Arguments Against Evolution Pt. 5

Missing links and a look at the Romer’s gap

The term “missing link” was coined in Darwin’s time and was used to denote the “hypothetical organisms that linked different groups, and especially humans with anthropoid apes.” Perhaps the most famous “missing links” are those linking humans to our more ape-like ancestors. The term “missing link” is misleading, however, because it supposes that all creatures are linked in a hierarchy or Chain of Being when the case is rather that all creatures share common ancestors. The term also implies that there are certain links that are missing and thus disprove the theory of evolution. Modern scientists speak of transitional forms instead of “missing links.”

Cotner and Moore define a transitional form as: “An organism having anatomical features intermediate between those of two major groups of organisms in an evolutionary sequence. Transitional forms show evolutionary sequences between lineages by having characteristics of ancestral and newer lineages. Since all populations are in evolutionary transition, a transitional form represents a particular evolutionary stage that is recognized in hindsight.” Why don’t we find something halfway between a hippo and a whale, then? Miller explains that transitional fossils are retrospective: “For example, transitional forms are not to be found between living whales and their closest living relatives the hippos, but between whales and their common ancestors with the hippos. Such forms will be unlike anything living today. Transitional forms are found by moving down the tree of life into the past, not by trying to jump from limb to limb.”

Keith B. Miller addresses two errors with regard to the fossil record and missing links: “There are two opposite errors that need to be countered about the fossil record: (1) that it is so incomplete as to be of no value in interpreting patterns and trends in the history of life, and (2) that it is so good that we should expect a relatively complete record of the details of evolutionary transitions within most or all lineages.”

David H. Bailey states that many of the gaps pointed out by creationists have been filled over the past few decades. Dawkins states that “for a large number of fossils, a good cause can be made that every one of them is an intermediate between something and something else.” It is true that there are gaps in the fossil record, but that is exactly what one would expect if one takes into consideration the difficult process of fossilization and the amount of strata which have been excavated. A rare occurrence known as fossil Lagerstätten took place where one encounters thick layers of fossil-rich rock. These are very rare indeed. Organisms that lack hard parts (eg. Ediacaran organisms, sponges, plants) have very little hope to be fossilized and even when an organism has hard parts, dissolution and recrystallization could erase any traces of fossilization. Erosion and changes in the formation of rock can also destroy fossil evidence. Terrestrial organisms are less likely to be fossilized than those in aquatic environments, because sediments in water increase the chances of fossilization. Even when there are fossil-rich layers, these may be situated in inaccessible places, e.g. on the bottom of the sea or in the subsurface. Long-lived and abundant species stand a bigger chance of being preserved in the fossil record than short-lived or scarce species. For example, a fossil impala would be more probable than a fossil aardvark. As Charles Darwin stated: “The crust of the earth is a vast museum; but the natural collections have been imperfectly made, and only at long intervals of time.”

One famous gap in the fossil record is called Romer’s gap and spans from the end of the Devonian period (about 360 million years ago) and the early Carboniferous period (about 340 million years ago). This gap basically correlates to the evolution of fish into amphibians. Several of these transitional forms have been discovered:

  • Eusthenopteron foordi, discovered in 1881 in a collection of Canadian fossils, is an example from the late Devonian period. At the bases if its fins, this creature had bones which are analogous to those of terrestrial animals. Eusthenopteron looked like a fish and probably spent its life in water.
  • Panderichthys rhombolepis is another specimen from the Devonian. It had less fins and thicker ribs than fish. Thicker ribs are needed to support the body when the creature is out of the water, but Panderichthys probably lived mostly in water.
  • Ichthyostega stensioei and Acanthostega gunnari looked like fish with legs. Their cranial structure and skeletons resembled that of a fish, but their ribs were even thicker than those of Panderichthys. Both creatures could breathe air. Between the two, Ichthyostega probably spent more time on land than Acanthostega and moved like a seal does on land. Ictheostega would be the first known vertebrate that did not move like a fish. In fish, the hyomandibular bone serves to support the gills. This bone corresponds to the ear bone in mammals, also called the stapes. In Acanthostega the stapes resemble the hyomandibular bone of a fish and could not vibrate, thus rendering it useless for the purposes of hearing. Later, in the Carboniferous period, amphibians possessed a hyomandibular bone that could be used for hearing.
  • Tiktaalik roseae was discovered in 2004 and had amphibian-like skull, neck, ribs, elbows, wrists, and fingers, yet had fins, scales, and gills like a fish. It could probably prop itself up using the elbows, wrists, and fingers. Tiktaalik did not have gill plates and could thus move its head from side to side.

Also see: http://waitbutwhy.com/2013/12/your-ancestor-is-jellyfish.html for a cute family history

Sources:

Bailey, D H 2010. Creationism and intelligent design: Scientific and theological difficulties. Dialogue: A journal of Mormon Thought 43/3, 62-81.

Cotner, S & Moore, R 2011. Arguing for evolution: An encyclopedia for understanding science. Greenwood: Santa Barbara.

Daintith, J & Martin, E (eds.) 2010. Oxford dictionary of science. Oxford: Oxford University Press.

