Common descent and common design
ClassificationTaxonomy, or systematics, is the science of biological classification, and seeks to arrange plants and animals into hierarchies of superior and subordinate groups on the basis of the features they have in common. Branching diagrams (cladograms) are drawn up showing the affinities between different species, and many taxonomists then interpret each node where a new branch begins as representing a hypothetical common ancestor. Alec Panchen says that common descent ‘seems so obviously the correct answer to the apparent relationships of classification, that any rejection of that explanation must surely be due to ignorance, stupidity or prejudice’.1 However, the father of modern taxonomy, the 18th-century botanist Carl Linnaeus, considered the ease with which plants and animals fell into an orderly groups-within-groups system of classification, or nested hierarchy, to be evidence for design.
Fig. 5.1. A cladogram.
Fig. 5.2. Four examples of more than seven competing cladograms for the supposed transformation of fish into tetrapods.2
A group of dissident scientists, called ‘transformed cladists’ by their opponents, reject the hypothesis of common ancestry as unnecessary and see cladograms solely as a representation of a natural hierarchy of characteristics. Although they reject the a priori assumption of ancestor-descendant sequences (phylogeny), and express notable dissatisfaction with evolutionary theory and methods, most transformed cladists are in fact evolutionists, even though their peers regard them as traitors. They merely recognize that virtually all groups, living or extinct, are already too specialized to be reasonably called directly ‘ancestral’ to any other, and that none of the logically required truly ancestral forms are to be found in the fossil record. Only the outer twigs on the supposed evolutionary tree can be verified; the ancestral forms constituting its trunk and boughs are missing. As Gareth Nelson and Norman Platnick wrote in 1984: ‘We believe that Darwinism is a theory that has been put to the test in biological systematics, and has been found false.’3
Since the fossil record has not provided any substantial evidence of the evolutionary tree of descent that Darwinists expected to find, they now often speak of a labyrinthine ‘bush’. They acknowledge, however, that it is often difficult to judge where any given fossil falls among the many branches of the tree or bush. Robert Wesson writes:
Charts depicting ancestries through the ages are sometimes fudged by drawing connections where they are assumed; the more honest ones have dotted lines.And Ernst Mayr says:
The gaps in the record are real ... The absence of a record of any important branching is quite phenomenal. Species are usually static, or nearly so, for long periods, species seldom and genera never show evolution into new species or genera but replacement of one by another, and change is more or less abrupt.4
It comes as rather a surprise to most nontaxonomists how uncertain our understanding of degrees of relationship among organisms still is today. For instance, it is still unknown for most orders of birds which other order is a given order’s nearest relative. The same is true for many mammalian families and genera ...Yet these uncertainties in the classification of higher vertebrates are very minor compared to those of the invertebrates, the lower plants, and most of all, the prokaryotes and viruses.5David Raup points out that many scientists think the fossil record is far more Darwinian than it really is due to oversimplified textbooks, semipopular articles, etc. plus wishful thinking; ‘some pure fantasy has crept into textbooks,’ he says. Various ‘tricks’ are used to strengthen the impression of Darwinian descent. For instance, some authors display a series of fossils which show a progression in morphology, but which are not chronologically successive, and therefore cannot be evolutionary sequences. Alternatively, a chronologically successive series of teeth, jaw bones, etc. may be displayed as an evolutionary sequence, even though the author may know that the body parts are from organisms that could not reasonably have formed a lineage.6
Homology, convergence and parallelismSimilarities in the structure, physiology or development of different species are said to be homologous if they are attributable to descent from a common ancestor. For instance, the forelimbs of humans, whales, dogs and bats are regarded as homologous, i.e. derived from an ancestor with similarly arranged forelimbs. Corresponding features with similar functions that are not thought to have originated by common descent are said to be analogous (or homoplasious). Examples are the wings of birds and flies, which are believed to have developed independently.
‘Homologous’ structures are supposed to have initially originated by the random accumulation of tiny advantageous mutations, and then to have been inherited by descendant species and further adapted, thanks to natural selection of further random mutations. ‘Analogous’ structures, on the other hand, are supposed to have arisen by random mutations several times and entirely independently – this is called convergent or parallel evolution. Parallel evolution refers to the appearance of similar patterns in more or less closely related plant and animal species, while convergent evolution refers to the appearance of striking similarities among organisms only very distantly related, but the boundary between the two terms is blurred.
