Science - General
Surprising similarities: shrubs and whales, trees and snails
In his fabulous nonsense poem, The Walrus and the Carpenter (1871), Lewis Carroll groups cabbages and kings together. Upon reflection, we might ask what cabbages and kings have in common. Probably nothing. Nevertheless, there are some cases in nature where similar groupings might call for a different answer. Let me riddle you this: what do marine cone snails have in common with a tall tree growing in tropical Australia? And what do sperm whales have in common with a desert shrub? Don’t be quick to confidently reply “nothing”! The true answer is, “You would be surprised!” Toxic tree and savage snail The Australian stinging tree's stems and leaves are covered with longish hairs a quarter inch long in a layer so thick it looks like velvet. Picture by Norbert Fischer and used under a Creative Commons Attribution-Share Alike 4.0 International license. The tree in question is the Australian stinging tree Dendrocnide excelsa which grows 35 m (115 ft) tall. Its stems and leaves are covered with longish hairs 1/4 inch long in a layer so thick it looks like velvet. But looks can be deceiving. These hairs are actually hollow tapering tubes with a small bulb at the tip. If anyone or anything happens to brush one or more of these trichomes/hairs, the victim receives an excruciatingly painful sting which can cause symptoms that last for days or even weeks. There are two features of this event that interest us, the delivery of the sting, and the nature of the poison. The sting mechanism is certainly interesting. According to a recent article, the needle-shaped hairs (trichomes) “act as hypodermic needles that, upon contact with skin, inject specific pharmacological mediators contained within the trichome fluid...”1 A leave that injects? That might seem a bit far-fetched. After all, how can a hollow tube inject anything? To answer that, a different study points out that it all comes from the complex design of the trichome (hair). Except for a flexible base, the rest of the hair is a hollow tube whose walls are made very stiff with calcium carbonate and silica. The interior of the hollow tube is filled with a cocktail of nasty compounds. The scene is set for the following event:
“The stinging cells are essentially hollow from the base to the bulbous tip and break off with the slightest touch. Breakage creates a sharp edge connected to a large liquid reservoir similar to a hypodermic needle. Pressure applied to the trichome will compress the bladder-like base and eject the irritant fluid from the tip in an action analogous to the plunger in a hypodermic syringe.”2Concerning that process, the authors of that paper declare: “Stinging hairs – even as mechanical structures – are not simple cells with mineralized walls, but stunning examples of unique plant microengineering.”3 That certainly sounds like design! The Australian stinging tree is classified in the same plant family as common stinging nettles. The nettle characteristics are very similar to the tree except for size (nettles are much smaller), and the nature of the irritant, which is not dangerous in the case of the nettles. Sinister similarity But finally getting back to our riddle, we now discover that the mode of delivery of the nasty chemicals in the tree (and the nettles) is very similar to what we see in some animals such as poisonous spiders and marine cone snails. Cone snails are dangerous predators that we see in tropical seas. Up to 22 cm or 9 inches long, these creatures hunt worms, other mollusks, or fish. Some of the 500 species exhibit toxin so potent that it can kill people. Interestingly, these nasty cone snails inject the poison into their victims by a syringe-like action similar to that of the stinging tree. However, it is in the appearance and action of the poisons that the similarity between stinging trees and cone snails becomes particularly clear. As a recent article declares:
“Our results provide an intriguing example of inter-kingdom convergent evolution of animal and plant venoms with shared modes of delivery , molecular structure, and pharmacology.”4Translating this into ordinary English, they are telling us that the poisons produced by the stinging tree and the cone snail are very similar to each other. The term “convergence” communicates the idea that these highly unusual products come from totally different sources. How the tree and the marine snail might have obtained these products through an evolutionary process, is unknown. Hence the term convergence suggests that organisms converged on the same obscure choice for unknown reasons by unknown processes. Despite the obscurity of the explanation, most scientists are sure that there must be an evolutionary explanation. The most remarkable aspect of the unexpected similarity between a tree and a marine snail is in the nature of the poisons that they produce. From the variety of compounds in the venomous liquids, the team found that the most effective products in the tree were “mini proteins” of only 36 amino acids long. Despite the fact the molecule is so short, the order of amino acids is unlike any other protein known in any other organism. Because the molecules are so unique to the stinging tree, the scientists called them gympietides (after the name for this tree in the local Gubbi Gubbi language). Although the mini protein is unique, its weird folding pattern or shape is similar to toxins found in some spiders and in cone snails. Another term for this molecular shape is “inhibitor cystine knot” (or aptly ICK or knottin). Apparently, the amino acid chain folds in on itself a couple of times, and sulphur atoms in one amino acid link up with another amino acid to hold the structure in a tight knot.5 The action of the gympietides (the knot) involves its victim’s nerves. If you recall your high school biology you’ll remember that the transmission of a signal along a nerve involves sodium ion gates that open in the nerve cell membrane allowing sodium to rush into the nerve cell. As the signal proceeds down the nerve cell, the previously opened gates slam shut so that the cell can return to its former condition in preparation for receiving a new signal. What the gympietide poison does is open the sodium gates and then doesn’t allow them to close or recover. Thus the scientific team reports that:
“The intense pain sensations and reflex flare observed after by Dendrocnide species are consistent with the potent activity of the gympietides at channels .”6While the order of amino acids in the protein chain from the stinging tree’s toxin has not been observed anywhere else, nevertheless the folding pattern confers on the molecule an effect similar to some spider and cone snail toxins.7 Thus the study authors conclude concerning the gympietides:
“Their structural similarity and a delivery mode identifiable as envenomation exemplify cross-kingdom convergence of venoms.”8The scientists can scarcely contain their surprise when they reflect that these close similarities in design are found between members of different kingdoms. Of course, plants and animals could scarcely be more different from each other in appearance, capabilities, and lifestyle needs. Whatever could lead to evolutionary processes which start so far apart but end up with a product so similar? As to whether there could be an evolutionary reason for a plant to produce animal venoms, the scientists declare that the issue remains “unclear.”9 Indeed it seems obvious that an evolutionary answer will never be found. Rather, the explanation is clearly that these were choices made by God. In our fallen world there are many agents of death and disease. That is not how it was supposed to be. Nevertheless, these agents demonstrate the same intricate characteristics as the rest of the Creation. Whale and shrub If similar compounds produced by a tropical tree and a marine snail are difficult to explain from an evolutionary point of view, how about liquid waxes from a whale and a desert shrub? According to an article from University of Washington Magazine, up to 1972 when the Endangered Species Act was passed in the United States, in North America alone up to 55 million pounds of sperm whale oil were used to protect automobile transmissions. According to the article, thanks to protection from whale oil, prior to 1972, car transmissions seldom failed. Within three years of the moratorium on whale killings, the rate of car transmission failures in the US increased 800%. Thus, the article declares: “Because the automatic transmission is the second-most expensive component in a car and the most complex to repair, total sales for transmission shops exceeded $50 billion by the 1990s.”10 The problem is that the sperm whale liquid wax was just the right product to provide for excellent lubrication in car transmissions and there was no other similar product available. The oil of the sperm whale Physeter macrocephalus is a liquid wax. The characteristics which made this product so perfect for lubrication included the following. For a start and most uniquely, this wax is liquid at room temperatures. Also, it is viscous (much thicker than water) but slippery and not sticky. And most importantly, this viscosity does not change much with greatly increased temperature and pressure such as we see in running motors. For example, if you were expecting a product to lubricate your engine, but the product became much more fluid with increasing temperature and pressure, your engine would soon seize up. Also helpful are the facts that liquid wax does not readily oxidize (breakdown) and it flows in cold weather rather than congealing. Deeply concerned that they had lost an exclusive and useful product, the automobile industry began desperately to search for alternatives. And they soon found one in seeds of a desert shrub, the Simmondsia chinensis, or jojoba. A professional oil chemists’ journal in 1979 declared: “The protected but still endangered sperm whale and desert-grown nuts from jojoba are the only major sources of liquid waxes.”11 Similarly, an article declared