"Microbe" redirects here. For other uses, see Microbe (disambiguation).
A microorganism, or microbe,[a] is a microscopicorganism, which may exist in its single-celled form or in a colony of cells.
The possible existence of unseen microbial life was suspected from ancient times, such as in Jain scriptures from 6th-century-BC India and the 1st-century-BC book On Agriculture by Marcus Terentius Varro. Microbiology, the scientific study of microorganisms, began with their observation under the microscope in the 1670s by Antonie van Leeuwenhoek. In the 1850s, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In the 1880s Robert Koch discovered that microorganisms caused the diseases tuberculosis, cholera and anthrax.
Microorganisms include all unicellular organisms and so are extremely diverse. Of the three domains of life identified by Carl Woese, all of the Archaea and Bacteria are microorganisms. These were previously grouped together in the two domain system as Prokaryotes, the other being the eukaryotes. The third domain Eukaryota includes all multicellular organisms and many unicellular protists and protozoans. Some protists are related to animals and some to green plants. Many of the multicellular organisms are microscopic, namely micro-animals, some fungi and some algae, but these are not discussed here.
They live in almost every habitat from the poles to the equator, deserts, geysers, rocks and the deep sea. Some are adapted to extremes such as very hot or very cold conditions, others to high pressure and a few such as Deinococcus radiodurans to high radiation environments. Microorganisms also make up the microbiota found in and on all multicellular organisms. A December 2017 report stated that 3.45 billion year old Australian rocks once contained microorganisms, the earliest direct evidence of life on Earth.
Microbes are important in human culture and health in many ways, serving to ferment foods, treat sewage, produce fuel, enzymes and other bioactive compounds. They are essential tools in biology as model organisms and have been put to use in biological warfare and bioterrorism. They are a vital component of fertile soils. In the human body microorganisms make up the human microbiota including the essential gut flora. They are the pathogens responsible for many infectious diseases and as such are the target of hygiene measures.
See also: History of biology and Microbiology § History
The possible existence of microorganisms was discussed for many centuries before their discovery in the 17th century. The existence of unseen microbial life was postulated by Jainism. In the 6th century BC, Mahavira asserted the existence of unseen microbiological creatures living in earth, water, air and fire. The Jain scriptures also describe nigodas, as sub-microscopic creatures living in large clusters and having a very short life, which were said to pervade every part of the universe, even the tissues of plants and animals. The earliest known idea to indicate the possibility of diseases spreading by yet unseen organisms was that of the Roman scholar Marcus Terentius Varro in a 1st-century BC book titled On Agriculture in which he called the unseen creatures animalcules, and warns against locating a homestead near a swamp:
… and because there are bred certain minute creatures that cannot be seen by the eyes, which float in the air and enter the body through the mouth and nose and they cause serious diseases.
In The Canon of Medicine (1020), Avicenna suggested that tuberculosis and other diseases might be contagious.
Akshamsaddin (Turkish scientist) mentioned the microbe in his work Maddat ul-Hayat (The Material of Life) about two centuries prior to Antonie Van Leeuwenhoek's discovery through experimentation:
|“||It is incorrect to assume that diseases appear one by one in humans. Disease infects by spreading from one person to another. This infection occurs through seeds that are so small they cannot be seen but are alive.||”|
In 1546, Girolamo Fracastoro proposed that epidemicdiseases were caused by transferable seedlike entities that could transmit infection by direct or indirect contact, or even without contact over long distances.
Antonie Van Leeuwenhoek is considered to be the father of microbiology. He was the first in 1673 to discover, observe, describe, study and conduct scientific experiments with microoorganisms, using simple single-lensed microscopes of his own design.Robert Hooke, a contemporary of Leeuwenhoek, also used microscopy to observe microbial life in the form of the fruiting bodies of moulds. In his 1665 book Micrographia, he made drawings of studies, and he coined the term cell.
