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News to me is that about 4500 of the 4900 minerals on Earth have been created by life. What are some examples of such processes? Are some minerals formed inside the human body?
News to me is that about 4500 of the 4900 minerals on Earth have been created by life.
After reading the article, this isn't what was said.
What was said is that life increases mineral diversity on a planet, most notably through biproducts reacting with existing minerals (like Oxygen - a biproduct of photosynthesis - reacting with iron to create iron-oxide).
So, life doesn't create new minerals, but it does change the abundance of elements at the surface which can undergo reactions with pre-existing minerals to form other minerals.
Not all of the 4500 "new" minerals on the Earth can be attributed to life. We don't know how many new mineral formations have formed because of life, but the article suggests the theory that increased surface diversity of minerals might be a good indicator of life.
How are minerals formed by biological processes? - Biology
Sulfur, an essential element for the macromolecules of living things, is released into the atmosphere by the burning of fossil fuels, such as coal. As a part of the amino acid cysteine, it is involved in the formation of disulfide bonds within proteins, which help to determine their 3-D folding patterns, and hence their functions. As shown in Figure 1, sulfur cycles between the oceans, land, and atmosphere. Atmospheric sulfur is found in the form of sulfur dioxide (SO2) and enters the atmosphere in three ways: from the decomposition of organic molecules, from volcanic activity and geothermal vents, and from the burning of fossil fuels by humans.
Figure 1. Sulfur dioxide from the atmosphere becomes available to terrestrial and marine ecosystems when it is dissolved in precipitation as weak sulfuric acid or when it falls directly to the Earth as fallout. Weathering of rocks also makes sulfates available to terrestrial ecosystems. Decomposition of living organisms returns sulfates to the ocean, soil and atmosphere. (credit: modification of work by John M. Evans and Howard Perlman, USGS)
Figure 2. At this sulfur vent in Lassen Volcanic National Park in northeastern California, the yellowish sulfur deposits are visible near the mouth of the vent.
On land, sulfur is deposited in four major ways: precipitation, direct fallout from the atmosphere, rock weathering, and geothermal vents (Figure 2). Atmospheric sulfur is found in the form of sulfur dioxide (SO2), and as rain falls through the atmosphere, sulfur is dissolved in the form of weak sulfuric acid (H2SO4). Sulfur can also fall directly from the atmosphere in a process called fallout. Also, the weathering of sulfur-containing rocks releases sulfur into the soil. These rocks originate from ocean sediments that are moved to land by the geologic uplifting of ocean sediments. Terrestrial ecosystems can then make use of these soil sulfates (SO4 − ), and upon the death and decomposition of these organisms, release the sulfur back into the atmosphere as hydrogen sulfide (H2S) gas.
Sulfur enters the ocean via runoff from land, from atmospheric fallout, and from underwater geothermal vents. Some ecosystems rely on chemoautotrophs using sulfur as a biological energy source. This sulfur then supports marine ecosystems in the form of sulfates.
Human activities have played a major role in altering the balance of the global sulfur cycle. The burning of large quantities of fossil fuels, especially from coal, releases larger amounts of hydrogen sulfide gas into the atmosphere. As rain falls through this gas, it creates the phenomenon known as acid rain. Acid rain is corrosive rain caused by rainwater falling to the ground through sulfur dioxide gas, turning it into weak sulfuric acid, which causes damage to aquatic ecosystems. Acid rain damages the natural environment by lowering the pH of lakes, which kills many of the resident fauna it also affects the man-made environment through the chemical degradation of buildings. For example, many marble monuments, such as the Lincoln Memorial in Washington, DC, have suffered significant damage from acid rain over the years. These examples show the wide-ranging effects of human activities on our environment and the challenges that remain for our future.
Soil is the thin layer of loose material covering the earth’s surface. It is composed of both organic and inorganic materials. The formation of soil is an extremely long process taking up to an average of a thousand years. Soil is formed when surface rocks break into several smaller particles, called regolith, which then gets mixed with varied organic matter. This whole process is called Weathering. So weathering happens through three major ways, namely
- Physical Weathering: This is the geological process when rocks get fragmented into smaller particles, without changing the chemical composition of the rocks. This primarily happens due to fluctuating temperatures causing the rocks to break apart.
- Chemical Weathering: This is the erosion of rocks and other surface materials caused due to chemical reactions. The rocks react with substances in the atmosphere, such as moisture, air, water etc. The resulting substance has a different chemical composition than the rock from which it formed. Hydration, Hydrolysis, Oxidation, Carbonation and Reduction are the chemical processes involved in chemical weathering.
- Biological Weathering: This is the process of disintegration of rocks due to actions of living organisms (animals, plants, microbes etc), like when a plant grows in the fissure of a rock and its roots exert pressure on the rock forcing in to break apart. Even microbes produce organic material that causes weathering.