in 2009: “Jojoba oil is very similar to that of spermaceti for which it is an excellent substitute.”12 Later in 2017 scientists writing in Biological Research describe jojoba oil as a “high-viscosity liquid-oil that differs from any other oil produced by plants”13 so that “The jojoba oil plant is a promising alternative to threatened sperm whale oil.”14 So, the world did an about-face and focused their attention on the desert instead of the sea. Slick similarity So why are these oils, from two such different sources, so similar and otherwise so unusual? The secret of these oils is their chemical identity as liquid waxes. Without embarking on a crash course in organic chemistry, we find that most organic oils are fats. Fats involve long chain fatty acids linking up with a glycerol molecule. Glycerol has only three carbon atoms, but each of them is usually connected with a long chain fatty acid. This makes quite a complicated molecule, like a glove with three very long fingers. Liquid waxes are totally different. A moderately short chain fatty acid links with a similar molecule which ends with an alcohol grouping instead of an acid. So, we just have one straight chain of carbons in a liquid wax. For whale oil liquid waxes, we generally see 28 to 32 carbons.15 As organic compounds go, these are small molecules. For jojoba, the liquid waxes are a little longer, from 38 carbons to 46 carbons.16 The commercial exploitation of jojoba liquid waxes is not totally straightforward. The oil is found in the seeds (up to 50% by weight), but less than half of the shrubs actually produce seeds. For some reason, there seems to be a bias to grow more male plants than female plants and one cannot identify the female plants until they flower, several years after germination. Although the plants tolerate quite terrible desert growing conditions, the flowers don’t always set seed well. Altogether jojoba liquid is very expensive to produce. Nowadays we see mostly synthetic products of jojoba oil for automotive uses. The intriguing issue is why two such different organisms happen to exhibit this highly unusual chemistry. Evolutionists would say that this capability came about by chance. Since no other organisms display this capability, it is obvious that these choices were not a case of the organisms needing these waxes for survival. It appears that the liquid wax does enhance germination of the jojoba seeds. Of course, whales don’t care about that. Several explanations have been proposed to explain the large amount of liquid wax in sperm whale heads. There certainly was no common condition encouraging the development of an unusual chemical product in these two creatures. We see rather God’s whimsical choices in conferring this valuable product on two such different creatures. At this point it seems appropriate to give thanks for the fascinating beauty that we see among living creatures of all types. We also see that diversity and unexpected complexity confer a richness on the Creation which never ceases to comfort us that God is in control.
Dr. Margaret Helder is the President of the Creation Science Association of Alberta which has just published an intriguing new book called "Wonderful and Bizarre Life forms in Creation" which you can learn more about and order by clicking here.Endnotes Edward K. Gilding et al. Neurotoxic peptides from the venom of the giant Australian stinging tree. Science Advances 6: September 16 pp. 1-9. See p. 1. Adeel Mustafa et al. Stinging hair morphology and wall biomineralization across five plant families. American Journal of Botany 105 (7): 1109-1122. See p. 1115. Mustafa et al. 1121. Gilding et al. 1. For people who like chemistry, the amino acid cysteine ends in a sulphur atom. And the cystine is formed from 2 cysteine residues joined end to end through the sulphur atoms (disulphide bond). Cystine is formed by linking cysteine residues through their sulphur atoms across different parts of the loop. In a knot, there are two cystine molecules connecting different parts of the chain and another in a different direction which ensures that the knot does not fall apart.] Gilding et al. 5. Gilding et al. 5 Gilding et al. 5 Gilding et al. 5 Jon Marmor. 2019. The Innovation File: Solving a Whale of a Problem. UW Magazine 1-5. See p. 2. K. Miwa and J. A. Rothfus. 1979. Extreme-Pressure Lubricant Tests on Jojoba and Sperm Whale Oils. Journal American Oil Chemists’ Society 56 #8 pp. 765-770. See p. 765. Vijayakumar et al. 2009. Synthesis of ester components of spermaceti and a jojoba oil analogue. Indian Journal of Oil Technology 16 pp. 377-381 September. See p. 377. Jameel R. Al-Obaidi et al. A review of plant importance, biotechnological aspects and cultivation challenges of jojoba plant. Biological Research 50:25. pp. 1-5. See p. 1. Al-Obaidi et al. 3. Vijayakumar et al. 377. Rogers E. Harry-O’Kura et al. Physical Characteristics of Tetrahydroxy and Acylated Derivatives of Jojoba liquid Wax in Lubricant Applications. Journal of Analytical Methods in Chemistry. 2018 Article ID 7548327 pp. 12. See p. 1.
Science - General
Pluto: Déjà vu all over again
Until the summer of 2015, we knew very little about Pluto. We knew that it was far away, 5 billion kilometers. We also knew it was very cold, at -223 ...
Science - General
A sixth sense? Yup, it's true!
We all know about the standard five senses – taste, touch, sight, smell, and hearing – but did you know some of God's creatures have a little some...
Science - General
Why we’ll never run out of things to discover
A few years ago National Geographic published a provocatively titled article: “Opinion: Science is running out of things to discover.” Author J...
Science - General
Your head is fearfully and wonderfully made
“A little science estranges men from God, but much science leads them back to Him.” – Louis Pasteur or maybe Blaise Pascal or perhaps someone else altogether **** It's unclear who exactly spouted this bit of wisdom above, but it is clear it isn't always true. Well-studied evolutionists, like a Richard Dawkins, or like documentarian David Attenborough (the fellow narrating those amazing Planet Earth videos), have looked at God's creation closely and remained evolutionists still. So, the principle doesn’t work always work. But there's still something to it. The deeper we dig into God’s creation, the more we find out how amazingly it's all been crafted. And then it is by choice, and not evidence, that one remains blind to God's artistry. From the neck up Consider just the human head. The human brain has more than 100 billion neurons, connected to maybe 1,000 other neurons (though some estimates up that by a factor of 10), for 100+ trillion electrical connections in all, making the human brain more complex than all the wiring done for all the houses in the world combined. All those interconnections then route into a very rigid, yet strangely flexible housing – your spinal column – that delivers messages to the rest of the body. Staying with our head, if we were to compare the human eye to a camera it's one with auto-focus, aperture control, and paired up to allow for depth perception. It has more than 100 million light-sensitive rods and cones that convert images into electrical impulses that our brain has the proper “program” to convert into images. There is said to be a blindspot where all the nerves bundle together in the back of the eye to head off to the brain and this is understood by critics to be evidence of the sort of bad design one might expect from accidental unguided evolution. But do you actually see any "blindspot" in your vision? No...because your brain, and the overlapping fields of vision from your two eyes, wonderfully compensate for it, such that it is only a theoretical and not actual blindspot. Astonishing! Your ears also come in pairs, allowing us to hear directionally. They are precision instruments, able to differentiate between thousands of different sounds. Their inner workings also give us our sense of equilibrium – our sense of balance – without which we really couldn't get around except on our hands and knees. Still sticking with our head, the tongue houses 10,000 tastebuds, is deft enough to tie a cherry stem in a knot, and tough enough to guide our food towards the teeth where it can begin to be digested. Those teeth first show up in a set of 20 shallowly rooted models, sized just right to fit our infant mouth. As we get bigger, these baby buds get replaced with teeth that are bigger too, with more of them, coming in a set of 32 that fills out our adult jaw. What wonderful timing! Concealing those teeth are our lips, which have the ability to express our moods, produce music, and, with our best beloved, smush other lips in a very agreeable manner! Let's not forget the nose, with its extreme sensitivity, filtration ability, and self-clearing capability (i.e. sneezing). Anyone not already amazed simply isn't paying attention. And we haven’t even looked at the rest of our body, like how our heart pumps 1,500 to 2,000 gallons a day, for 75 years, and yet weighs a mere 12 ounces. We haven’t looked at the skin, just a 20th of an inch thick, yet our body’s biggest organ, self-repairing, infection sparing, touch sharing. And what of our bones, all 206 of them, flexible during birth when they need to be, then toughening up to function as the scaffolding for all our other parts, and also produce the white blood cells that help us fight infection. Conclusion Of course, if we were to venture south of the jawline to start exploring God's engineering genius on display there too, this article might never end. So we'll have to limit ourselves to just the neck and up, and that is more than enough to make our point. Yes, educated men and women can deny God's evident artistry, they can choose not to see it, but that's only because it is possible for Man to suppress and deny the truth (Romans 1:18). But any with eyes to see – creatively and brilliantly crafted eyes! – the deeper we look, the more evident it becomes that from the top of our heads down, we are fearfully and wonderfully made (Ps. 139:14)! ...