Louis Pasteur (1822–1895) exposed boiled broths to the air, in vessels that contained a filter to prevent particles from passing through to the growth medium, and also in vessels without a filter, but with air allowed in via a curved tube so dust particles would settle and not come in contact with the broth. By boiling the broth beforehand, Pasteur ensured that no microorganisms survived within the broths at the beginning of his experiment. Nothing grew in the broths in the course of Pasteur's experiment. This meant that the living organisms that grew in such broths came from outside, as spores on dust, rather than spontaneously generated within the broth. Thus, Pasteur dealt the death blow to the theory of spontaneous generation and supported the germ theory of disease.
In 1876, Robert Koch (1843–1910) established that microorganisms can cause disease. He found that the blood of cattle which were infected with anthrax always had large numbers of Bacillus anthracis. Koch found that he could transmit anthrax from one animal to another by taking a small sample of blood from the infected animal and injecting it into a healthy one, and this caused the healthy animal to become sick. He also found that he could grow the bacteria in a nutrient broth, then inject it into a healthy animal, and cause illness. Based on these experiments, he devised criteria for establishing a causal link between a microorganism and a disease and these are now known as Koch's postulates. Although these postulates cannot be applied in all cases, they do retain historical importance to the development of scientific thought and are still being used today.
The discovery of microorganisms such as Euglena that did not fit into either the animal or plant kingdoms, since they were photosynthetic like plants, but motile like animals, led to the naming of a third kingdom in the 1860s. In 1860 John Hogg called this the Protoctista, and in 1866 Ernst Haeckel named it the Protista.
The work of Pasteur and Koch did not accurately reflect the true diversity of the microbial world because of their exclusive focus on microorganisms having direct medical relevance. It was not until the work of Martinus Beijerinck and Sergei Winogradsky late in the 19th century that the true breadth of microbiology was revealed. Beijerinck made two major contributions to microbiology: the discovery of viruses and the development of enrichment culture techniques. While his work on the Tobacco Mosaic Virus established the basic principles of virology, it was his development of enrichment culturing that had the most immediate impact on microbiology by allowing for the cultivation of a wide range of microbes with wildly different physiologies. Winogradsky was the first to develop the concept of chemolithotrophy and to thereby reveal the essential role played by microorganisms in geochemical processes. He was responsible for the first isolation and description of both nitrifying and nitrogen-fixing bacteria. French-Canadian microbiologist Felix d'Herelle co-discovered bacteriophages and was one of the earliest applied microbiologists.
Classification and structure
Microorganisms can be found almost anywhere on Earth. Bacteria and archaea are almost always microscopic, while a number of eukaryotes are also microscopic, including most protists, some fungi, as well as some micro-animals and plants. Viruses are generally regarded as not living and therefore not considered as microorganisms, although a subfield of microbiology is virology, the study of viruses.
Further information: Timeline of evolution and Earliest known life forms
Single-celled microorganisms were the first forms of life to develop on Earth, approximately 3–4 billion years ago. Further evolution was slow, and for about 3 billion years in the Precambrianeon, (much of the history of life on Earth), all organisms were microorganisms. Bacteria, algae and fungi have been identified in amber that is 220 million years old, which shows that the morphology of microorganisms has changed little since the Triassic period. The newly discovered biological role played by nickel, however — especially that brought about by volcanic eruptions from the Siberian Traps — may have accelerated the evolution of methanogens towards the end of the Permian–Triassic extinction event.
Microorganisms tend to have a relatively fast rate of evolution. Most microorganisms can reproduce rapidly, and bacteria are also able to freely exchange genes through conjugation, transformation and transduction, even between widely divergent species. This horizontal gene transfer, coupled with a high mutation rate and other means of transformation, allows microorganisms to swiftly evolve (via natural selection) to survive in new environments and respond to environmental stresses. This rapid evolution is important in medicine, as it has led to the development of multidrug resistantpathogenic bacteria, superbugs, that are resistant to antibiotics.