Convergent evolution demonstrates that similarity does not always imply homology, i.e. inheritance from a common ancestor. There are many cases where similar features once classed as homologous have later been reclassified as analogous. Moreover, traits controlled by identical genes are not necessarily homologous and homologous structures need not be controlled by identical genes. Regulatory genes that are considered homologous may be dedicated to non-homologous morphology. There are many examples where homologous structures develop via completely different embryological routes. For instance, the alimentary canal is formed from the roof of the embryonic gut cavity in sharks, from the floor in the lamprey, from the roof and floor in frogs, and from the lower layer of the blastoderm in birds and reptiles.1
There are hosts of convergences in the plant world. Very similar leaf patterns, for example, have appeared again and again in separate genera and families. Green plants depend for their survival on photosynthesis, whereby sunlight is used to convert water and carbon dioxide into energy-rich carbohydrates. 3% of plants use C4 photosynthesis, in which CO2 is first fixed into a four-carbon acid with the aid of an enzyme called PEPC. These acids then diffuse to the cells in an airtight structure known as the bundle sheath, where they are broken down into CO2 molecules, after which photosynthesis proceeds as normal. This highly complex and efficient process allows plants to grow faster and use less water. According to Williams et al., ‘C4photosynthesis has independently evolved from the ancestral C3 pathway in at least 60 plant lineages, but, as with other complex traits, how it evolved is unclear.’2
Fig. 5.3. Three species of South American butterflies which closely mimic each other, even though they belong to distinct families: Melinaea lilis imitata, Helinconius ismenius telchinia, Dismorphia amphione praxinoe.3 Many close similarities are found in the wing colouration patterns of butterflies, both within and between families.
Fig. 5.4. Convergent evolution of the raptorial foreleg of the praying mantis and an insect known as Mantispa. It is derived from a generalized insect leg, modified for catching and grasping prey. It also evolved independently in a third group of insects, the rhachiberothidids.4
A striking example of convergent evolution is provided by the two main branches of the mammals, the placentals and marsupials, which have supposedly followed independent evolutionary pathways, after splitting off from some primitive mammalian common ancestor in the late Cretaceous. (Placentals bear their young fully developed, while marsupials give birth prematurely and nurture their young in a pouch.) The marsupials of Australia have evolved in isolation from placental mammals elsewhere yet have given rise to a whole range of similar forms: pouched versions of anteaters, moles, flying squirrels, cats, wolves, etc. Much the same phenomenon occurred in South America, where marsupials independently gave rise to a range of parallel forms.
Fig. 5.5. Examples of convergence: placental and marsupial mouse, placental wolf and marsupial Tasmanian wolf, marsupial flying phalanger and placental flying squirrel.
Fig. 5.6. Convergence in the sabre-tooth: drawing by Carl Buell of the placental Smilodon (top) and the marsupialThylacosmilus.5
The eye has appeared many times in unrelated groups of animals. There are two main types of eye: the compound eye found in arthropods, and the camera eye. The camera eye has evolved independently at least seven times – in mammals (e.g. humans), cephalopods (e.g. squid and octopus), certain annelid worms, cubozoans (a form of jellyfish), and three separate forms of snail. Wings allegedly evolved independently no less than four times: in insects, flying reptiles, birds and bats. Electrogeneration in fish has appeared independently at least six times and in each case involved the modification of muscle cells. Bioluminescence – the ability of creatures to produce their own light with chemicals – is said to have evolved independently 40 to 50 times. The whale, dolphin, extinct ichthyosaurus of the Mesozoic, and shark all look similar, yet the shark is a fish, the ichthyosaurus was an aquatic reptile, and the whale and dolphin are mammals. Other convergences include the production of silk threads by spiders, silk moths, larval caddis flies and weaver ants, sonar-like echolocation systems in microbats, toothed whales and shrews, and warm-bloodedness in birds, mammals and certain fish.
Fig. 5.7. Convergence of the camera eye in humans (vertebrate) and the octopus (cephalopod). The eyes are ‘wired’ differently: in humans light passes through the nerves on the way to the photoreceptors (retina), whereas in the octopus it does not. 1 = retina; 2 = nerve fibres; 3 = optic nerve; 4 = blind spot in humans, caused by nerve fibres passing through the retina.