News, Science - General
Genetically-engineered babies have now been born
Human experimentation has been happening around the world for the past four decades, with research scientists actively carrying out experiments on human embryos. The stated objective, in usually something noble-sounding: to learn more about human biology, or to possibly treat some disease conditions. And while few scientists will admit to an interest in cloning people, or in actually producing genetically-altered individuals, this is the direction our society is heading. Indeed, modern society does not value unborn babies enough to protect them, and at the same time society is terribly afraid of genetic abnormalities. Under these conditions – little respect for unborn human life, and little respect for those with genetic abnormalities like Down syndrome – it would seem human cloning and gene alteration is inevitable. But it isn’t acceptable yet. That became clear when, on November 26, 2018, the scientific and medical world reacted in horror to the announcement by Dr. Jiankui He at the Second International Summit on Human Genome Editing in Hong Kong, that he had created modified human embryos. These embryos had been implanted in their mother, and in early November, twin baby girls had been born in China. This was a world-wide first – the first genetically-edited full-term human babies. What happened Ever since the 1970s introduction of in vitro fertilization of human eggs with sperm outside the womb, the stage was set for scientists to experiment on such embryos. Many people, mindful of the special nature of humans at every level of development, protested against such work. Even some scientists were nervous about the implications of these experiments. However, for many, the concern was only that individuals damaged in laboratory experiments should not be allowed to develop to term. They were okay with the human experimentation – they just didn’t want these babies to be born. As a result, a general understanding was reached between ethicists and scientists, that no experiments on embryos would continue longer than 14 days – at this point these embryos were to be destroyed. The 14-day limit was chosen because it is at this point that the embryos begin to develop specialized tissues and thus becomes more obviously human (Nature July 5, 2018 p. 22). But as the experimentation has become more sophisticated, scientists have begun to promote the idea of a longer timeline for their investigations. Thus, a conference was held in May at Rice University at which 30 American scientists and ethicists discussed “whether and how to move the boundary” (Nature July 5, 2018 p. 22). About the same time, Nature magazine published an announcement concerning such research: “At present, many countries …prohibit culture beyond 14 days, a restriction that reflects the conclusions of the 1984 UK Report of the Committee of Inquiry into Human Fertilization and Embryology (also known as the Warnock Report. Whether this rule should be relaxed is currently being debated” (May 3, 2018 p. 6, emphasis mine). Scientists are clearly seeking to relax the rules governing their studies. “Germ-line changes” Research on human embryos has continued worldwide since those early days. However, all parties once agreed that on no account should modified embryos be implanted into a mother and be allowed to develop. The reasons included society’s disapproval of experiments on people, but especially because such individuals would carry “germ-line changes.” Changes to most cells in the human body have no impact on future generations – these changes die with that individual. However, changes to the gametes (egg and sperm) are called germ-line changes because these modifications will be passed on to each subsequent generation. It is not that the scientists involved actually object to germ-line changes. The problem is that they want their results to be predictable and “safe.” Any uncertainties could lead to catastrophic results, ensuing hostile public opinion and big lawsuits. It would be far better to proceed cautiously. Thus, it is illegal in the US and many other countries to alter genes of human embryos or gametes. However, within the last decade, another new biomedical technology has appeared on the scene that has drastically streamlined gene editing in numerous organisms. The CRISPR-Cas9 technology has made gene editing much easier and much more precise.* Obviously, it was a mere matter of time before someone used this to try his hand at gene editing in human embryos. The scientific community offered no serious objections when Dr. Jiankui He of China presented an account of such work at a conference at Cold Spring Harbor Laboratory in New York during the spring of 2018. At this conference, Dr. He discussed the editing of embryos from seven couples. However, at that point, this man made no mention that any of these embryos had been implanted into their mothers. Dr. He “edits” babies to be HIV-resistant According to a Nov. 28 news item at Nature.com (David Cyranoski's "CRISPR-baby scientist fails to satisfy critics") Dr. He recruited couples in which the male was HIV positive but the female was normal. Individual sperm cells were washed to remove any viruses and the cells were injected into eggs along with CRISPR-Cas9 enzymes carrying a gene for resistance to HIV infection. A total of 30 fertilized embryos resulted of which 19 were deemed viable (able to live) and apparently healthy. These were tested for the CCR5 mutation which confers resistance to HIV infection. From one couple, two of four embryos tested positive for the mutation. One embryo carried the mutated gene on one chromosome and a normal gene on the other, while the other embryo carried the mutation on both maternal and paternal chromosomes. These embryos were implanted into the mother who successfully gave birth to twin baby girls early in November. No information was forthcoming on the fate of the other embryos, although Dr. He now says that another woman may be pregnant. The response of the scientific community has been shock and horror. But why are they so horrified? Is this not what they have been working towards? The scientific community is afraid because the risks of this procedure at this preliminary stage of research, are substantial. There are, at present, major questions as to whether the genetic modifications will actually have the desired effect. A well-known problem is that the CRISPR apparatus sometimes cuts the chromosomes at other places as well as/ or instead of the desired location. This off-target effect has been found to be a major problem in some studies. In addition, most genes are known to influence a number of seemingly unrelated traits. This phenomenon is called pleiotropic impact of one gene on other genes. These risks are particularly serious when we consider that these are germ-line changes, that will impact subsequent generations from this individual. Response The same Nov. 28 Nature.com news item declared: “Fears are now growing in the gene-editing community that He’s actions could stall the responsible development of gene editing in babies.” Indeed, a commentator on one website reflected that “if this experiment is unsuccessful or leads to complications later in life … set the field of gene therapy back years if not decades.” In view of these concerns, many individuals and medical and scientific institutions released statements expressing condemnation for this gene-editing work. Dr. Francis Collins, director of the National Institutes of Health in the United States, declared that the NIH “does not support the use of gene-editing technologies in human embryos.” The Chinese Academy of Sciences declared that Dr. He’s work “violates internationally accepted ethical principles regulating human experimentation and human rights law." A colleague and friend of Dr. He suggested that the gene-editing work lacked prudence, that it could, unfortunately, serve to create distrust in the public. Obviously, an important concern on the part of the scientists was that the promise of this technology not be rejected by the public. Dr. David Liu of Harvard and MIT’s Broad Institute (heavily involved in CRISPR research), insisted of He’s work: “It’s an appalling example of what not to do about a promising technology that has great potential to benefit society.” Dr. George Daley, dean of Harvard Medical School, summed up the feelings of many colleagues when he said: “It’s possible that the first instance came forward as a misstep, but that should not lead us to stick our heads in the sand and not consider more responsible pathway to clinical translation.” In other words, many scientists seek to continue to pursue the goals also sought by Dr. He, only the rest of them will proceed more slowly and carefully. Conclusion It is largely Christian objections to treating human embryos as things, rather than as persons (made in the image of God), that has led to the ethical rules that control this research. It is a vestige of our Judeo-Christian heritage which limits scientists from just doing whatever they want. They have to obtain permission from ethics committees to conduct their particular research program. Of course, Christians want to see this work made completely