A possible transitional form of microorganism between a prokaryote and a eukaryote was discovered in 2012 by Japanese scientists. Parakaryon myojinensis is a unique microorganism larger than a typical prokaryote, but with nuclear material enclosed in a membrane as in a eukaryote, and the presence of endosymbionts. This is seen to be the first plausible evolutionary form of microorganism, showing a stage of development from the prokaryote to the eukaryote.
Main article: Archaea
Further information: Prokaryote
Archaea are prokaryotic unicellular organisms, and form the first domain of life, in Carl Woese's three-domain system. A prokaryote is defined as having no cell nucleus or other membrane bound-organelle. Archaea share this defining feature with the bacteria with which they were once grouped. In 1990 the microbiologist Woese proposed the three-domain system that divided living things into bacteria, archaea and eukaryotes, and thereby split the prokaryote domain.
Archaea differ from bacteria in both their genetics and biochemistry. For example, while bacterial cell membranes are made from phosphoglycerides with ester bonds, archaean membranes are made of ether lipids. Archaea were originally described as extremophiles living in extreme environments, such as hot springs, but have since been found in all types of habitats. Only now are scientists beginning to realize how common archaea are in the environment, with Crenarchaeota being the most common form of life in the ocean, dominating ecosystems below 150 m in depth. These organisms are also common in soil and play a vital role in ammonia oxidation.
The combined domains of archaea and bacteria make up the most diverse and abundant group of organisms on Earth and inhabit practically all environments where the temperature is below +140 °C. They are found in water, soil, air, as the microbiome of an organism, hot springs and even deep beneath the Earth's crust in rocks. The number of prokaryotes is estimated to be around five million trillion trillion, or 5 × 1030, accounting for at least half the biomass on Earth.
The biodiversity of the prokaryotes is unknown, but may be very large. A May 2016 estimate, based on laws of scaling from known numbers of species against the size of organism, gives an estimate of perhaps 1 trillion species on the planet, of which most would be microorganisms. Currently, only one-thousandth of one percent of that total have been described.
Main article: Bacteria
Bacteria like archaea are prokaryotic – unicellular, and having no cell nucleus or other membrane-bound organelle. Bacteria are microscopic, with a few extremely rare exceptions, such as Thiomargarita namibiensis. Bacteria function and reproduce as individual cells, but they can often aggregate in multicellular colonies. Some species such as myxobacteria can aggregate into complex swarming structures, operating as multicellular groups as part of their life cycle, or form clusters in bacterial colonies such as E.coli.
Their genome is usually a circular bacterial chromosome – a single loop of DNA, although they can also harbor small pieces of DNA called plasmids. These plasmids can be transferred between cells through bacterial conjugation. Bacteria have an enclosing cell wall, which provides strength and rigidity to their cells. They reproduce by binary fission or sometimes by budding, but do not undergo meioticsexual reproduction. However, many bacterial species can transfer DNA between individual cells by a horizontal gene transfer process referred to as natural transformation. Some species form extraordinarily resilient spores, but for bacteria this is a mechanism for survival, not reproduction. Under optimal conditions bacteria can grow extremely rapidly and their numbers can double as quickly as every 20 minutes.
Main article: Eukaryote
Most living things that are visible to the naked eye in their adult form are eukaryotes, including humans. However, a large number of eukaryotes are also microorganisms. Unlike bacteria and archaea, eukaryotes contain organelles such as the cell nucleus, the Golgi apparatus and mitochondria in their cells. The nucleus is an organelle that houses the DNA that makes up a cell's genome. DNA (Deoxyribonucleic acid) itself is arranged in complex chromosomes. Mitochondria are organelles vital in metabolism as they are the site of the citric acid cycle and oxidative phosphorylation. They evolved from symbiotic bacteria and retain a remnant genome. Like bacteria, plant cells have cell walls, and contain organelles such as chloroplasts in addition to the organelles in other eukaryotes. Chloroplasts produce energy from light by photosynthesis, and were also originally symbiotic bacteria.