You can download Natural Resources Cheat Sheet by clicking on the download button below
Soil is essential a mix of various particles and substances. So let us have a look at all the things that make up soil,
- Minerals: A very important substance found in soil. Minerals basically formed by the break down of large rocks. Some of the most common minerals found in soil are, Iron, Potassium, Magnesium, Calcium, Sulphur etc.
- Humus: Humus is the organic substances that are formed due to decomposition of dead and decomposing plants and animals. It lends the soil its fertility.
- Living Organisms: These are mostly microbes and other organisms (such as worms, bacteria, fungi etc.) that live in the soil and perform the decomposition of animals and plants that gives the soil humus.
- Water and Air: Water and air form a part of the soil and allow living organisms to perform their functions. They also help in the process of photosynthesis.
At a Christmas party on December 6, 2006, Harold Morowitz asked me a simple question: “Were there clay minerals in the Archean?” That question has important implications for origin-of-life models that depend on clays, but the answer is not at all obvious. And it’s a question that mineralogists never thought to ask. I was immediately struck by the idea that Earth’s mineralogy must have changed over 4.5 billion years of history in ways that had never been thoughtfully explored. After several sleepless nights, and a year of development with a growing list of collaborators including geobiologist Dominic Papineau (CIW), paleotectonics expert Wouter Bleeker (Geological Survey of Canada), metamorphic petrologist John Ferry (Johns Hopkins), meteorite expert Tim McCoy (Smithsonian), geochemist Dimitri Sverjensky (Johns Hopkins), and mineralogists Robert Downs and Hexiong Yang (University of Arizona), we published a paper entitled “Mineral evolution” (American Mineralogist, v.93, pp.1693-1720, 2008) that essentially reframes the science of mineralogy in an historical context.
Mineral evolution posits that the mineralogy of terrestrial planets and moons evolves as a consequence of varied physical, chemical, and biological processes that lead to the formation of new mineral species. The novelty of mineral evolution is epitomized by the new questions it raises about the history of mineralogy. For example, we could find no reference to the question, “What was the first mineral in the cosmos?” That is, what was the first crystalline material to form after the Big Bang? It was too hot following the Big Bang, and the first generation of atoms—mostly hydrogen and helium—are gases. No crystals formed in the first stars, either. But stars produce heavier elements, including such mineral-forming atoms as carbon, oxygen, silicon, and magnesium. We concluded that the first mineral was diamond—pure carbon condensed from the expanding atmospheres of energetic stars. Approximately a dozen “ur-minerals,” including nitrides, carbides, oxides, and silicates, condensed as micro-crystals at temperatures greater than 1500°C. The central question of mineral evolution is thus how a dozen phases with 10 essential elements were transformed to the >5000 minerals with 72 essential elements we see today.
II. STAGES OF MINERAL EVOLUTION
While an exact division of geological history into stages of mineral evolution is somewhat arbitrary, we propose that Earth's mineral evolution can be divided into at least ten stages, each of which increased the mineral diversity of the planet. Stage 1 occurred in the stellar nebula prior to planetary accretion, when presolar “dust bunnies” were melted into droplets (“chondrules”) by the fitful early Sun. These droplets accumulated in the earliest generations of meteorites, called chondrites. Unaltered chondritic material with approximately 60 different refractory minerals thus represents the starting point of the mineral evolution of all planets and moons in our solar system.
Chondrites clumped together by gravitational attraction into larger and larger “planetesimals.” Subsequent aqueous and thermal alteration of chondrites, asteroidal accretion and differentiation, and the consequent formation of achondrites results in a Stage 2 mineralogical repertoire limited to the approximately 250 minerals now found in the diverse suites of unweathered lunar and meteorite samples. Among the important minerals seen for the first time are quartz (of beach sand fame), carbonates (which today form limestone ridges and reefs), and the first clay minerals.
Following planetary accretion and differentiation, the mineral evolution of a terrestrial planet depends initially on a sequence of geochemical and petrologic processes, which depend principally on the size and volatile content of the body—proceses that define Stages 3, 4, and 5. These processes may include volcanism and degassing, fractional crystallization, crystal settling, assimilation reactions, regional and contact metamorphism, plate tectonics, and associated large-scale fluid-rock interactions.
Stage 3 is defined as the period of planetary differentiation into the major layers of metallic core, silicate mantle, and volcanic-derived basaltic crust. Earth’s crustal minerals diversified most notably by interactions with the earliest oceans and atmosphere. New hydrous minerals such as clay minerals, evaporites including salt, and ices at the frigid poles were produced in this early period. Igneous rocks also hosted suites of minerals, as described in The Evolution of the Igneous Rocks by Norman Bowen, a long-time Staff Scientist at the Geophysical Laboratory.
Recent work (R.M. Hazen, “Paleomineralogy of the Hadean Eon,” American Journal of Science, 2013) suggests that as many as 420 mineral species may have occurred during this early stage of Earth’s mineral evolution.