illegal, but if political realities make such a ban impossible, then we can still seek to restrict this work as much as possible. It is interesting that a news feature in Nature (July 5, 2018 p. 22) articulated the fascination and unease that some scientists derive from this work. Bioethicist Dr. Jennifer Johnston of the Hastings Center in upstate New York, reflected on the respect that the human embryo commands even in secular observers: “That feeling of wonder and awe reminds us that this is the earliest version of human beings and that’s why so many people have moral misgivings ….. It reminds us that this is not just a couple of cells in a dish.” Are there any good results from this controversy over genetically-engineered babies? Perhaps there is one. The event may cause more people to pay critical attention to the experiments that are, every day, conducted on human embryos. Let the whole world know that we are fearfully and wonderfully made, from the very first cell onward, and manipulation in laboratories should have no place in our society. For further study * For more on this topic, see: Dr. Helder’s book No Christian Silence on Science pages 32-39 for a discussion on Clustered Regularly Interspaced Short Palindromic Repeats (ie. CRISPR). Jennifer Doudna and Samuel Sternberg’s book A Crack in Creation: the new power to control evolution, page 281. Dr. Helder's article, providing further background to CRISPR, Natural Firewalls in Bacteria ...
Science - General
Don’t push Dad into the pond (and don’t tell Mom about the bugs!)
An aquarium-based science experiment for the whole family ***** Summer is here and there are any number of projects in which the whole family can participate. Of course, some are more fun that others – painting the fence, for example, will not rank high on anyone’s list. This is especially so if the junior members of the establishment spill the paint, or elect to decorate the family car with it. However, almost everyone enjoys splashing about in water, so why not consider an expedition to a pond in your area to start off your own family aquarium? Be warned: some individuals may get a little wet while chasing aquatic insects with a bucket or net. And dad may have to venture the farthest out to catch some particularly elusive creature. But children, just remember that if you want the project to be a happy experience, don’t push your Daddy into the pond! If anyone gets pneumonia, the project will definitely not be judged a success! Step 1 – set up the aquarium The first thing to do is acquire an aquarium. It doesn’t need to be too big, and you can probably find something used on Kijiji or Craigslist for $50. The aquarium should be placed in a window where it will receive moderate light, or it should be equipped with a fluorescent light. Place about an inch of gravel in the bottom – soil works too, but it is messier. Next some structure should be provided in the form of a few larger stones, a rock, sea shells, or pieces of waterlogged wood. Don’t overdo the structure. Only a small proportion of the volume and at most a quarter of the bottom area should be occupied by solid objects. These are important because they provide hiding places for various animals and surfaces on which to grow. Living aquatic plants also provide structure. Several inches of water may then be added. City water contains chlorine, which isn’t good for our aquatic life so if you are using it, be sure to leave it out to sit for several days to allow the chlorine to escape. Once living creatures are in the aquarium, then any new city tap water you add (to make up for whatever evaporates) must be boiled and thoroughly cooled first, in order to remove the chlorine. Step 2 – just add life! The aquarium is now ready for the addition of pond water with its contained organisms. The objective is to set up a self-perpetuating ecosystem (physical environment with its contained living creatures). Ideally all you will need to add once the system is established is water and light. Plants use the light to combine water, dissolved carbon dioxide, and mineral nutrients into food for the rest of the organisms in the aquarium. Moreover, plants in the light release oxygen into the water. This is essential if the aquatic animals are to stay healthy. Gathering your aquatic animals is a particularly fun part. Before setting out for the pond, make sure that mom and dad and all the offspring are equipped with rubber boots and buckets or large jars all with tops. Scoop nets are optional. The best procedure is to fill the bucket with pond water and some submerged pond weeds. You will acquire many pond creatures simply by collecting water and weeds. A few small pieces of decaying vegetation are good to collect too. These will have other organisms growing on them and, besides the dead material will provide for scavengers. However, don’t collect very much of this “nonvigorous” (i.e. decaying) plant material because too much decay will result in all the oxygen being used up. And without oxygen many animals will die and soon the whole aquarium will smell “swampy,” releasing hydrogen sulfide gas and methane into the atmosphere. At this point some mothers might banish the whole system right out of the house! Step 3 – let’s find out what we have Once the aquarium is filled with water and pond weeds, then you and your children can peer into the water to discover what you have collected. Some creatures last only a few days, others last almost indefinitely. Among the animals in your fresh water ecosystem, some will be easy to see, others hard to see because they are small or because they hide. Some will be so small they’ll only be visible with a microscope. While all have fascinating life stories we will discuss only easy-to-see animals. Here are your possible cast of characters. Gammarus In our family the favorite pond inhabitants are the amphipods or scuds known by the Latin name Gammarus. These delightful creatures do well in an aquarium. They swim through the water in a conspicuous way so that it is easy to show doubters that indeed there are animals present. Gammarus look much like marine shrimp. Their bodies are protected by a hard exterior skeleton or surface made of chitin. That is a hard, not easily decomposed material like our hair and fingernails. The body is divided into numerous sections and each segment bears a pair of legs. There are five different kinds of legs. Some have gills attached. The legs are used for swimming, for grasping food, and for obtaining adequate oxygen. These animals swoop through shallow water in semicircular arcs. They feed on bacteria, algae, and decaying plant and animal material. Mostly they confine their activities to within 20 cm of the bottom sediments. When collected in the summer Gammarus are at most one-and-one-half centimeters long. They continue to grow, however, as long as they live. By March, Gammarus which were collected the previous summer are three cm long (approximately twice as long as their maximum size in nature). Few will survive beyond April. Outside, in the Canadian climate, they would have died with the frosts of the fall. I add small pieces of boiled and cooled lettuce to the aquarium when the food supply for Gammarus seems low. If these “shrimp” are observed swimming round and round the aquarium, it is a safe bet that they are short of food. They seem to have a chemical sense for detecting food. When lettuce is placed into the water, they circle closer and closer. One individual may find the lettuce within seconds, eight or more within three minutes. As far as reproduction is concerned, in nature this proceeds throughout the summer. Both sexes are found in the population. The females carry their eggs and developing young in a brood pouch. The young resemble adults in miniature. One or two young have appeared in our aquarium during the winter months. Water fleas Most likely your aquarium will harbor water fleas as tiny as they are numerous. The white specks which move in jerky fashion through the water, are most probably Daphnia. You might even catch a species bigger than the tiny ones which presently populate our aquarium. The largest species of all can be found in very productive waters like the Delta Marsh of Manitoba. It boasts individuals as large as the fingernail on a lady’s fifth finger. All water fleas are crustaceans, as are Gammarus. They have an exterior skeleton of chitin and numerous jointed legs. Water fleas are an important source of food for aquatic insects, larger crustaceans, and various fish. Each Daphnia has a small head from which extend a pair of branched antennae. By moving these projections like oars, the animal is able to make awkward progress through the water. Five pairs of legs are attached to the body, but they do not show, nor are they used for swimming. Like the rest of the body except for the head, they are enclosed in a convex shell which is hinged along the back and opens along the front. Constantly moving within their confined space, the legs create a current of water which brings in oxygen to bathe the body surface and also a stream of food particles. The numerous hairs on the legs filter out the food particles and push them forward to the mouth. During most of the growing season only females can be found