Unicellular eukaryotes consist of a single cell throughout their life cycle. This qualification is significant since most multicellular eukaryotes consist of a single cell called a zygote only at the beginning of their life cycles. Microbial eukaryotes can be either haploid or diploid, and some organisms have multiple cell nuclei.
Unicellular eukaryotes usually reproduce asexually by mitosis under favorable conditions. However, under stressful conditions such as nutrient limitations and other conditions associated with DNA damage, they tend to reproduce sexually by meiosis and syngamy.
Main article: Protista
Of eukaryotic groups, the protists are most commonly unicellular and microscopic. This is a highly diverse group of organisms that are not easy to classify. Several algaespecies are multicellular protists, and slime molds have unique life cycles that involve switching between unicellular, colonial, and multicellular forms. The number of species of protists is unknown since only a small proportion has been identified. Protist diversity is high in oceans, deep sea-vents, river sediment and an acidic river, suggesting that many eukaryotic microbial communities may yet be discovered.
Main article: Fungus
The fungi have several unicellular species, such as baker's yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe). Some fungi, such as the pathogenic yeast Candida albicans, can undergo phenotypic switching and grow as single cells in some environments, and filamentous hyphae in others.
Main article: Plant
The green algae are a large group of photosynthetic eukaryotes that include many microscopic organisms. Although some green algae are classified as protists, others such as charophyta are classified with embryophyte plants, which are the most familiar group of land plants. Algae can grow as single cells, or in long chains of cells. The green algae include unicellular and colonial flagellates, usually but not always with two flagella per cell, as well as various colonial, coccoid, and filamentous forms. In the Charales, which are the algae most closely related to higher plants, cells differentiate into several distinct tissues within the organism. There are about 6000 species of green algae.
Main article: Microbial ecology
Microorganisms are found in almost every habitat present in nature, including hostile environments such as the North and South poles, deserts, geysers, and rocks. They also include all the marine microorganisms of the oceans and deep sea. Some types of microorganisms have adapted to extreme environments and sustained colonies; these organisms are known as extremophiles. Extremophiles have been isolated from rocks as much as 7 kilometres below the Earth's surface, and it has been suggested that the amount of organisms living below the Earth's surface is comparable with the amount of life on or above the surface. Extremophiles have been known to survive for a prolonged time in a vacuum, and can be highly resistant to radiation, which may even allow them to survive in space. Many types of microorganisms have intimate symbiotic relationships with other larger organisms; some of which are mutually beneficial (mutualism), while others can be damaging to the host organism (parasitism). If microorganisms can cause disease in a host they are known as pathogens and then they are sometimes referred to as microbes. Microorganisms play critical roles in Earth's biogeochemical cycles as they are responsible for decomposition and nitrogen fixation.
Bacteria use regulatory networks that allow them to adapt to almost every environmental niche on earth. A network of interactions among diverse types of molecules including DNA, RNA, proteins and metabolites, is utilised by the bacteria to achieve regulation of gene expression. In bacteria, the principal function of regulatory networks is to control the response to environmental changes, for example nutritional status and environmental stress. A complex organization of networks permits the microorganism to coordinate and integrate multiple environmental signals.
Main article: Extremophile
Further information: List of microorganisms tested in outer space
Extremophiles are microorganisms that have adapted so that they can survive and even thrive in extreme environments that are normally fatal to most life-forms. Thermophiles and hyperthermophiles thrive in high temperatures. Psychrophiles thrive in extremely low temperatures. – Temperatures as high as 130 °C (266 °F), as low as −17 °C (1 °F)Halophiles such as Halobacterium salinarum (an archaean) thrive in high salt conditions, up to saturation.Alkaliphiles thrive in an alkalinepH of about 8.5–11.Acidophiles can thrive in a pH of 2.0 or less.Piezophiles thrive at very high pressures: up to 1,000–2,000 atm, down to 0 atm as in a vacuum of space. A few extremophiles such as Deinococcus radiodurans are radioresistant, resisting radiation exposure of up to 5k Gy. Extremophiles are significant in different ways. They extend terrestrial life into much of the Earth's hydrosphere, crust and atmosphere, their specific evolutionary adaptation mechanisms to their extreme environment can be exploited in biotechnology, and their very existence under such extreme conditions increases the potential for extraterrestrial life.
