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Biologists tell us that the ability to detect and identify odours is perhaps the most important sense that animals need to survive. By means of odour detection, insects locate food, avoid toxins and predators, and communicate with others of their own species. Their sense of smell is located mainly in their antennae.

One insect that is particularly talented in many respects, is none other than the famous fruit fly. For example, these red-eyed beauties exhibit extremely good abilities to find rotting fruit. Because fruit flies are easy to culture, biologists first studied odour detecting talents in these creatures. The study was expected to be interesting but scarcely earth-shattering. But guess what! Drosophila (fruit fly) was the tip of the iceberg to reveal that insects exhibit odour detecting abilities that are highly unusual and a major problem for evolutionary expectations. Since then similar studies have been conducted on moths, beetles, other flies, cockroaches and social insects.

When biologists discuss a phenomenon in terms of its “unexpected” features such that it is “surprisingly unconventional” or “surprisingly different” (as per Benton, Sachse, Michnick, and Vosshall. 2006 PLoS Biology; and Tal Soo Ha and Dean P. Smith. 2009.  Front Cell Neuroscience), we understand that the phenomenon does not fit evolutionary expectations (theory). These scientists were referring to the system of detecting odours which they had observed in insects. Apparently the odour detection apparatus in insects is different from that of all other animals. In addition, the composition of the proteins is not only totally different from those of other animals but there is an astonishingly high variety of these molecules, even among insects themselves.  Indeed, a recent article in Nature refers to relevant proteins as displaying “striking sequence diversity, with an average of only about 20% amino-acid identity shared between odour receptors, either within or across species. (Butterwick et al. 2018. Nature August 23 p. 447). According to known biochemical processes, this large amount of variety could never develop naturally!

According to Darwinian theory, new proteins appear through gradual change over time from already existing molecules. Recent studies however suggest that it is impossible to produce a useful protein through this process. How much more so, the possibility of developing a protein from scratch is clearly a literal impossibility, even with the most optimistic evolutionary explanations. This relates to the nature of proteins (which form most of the structures in living creatures and the living cell.)

Suppose we seek to obtain a protein which fulfills a specific purpose.  A protein is made up of a particular order (chain) of small molecules called amino acids which have been assembled in the cell. This chain must fold into a very particular three-dimensional shape if it to exhibit its function. This ability to fold is determined by the electrical attractions of the component amino acids. Douglas Axe, of the Discovery Institute but then at Cambridge, performed experiments on proteins to discover how common (compared to all possible sequences of amino acids) functional proteins might be. He discovered that they are exceedingly rare. Thus he declared in his book Undeniable (2016): “Of the possible genes encoding protein chains 153 amino acids in length, only about one in a hundred trillion trillion trillion trillion trillion trillion  is expected to encode a chain that folds well enough to perform a biological function!” (p. 181 italics his)

A chain of 150 amino acids is actually small, many proteins are composed of thousands of amino acids, so the probabilities of finding such a protein become even more remote. The probabilities are far too small to consider random development of any protein to be possible. Thus evolution theory cannot explain the development of even one new unique protein. But among insects, possibly hundreds of thousands of odour receptor proteins show no similarity to other proteins, so they cannot be explained as developing by gradual change over time (the favoured Darwinian explanation.) The only way that these proteins could come about, is through the skill and choices of an intelligent supernatural designer!

Not only are insect odour receptors “the largest family of ion channels found in nature” (p. 452) but they lack similarity (homology) to any other protein family. (p. 447) This means that the odour receptor proteins in insects are not like any other protein known from any other creature for any other use. They are absolutely unique! The scientists assure us that “different species [of insects] have evolved unique repertoires of receptors suited to their specific chemical environments.” (p. 447) When one thinks of insects as needing to locate everything from dung, to carrion, to beautiful flowers and warm-blooded people, one can understand that a wide array of odour receptors is needed among this group of organisms.  Thus the authors of the Nature article remark that “A hallmark of insect olfactory receptors is their inordinate diversity within and across insect lineages.” (p. 451)

The shape of the odour receptors is actually a thing of beauty. Imagine a living cell’s protective membrane as a thickish layer extending around the cell. Extending through the layer are vase shaped pores. Covering each quarter of the pore, from top to bottom, is a seven-layer protein. This protein coating is flared outward at the upper and lower cell membrane edges to allow for a seven-fold penetration to the exterior and interior of the cell. Two of the four pore coating proteins are a standard composition which is unique to insects but basically the same form for all of them. The other two proteins look similar but they are highly unique, even among insects.

Odour causing molecules attach to the unique seven loops which extend outside the cell membrane. A nearby nerve ending is stimulated to send an electrical signal to the brain. Depending upon the number of different kinds of odour receptor molecules stimulated, the brain identifies an odour of interest to that insect.   The damselfly has just 4 different kinds of odour receptor molecule whereas some ants possess more than 350. Obviously the ants live a much more complex life-style.

Organisms with the capacity to smell, other than insects, also possess a seven transmembrane oderant receptor, but composition of the proteins is totally different from in insects. Despite the significant problems for evolutionists in explaining the sudden appearance of insect odour receptors, some experts point to a common blueprint that both insects and other animals display. Benton et al. in PLoS Biology declare that there are anatomical and functional parallels in odour detection despite the “completely different molecular solution” between these groups. They appeal to that popular term “convergence” to explain what evolution theory cannot in fact explain: “That their odour receptor families should have unrelated evolutionary origins highlights the remarkable convergence in anatomical and physiological mechanisms that mammals and insects display.” How did they by chance develop a similar way of operating, when the structural components are so different?

What we have discovered is another case of a common blueprint expressed in different ways that could never have developed via an evolutionary pathway. Indeed, as Casey Luskin declared: “[M]odern genome sequencing has discovered thousands of ‘orphan genes’ – unique genes that exhibit no homology (sequence similarity) to any other known gene. These genes ought to refute common ancestry because they cannot be compared to genes from other species, and thus do not fit into any phylogenetic [evolutionary] tree. The problem is usually ignored.” (Theistic Evolution. 2017. p. 391-2). Let us therefore not ignore this information but  reflect on the One who is able to design molecular machines and the amazing variety of molecules to form those machines.

For discussion of human noses see “Nifty Noses” Dialogue October 2004   www.create.ab.ca/nifty-noses/#more-446


Margaret Helder
January 2019

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