Darwin, C 1909. Origin of species. New York: P F Collier and Son.

Dawkins, R 2009. The greatest show on earth: The evidence for evolution. London: Bantam Press.

Miller, K B 2003. Common descent, transitional forms, and the fossil record, in Miller, K B (ed.) Perspectives on an evolving creation. Grand Rapids: William B Eerdmans.152-181.

Rice, S A 2007. Encyclopedia of evolution. New York: Facts on File.

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Arguments Against Evolution Pt. 4

Radiometric dating is faulty

Old earth creationists are more accepting of radiometric dating and its findings, but young earth creationists reject the technique. Robert T. Pennock states that “young-earthers still try to argue that the radioisotope data cannot be trusted, suggesting that rates of decay were not constant but had accelerated at times, thus skewing the data so the earth appears to be much older.”

Cotner and Moore write the following:

Andrew Snelling of the antievolution organization Answers in Genesis claims that radiometric dating is inaccurate because it contradicts the Bible and because “we now have impeccable evidence that radioactive decay rates were greatly sped up at some point during the past, for example, during the global catastrophic Genesis Flood.” This alleged evidence has never been published in a peer-reviewed scientific journal. Just as there is no evidence for a global flood, so too is there no evidence that rates of radiometric decay have changed significantly over time, nor is there any evidence that the laws of physics change during floods.

Radiometric dating works with the rate at which radioactive elements and isotopes decay. Isotopes are atoms of the same element that contain a different number of neutrons in the nucleus. The element is defined by the number of protons present in the nucleus. Carbon has six protons and six neutrons, Carbon-12 has six protons and 12 neutrons. The half-life is the amount of time it takes for half of the atoms to decay. Radiometric dating is useful in dating the igneous rocks that are found between layers of sedimentary rock, because only volcanic rock can be dated with this method.

Stanley Rice provides two ways in which isotopes are useful in evolutionary science:

  • Many isotopes are radioactive—that is, the extra neutrons destabilize the nucleus, which ejects particles and changes into another kind of atom at a constant rate. This makes radioactive isotopes useful for determining the ages of some rocks. 14C is radioactive and is the basis of radiocarbon dating.
  • Nonradioactive isotopes can be useful as indicators of environmental conditions or biological activity in ancient deposits, fossils, or remnants of organisms. 13C is an example of a nonradioactive isotope.

Cotner & Moore explain that “[r]adioactive decay is exponential, meaning that the rate of decay does not involve fixed amounts of atoms, but instead involves fixed proportions of atoms. After one half-life, half of the original radioactive atoms are present. This rate remains constant regardless of how many atoms have already decayed.” The technique was proposed by Ernest Rutherford in 1905.

Uranium-lead dating is a type of radiometric dating that is used on zircon crystals and works on the ratio of uranium-238 atoms that have decayed into lead-206, or uranium-235 to lead-207 atoms. Clair Patterson developed the uranium-lead method in 1948.

Potassium-argon dating is another kind of radioactive dating. Potassium-40 decays into argon-40. Potassium-containing minerals are tested to find the amount of argon-40 and then to calculate the time that has passed since the mineral cooled to about 300 degrees. Potassium-argon dating can be used on materials such as mica, feldspar, and other minerals. The decay of rubidium-87 into strontium-87 can also be used for dating.

The radiocarbon method is the method for organic materials and was developed by Willard Libby in 1947. Cosmic radiation causes a small percentage of the nitrogen in the atmosphere to be transformed into carbon-14 atoms. Some of these carbon-14 atoms are absorbed by plants during photosynthesis. When the plant dies, photosynthesis stops and the ratio between radioactive and stable carbon atoms begins to decrease. This ratio can then be measured to determine the time that has passed since the death of the plant.

Another type of radiometric dating is called fission-track dating and is based on the tracks made in volcanic rock by the decay of uranium-238, which decays into lead.

Dating fossils by sedimentary layers is circular reasoning

John Philips was the first to use strata to date sediments. William Smith, in 1796, realized that there are fossils that are specific to each stratum and constructed geological maps according to the fossil species found in each stratum. His findings helped to establish the science of biostratigraphy. Georges Cuvier, a famous anatomist, made the following remark in 1801: “the older the beds in which [fossils] are found, the more they differ from those of animals that we know today. [This is] the most remarkable and astonishing result that I have obtained from my research.” Darwin himself wrote that “a discerning eye might have seen that some form or other of the doctrine of transmutation was inevitable, from the time when the truth enunciated by William Smith that successive strata are characterised by different kinds of fossil remains, became a firmly established law of nature.”

Over time, geologists have developed a standard column illustrating the different layers and when they were laid down (like a map of strata). Fossils are then dated relative to the layers in which they were found. Hurd explains that “[b]iostratigraphic dating rests on the fact that certain extinct ancestor of the modern horse, cow, or elephant always appear in specific locations in the standard geographical column.” Anachronistic fossils have never been found.

Stratigraphy and biostratigraphy are not the only methods used to date fossils. The radiometric dating techniques discussed in the previous section are used in tandem with stratigraphy and biostratigraphy.

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