Main article: Soil biology
The nitrogen cycle in soils depends on the fixation of atmospheric nitrogen. This is achieved by a number of diazotrophs. One way this can occur is in the nodules in the roots of legumes that contain symbiotic bacteria of the genera Rhizobium, Mesorhizobium, Sinorhizobium, Bradyrhizobium, and Azorhizobium.
A lichen is a symbiosis of a macroscopic fungus with photosynthetic microbial algae or cyanobacteria.
Main article: Microbes in human culture
Microorganisms are useful in producing foods, treating waste water, creating biofuels and a wide range of chemicals and enzymes. They are invaluable in research as model organisms. They have been weaponised and sometimes used in warfare and bioterrorism. They are vital to agriculture through their roles in maintaining soil fertility and in decomposing organic matter.
Main articles: Fermentation in food processing and Food microbiology
Microorganisms are used in a fermentation process to make yoghurt, cheese, curd, kefir, ayran, xynogala, and other types of food. Fermentation cultures provide flavor and aroma, and inhibit undesirable organisms. They are used to leavenbread, and to convert sugars to alcohol in wine and beer. Microorganisms are used in brewing, wine making, baking, pickling and other food-making processes.
Main article: Wastewater treatment
Sewage treatment works depend for their ability to clean up water contaminated with organic material on microorganisms that can respire dissolved substances. Respiration may be aerobic, with a well-oxygenated filter bed such as a slow sand filter.Anaerobic digestion by methanogens generate useful methane gas as a by-product.
Main articles: Algae fuel, Cellulosic ethanol, and Ethanol fermentation
Microorganisms are used in fermentation to produce ethanol, and in biogas reactors to produce methane. Scientists are researching the use of algae to produce liquid fuels, and bacteria to convert various forms of agricultural and urban waste into usable fuels.
Microorganisms are used to produce many commercial and industrial chemicals, enzymes and other bioactive molecules. Organic acids produced on a large industrial scale by microbial fermentation include acetic acid produced by acetic acid bacteria such as Acetobacter aceti, butyric acid made by the bacterium Clostridium butyricum, lactic acid made by Lactobacillus and other lactic acid bacteria, and citric acid produced by the mould fungus Aspergillus niger.
Microorganisms are used to prepare bioactive molecules such as Streptokinase from the bacterium Streptococcus,Cyclosporin A from the ascomycete fungus Tolypocladium inflatum, and statins produced by the yeast Monascus purpureus.
Microorganisms are essential tools in biotechnology, biochemistry, genetics, and molecular biology. The yeastsSaccharomyces cerevisiae, and Schizosaccharomyces pombe are important model organisms in science, since they are simple eukaryotes that can be grown rapidly in large numbers and are easily manipulated. They are particularly valuable in genetics, genomics and proteomics. Microorganisms can be harnessed for uses such as creating steroids and treating skin diseases. Scientists are also considering using microorganisms for living fuel cells, and as a solution for pollution.
Main articles: Biological warfare and Bioterrorism
In the Middle Ages, as an early example of biological warfare, diseased corpses were thrown into castles during sieges using catapults or other siege engines. Individuals near the corpses were exposed to the pathogen and were likely to spread that pathogen to others.
In modern times, bioterrorism has included the 1984 Rajneeshee bioterror attack and the 1993 release of anthrax by Aum Shinrikyo in Tokyo.