Palaeobiologist Simon Conway Morris has catalogued the extraordinary variety of convergences in animals and plants. He says that the extent and importance of convergence have been consistently underestimated, and that most examples are known only to specialists. Descriptions of convergences are full of adjectives like ‘remarkable’, ‘striking’, ‘extraordinary’, ‘astonishing’ and ‘uncanny’. Morris says that ‘there is almost a feeling of unease in the similarities’, and that some biologists ‘sense the ghost of teleology looking over their shoulders’. Life, he says, ‘shows a kind of homing instinct’;6 the ubiquity of convergence ‘means that life is not only predictable at a basic level, it also has direction’.7 But he has no explanation other than the standard neo-Darwinian tale that similar forms and structures evolve because random mutations are sifted by similar selection pressures, and because there may be only a very limited number of ways of solving particular challenges (e.g. designing an eye). However, it is difficult enough to imagine how a complex organ or organism could have evolved even once by a combination of thousands of randomly generated ‘beneficial’ mutations; the idea that it could have happened more than once beggars belief. Moreover, when related species independently evolve similar physical traits they sometimes use the same genes to do so – which deals a further blow to the idea that evolution is essentially a random process.8
Numerous examples from the fossil record therefore suggest that particular evolutionary pathways are repeated: organisms with features almost identical to previous species appear again and again. Instead of thinking in terms of random mutations, it seems more reasonable to suppose that records of past features and structures are stored in some way, and that these records can be tapped into and modified during the design of later creatures.
EmbryologyVertebrate embryos pass through a series of similar stages in early development. As Rupert Sheldrake explains:
The early stages of embryology often resemble those of numerous other species, or even families and orders. As development proceeds, the particular features of the order, family, genus and finally species tend to appear sequentially and the relatively minor differences that distinguish the individual organism from other individuals of the same species generally appear last.1In 1866 Ernst Haeckel formulated the ‘biogenetic law’, which states that ‘ontogeny recapitulates phylogeny’, meaning that embryological development recapitulates ancestry. He argued that an organism evolves by tacking on new stages to its process of embryonic development, so that as an organism passes through embryonic development it retraces every adult stage of its evolutionary ancestors. Biologists soon discarded the idea that evolution is limited to changes added at the end of the development process, and took the view that evolution can affect all phases of development, removing developmental steps as well as adding them, so that embryology is not a strict replay of ancestry.
Fig. 5.8. Above: Haeckel’s infamous drawings of vertebrate embryos. Left to right: fish, salamander, turtle, chicken, pig, cow, rabbit, human. Haeckel had modified his drawings to make their early stages appear more alike than they really are. Below: Photos of (from top to bottom) a human, pig, chick, and fish embryo at similar stages of development.2
The embryo starts as a single cell, then divides into a tiny multicellular ball. A mammal embryo continues through stages resembling fish and reptiles before finishing as a fully formed mammalian youngster. Comparative embryology shows how different adult structures of many animals have the same embryonic precursors. Darwinists interpret these shared developmental features as evidence that many animals have ancestors in common; closely related animals show more similarities than more distantly related animals. For instance, at a certain stage of development, vertebrate embryos develop pharyngeal pouches resembling the gill pouches found in fish, though these features are never functioning gills, not even in embryonic fish. These features then go on to develop into very different adult structures – gills in the fish, and ear, jaw and pharynx in the mammal. This is interpreted to mean that all mammals share a common ancestor whose embryo had pharyngeal pouches.
Theosophy agrees that embryology provides information about evolutionary history, but rejects the Darwinian notion that every new type of organism arose through the continuous transformation of physical ancestors (see section 8). It should be noted that materialistic science cannot truly explain any aspect of embryonic development. For example, how does an embryo know when to stop making liver cells and to start making kidney cells? Chemical signals are believed to trigger the changes, switching certain combinations of genes on and off at just the right moments – but this raises more questions than it answers. Moreover, no known genetic mechanism explains morphogenesis or how organisms are able to retain a memory of ‘ancestral’ forms.
Another way of looking at embryological development is expressed in Von Baer’s laws, which were formulated before Haeckel’s biogenetic law. They indicate that the most generalized characters tend to appear earliest in ontogeny, followed by less generalized characters and finally the most specialized. This means that those structures that develop early in the embryo are common to many different species, whereas structures that develop late in the embryo are the ones that can be used to distinguish between species. In other words, life forms tend to begin near a common point and diverge outward, each on its own unique path, like the diverging spokes of a wheel. Von Baer was a creationist and formulated this law in opposition to evolution, but Darwinists believe that the stage of development at which two species diverge depends on how closely they are related – the assumption being that the only way they can be related is by physical descent. Theosophy postulates the existence of astral root-types, which were then developed in many different directions – not in a random fashion, but guided by nature’s instinctive intelligence.
Darwinists find further evidence of common descent in ‘vestigial organs’, which they view as the remains of what were once fully functional organs in the evolutionary ancestors of the species concerned. Some organs once labelled ‘vestigial’ have been shown to perform useful functions, e.g. the appendix. The human coccyx (tailbone) is seen as a vestigial tail and evidence that some of our ancestors had a tail.3 The remains of a hip girdle and hind limbs in whales, and the reduced hind limbs of primitive snakes are interpreted as incomplete modifications of the structures of their ancestors. But this sort of evidence is also compatible with some kind of conscious design, since modification of certain basic structures would be more efficient than designing everything from scratch. Moreover, the lack of any substantial fossil evidence for gradual evolutionary change is consistent with the theosophical view that the preparations for new physical features and forms take place on the ethereal level.
