Human biology is an interdisciplinary area of academic study that examines humans through the influences and interplay of many diverse fields such as genetics, evolution, physiology, anatomy, epidemiology, anthropology, ecology, nutrition, population genetics, and sociocultural influences. [1] [2] It is closely related to the biomedical sciences, biological anthropology and other biological fields tying in various aspects of human functionality. It wasn't until the 20th century when biogerontologist, Raymond Pearl, founder of the journal Human Biology , phrased the term "human biology" in a way to describe a separate subsection apart from biology. [3]
It is also a portmanteau term that describes all biological aspects of the human body, typically using the human body as a type organism for Mammalia, and in that context it is the basis for many undergraduate University degrees and modules. [4] [5]
Most aspects of human biology are identical or very similar to general mammalian biology. In particular, and as examples, humans :
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The study of integrated human biology started in the 1920s, sparked by Charles Darwin's theories which were re-conceptualized by many scientists. Human attributes, such as child growth and genetics, were put into question and thus human biology was created.
The key aspects of human biology are those ways in which humans are substantially different from other mammals. [6]
Humans have a very large brain in a head that is very large for the size of the animal. This large brain has enabled a range of unique attributes including the development of complex languages and the ability to make and use a complex range of tools. [7] [8]
The upright stance and bipedal locomotion is not unique to humans but humans are the only species to rely almost exclusively on this mode of locomotion. [9] This has resulted in significant changes in the structure of the skeleton including the articulation of the pelvis and the femur and in the articulation of the head.
In comparison with most other mammals, humans are very long lived [10] with an average age at death in the developed world of nearly 80 years old. [11] Humans also have the longest childhood of any mammal with sexual maturity taking 12 to 16 years on average to be completed.
Humans lack fur. Although there is a residual covering of fine hair, which may be more developed in some people, and localised hair covering on the head, axillary and pubic regions, in terms of protection from cold, humans are almost naked. The reason for this development is still much debated.
The human eye can see objects in colour but is not well adapted to low light conditions. The sense of smell and of taste are present but are relatively inferior to a wide range of other mammals. Human hearing is efficient but lacks the acuity of some other mammals. Similarly human sense of touch is well developed especially in the hands where dextrous tasks are performed but the sensitivity is still significantly less than in other animals, particularly those equipped with sensory bristles such as cats.
Human biology tries to understand and promotes research on humans as living beings as a scientific discipline. It makes use of various scientific methods, such as experiments and observations, to detail the biochemical and biophysical foundations of human life describe and formulate the underlying processes using models. As a basic science, it provides the knowledge base for medicine. A number of sub-disciplines include anatomy, cytology, histology and morphology.
The capabilities of the human brain and the human dexterity in making and using tools, has enabled humans to understand their own biology through scientific experiment, including dissection, autopsy, prophylactic medicine which has, in turn, enable humans to extend their life-span by understanding and mitigating the effects of diseases.
Understanding human biology has enabled and fostered a wider understanding of mammalian biology and by extension, the biology of all living organisms.
Human nutrition is typical of mammalian omnivorous nutrition requiring a balanced input of carbohydrates, fats, proteins, vitamins, and minerals. However, the human diet has a few very specific requirements. These include two specific amino acids, alpha-linolenic acid and linoleic acid without which life is not sustainable in the medium to long term. All other fatty acids can be synthesized from dietary fats. Similarly, human life requires a range of vitamins to be present in food and if these are missing or are supplied at unacceptably low levels, metabolic disorders result which can end in death. The human metabolism is similar to most other mammals except for the need to have an intake of Vitamin C to prevent scurvy and other deficiency diseases. Unusually amongst mammals, a human can synthesize Vitamin D3 using natural UV light from the sun on the skin. This capability may be widespread in the mammalian world but few other mammals share the almost naked skin of humans. The darker the human's skin, the less it can manufacture Vitamin D3.