Main article: Soil microbiology
Microbes can make nutrients and minerals in the soil available to plants, produce hormones that spur growth, stimulate the plant immune system and trigger or dampen stress responses. In general a more diverse set of soil microbes results in fewer plant diseases and higher yield.
Human gut flora
Further information: Human microbiota and Human Microbiome Project
Microorganisms can form an endosymbiotic relationship with other, larger organisms. For example, microbial symbiosis plays a crucial role in the immune system. The microorganisms that make up the gut flora in the gastrointestinal tract contribute to gut immunity, synthesize vitamins such as folic acid and biotin, and ferment complex indigestible carbohydrates. Some microorganisms that are seen to be beneficial to health are termed probiotics and are available as dietary supplements, or food additives.
Main articles: Pathogen and Germ theory of disease
Further information: Medical microbiology
Microorganisms are the causative agents (pathogens) in many infectious diseases. The organisms involved include pathogenic bacteria, causing diseases such as plague, tuberculosis and anthrax; protozoa, causing diseases such as malaria, sleeping sickness, dysentery and toxoplasmosis; and also fungi causing diseases such as ringworm, candidiasis or histoplasmosis. However, other diseases such as influenza, yellow fever or AIDS are caused by pathogenic viruses, which are not usually classified as living organisms and are not, therefore, microorganisms by the strict definition. No clear examples of archaean pathogens are known, although a relationship has been proposed between the presence of some archaean methanogens and human periodontal disease.
Main articles: Hygiene and Food microbiology
Hygiene is a set of practices to avoid infection or food spoilage by eliminating microorganisms from the surroundings. As microorganisms, in particular bacteria, are found virtually everywhere, harmful microorganisms may be reduced to acceptable levels rather than actually eliminated. In food preparation, microorganisms are reduced by preservation methods such as cooking, cleanliness of utensils, short storage periods, or by low temperatures. If complete sterility is needed, as with surgical equipment, an autoclave is used to kill microorganisms with heat and pressure.
- ^Tyrell, Kelly April (18 December 2017).
- ^The word microorganism () uses combining forms of micro- (from the Greek: μικρός, mikros, "small") and organism from the Greek: ὀργανισμός, organismós, "organism"). It is usually styled solid but is sometimes hyphenated (micro-organism), especially in older texts. The informal synonym microbe () comes from μικρός, mikrós, "small" and βίος, bíos, "life".
“Don’t touch that! You’ll soil it.” – Carl Fredricksen in Pixar’s Up
A few years ago, I went to a scientific meeting to present my research. When we got to the hotel, we checked in and discovered that our room was on an upper floor. When we boarded the elevator, I stepped on first and felt the social obligation to press the number for our floor. Without thinking twice, I did what I normally do when out in public: I used my elbow to touch the button for our hotel floor. And that’s when it happened: my friend chuckled to himself loud enough for me to actually hear it. When I turned back to see what he was laughing at, he quit chuckling almost immediately. It dawned on me after some reflection that he was actually laughing at me (not with me) for using my elbow to touch the elevator button.
In sharing this story, I want to calm all the germophobes reading this. I step up to the line of germophobia, but take one step back. We need to balance our understanding of the microscopic world because it is an essential part of and critically affects our everyday life. A recent study compared skin germs between humans and apes to better understand just how microbes affect our everyday life and personal hygiene in a genuine (though misguided) effort to further prove common ancestry. But before we can understand how the microbiome is part of God’s original creation and better appreciate His marvelous design (yes, even in our armpits!), we must first define some important terms.
Microbes are the earliest forms of life on earth.1 Biology is difficult enough, but microbiology presents a whole new challenge because it deals with organisms that you can’t even see with the naked eye. To clarify, think of microbiology as biology under a microscope. For us microbiologists, the living world we see without using a microscope is relatively boring compared to the unseen living world at the microscopic level (cf. Colossians 1:16). Bacteria are just one type of organism among many at the microscopic level.2 While diversity of life at the microscopic level is not only bacterial, most scientists generally refer to microbes as bacteria. The importance of referring to microbes with only bacteria in mind is important when describing the microbiome.
