phylogeny based on similarity of form is fundamentally unsound because of the adaptation and convergent evolution witnessed in nature.” This statement is more outspoken and controversial than Truth in Science’s mildly-worded criticisms, but we are glad that Nature is now in basic agreement with us.

Since September 2006, Truth in Science has argued that theories for the origin of life taught in schools are flawed. Today, Nature writes: “Speculations on the chemical origins of life are almost universally covered in school curricula under ‘Evolution’, despite the questionable relevance of the topic for evolution, and its rather uncertain scientific basis...it is far from sound evolutionary theory.” Again, we are pleased that we now agree with the prestigious British journal on this point.

Nature even criticises teaching based on the fossil record (covered by Truth in Science here), writing: “Worse still, the understanding they [pupils] have — based on the fossil record — is easy prey to specious arguments from anti-science movements.” The fossil record is apparently now seen as vulnerable evidence. At Truth in Science we reject specious arguments by anti-science movements, but we do hold there to be valid scientific criticisms of the fossil evidence that is claimed for the theories of natural selection and universal common ancestry.

The Nature article, written by Andrew Moore of the Science & Society Programme at the European Molecular Biology Organization, suggests that many teachers have trouble with basic concepts in molecular evolution. It argues that teachers need to be re-educated: “many teachers are not scientifically capable of teaching evolution using modern approaches”, it claims.

While Truth in Science welcomes the fact that some of its criticisms of the evidence for evolution are being heard, it seems that a simple desire for truthfulness is not the only motivation felt by Dr Moore. He holds that trust in Darwin is a very serious issue. After discussing the need for molecular biology education early in biology teaching, he writes: “There is something more serious at stake: the erosion of public trust in Darwin’s original theory of evolution by natural selection in the face of ‘alternative theories’ from the Intelligent Design movement”.

We hope that Nature’s article will result give new momentum to the removal of misleading evidence for evolution from British schools, and look forward to analysing new resources on molecular evolution.

 
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The presence or absence of a creative super-intelligence is unequivocally a scientific question...

Richard Dawkins (2006)

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