Truth in Science

Perhaps the most complete set of transitional fossils is the so-called "fishibian" sequence showing the steps by which fish crawled out of the water and onto the land during the Devonian period … The latest fishibian is Tiktaalik from Ellesmere Island in the Canadian Arctic.

Tiktaalik is a lobe-finned fish with an unusual combination of characters shared with other lobe-fins and aquatic tetrapods of the Upper Devonian. However, it also had some unique characters not found in its presumed ancestors or descendants. Although evolutionists have interpreted Tiktaalik as a transitional form, it was clearly a fish with paired fins and its discovery sheds little light on the origin of limbs bearing digits.

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As reported in a previous blog, the issue of New Scientist dated 27 February 2008 carried a major article on intermediate or transitional forms in nature. 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. His book “Evolution: What the fossils say and why it matters” is published by Columbia University Press.

In this second blog item, we consider Professor Prothero’s suggestion that:

Another key transition in animal evolution was the appearance of the vertebrates. For more than a century, evidence has been accumulating from anatomy and embryology that the Chordata phylum (which includes the vertebrates) evolved from the echinoderms - sea urchins, starfish and their kin. This has now been corroborated by molecular biology. We also have an array of fossils and living organisms to tell the story of the transition.

Professor Prothero is dogmatic. Chordates (and therefore vertebrates) have evolved from echinoderm (spiny skin) ancestors. Although sea urchins and starfish fossils (and their kin) do not appear in Cambrian strata, there are some strange and extinct echinoderms. These include Edrioasteroids, eocrinoids and helicoplacoids.

In 2004, Shu and his team described another group of early Cambrian echinoderms, namely, the vetulocystids. In the same issue of Nature, Andrew Smith, Merit Researcher at the Natural History Museum in London, wrote a review of the Shu paper entitled “Echinoderm Roots”. The full article is available here. On the second page of this review, we see a figure of the main deuterostome groups.

Deuterostomes comprise a super phylum which encompasses the echinoderms and the chordates (including the vertebrates). You will notice from this diagram that Professor Prothero’s suggestion in the New Scientist that “the Chordata phylum (which includes the vertebrates) evolved from the echinoderms” is without any scientific foundation. Furthermore, Andrew Smith states in this Nature article:

There is now direct fossil evidence that all of the major deuterostome groups were established by about 520 million years ago. Fossil vertebrates (yunnanozoans), tunicates and both asymmetric and radiate echinoderms (homalozoans, helicoplacoids) have all now been discovered in early Cambrian deposits.

Next up are the sea squirts, or tunicates. Though adult sea squirts are similar to pterobranchs, the larvae look much like primitive fish, with a muscular tail supported by a "backbone" of cartilage, the notochord - the defining feature of the chordates.

Although this is somewhat confusing, the Professor states correctly that tunicates are classified as chordates since they possess a notochord (cartilaginous rod) but only in their juvenile form.

Chen reported the discovery of eight specimens of an early Cambrian fossil tunicate Shankouclava near Kunming (South China). The full paper is available here. Again the fossil record clearly indicates that there were tunicates in the early Cambrian. Accordingly, it is not possible to conclude on the basis of the actual evidence that tunicates have evolved from echinoderms or from anything else. It is simply inferred from the general appearance of extant forms of these phyla. Maybe this is an alternative updated example of "phylogeny recapitulates ontogeny" that was originally proposed by Ernst Haeckel on the basis of his dubious embryonic diagrams.

Nevertheless, appearances can be very deceptive. We recommend looking up an image of a tunicate larva and considering whether Professor Prothero’s suggestion that they “look like primitive fish” has any basis in reality. Nevertheless, he does not give up:

The transitional sequence continues with a group of obscure invertebrates called the lancelets. These resemble [emphasis added] tunicate larvae, and probably evolved from a tunicate-like creature through "neoteny" - retention of juvenile features in adulthood. With a notochord, muscular tail, gill slits, a digestive tract along the belly and many other chordate features, lancelets are the most fish-like invertebrates known. They have been around since the Cambrian: we have a number of good lancelet fossils such as Pikaia from the Burgess Shale and similar fossils from Chengjiang.

What is certain is that these fossil lancelets appear very similar to the modern and not so obscure amphioxus (a living example of a cephalochordate) which is alive and very well on planet Earth. The amphioxus is extremely common in shallow sandy environments such as Discovery Bay in Jamaica where up to five thousand individuals per square metre of sand have been reported. Amphioxus is commercially harvested and eaten by humans and domestic animals in some parts of Asia.

A question that is never answered is this: If lancelets are intermediate transitional forms leading to the evolution of vertebrates, why do they appear essentially unchanged after 500 to 600 million years of evolutionary time? In addition, when and how do lancelets move away from being lancelets to become something other? Again, the fossil record provides no help in answering these questions because representative fossils of all the particular groups are found in the same strata.