Genetic affinitiesDarwinists explain not only similar bodily structures but also genetic similarities in terms of common descent. But again, such similarities show nothing definite about how the organisms originated, and could just as easily be attributed to some form of conscious design.
Darwinists use differences in proteins and DNA as a ‘molecular clock’ to estimate how long ago different species diverged from a common ancestor. Each gene or protein is a separate clock, which ‘ticks’ at a different rate. For instance, it is estimated that 600 million years are required to produce a 1% difference in the histones of two different organisms, compared with 20 million years for cytochrome C, 5.8 million years for haemoglobin, and only 1.1 million years in the case of the fibrinopeptides. However, the evolutionary trees based on different classes of proteins sometimes show considerable differences, and there are also major discrepancies between family trees based on comparative anatomy and those based on molecular biology.1Evolution rates based on the fossil record, for example, are much higher than those predicted from genetics.2 Different molecular clock studies indicate that the hypothetical common ancestor of all animals lived anywhere from about 2 billion to 274 million years ago (the latter date falls about 250 million years after the Cambrian explosion!).3
The meaning of overall DNA similarity between two organisms is a matter of debate. For instance, the genetic similarity of humans and chimpanzees has been put at 95%, 98.5%, and even 99.4%; yet humans possess selfconscious intelligence while apes do not. On the other hand, there are two species of fruit fly (Drosophila) that look alike but have only 25% of their DNA sequences in common. One study found that the snake and the crocodile (both reptiles) had only around 5% of their DNA sequences in common, whereas the crocodile and chicken had 17.5% of sequences in common – the opposite of what neo-Darwinism predicts. There are more than 3000 species of frog, all of which look superficially the same, but there is greater variation of DNA among them than between the bat and the blue whale.4 This is a further indication that far more than DNA is required to build an organism.
- Alec Panchen, Evolution, London: Bristol Classical Press, 1993, p. 59.
- John D. Morris and Frank J. Sherwin, The Fossil Record: Unearthing nature’s history of life, Dallas, TX: Institute for Creation Research, 2010, p. 63.
- Quoted in Alexander Mebane, Darwin’s Creation-Myth, Venice, FL: P&D Printing, 1994, p. 30.
- Robert Wesson, Beyond Natural Selection, Cambridge, MA: MIT Press, 1994, pp. 39, 45.
- Quoted in Walter J. ReMine, The Biotic Message: Evolution versus message theory, Saint Paul, MN: St. Paul Science, 1993, p. 311.
- Ibid., pp. 280, 409.Homology, parallelism and convergence
- Antony Latham, The Naked Emperor: Darwinism exposed, London: Janus Publishing Company, 2005, pp. 176-8.
- B.P. Williams, I.G. Johnston, S. Covshoff and J.M. Hibberd, ‘Phenotypic landscape inference reveals multiple evolutionary paths to C4 photosynthesis’, eLife, 2:e00961, 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3786385.
- Simon Conway Morris, Life’s Solution: Inevitable humans in a lonely universe, New York: Cambridge University Press, 2003, pp. 128-9.
- Life’s Solution, pp. 128, 20.
- Simon Conway Morris, ‘We were meant to be ...’, New Scientist, 16 Nov. 2002, pp. 26-9.
- Ananthaswamy Anil, ‘Evolution returns to same old genes again and again’, New Scientist, 23 Aug. 2003, p. 15.Embryology
- Rupert Sheldrake, A New Science of Life: The hypothesis of formative causation, London: Icon Books, 3rd ed., 2009, p. 139.
- www.pbs.org/wgbh/nova/odyssey/clips; [www.geocities.com/a_and_e_uk/PerloffC10.htm].
- See Human evolution: the ape-ancestry myth, section 6, http://davidpratt.info.Genetic affinities
- Morris and Sherwin, The Fossil Record, p. 158.
- William R. Corliss (comp.), Biological Anomalies: Mammals II, Glen Arm, MD: Sourcebook Project, 1996, pp. 182-8, 191-2.
- Stephen C. Meyer, Darwin’s Doubt: The explosive origin of animal life and the case for intelligent design, New York: HarperOne, 2013, pp. 102-13.
- ReMine, The Biotic Message, p. 449; Richard Milton, ‘Darwinism – the forbidden subject’, [www.alternativescience.com/darwinism.htm].