The word microbiome comes from the root word microbe. Anytime the letters -ome are added to the end of a word, the meaning of the word changes to mean “all of the” word appearing before it. So the microbiome includes all of the microbes for a given location. While sequencing the human genome was significant, sequencing of the human microbiome could be just as important, since the human body houses 10 bacteria cells for every single human cell. The microbiome is usually measured based on DNA sequencing of the 16S ribosomal subunit to generate what’s called a molecular signature.3 The molecular signature acts like a fingerprint to reveal the bacterial identity.
Microbiome scientists are interested in questions such as “What bacterial species are present? And in what abundance?” Scientists think of microbiomes like a chef might think of food when planning to cater for a party. Chefs need to know both how many guests there are in addition to what type of food they like. At the microbial level, microbiome scientists measure the human microbiome by considering who is there and how many. The current scientific model of the microbiome follows the Baas-Becking hypothesis that “everything is everywhere, but the environment selects.” Therefore, scientists expect a certain degree of microbiome similarity between similar locations. But the contrast is also true: if two environments are different, then the microbiomes will be different. So how is our microbiome designed?
Your Designer Microbiome
Most people are horrified when they learn just how many bacteria live on and in us.4 Oftentimes, people react by actively disinfecting all of their personal things. Many are acutely aware of the bad germs surrounding them when they are sick. If we feel ill, we seek antibiotics. Ironically, we’re also supposed to eat lots of yogurt and take probiotics (good germs) on a regular basis—all in the name of health. We misunderstand health and sickness because we want to have our bacteria and kill them too. If we don’t understand the origin and purpose of bacteria, then we are downplaying God’s design and affecting our overall health. Is there a balance?
From the oceans to the soil to the human body, our planet could not exist without microbes. In Scripture, we learn that God first creates something and then He fills it (based on Genesis 1:2). Everything God made was mature, which means microbes were created in association with all of creation to benefit the earth. Dr. Joe Francis does an excellent job explaining the ubiquity and design of microbes with his concept of the biomatrix. The original “very good” creation must have included microbes because they are essential to life. So God created man with bacteria both inside and outside. We find myriad examples of beneficial bacteria in our intestine, and a growing body of evidence suggests that the bacteria on our skin also benefit and protect us.
Bacteria Are the Only Culture Some People Have
Confession time: one of my pet peeves is when someone gets a paper cut and overly worries that it will get “infected.”5 Truth be told, you were “infected” before, during, and after the paper cut.6 Bacteria that harmlessly live in association with us are called our normal microbiota.7 The normal microbiota of human skin is largely determined by a relatively high salt concentration (in case it’s been a while, try sucking your thumb to figure out just how salty it is).8 Actually, it is a wonderful design feature because the relatively high salt concentration creates an unfavorable environment for many bacteria, preventing major skin diseases. Furthermore, the same glands that produce the relatively high salt concentration also provide bacteria with nutrients. The fact that the same bacteria that can withstand a relatively high salt concentration can also thrive on the nutrients secreted by those same salt-producing glands screams that this skin-microbe symbiosis was designed. At the same time, though, these skin bacteria are also responsible for body odor. While you may not consider your body odor a wonderful design, there are additional points to consider.
In any biology textbook, you can find a chapter explaining how animals regulate their body temperature. When any creature’s temperature is outside acceptable limits, there are mechanisms to bring the temperature within normal limits. Our sweat glands lower our temperature through evaporative cooling, but some creatures lower their temperatures using a different mechanism. For instance, man’s best friend (the dog) does not have sweat glands to mediate evaporative cooling. Instead, when overheated, dogs pant heavily to cool themselves. Among the many things that evolutionists try to use as a similarity between humans and apes, they highlight the fact that we both have hair and sweat glands. But what they don’t tell you is how gloriously different our Creator God made us.