Stage 4 marks the appearance of Earth’s first extensive terrains of granite, a silica-rich rock that forms when wet basalt partially melts. The resulting granite melt is 10% less dense than basalt, so it rises to form the cores of continents. Granite formation also may result in the formation of pegmatite, which represent the final stages of granite crystallization. Pegmatite often concentrate rare “incompatible” elements that don’t find a comfortable home in common minerals. Numerous new minerals of such elements as beryllium, boron, lithium, tantalum, tin, and uranium thus occur in so-called “complex” pegmatite.
Stage 5 of Earth’s mineral evolution arises from the great global-scale process of plate tectonics, by which wet crustal rocks are recycled into the mantle by subduction. New mineral-forming processes arise from consequent fluid-rock interactions that operate on a vast scale. Immense hydrothermal ore deposits, vast metamorphic terrains, and the appearance of high-pressure minerals at Earth’s surface all characterize Stage 5, which increased mineral diversity to perhaps 1500 species formed by purely physical and chemical processes. According to some origin-of-life scenarios, a planet must progress through at least some of these stages of chemical processing as a prerequisite for life.
A major unresolved question is when plate tectonics began on Earth. Some researchers claim that some form of subduction was in operation during the first half-billion years, more than 4 billion years ago. Others, however, posit a commencement of modern-style plate tectonics no earlier than 3 billion years ago.
Biological processes began to affect Earth’s surface mineralogy by the Paleoarchean (
3.8 Ga), when large-scale surface mineral deposits, including carbonate and banded iron formations, were precipitated under the influences of changing atmospheric and ocean chemistry.
The Paleoproterozoic “great oxidation event” (Stage 7 2.5 to 1.9 Ga), when atmospheric oxygen may have risen to >1% of modern levels, and the Neoproterozoic increase in atmospheric oxygen following several major glaciation events, gave rise to multicellular life and skeletal biomineralization and irreversibly transformed Earth’s near-surface mineralogy. We estimate that 70% of the diversity of species on Earth arise indirectly from biological changes of the atmosphere and oceans. Most of these mineral species incorporate one or more redox-sensitive elements that can occur in two or more oxidation states. Thus, hundreds of new minerals incorporate iron (Fe 2+ vs. Fe 3+ ), copper (Cu 1+ vs. Cu 2+ ), and uranium (U 4+ vs. U 6+ ).
1.85 Ga, when the production of banded iron formations ceased relatively abruptly, signaling a significant change in ocean chemistry likely driven by microbial activity. This gradual change to an “intermediate ocean” appears to have resulted from increased microbial sulfide reduction and surface oxidation. This long time span—approximately 20% of Earth history—has been interpreted as period when the oceans gradually became oxygenated. No new mineral-forming processes have been identified from Stage 8 nevertheless, Earth’s mineralogical repertoire continued to diversify significantly as a result of ongoing physical, chemical, and biological processes.
Stage 9 featured the “Snowball Earth” (1.0 to 0.57 Ga). Multiple lines of evidence indicate that Earth experienced dramatic fluctuations in climate and atmospheric composition between about 1.0 and 0.57 Ga, with at least two (and possibly as many as four) snowball Earth events between about 0.75 and 0.57 Ga. During the coldest periods, ice was Earth’s most abundant surface mineral. However, mineral diversity did not significantly increase during Stage 9.
The most recent Stage 10 of Earth’s mineral evolution saw the biological innovations of shells, teeth, and bones, as well as the rise of the terrestrial biosphere. Dozens of new organic mineral species have appeared during the Phanerozoic Eon.
A principal conclusion of mineral evolution is that sequential stages of mineral evolution arise from three primary mechanisms: (1) the progressive separation and concentration of the elements from their original relatively uniform distribution in the presolar nebula (2) the increase in range of intensive variables such as pressure, temperature, and the activities of H2O, CO2, and O2 and (3) the generation of far-from-equilibrium conditions by living systems. The sequential evolution of Earth’s mineralogy fr om chondritic simplicity to Phanerozoic complexity introduces the dimension of geologic time to mineralogy and thus provides a dynamic alternate approach to framing, and to teaching, the mineral sciences.
The general principles observed for the emergence of mineralogical complexity on Earth apply equally to any differentiated asteroid, moon, or terrestrial planet. In every instance mineral evolution will occur in a progression of stages as a result of local, regional, and global selective processes. The degree to which a body will advance in mineralogical complexity beyond the relatively simple achondrite stage is dictated by the nature and intensity of subsequent cycling (and hence repeated separation and concentration of elements). Consequently, a planet’s surface mineralogy will directly reflect the extent to which cyclic processes have affected the body’s history. Accordingly, remote observations of the mineralogy of other moons and planets may provide crucial evidence for biological influences beyond Earth.