in the Daphnia population. Like dandelions which reproduce without benefit of sex, so water fleas also reproduce by parthenogenesis. Females produce eggs which do not need to be fertilized. These develop directly into more females. A pond can fill up with females in a very short time! The number of eggs per clutch varies from two to forty, depending on the species. The eggs are deposited within the female’s body into a brood chamber or cavity under the protective shell on the animal’s back. The eggs develop there and hatch to look like miniature adults. They remain within the pouch under the shell until the female molts, shedding her external skeleton and shell. Then the young are released. As conditions in the pond become unfavorable through drought, cold weather, or decline in food supply, fewer parthenogenetic eggs are produced. Now some eggs, by a mechanism which is poorly understood, develop into males! Other eggs at this stage require fertilization in order to develop. The brood pouch around eggs which have been fertilized, now thickens into a saddle-shaped structure called an ephippium. These are released to sit through long periods of drought or freezing. Ephippia can be transported from pond to pond in the intestines of aquatic birds or simply by clinging to their wet feet. When favorable conditions return, ephippia hatch exclusively into parthenogenetic females. Plants Perhaps we should turn our attention to some suitable pond plants as well. The duckweeds are the easiest to identify. Exceedingly widespread, lesser duckweed (Lemna minor) is common in quiet ponds. Often these tiny leaves will form a mat over an entire pond. In these circumstances hardly any plant life grows below the water surface because the duckweed has intercepted almost all the light. In an aquarium this species does not grow well unless it has very bright light available. Dying leaves are quickly eaten by snails and Gammarus. Another species, ivy duckweed (Lemna trisculca), is much more suitable for aquaria. The leaves grow in T-shaped configurations which remain tangled in large clumps below the water surface. It does very well with moderate light and it is an important oxygenating agent in the water. Coontail and milfoil are similar plants often found floating free in tangles beneath the surface in ponds. Coontail (Ceratophyllum) is known for its densely bushy stem tips. The leaves, which occur in whorls, have tiny toothlike projections. This plant does only moderately well in aquaria. Perhaps the best that can be said is that the plants may take all winter to die and be eaten by scavengers. Milfoil (Myriophyllum) has whorled, finely divided leaves which look like fern fronds. These plants are good aerators of pond water and should do well in an aquarium. Waterweed or Elodea is so suitable for aquarium culture that you can buy it in pet stores. More enterprising individuals may simply fish some out of a pond. The stems are bushy with whorls of three oval leaves arranged along the stem. These plants start out rooted but can become free floating. Elodea has been popular in biology laboratories for generations. Students can perform experiments on oxygen production on whole submerged plants. Individual leaves, which have only two layers of cells, are good for examination under the microscope. A handy reference booklet, available for generations, is Pond Life (a Golden Guide) which was last updated in 2001. USOs – Unidentified Swimming Objects Having acquired an aquarium, pond water, and pond plants, your family may at this moment be scanning several unidentified swimming objects. Some of these may well prove to be aquatic insects. Among the varied inhabitants of ponds, the insects provide the greatest interest for many people. All insects have an exterior skeleton much like that of crustaceans, but, whereas crustaceans have numerous legs, insects have only six. Many insects make fresh water their home during part or all of their lives. Most, including those which spend all stages of their development in the water, have one or two pairs of wings as adults. The young of some insects have the same general build as their parents. They resemble miniature adults and differ from them only in the partial development or their wings and the lack of sexual organs. Mayflies and dragonflies produce such young called nymphs. These develop in fresh water, but the adults spend their lives in the air. Among the true bugs, of the fresh water representatives, water boatmen are the easiest to find. They live in water throughout their lives. Many other insects have young quite unlike the adults. These young often seem quite wormlike. Such larvae must enter a resting stage, the pupa, before an adult emerges. During the pupal stage, an individual’s tissues are broken down and reassembled into those of an adult. Among such insects, caddisflies spend immature stages in the water and adult stages on land. So do certain flies including crane flies and phantom gnats. Mosquitos act the same way. Aquatic representatives among the beetles, however, spend their complete lives in or on the water. These include whirligig beetles and predaceous diving beetles often called water tigers. Mayflies Nymphs are typically found clinging to stems or stones in the water. Their abdomens curve upward towards the rear and the tip is equipped with three feathery tails. The abdomen sweeps continuously back and forth, perhaps to create a current in the water. In side view the numerous paired flaps down each side of the body cannot be seen. Viewed from above, however, these structures, called gills, are visible. Although the flaps are called gills, they seem not to be involved in gas exchange. Nymphs feed on small plants, on animals, and on organic debris. They live a few months to three years in the water, depending upon the species. This fall at least one adult successfully emerged into our living room after several weeks sojourn in an aquarium. Adults have four nearly transparent wings which they hold vertically when at rest. Adults are unable to eat, and they die shortly after mating. The females lay their eggs in water. Dragonflies Nymphs are solid looking, flattened creatures up to 5 cm long. They do not swim much, preferring rather to wait until some suitable prey happens to pass. Then they suddenly extend a huge hinged “mask” or folding lower lip to seize the unsuspecting victim. They feed on insect larvae, worms, small crustaceans, and even small fish. They are very fierce, and I, for one, would not offer a finger to any of them. I maintained two nymphs for several months by feeding them small pieces of hamburger. They would seize the meat only as it was sinking. Often, they would fail to notice the food. In order to keep the aquarium from becoming foul due to meat decay, I usually retrieved the missing pieces (with tongs) and dropped them in a second time near the nymph. Some dragonfly species complete their development from egg to adult in three months, while others take as long as five years. During this time, they molt frequently. At about the fifth molt, wings begin to form. Adult dragonflies have slender silhouettes and they hold their transparent wings horizontally at right angles to the body. With their legs or jaws, adults grasp insect prey such as mosquitos, and they eat them while in flight. They live only a few months, but during that stage adults mate while in flight. The female often drops her eggs from the air into the water. Water boatmen These adult bugs are one of the easiest insects to spot in ponds, but they do not do well in an aquarium. This is probably because they are strong fliers and can leave any body of water which they do not like. Adults appear silvery in the water since air taken at the surface surrounds them like a silvery envelope. Strong flattened hind legs enable these bugs to swim strongly. They feed on algae and decaying matter sucked out of the bottom mud. Adults lay their eggs on aquatic plants. In our aquarium, boatmen have reacted very negatively to the glassy confines of their new home. They spend their time frantically trying to swim through the glass walls. None lasted more than a day. Caddisflies The larvae of these insects are generally easy to identify. Only the head and front legs can be seen peeping out of tube-like cases made of green leaves, sand, twigs, or bark. Each species fashions a different characteristic house for itself. The adult emerges into the air and looks much like a moth. Crane flies Last fall our children spotted a revolting, pudgy-looking worm just under the water surface of our aquarium. It was the larva of a crane fly lurking among the aquatic weeds. It always positioned itself so that its rear tip projected up into the air. This creature had no legs at all. Our tentative identification proved correct when after several weeks a crane fly, like a large mosquito with long legs, appeared in our living room. Apparently, we had missed the pupa stage. Adults of some species feed on nectar, others do not eat at all. None bites. Phantom gnats If you peer intensely into your aquarium, you may see one or two phantom larvae. Except for prominent eyes and a threadlike intestine running the length of the body, the rest of this creature is almost transparent. The