While monkeys and apes have skin glands, it is important to note the difference in the location and type of basic skin glands between humans and apes. There are three basic types of skin glands: apocrine, eccrine, and sebaceous glands. The difference between human skin and ape skin is striking.
The distribution, function and secretion of the different types of human skin glands (sebaceous, apocrine and eccrine) are briefly described. . . . Eccrine glands are the best developed and most abundant glands in humans and are widely distributed over the general body surface. By contrast, in most mammalian groups (including prosimians, monkeys and apes, with the exception of great apes) eccrine glands are limited to the friction surfaces of the hands, feet and tail. Apocrine glands, which play an important role in chemical communication, have a restricted distribution in most mammals including humans. . . . All prosimians, monkeys, and apes have thermal apocrine glands associated with hair follicles. The chimpanzee and the gorilla exhibit a distribution ratio . . . [only slightly different from] . . . monkeys, the gibbon, and orangutan. . . . By contrast, humans mainly possess eccrine and relatively few apocrine glands.9
You should cry “foul” when anyone tries to compare human skin to any monkey or ape skin because the similarities are just too few. Regardless of these major differences, scientists recently decided to analyze the armpit microbiomes from humans, chimpanzees, gorillas, baboons, and rhesus macaques.10 In the article, the authors even admit that “the composition of microbes on human skin might be expected to differ significantly from that of our closest relatives, the non-human primates, for at least three reasons.”11 As creationists (and scientists), we expect to find differences based on empirical science. The Baas-Becking hypothesis previously mentioned says similar microbes are found in environments that are similar. Since the environments in armpits of humans and apes have (1) completely different glands, (2) different chemicals secreted, and (3) different concentrations, then the logical expectation based on empirical science is to find significant differences between the skin microbiome of humans and primates (as well as differences in the armpit microbiomes on other animals, because humans were created uniquely from the rest of creation). The only people committed to expecting strong similarities are Darwinists because (and only because) they are committed to a worldview despite empirical evidence to the contrary. Not too surprisingly, the Darwinists were surprised. What did they find? The armpits between humans and apes have few similarities and carry different bacteria. The assortment and diversity of bacteria found in different microenvironments are not surprising between humans and apes when you acknowledge the unique design of each creature and approach science without the wrong presuppositions. The differences between human microbiomes and ape microbiomes are so unique that mosquitoes detect these differences and prefer feeding from certain creatures (i.e., humans) over others (i.e., everything else).12
Want to tell the difference between human and monkey sweat? So easy, even a mosquito can do it!
If even mosquitoes can tell the difference between the human and ape microbiomes, then how do evolutionists interpret the empirical evidence to fit their worldview? The authors of this microbiome study (along with other evolutionists) claim that the evolution of personal hygiene is the culprit. A recent article proposes that we should only shower once a week because we’re “harming” the environment due to personal hygiene products.13 Furthermore, we are often told that the reason humans groom each other is because of our evolutionary history of apes grooming one another. But when you scientifically examine ape-grooming behavior, the irony is that they actually groom out of fear; it is a dominance behavior.14 And when you scientifically examine any other evolutionary claim, you find yourself trying to work out of an armpit existence. Evolution is foul smelling, dark, and damp because it is logically incoherent. Creationists are not surprised to find differences between human and ape skin microbiomes because we are not committed to a worldview claiming humans and apes share common ancestry. As a result, creation scientists are open-minded to existing differences and can ask more sophisticated questions aimed at understanding the skin microbiome and improving health.
The next time you work out, engage in physical activity, or otherwise find yourself sweating, wipe your brow in praise to our Creator who gave us everything we need in our existence. Don’t sweat the small things in life. Keep a cool head. Even as seemingly gross as the microbiome is in this fallen world, there is no doubt that our loving Creator fashioned it to help us when things get tough.