A number of papers amplify the original mineral evolution concept:
Hazen, R.M., Ewing, R.J and Sverjensky, D.A. (2009) Evolution of uranium and thorium minerals. American Mineralogist 94. 1293-1311.
Hazen, R.M. and J. M. Ferry (2010) Mineral evolution: Mineralogy in the fourth dimension. Elements 6, #1, 9-12.
Hazen, R.M. and N. Eldredge (2010) Themes and variations in complex systems. Elements 6, #1, 43-46.
Hazen, R.M. (2010) The evolution of minerals. Scientific American 303, #3, 58-65.
Grew, E.S., Bada J.L., Hazen R.M. (2011) Borate minerals and the origin of the RNA world, Origins of Life and Evolution of the Biosphere, 41, 307-316.
Hazen R.M., Bekker A, Bish DL, Bleeker W, Downs RT, Farquhar J, Ferry JM, Grew ES, Knoll AH, Papineau D, Ralph JP, Sverjensky DA, Valley JW (2011) Needs and opportunities in mineral evolution research. American Mineralogist, 96, 953-963.
Golden, J., M.McMillan, R.T.Downs, G.Hystad, H.J.Stein, A.Zimmerman, D.A.Sverjensky, J.Armstrong, R.M.Hazen (2012) The Great Subsurface Oxidation “Event”: Evidence from Re Variations in Molybdenite (MoS2
Geology, in review.
Hazen, R.M., R.T.Downs, J.Golden, E.S.Grew, D.Azzolini, D.A.Sverjensky (2012) Mercury (Hg) mineral evolution: A mineralogical record of supercontinent assembly, changing ocean geochemistry, and the emerging terrestrial biosphere. American Mineralogist, in review.
We've received lots of publicity since the mid-November 2008 release of the paper. Here's a sampling:
Selected Articles on “Mineral Evolution”
Minik Rosing (2008) “On the evolution of minerals.” Nature 456, 456-458.
Sid Perkins (2008) “As life evolves, minerals do too.” Science News, December 6, 2008, 10.
Phil Bernardelli (2008) “Earth’s minerals evolved, too.” ScienceNOW Daily News, Noember 14, 2008. (http://sciencenow.sciencemag.org)
Crisogono Vasconcelos and Judith McKenzie (2009) “The descent of minerals.” Science 323, 218-219.
Brian Fisher Johnson (2009) “Minerals take on a new life.” Earth, January 2009, 14-15.
Harvey Leifert (2009) “Rocky Road.” Natural History, February 2009, 14.
Science News (2009) News of the Year issue, “Minerals evolve too.” January 3, 2009, 26.
American Scientist (2009) “Rocks evolve too.” January-February 2009, 25.
Colin Nickerson (2009) “The blurry line between life, nonlife.” Boston Globe, January 12, 2009, A9.
Boris Bellanger (2009) “Mineraux sans la vie, il n’en existerait pas autant!” Science et Vie, March 2009, 102-104.
The impact of food processing on the nutritional quality of vitamins and minerals
Processing (including preparation) makes food healthier, safer, tastier and more shelf-stable. While the benefits are numerous, processing can also be detrimental, affecting the nutritional quality of foods. Blanching, for example, results in leaching losses of vitamins and minerals. Also, milling and extrusion can cause the physical removal of minerals during processing. The nutritional quality of minerals in food depends on their quantity as well as their bioavailability. The bioavailability of key minerals such as iron, zinc and calcium is known to be significantly affected by the fiber, phytic acid, and tannin content of foods. Concentrations of these constituents are altered by various processing methods including milling, fermentation, germination (sprouting), extrusion, and thermal processing. Vitamins, especially ascorbic acid, thiamin and folic acid, are highly sensitive to the same processing methods. The time and temperature of processing, product composition and storage are all factors that substantially impact the vitamin status of our foods.
Earth’s Mineral Evolution
Evolution isn’t just for living organisms. Scientists at the Carnegie Institution have found that the mineral kingdom co-evolved with life, and that up to two thirds of the more than 4,000 known types of minerals on Earth can be directly or indirectly linked to biological activity. The finding, published in American Mineralogist, could aid scientists in the search for life on other planets.
Robert Hazen and Dominic Papineau of the Carnegie Institution’s Geophysical Laboratory, with six colleagues, reviewed the physical, chemical, and biological processes that gradually transformed about a dozen different primordial minerals in ancient interstellar dust grains to the thousands of mineral species on the present-day Earth. (Unlike biological species, each mineral species is defined by its characteristic chemical makeup and crystal structure.)
"It’s a different way of looking at minerals from more traditional approaches," says Hazen."Mineral evolution is obviously different from Darwinian evolution – minerals don’t mutate, reproduce or compete like living organisms. But we found both the variety and relative abundances of minerals have changed dramatically over more than 4.5 billion years of Earth’s history."