rear is capped with a tuft of obvious projecting hairs. There are no legs. These larvae, 1-2 cm long, hover horizontally well down in the water. This animal is unusual among insects in its ability to maintain such a stationary position in the water. Antennae attached to the head allow these larvae to prey on mosquito larvae and other small animals. The adults, which develop from a pupal stage, look much like mosquitos, but they do not feed and hence do not bite. Mosquitos Probably no aquarium is complete without several wrigglers (mosquito larvae). These bend double and extend to their full 1 cm length again as they wriggle through the water. They too lack legs. Frequently they return to hang almost vertically from the surface. A tube extending from near the rear tip is extended up into the air to get oxygen. The larvae feed on microscopic organisms or organic debris. Within a few days, after passing through a pupal stage, the adults emerge. The females must obtain a blood meal in order to be able to lay eggs. Males feed on nectar and ripe fruit. If your mother does not like mosquitos emerging into her house, do not call them to her attention. Alternatively, you could place a screen over the aquarium. Whirligig beetles Often the most conspicuous insects in a pond are swarms of small oval shiny black beetles darting frenetically back and forth on the surface of the water. Their eyes are divided into upper and lower parts. They are believed to be able to see both above and below the water surface at the same time. They eat anything they can find. Their front legs are long and slender, the others are shortened and flattened to serve as paddles. They can dive down into the water very suddenly if alarmed. Everyone chases these beetles, but they are difficult to catch. Anyway, they do not do well in aquaria. Dytiscus Among the hungriest and meanest of aquatic insects are the larvae and adult stages of the predaceous (from predator) diving beetles. The streamlined larvae, up to 3 cm long, with upturned abdomen and fierce jaws open, stand awaiting the arrival of prey. Konrad Lorenz, in his classic book King Solomon’s Ring, devotes several pages to the nasty personalities of Dytiscus larvae. These larvae will attack other insects, tadpoles, minnows, or anything that smells of animal in any way. They will bite a finger or even attack other larvae of their own kind. Through hollow jaws they inject a digestive juice which dissolves the insides of most of their victims. For people, the bite is simply extremely painful. We had several such larvae in our aquarium, but they died within several days, probably because of lack of suitable food. The shiny oval adult beetles also manage in the air and they may grow to be as large as 3-4 cm long. The beetles enjoy much the same menu as the larvae, but the former are also strong fliers when they so desire. Other easy-to-culture animals Both leaches and snails are easy to identify and easy to keep in an aquarium. A leach has done well all winter in our aquarium. It occasionally appears undulating through the water. It is growing, so it must be doing well eating bacteria. Certainly, it is not obtaining any blood meals. Our giant pond snails also do extremely well. With a thin, narrowly spiraled shell, these animals grow to be about 5 cm long. Often you can see the mouth opening and closing as one oozes forward along the glass. Inside the mouth is a rasping tongue which scrapes algae and bacteria off all surfaces over which it moves. Occasionally, jelly-like masses of snail eggs appear on underwater surfaces. These soon hatch into numerous tiny snails which immediately begin eating their way around the aquarium. Keep it going Now the whole family is organized for a project which can last all year. Remember not to load too many relatively large animals into an aquarium. The larger the total volume of animal life, the more likely it is that you will have to bubble in air and supplement the food supply. One minnow, for example, could eat everything living and require oxygen besides. This is not your objective. Stock with more, but smaller animals! Tadpoles, too, will require oxygen and will eat everything in sight. Make it a practice to observe life in your aquatic ecosystem every day. It makes a wonderful topic for conversation at the supper table. You will have expanded your interests and your pleasure in God’s creation....
Science - General
Plants that pack an explosive punch!
Sometimes when my husband and I sit quietly in our house, maybe reading, or drinking coffee, we hear a barely audible “pop” followed by a tiny clattering sound of something hitting the floor. Mind-blowing mechanisms The “something” here are seeds, each about two millimeters wide, landing up to a meter away from the plant that has launched them. This happens a lot in our house because we started with two such plants about 15 or 20 years ago, and now we have many of these Euphorbia leuconeura or “Madagascar Jewels.” Their seeds often land in their own pot or in the pots of other plants where they happily germinate. While the plant is threatened because of habitat loss in its native Madagascar, that is not so at our house! It grows well, up to six feet tall in areas that are not too bright. The angular stem looks something like a cactus, as do some other Euphorbias, and it contains a mildly toxic milky fluid which has never been a problem to us, our grandchildren or our pets as everybody “leaves” the plant alone. The flowers of Euphorbias are all very small – the Madagascar Jewel has just tiny white flower clusters. The plant’s claim to fame, apart from its attractive and unusual appearance, is definitely its habit of explosively dispersing its seed far and wide. Flowering plants have been designed with various interesting seed dispersal mechanisms, everything from prickly burrs that ride along on passersby, to wings or parachutes attached to seeds to enable them to ride along on wind currents. Some seeds are even dispersed from the intestines of animals that ate the fruits. However the device of explosively ejecting seeds requires some fancier engineering than many seed dispersal mechanisms. Too fast for the naked eye to track One plant that has recently attracted attention in this regard is Ruellia ciliatiflora or “hairy-flower wild petunia.” Ruellia is no relation of real petunias. Rather hairy-flower wild petunia is classified in the family Acanthaceae, made up of mostly tropical herbs, shrubs and vines. The flowers in this family all develop into a two-celled fruit capsule that ejects seeds more or less explosively. Ruellia (named after a 16th century French botanist Jean Ruelle) may be toxic and it may be used in some medicinal applications, but, once again, its real claim to fame is the highly explosive ejection of its seeds from the fruit capsule. Ruellia‘s specialized seed dispersal has attracted the attention of a team of scientists with fancy high-speed cameras. Their research consisted of setting up the camera near suitable plants and filming the release of the seed. They then analyzed the recording frame by frame, and from there they calculated velocities and other details. And what interesting details they found! The seeds of the hairy-flower wild petunia are disk-shaped, about 2.5 mm in diameter and almost 0.5 mm thick. They are ejected from the fruit capsule at speeds of 15 meters/second, or roughly 60 kilometers per hour! They've even got backspin! The plant achieves this extraordinary result by stabilizing the seeds so that they sit vertically in the air like bicycle tires. The disks spin backwards while moving forward on a rising trajectory. (It is their spinning which stabilizes their orientation.) The backspin was measured at an extraordinary 1660 cycles per second. The fact that the seeds spin backward means that drag on the surface is greatly reduced. The reduced drag means that the energy required to disperse the seeds is reduced by a factor of five. Thus the seeds are shot up to seven meters (23 feet) from the small low-lying parent plant. These features of the hairy-flower wild petunia rightly amaze us when we consider where the energy comes from. Obviously, the energy comes from the design of the fruit capsule. It has to be so constructed that the capsule will open suddenly. This means that the connecting region between the two halves of the fruit develops a much weakened zone and a strong hinge to pull the halves apart quickly. Also the seeds have to be so shaped that they will spin and so loosely connected to their growth center in the fruit that they will be shot out spinning backward but moving forward. Any mechanical engineer will admit that the engineering of this system requires a lot of fine tuning in order to achieve these results. Such a fancy system did not just develop spontaneously (by chance) but exhibits the work of a supremely intelligent Designer. For more on exploding seed pods, see “Imagine that” from October 2005 issue of the "Creation Science Dialogue." This is about the dispersal of pollen grains from Bunchberry (Cornus canadensis) which has similar amazing properties – it is because of this plant that I first learned what a French implement of war, the trebuchet, was! Also, take a look at the video below. ...