Needless to say, of particular interest are the ancient fish fossils that have been found in the Cambrian. For example, in 1999, Shu and his group reported the finding of two species of ancient jawless fish, namely, Haikouichthys ercaicunensis and Myllokunmingia fengjiaoa. A report of this discovery is found on the BBC website In this article, Professor Simon Conway Morris (University of Cambridge) is quoted as saying:

Until now, the early history of the fish has been extremely sporadic and sometimes difficult to interpret. This discovery shows that fish evolved much earlier than was thought. It indicates also that the rates of evolution in the oceans during the Cambrian period must have been exceptionally fast. Not only do we see the appearance of the fish, but also a whole range of different animal types.

a heart, ventral and dorsal aorta, an anterior branchial arterial, gill filaments, a caudal projection, a neural cord with a relatively large brain, a head with possible lateral eyes, and a ventrally situated buccal cavity with short tentacles. These findings indicate that Haikouella probably represents a very early craniate-like chordate that lived near the beginning of the Cambrian period during the main burst of the Cambrian explosion.

More recently, Shu reported further studies made possible by the discovery of numerous specimens of the early Cambrian vertebrate Haikouichthys ercaicunensis. The paper presents further evidence that Haikouichthys was a fossil agnathan.

Agnatha are jawless fish and are represented today by hagfish and lampreys. Professor Prothero admits to the presence of these ancient vertebrates in the Cambrian:

Cambrian rocks in China have also yielded fossils of the earliest-known vertebrates, the soft-bodied jawless fish Haikouella, Haikouichthys, and Myllokunmingia. These creatures did not yet have a hard bony skeleton, but have all the other features of jawless fish supported by a skeleton of cartilage.

Placed in sequence, the acorn worms, tunicates, lancelets and soft-bodied jawless fish show the complete set of steps needed to evolve a vertebrate from an invertebrate ancestor.

We suggest that this very superficial assessment is circular reasoning. The sequence chosen is based on the assumption that the Darwinian hypothesis is true. The resulting sequence is then used as proof of the assumption. Furthermore, the suggestion by Professor Prothero that molecular biology corroborates his interpretation is similarly without support in the academic literature. For example, Frederick Delsuc and his co-workers published a paper in Nature in 2006. It’s worth reading the abstract!

So recent advances in molecular biology do not corroborate Professor Prothero’s imagined sequence and his is only one of many that could be constructed. It all sounds very fishy to me!

One of the world’s leading evolutionary biologists has recently published a book which, as a central theme, questions the importance of natural selection in evolution.

Dr Michael Lynch is a distinguished Professor at Indiana University and one of the most influential figures in evolutionary genetics research. His CV lists 157 peer-reviewed scientific articles (to place this in context, it is over twice that of Richard Dawkins). In 2005, he wrote in a letter to Nature that "evolution is as much a fact as respiration and digestion” and dismissed intelligent design as “intellectual laziness".

Dr Lynch’s new book The Origins of Genome Architecture (Sinaeur, 2007) is a landmark professional text that seeks to apply evolutionary theory and population genetics to the study of whole genomes. Throughout the book, Lynch argues that the effectiveness of natural selection has been over-rated by many of his fellow evolutionists. For example, on page 367 of his book, Dr Lynch suggests that:

For the vast majority of scientists, evolution is nothing more than natural selection. This view reduces the study of evolution to the simple documentation of differences between species, proclamation of a belief in Darwin, and concoction of a superficially reasonable tale of adaptive divergence.

Lynch has several reasons for questioning the role of natural selection. In particular,  the effectiveness of selection is very dependent on the size of the population it is acting upon: it is more effective in large populations than small ones.  Smaller, simpler organisms (such as bacteria) tend to have much larger population sizes than larger, more complex organisms (such as mammals). So natural selection should be much less effective in mammals than in bacteria.

Instead of natural selection, Lynch suggests that much complexity has evolved passively. Due to the way in which organisms reproduce and mutations occur, complexity could gradually accumulate in biological lineages. Much of the book is devoted to explaining various non-adaptive mechanisms by which features of genomes could evolve.

That is not to say that natural selection is unimportant: Lynch still believes that it plays a major role in evolution. He considers that he is in the line of Darwin when he argues that natural selection should not be over-emphasised. He is concerned that the public may have been misled on this point:

Dawkins’s effort to spread the gospel of the awesome power of natural selection has been quite successful, but it has come at the expense of reference to any other mechanisms, and because more people have read Dawkins than Darwin, his words have in some ways been profoundly misleading (page 369).

He is equally critical of individuals involved in the education of children:

Numerous popularizers of evolution, some with careers focused on defending the teaching of evolution in public schools, are entirely satisfied that a blind adherence to the Darwinian concept of natural selection is a license for such activities (page 366).

He even suggests (on page 368) that:

the uncritical acceptance of natural selection as an explanatory force for all aspects of biodiversity (without any direct evidence) is not much different than invoking an intelligent designer (without any direct evidence).

The Origins of Genome Architecture received a glowing review in the leading science journal Nature on 14 February 2007. “This book is a must-read for every genome researcher,” wrote evolutionist Axel Meyer. He welcomed the controversial aspects of the book: “Not every evolutionary biologist, genome researcher or ‘evo-devo-ist’ will agree with Lynch's strong opinions that largely non-adaptive forces shaped genomes, but it is a debate worth having,” he wrote.