All the chemical elements were present from the start in the solar system’s primordial dust, but they formed comparatively few minerals. Only after large bodies such as the sun and planets congealed did there exist the extremes of temperature and pressure required to forge a large diversity of mineral species. Many elements were also too dispersed in the original dust clouds to be able to solidify into mineral crystals.
As the solar system took shape through "gravitational clumping" of small, undifferentiated bodies – fragments of which are found today in the form of meteorites – about 60 different minerals made their appearance. Larger, planet-sized bodies, especially those with volcanic activity and bearing significant amounts of water, could have given rise to several hundred new mineral species. Mars and Venus, which Hazen and coworkers estimate to have at least 500 different mineral species in their surface rocks, appear to have reached this stage in their mineral evolution.
However, only on Earth – at least in our solar system – did mineral evolution progress to the next stages. A key factor was the churning of the planet’s interior by plate tectonics, the process that drives the slow shifting continents and ocean basins over geological time. Unique to Earth, plate tectonics created new kinds of physical and chemical environments where minerals could form, and thereby boosted mineral diversity to more than a thousand types.
What ultimately had the biggest impact on mineral evolution, however, was the origin of life, approximately 4 billion years ago. "Of the approximately 4,300 known mineral species on Earth, perhaps two-thirds of them are biologically mediated," says Hazen." This is principally a consequence of our oxygen-rich atmosphere, which is a product of photosynthesis by microscopic algae." Many important minerals are oxidized weathering products, including ores of iron, copper and many other metals.
Microorganisms and plants also accelerated the production of diverse clay minerals. In the oceans, the evolution of organisms with shells and mineralized skeletons generated thick, layered deposits of minerals such as calcite, which would be rare on a lifeless planet.
"For at least 2.5 billion years, and possibly since the emergence of life, Earth’s mineralogy has evolved in parallel with biology," says Hazen. "One implication of this finding is that remote observations of the mineralogy of other moons and planets may provide crucial evidence for biological influences beyond Earth."
Stanford University geologist Gary Ernst called the study "breathtaking," saying that "the unique perspective presented in this paper may revolutionize the way Earth scientists regard minerals."
Our editors will review what you’ve submitted and determine whether to revise the article.
Morphogenesis, the shaping of an organism by embryological processes of differentiation of cells, tissues, and organs and the development of organ systems according to the genetic “blueprint” of the potential organism and environmental conditions.
Plant morphogenesis is brought about chiefly through differential growth. Permanent embryonic tissue results in a morphogenetic potential that varies greatly with the environment and continues to produce new organs throughout the life of the plant. Animal morphogenesis is accomplished by growth and by cell movement. A fixed pattern is established early the organism is determined as to shape, size, and organ complement. Once organs are formed, no new ones (with few exceptions) are produced. See also histogenesis organogenesis.
This article was most recently revised and updated by Robert Lewis, Assistant Editor.
Magnesium regulates our electrolyte balance.
Within every cell in the body, a proper balance of mineral content must be maintained. Magnesium’s role in the healthy balance (“homeostasis”) of important minerals such as calcium, sodium and potassium affects the conduction of nerve impulses, muscle contraction, and heart rhythms.
The body allows mineral ions to flow into and out of the cell from the extra-cellular fluid, depending on concentrations inside or outside the cell. Minerals, in their ionic form, seek to equalize their concentrations by flowing through open membrane channels designed to allow movement of ions, water molecules, and small water-soluble compounds.
However, ideal levels for minerals inside and outside the cells is not equal, as minerals serve various purposes inside the body and the cells. To keep cells healthy, a distribution such as the following must be maintained.
|Inside the Cells||Outside the Cells|
Because of the tendency of ions to equalize across membranes, like water flowing toward the sea, the cell must actively move ions into or out of the cell, expending energy to create a healthy balance using special “exchange pumps”.
These mineral exchange pumps perform one of the most vital functions of the cell membrane, regulating the electrical action potential inside and outside of the cell, and maintaining homeostasis of minerals in the body. Without constant efforts by exchange pumps, cells would be flooded with calcium and sodium moving in, and potassium and magnesium moving out as they strived to achieve an equilibrium.
One such exchange pump, known as the “sodium-potassium” pump, pumps sodium out of the cell in exchange for potassium. Embedded in the cell membrane, the sodium-potassium pump is activated by magnesium inside the cell.
Magnesium deficiency impairs the sodium-potassium pump, allowing potassium to escape from the cell, to be lost in the urine, potentially leading to potassium deficiency (hypokalemia). Those with a known potassium deficiency, therefore, often do not respond to treatment until magnesium deficiency is also corrected.
Similarly, magnesium’s role in calcium regulation is pivotal to its role in maintaining heart health. Magnesium is a known modulator of calcium, competing with calcium for entrance into cells and keeping many cellular processes in balance.