Science - General
Amazing green meat-eaters!
The first thing a student of nature learns, is that it is fatal to generalize – an exception can be found to almost any general rule. Most of us, fo...
Science - General
DNA: good discovery, bad agenda
What a difference 65 years makes. It was in April of 1953 that a one-page letter appeared in the journal Nature. Two young scientists believed that ...
Science - General
WONDERFUL WHALES: Design on a gigantic scale
When we look at nature, we can hardly miss the design that is everywhere so apparent in living creatures. We recognize it every time we see aspects of an organism that are elegant, beautiful and useful. There are many famous examples of design in nature, traits that are not only beautiful, but which work beautifully as well....but one can look anywhere! Some examples are more interesting to us than others, but all are worth considering. Design done big Consider for example the difficulties that the largest animals on earth, the rorqual whales must overcome to obtain enough food. The blue whale is the most famous and largest example of a rorqual. Another is the humpback. Such big animals are not going to be good at chasing smaller more agile prey. Their solution is to find very thick schools of small fish, and then to lunge forward and gulp in a huge mouthful of water containing lots of fish. The whales engulf the water and fish before the latter have a chance to panic and escape. The whales then push the water back out of their mouths through a special filtering system like Venetian blinds, which in this case is called baleen. What is left in the mouth, the whale swallows. It all sounds relatively uncomplicated, but it is not. Without a number of special and unique design features, these whales would starve. 1. Pleated throats The rorqual whales are named for their specially pleated throats (extending from mouth to navel) which can expand tremendously to accommodate 60 - 80 cubic meters of water and prey, "a volume equal to or greater than that of the individual rorqual itself" (Pyenson et al. Nature, 2012 p. 498, emphasis mine). 2. Filtration system The prey must now be separated out from all that water. What the whale does is push the water out of its mouth through a sieve-like structure which replaces teeth. This filtering system or baleen, consists of keratin, like our fingernails and hair. The baleen whale’s “suspension feeding system” – which involved feeding on, and straining out, suspended food particles from water – is unique among mammals and the pleated throat of the rorquals is unique to this even smaller group of baleen whales. That is not the end of the story. Without further special design features these whales would still be "dead in the water." No group other than the rorqual whales engulfs a massive volume of water in a single gulp. In order to do this, the animal lunges forward, accelerating to high speed, and then gulping in that huge volume of water, all within six seconds. But how does the whale know what volume of water to engulf? And how does it manage to engulf a volume larger than its own body? How does it know what water to gulp? If the whale just went around gulping random volumes of water, it would certainly starve – schools of fish are patchy in their distribution, and thus cannot be found in any old place. 3. The hair of their chinny chin For a start, the whale has bristles on its chin which function sort of like whiskers. These allow the animal to identify schools of fish that are sufficiently dense. Now the whale must take advantage of this dense concentration of fish. To do this, the rorqaul must control the rate of mouth opening and throat-pouch expansion so as to maximize the intake volume. All this must happen while the whale is lunging forward at high speed. 4. Jaw that splits down the middle We now discover more unique design features of the rorquals. The lower jaw consists of left and right halves which are only loosely connected by fibres, and also are only loosely connected to the skull. This allows for great flexibility of the mouth opening. As the rorquals lunge forward, they rotate the components of the jaw so that the opening is close to 90 degrees at the peak of the lunge. The tongue becomes convex and the throat pleats expand. Soon the jaws clamp around a huge volume of water and the whale begins the process of expelling the water and retaining the fishy harvest. 5. Always new wonders to find New research has shown that the rorquals enjoy the benefits of yet another design feature which enables them to be successful in this unusual lifestyle. In the centre of the lower jaw (between the two loosely connected halves) is a special and completely unique sensory organ. In its basic design it is something like the semicircular canals in our inner ear which allow us to figure out the orientation of our bodies. Inside the canals in our ears, there is clear gel and particles which occupy one position or another. Similarly, in the jaws of these whales there is a structure which has papillae (soft projections) surrounded by a gel-like matrix. This seems much like the mechanoreceptors in our inner ears. Apparently, this organ in the whale jaw informs the animal as to the extent of the rotation of the jaws and the expansion of the pleats during mouth opening. The rorquals alone possess this organ between the unfused halves of the lower jaw. Scientists consider that this sensory organ plays a fundamental role in the extreme feeding method of these largest animals on earth. Conclusion It is evident from details of the lifestyle of the rorquals that even apparently uncomplicated methods of feeding require special design features. The rorquals are certainly an example of irreducible complexity. Even with baleen instead of teeth, if they didn’t have the unique unfused lower jaw, pleats in the throat, the special sensory organ in the jaw, and the sensitive bristles on their chin, these largest of animals could never survive. Evolutionists have no adequate explanations for how these unique features could have developed through spontaneous processes. This is an excerpt from Dr. Margaret Helder's “No Christian Silence on Science” which you can buy here and which we review here....
Science - General
How the nose knows!
