"Creation scientists" try to counter this body of biochemical evidence by claiming that certain protein comparisons actually show humans to be more closely related to vastly different organisms (e.g. bullfrogs, chickens, rattlesnakes) than to chimpanzees. A classic example comes from early writings of former biologist Gary Parker, formerly of the ICR: Creation: The Facts of Life, Creation-Life Publishers, 1980; also Homology, Embryology, and Vestigial Organs: Common Ancestor or Common Plan?, Institute for Creation Research). In them, he names a number of molecules that purportedly show humans to be more closely related to quite different organisms than to apes. Frank T. Awbrey and William M. Thwaites listed Parker's molecules in their article, "A Closer Look at Some Biochemical Data that 'Support' Creation"
(_Creation/Evolution_ Issue VII, 1982, pp 14-17):
Molecule Nearest Relative to Humans
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Fetal Hemoglobin ==>Horse
Tear Enzymes ==>Chicken
Albumin ==>Bullfrog
Blood Antigen A ==>Butterbean
Cholesterol Level ==> Gartersnake
Milk Chemistry ==>Donkey
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[NOTE: The current edition of Parker's Creation: The Facts of Life is
a revised edition published in 1994. In that revised edition, this claim for all the molecules listed above has been removed, except for the chicken tear enzyme,lysozyme. That claim is described in more detail later in this article.]
Then Drs. Awbrey and Thwaites examined the literature and Parker's referencesand found (quoting freely) that for:
Fetal Hemoglobin --
Hemoglobin has four globin molecules, each arranged around a central iron atom and a porphyrin ring. Human fetalhemoglobin has two alpha globins and two gamma globins,each with 146 amino acids. Horses don't have gamma globins. Chimpanzees do, and it is identical to that of humans. So creationists conclude that a molecule that doesn't existis more similar to a human molecule than is an identical chimpanzee molecule.
Tear Enzymes --
The enzyme referred to here is lysozyme, which is found in human milk, tears, leukocytes, etc. Variants exist in tissues of other species, for example, in chicken egg whites. Chicken lysozyme differs from human lysozyme by 51 out of 130 amino acids. Chimpanzee lysozyme is identical to human lysozyme. Either creationists have ignored the literature or they apparently believe that 51 is less than zero.
Albumin --
Human and chimpanzee albumin differ by six out of 580 amino acids. Human and bullfrog albumins differ so much that they don't cross-react in immunological tests.
Blood Antigen A --
This is one of the molecules that determine blood types. They are called glycoproteins because they have sugars attached to a protein. Butterbeans contain a sugar configuration that is similar enough to the glycoprotein sugar that it can react with antibodies directed against the A blood type if the butterbean sugar is at a high concentration. Chimpanzees have blood antigens that are identical or nearly identical to those of humans. Having no blood, butterbeans obviously have no blood antigens.
Cholesterol Level --
Cholesterol is a simple lipid (a wax) and its structure doesn't vary among species. Furthermore, its concentration can vary several hundredfold in an individual human depending upon diet and genetic background. Therefore, it is a useless molecule for determining genetic similarity. This datum isn't just wrong, it's nonexistent.
Milk Chemistry --
No direct comparison of human and chimpanzee milk chemistry could be found. However, it was found that human milk proteins (whey and casein) are much more like macaque milk than donkey milk. Human and chimpanzee milk lysozymes are identical. Even this limited comparison disproves the creationist claim that the donkey is our nearest relative based on milk chemistry.
The Bullfrog Affair itself starts with the KPBS production, "Creation vs Evolution: Battle in the Classroom", which aired 7 July 1982. After Dr. Doolittle related his story of the chimpanzee blood proteins (see above), Dr. Duane Gish responded:
"If we look at certain proteins, yes man then, it can be assumed that man is more closely related to a chimpanzee than other things. But, on the other hand, if you look at certain proteins, you will find that man is more closely related to a bullfrog than he is to a chimpanzee. If you focus your attention on other proteins, you'll find that man is more closely related to a chicken than he is to a chimpanzee."
This was immediately followed by Dr. Doolittle's response, "Oh bullfrog! I've heard that gibberish before, I have to tell you." This was the first recorded use of "Bullfrog" that I am aware of. Then Doolittle indicated a book full of amino acid sequences from thousands of proteins taken from many hundreds of species and offered Gish all his worldly belongings, a '63 VW and half a house, if Gish could find just one protein in chickens or bullfrogs that is more closely related to human proteins than chimpanzee proteins.