- The effect of magnesium on blood vessels is one of dilation, whereas calcium promotes contraction.
- Magnesium is also thought to antagonize calcium promotion of blood clotting.
You require oxygen to produce energy that is necessary for every bodily function and process. Red blood cells -- or erythrocytes -- carry oxygen to each of your infinite cells, where it is used to generate energy. Red blood cells contain a heme or iron component that binds to oxygen so that it can be transported. Without the iron molecules, oxygen could not be attached to the blood cells and the body would not be able to produce the energy necessary for life. Iron is an essential mineral, and failing to get enough from your diet can lead to a condition called anemia, which causes weakness and fatigue. This mineral is primarily found in the blood, and it is also stored in your liver, spleen, bone marrow and muscles.
1.2 The Process of Science
Like geology, physics, and chemistry, biology is a science that gathers knowledge about the natural world. Specifically, biology is the study of life. The discoveries of biology are made by a community of researchers who work individually and together using agreed-on methods. In this sense, biology, like all sciences is a social enterprise like politics or the arts. The methods of science include careful observation, record keeping, logical and mathematical reasoning, experimentation, and submitting conclusions to the scrutiny of others. Science also requires considerable imagination and creativity a well-designed experiment is commonly described as elegant, or beautiful. Like politics, science has considerable practical implications and some science is dedicated to practical applications, such as the prevention of disease (see Figure 1.15). Other science proceeds largely motivated by curiosity. Whatever its goal, there is no doubt that science, including biology, has transformed human existence and will continue to do so.
The Nature of Science
Biology is a science, but what exactly is science? What does the study of biology share with other scientific disciplines? Science (from the Latin scientia, meaning "knowledge") can be defined as knowledge about the natural world.
Science is a very specific way of learning, or knowing, about the world. The history of the past 500 years demonstrates that science is a very powerful way of knowing about the world it is largely responsible for the technological revolutions that have taken place during this time. There are however, areas of knowledge and human experience that the methods of science cannot be applied to. These include such things as answering purely moral questions, aesthetic questions, or what can be generally categorized as spiritual questions. Science cannot investigate these areas because they are outside the realm of material phenomena, the phenomena of matter and energy, and cannot be observed and measured.
The scientific method is a method of research with defined steps that include experiments and careful observation. The steps of the scientific method will be examined in detail later, but one of the most important aspects of this method is the testing of hypotheses. A hypothesis is a suggested explanation for an event, which can be tested. Hypotheses, or tentative explanations, are generally produced within the context of a scientific theory . A scientific theory is a generally accepted, thoroughly tested and confirmed explanation for a set of observations or phenomena. Scientific theory is the foundation of scientific knowledge. In addition, in many scientific disciplines (less so in biology) there are scientific laws , often expressed in mathematical formulas, which describe how elements of nature will behave under certain specific conditions. There is not an evolution of hypotheses through theories to laws as if they represented some increase in certainty about the world. Hypotheses are the day-to-day material that scientists work with and they are developed within the context of theories. Laws are concise descriptions of parts of the world that are amenable to formulaic or mathematical description.
What would you expect to see in a museum of natural sciences? Frogs? Plants? Dinosaur skeletons? Exhibits about how the brain functions? A planetarium? Gems and minerals? Or maybe all of the above? Science includes such diverse fields as astronomy, biology, computer sciences, geology, logic, physics, chemistry, and mathematics (Figure 1.16). However, those fields of science related to the physical world and its phenomena and processes are considered natural sciences . Thus, a museum of natural sciences might contain any of the items listed above.
There is no complete agreement when it comes to defining what the natural sciences include. For some experts, the natural sciences are astronomy, biology, chemistry, earth science, and physics. Other scholars choose to divide natural sciences into life sciences , which study living things and include biology, and physical sciences , which study nonliving matter and include astronomy, physics, and chemistry. Some disciplines such as biophysics and biochemistry build on two sciences and are interdisciplinary.
One thing is common to all forms of science: an ultimate goal “to know.” Curiosity and inquiry are the driving forces for the development of science. Scientists seek to understand the world and the way it operates. Two methods of logical thinking are used: inductive reasoning and deductive reasoning.
Inductive reasoning is a form of logical thinking that uses related observations to arrive at a general conclusion. This type of reasoning is common in descriptive science. A life scientist such as a biologist makes observations and records them. These data can be qualitative (descriptive) or quantitative (consisting of numbers), and the raw data can be supplemented with drawings, pictures, photos, or videos. From many observations, the scientist can infer conclusions (inductions) based on evidence. Inductive reasoning involves formulating generalizations inferred from careful observation and the analysis of a large amount of data. Brain studies often work this way. Many brains are observed while people are doing a task. The part of the brain that lights up, indicating activity, is then demonstrated to be the part controlling the response to that task.