Of the five senses that keep us in touch with the world, one that we tend to take for granted is the sense of smell. Compared to the others, this sense may not seem very complicated or amazing. Nevertheless a little research reveals that our sense of smell is not only exquisitely designed, but it is also poorly understood by biologists. Of all our senses, that of smell seems to be the most complicated. Eye and ear vs. nose When we consider the other senses, we discover that with our sight, color involves only three kinds of receptor: specifically for green, red and blue light. All visual images come from messages to the brain sent from these three color receptors as well as from a receptor for light itself. The ear, on the other hand, could be thought the most sensitive human organ. The hair cells in the inner ear are designed to detect bass tones (low frequency sound waves) or treble tones (high frequency sound waves) or anything in between. Besides that they are able to detect extremely soft, low energy sound, and louder tones up to billions of times more energetic. However, all the receptors are much alike, whether they detect low or high pitched sounds. But the sense of smell is quite a different proposition. Imagine a sense which involves 350 entirely different kinds of receptor. It is evident that smell is more interesting than we might have expected. The nose is huge! Biologists expect that the number of odors which an organism can detect, is proportional to the number of relevant genes. In people, about 350 different genes code for 350 different receptors. The reason that we need so many receptors is because of the great chemical diversity in odor-causing molecules in the air. The receptor molecules in the nose are located on tiny projections emerging from nerve cells. These projections are situated in the mucous membranes high up in the nose. When an odor molecule collides with an appropriate receptor, the two fit together like lock and key. The receptor protein then initiates a chain of chemical reactions in the nerve cell’s membrane so that the electrical condition in the nerve cell changes. As a result, the nerve cell sends an electrical impulse toward the brain. The stimulation of different combinations of the 350 different kinds of receptor in the nose, results in the perception of at least 10,000 different odors. Each receptor responds to just one part of a molecule’s structure. Thus, if there are several reactive sites on the surface of one molecule, several different receptors may be stimulated at the same time by this one type of molecule. The blending in the brain of the different messages, leads to the sensation of a specific odor. Some smells are mixtures of large numbers of aromatic molecules. Wines, for example, may consist of as many as 200 different kinds of molecule, and that lovely aroma of coffee contains about 500 different kinds of molecule. Although we understand these basics, the chemistry of our sense of smell is nevertheless far from clear. Some molecules with very different compositions nevertheless smell much the same. Moreover, some molecules that are extremely alike, nevertheless elicit entirely different sensations of smell. Mirror images of an organic molecule called carvone, for example, smell either like cumin or peppermint, depending upon which arrangement the component atoms assume. Fearfully and wonderfully made We really don't appreciate the wonder that are noses are, and how important the sense of smell is...at least, not until our noses are clogged. In each nostril, an area about two square centimeters in diameter lies high up in the nasal cavity, just below the brain. This area is packed with tiny thread like extensions from the myriad nerve cells. Each nerve cell deals only with one kind of chemical receptor. Thus all the cilia leading to one nerve cell, have only one kind of receptor on them. Many nerve cells with identical receptors are connected by “wiring” which passes through the skull into collector systems called glomeruli in the brain. The glomeruli are located in two small extensions of the brain which are called olfactory bulbs. These bulbs are about the size of small grapes and there is one above each nostril. The bulbs are lined by the glomeruli, small collection centers, each for the extensions from about 2000 identical nerve cells. Since there are about 350 kinds of receptor, this means there are also 350 kinds of nerve cells. Groups of identical nerve cells send messages to one collection centre or glomerulus. Thus all the messages going to one glomerulus come from stimulation of the same kind of receptor. From the glomeruli, the messages pass to other nerve cells which transmit further into the brain. How the stimulated parts of the brain make any sense of the incredible plethora of messages, is something scientists do not yet understand. Better than a dog’s nose? An article in the online journal Public Library of Science Biology (May 2004) was entitled “Unsolved Mystery – The Human Sense of Smell: Are We Better Than We Think?” The popular perception, so author Gordon Shepherd declares, is that the human sense of smell is vastly inferior to that of some other mammals such as dogs, cats and rodents. Well maybe we should think again! Although humans have only 350 functional olfactory receptor genes, compared to much higher numbers for other mammals, it turns out that humans perform extremely well in odor detection tests. For example, when tested for the lowest amount of a chemical which they can detect, people performed better than dogs in some tests and much better than rats in others. Moreover, humans outperformed even the most sensitive machines (such as the gas chromatograph) designed to detect air-borne chemicals. Thus the author concludes “humans are not poor smellers …. But rather are relatively good, perhaps even excellent smellers.” The author ponders how it is that people have such excellent noses when they have so “few” detector molecules compared to other mammals. The popular evolutionary interpretation is that people lost their sense of smell as they gained in brain power and bipedal locomotion. Obviously the scientists need to reconsider. A very brainy nose We now know that people smell very well with far fewer kinds of receptor than animals require. The reason people are able to do this, apparently, lies in the much more sophisticated interpretive capability of the human brain. For any individual odor, the brain calculates how many different kinds of receptor are simulated and what is the relative proportion of these stimulated receptors. Scientists have also recently discovered that smell perception involves many more areas of the brain than previously thought. The regions dedicated to odor interpretation include the olfactory cortex, olfactory tubercle, entorhinal cortex, parts of the amygdala, parts of the hypothalamus, the mediodorsal thalamus, the medial and lateral orbitofrontal cortex, and parts of the insula ("Unsolved Mystery..." p. 574). Dr. Shepherd points out that all these regions of the brain are involved in the immediate distinguishing of an odor. If memory is also involved, as is typical with smells, then the temporal and frontal lobes of the brain also become involved. It is the view of Dr. Shepherd that people need such a sophisticated system for identifying smells. Not only do we need to identify natural smells, but we also create all sorts of artificial aromas such as those from cooking and manufacturing. The design of our olfactory system (for smell) thus involves not only the hardware such as nerve receptors and wiring in the brain, but also software design so that these inputs can be interpreted. It is evident that scientists who try to draw conclusions about organisms based on comparisons of their chemical components, may be in for a surprise. Dr. Shepherd therefore remarks: “The mystery being addressed here is a caution …. against any belief that behavior can be related directly to genomes, proteomes, or any other type of ‘-ome’” (p. 575). None of these measures adequately characterizes an organism and its capabilities. An experiment to try on your friends/victims Now that we have established that the human sense of smell is extremely remarkable, we can turn our attention to the results of this gift. Most people understand, whether they are trained in biology or not, that our sense of smell is extremely important to our sense of taste. In this context, you might like to try a simple experiment on your friends or enemies. Separately puree some raw potato, apple and onion. Place each sample in an airtight container and provide each container with a medicine style dropper (or pipette). Now invite your friend (victim?) to undergo a taste test. Have the individual hold their nose and open their mouth. Drop a sample of puree on the tongue (apple first). As long as the nose is held, the person will not be able to identify the flavor except to say that it is sweet. Allow the individual to breathe through the nose in order to identify the sample. Repeat with the other samples with the onion administered last because after that the person will a) refuse to cooperate further b) chase you out of town c) run for a glass of water or d) all of the above. Anyway, the experiment is lots of fun and it amply demonstrates the role of smell in flavor appreciation. Apparently the flavors of coffee, wine and chocolate are all largely controlled by our sense of smell as are those of many other foods. That is why food is tasteless when one is suffering from a cold. In recent years, many people have become interested in the ways in which odors affect peoples’ moods. Obviously there is nothing like the aroma of freshly baked bread or of cinnamon buns to raise one’s spirits. It is said that the penetrating but pleasant fragrance of lily-of-the-valley or of peppermint enable some individuals to concentrate better on a given task. In some cultures the scents of lemon, jasmine or lavender may have the same effect. Other people have found that spiced apple scent or heliotropine (like vanilla and almond scents combined) are able to exert a relaxing effect. Not surprisingly, culture can affect our responses to certain stimuli. For example, a manufacturer tested three detergent samples which were identical except for scent. Test subjects in Toronto and Montreal were asked to compare the cleaning abilities of these three products. The people in Montreal (largely French speaking) preferred the sample which smelled the most like perfume. In Toronto (largely English speaking), on the other hand, the test subjects suspected that something this good smelling must not work very well. Thus they rated the perfumed product as least effective. The amusing thing is that all three samples were identical except for fragrance. There was no difference in their cleaning effectiveness. Now that we know the nose… Through the ages there have existed commercial interests which attempt to exploit the human sense of smell for commercial gain. Obviously the companies which market expensive perfumes and colognes top this list. There are other more subtle applications as well. The aroma of fresh baking can be purchased by store owners who keep their product protected in display cases. Furniture salesmen may spray an artificial scent of leather around their showrooms. Movie theaters may spray an artificial odor of fresh popcorn into the air. If there is a way to exploit people, we can be sure that someone will think of it. The use of scent has simply become another tool in that process. For most people, smells that remind one of beautiful locations or happy events are the best scents of all. The scents of the sea shore, or of freshly mown grass, or of a roast beef dinner all conjure happy memories (or happy anticipation) in most of us. Now that we understand how complicated the design of our odor detection system really is, we will be doubly thankful for the wonderful gift of smell. This was first published in the July/August 2004 issue. Dr. Margaret Helder is the author of "No Christian Silence on Science" which you can buy here....