Deductive reasoning or deduction is the type of logic used in hypothesis-based science. In deductive reasoning, the pattern of thinking moves in the opposite direction as compared to inductive reasoning. Deductive reasoning is a form of logical thinking that uses a general principle or law to predict specific results. From those general principles, a scientist can deduce and predict the specific results that would be valid as long as the general principles are valid. For example, a prediction would be that if the climate is becoming warmer in a region, the distribution of plants and animals should change. Comparisons have been made between distributions in the past and the present, and the many changes that have been found are consistent with a warming climate. Finding the change in distribution is evidence that the climate change conclusion is a valid one.
Both types of logical thinking are related to the two main pathways of scientific study: descriptive science and hypothesis-based science. Descriptive (or discovery) science aims to observe, explore, and discover, while hypothesis-based science begins with a specific question or problem and a potential answer or solution that can be tested. The boundary between these two forms of study is often blurred, because most scientific endeavors combine both approaches. Observations lead to questions, questions lead to forming a hypothesis as a possible answer to those questions, and then the hypothesis is tested. Thus, descriptive science and hypothesis-based science are in continuous dialogue.
Biologists study the living world by posing questions about it and seeking science-based responses. This approach is common to other sciences as well and is often referred to as the scientific method. The scientific method was used even in ancient times, but it was first documented by England’s Sir Francis Bacon (1561–1626) (Figure 1.17), who set up inductive methods for scientific inquiry. The scientific method is not exclusively used by biologists but can be applied to almost anything as a logical problem-solving method.
The scientific process typically starts with an observation (often a problem to be solved) that leads to a question. Let’s think about a simple problem that starts with an observation and apply the scientific method to solve the problem. One Monday morning, a student arrives at class and quickly discovers that the classroom is too warm. That is an observation that also describes a problem: the classroom is too warm. The student then asks a question: “Why is the classroom so warm?”
Recall that a hypothesis is a suggested explanation that can be tested. To solve a problem, several hypotheses may be proposed. For example, one hypothesis might be, “The classroom is warm because no one turned on the air conditioning.” But there could be other responses to the question, and therefore other hypotheses may be proposed. A second hypothesis might be, “The classroom is warm because there is a power failure, and so the air conditioning doesn’t work.”
Once a hypothesis has been selected, a prediction may be made. A prediction is similar to a hypothesis but it typically has the format “If . . . then . . . .” For example, the prediction for the first hypothesis might be, “If the student turns on the air conditioning, then the classroom will no longer be too warm.”
A hypothesis must be testable to ensure that it is valid. For example, a hypothesis that depends on what a bear thinks is not testable, because it can never be known what a bear thinks. It should also be falsifiable , meaning that it can be disproven by experimental results. An example of an unfalsifiable hypothesis is “Botticelli’s Birth of Venus is beautiful.” There is no experiment that might show this statement to be false. To test a hypothesis, a researcher will conduct one or more experiments designed to eliminate one or more of the hypotheses. This is important. A hypothesis can be disproven, or eliminated, but it can never be proven. Science does not deal in proofs like mathematics. If an experiment fails to disprove a hypothesis, then we find support for that explanation, but this is not to say that down the road a better explanation will not be found, or a more carefully designed experiment will be found to falsify the hypothesis.
Each experiment will have one or more variables and one or more controls. A variable is any part of the experiment that can vary or change during the experiment. A control is a part of the experiment that does not change. Look for the variables and controls in the example that follows. As a simple example, an experiment might be conducted to test the hypothesis that phosphate limits the growth of algae in freshwater ponds. A series of artificial ponds are filled with water and half of them are treated by adding phosphate each week, while the other half are treated by adding a salt that is known not to be used by algae. The variable here is the phosphate (or lack of phosphate), the experimental or treatment cases are the ponds with added phosphate and the control ponds are those with something inert added, such as the salt. Just adding something is also a control against the possibility that adding extra matter to the pond has an effect. If the treated ponds show lesser growth of algae, then we have found support for our hypothesis. If they do not, then we reject our hypothesis. Be aware that rejecting one hypothesis does not determine whether or not the other hypotheses can be accepted it simply eliminates one hypothesis that is not valid (Figure 1.18). Using the scientific method, the hypotheses that are inconsistent with experimental data are rejected.
In recent years a new approach of testing hypotheses has developed as a result of an exponential growth of data deposited in various databases. Using computer algorithms and statistical analyses of data in databases, a new field of so-called "data research" (also referred to as "in silico" research) provides new methods of data analyses and their interpretation. This will increase the demand for specialists in both biology and computer science, a promising career opportunity.
In the example below, the scientific method is used to solve an everyday problem. Which part in the example below is the hypothesis? Which is the prediction? Based on the results of the experiment, is the hypothesis supported? If it is not supported, propose some alternative hypotheses.
- My toaster doesn’t toast my bread.
- Why doesn’t my toaster work?
- There is something wrong with the electrical outlet.
- If something is wrong with the outlet, my coffeemaker also won’t work when plugged into it.
- I plug my coffeemaker into the outlet.
- My coffeemaker works.
In practice, the scientific method is not as rigid and structured as it might at first appear. Sometimes an experiment leads to conclusions that favor a change in approach often, an experiment brings entirely new scientific questions to the puzzle. Many times, science does not operate in a linear fashion instead, scientists continually draw inferences and make generalizations, finding patterns as their research proceeds. Scientific reasoning is more complex than the scientific method alone suggests.
Basic and Applied Science
The scientific community has been debating for the last few decades about the value of different types of science. Is it valuable to pursue science for the sake of simply gaining knowledge, or does scientific knowledge only have worth if we can apply it to solving a specific problem or bettering our lives? This question focuses on the differences between two types of science: basic science and applied science.
Basic science or “pure” science seeks to expand knowledge regardless of the short-term application of that knowledge. It is not focused on developing a product or a service of immediate public or commercial value. The immediate goal of basic science is knowledge for knowledge’s sake, though this does not mean that in the end it may not result in an application.
In contrast, applied science or “technology,” aims to use science to solve real-world problems, making it possible, for example, to improve a crop yield, find a cure for a particular disease, or save animals threatened by a natural disaster. In applied science, the problem is usually defined for the researcher.
Some individuals may perceive applied science as “useful” and basic science as “useless.” A question these people might pose to a scientist advocating knowledge acquisition would be, “What for?” A careful look at the history of science, however, reveals that basic knowledge has resulted in many remarkable applications of great value. Many scientists think that a basic understanding of science is necessary before an application is developed therefore, applied science relies on the results generated through basic science. Other scientists think that it is time to move on from basic science and instead to find solutions to actual problems. Both approaches are valid. It is true that there are problems that demand immediate attention however, few solutions would be found without the help of the knowledge generated through basic science.
One example of how basic and applied science can work together to solve practical problems occurred after the discovery of DNA structure led to an understanding of the molecular mechanisms governing DNA replication. Strands of DNA, unique in every human, are found in our cells, where they provide the instructions necessary for life. During DNA replication, new copies of DNA are made, shortly before a cell divides to form new cells. Understanding the mechanisms of DNA replication enabled scientists to develop laboratory techniques that are now used to identify genetic diseases, pinpoint individuals who were at a crime scene, and determine paternity. Without basic science, it is unlikely that applied science could exist.
Another example of the link between basic and applied research is the Human Genome Project, a study in which each human chromosome was analyzed and mapped to determine the precise sequence of DNA subunits and the exact location of each gene. (The gene is the basic unit of heredity represented by a specific DNA segment that codes for a functional molecule.) Other organisms have also been studied as part of this project to gain a better understanding of human chromosomes. The Human Genome Project (Figure 1.19) relied on basic research carried out with non-human organisms and, later, with the human genome. An important end goal eventually became using the data for applied research seeking cures for genetically related diseases.
While research efforts in both basic science and applied science are usually carefully planned, it is important to note that some discoveries are made by serendipity, that is, by means of a fortunate accident or a lucky surprise. Penicillin was discovered when biologist Alexander Fleming accidentally left a petri dish of Staphylococcus bacteria open. An unwanted mold grew, killing the bacteria. The mold turned out to be Penicillium, and a new antibiotic was discovered. Even in the highly organized world of science, luck—when combined with an observant, curious mind—can lead to unexpected breakthroughs.
Reporting Scientific Work
Whether scientific research is basic science or applied science, scientists must share their findings for other researchers to expand and build upon their discoveries. Communication and collaboration within and between sub disciplines of science are key to the advancement of knowledge in science. For this reason, an important aspect of a scientist’s work is disseminating results and communicating with peers. Scientists can share results by presenting them at a scientific meeting or conference, but this approach can reach only the limited few who are present. Instead, most scientists present their results in peer-reviewed articles that are published in scientific journals. Peer-reviewed articles are scientific papers that are reviewed, usually anonymously by a scientist’s colleagues, or peers. These colleagues are qualified individuals, often experts in the same research area, who judge whether or not the scientist’s work is suitable for publication. The process of peer review helps to ensure that the research described in a scientific paper or grant proposal is original, significant, logical, and thorough. Grant proposals, which are requests for research funding, are also subject to peer review. Scientists publish their work so other scientists can reproduce their experiments under similar or different conditions to expand on the findings.
There are many journals and the popular press that do not use a peer-review system. A large number of online open-access journals, journals with articles available without cost, are now available many of which use rigorous peer-review systems, but some of which do not. Results of any studies published in these forums without peer review are not reliable and should not form the basis for other scientific work. In one exception, journals may allow a researcher to cite a personal communication from another researcher about unpublished results with the cited author’s permission.