Human biology also encompasses all those organisms that live on or in the human body. Such organisms range from parasitic insects such as fleas and ticks, parasitic helminths such as liver flukes through to bacterial and viral pathogens. Many of the organisms associated with human biology are the specialised biome in the large intestine and the biotic flora of the skin and pharyngeal and nasal region. Many of these biotic assemblages help protect humans from harm and assist in digestion, and are now known to have complex effects on mood, and well-being.
Humans in all civilizations are social animals and use their language skills and tool making skills to communicate.
These communication skills enable civilizations to grow and allow for the production of art, literature and music, and for the development of technology. All of these are wholly dependent on the human biological specialisms.
The deployment of these skills has allowed the human race to dominate the terrestrial biome [12] to the detriment of most of the other species.
Biology – The natural science that studies life. Areas of focus include structure, function, growth, origin, evolution, distribution, and taxonomy.
Food is any substance consumed by an organism for nutritional support. Food is usually of plant, animal, or fungal origin and contains essential nutrients such as carbohydrates, fats, proteins, vitamins, or minerals. The substance is ingested by an organism and assimilated by the organism's cells to provide energy, maintain life, or stimulate growth. Different species of animals have different feeding behaviours that satisfy the needs of their metabolisms and have evolved to fill a specific ecological niche within specific geographical contexts.
A mammal is a vertebrate animal of the class Mammalia. Mammals are characterized by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle ear bones. These characteristics distinguish them from reptiles and birds, from which their ancestors diverged in the Carboniferous Period over 300 million years ago. Around 6,400 extant species of mammals have been described and divided into 29 orders.
Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain the required amount of nutrients causes malnutrition. Nutritional science is the study of nutrition, though it typically emphasizes human nutrition.
Vitamin C is a water-soluble vitamin found in citrus and other fruits, berries and vegetables. It is also a generic prescription medication and in some countries is sold as a non-prescription dietary supplement. As a therapy, it is used to prevent and treat scurvy, a disease caused by vitamin C deficiency.
Zoology is the scientific study of animals. Its studies include the structure, embryology, classification, habits, and distribution of all animals, both living and extinct, and how they interact with their ecosystems. Zoology is one of the primary branches of biology. The term is derived from Ancient Greek ζῷον, zōion ('animal'), and λόγος, logos.
7-Dehydrocholesterol (7-DHC) is a zoosterol that functions in the serum as a cholesterol precursor, and is photochemically converted to vitamin D3 in the skin, therefore functioning as provitamin-D3. The presence of this compound in human skin enables humans to manufacture vitamin D3 (cholecalciferol). Upon exposure to ultraviolet UV-B rays in the sun light, 7-DHC is converted into vitamin D3 via previtamin D3 as an intermediate isomer. It is also found in the milk of several mammalian species. Lanolin, a waxy substance that is naturally secreted by wool-bearing mammals, contains 7-DHC which is converted into vitamin D by sunlight and then ingested during grooming as a nutrient. In insects 7-dehydrocholesterol is a precursor for the hormone ecdysone, required for reaching adulthood. 7-DHC was discovered by Nobel-laureate organic chemist Adolf Windaus.
Vitamin A is a fat-soluble vitamin that is an essential nutrient. The term "vitamin A" encompasses a group of chemically related organic compounds that includes retinol, retinyl esters, and several provitamin (precursor) carotenoids, most notably β-carotene (beta-carotene). Vitamin A has multiple functions: growth during embryo development, maintaining the immune system, and healthy vision. For aiding vision specifically, it combines with the protein opsin to form rhodopsin, the light-absorbing molecule necessary for both low-light and color vision.
A nutrient is a substance used by an organism to survive, grow and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi and protists. Nutrients can be incorporated into cells for metabolic purposes or excreted by cells to create non-cellular structures such as hair, scales, feathers, or exoskeletons. Some nutrients can be metabolically converted into smaller molecules in the process of releasing energy such as for carbohydrates, lipids, proteins and fermentation products leading to end-products of water and carbon dioxide. All organisms require water. Essential nutrients for animals are the energy sources, some of the amino acids that are combined to create proteins, a subset of fatty acids, vitamins and certain minerals. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves. Fungi live on dead or living organic matter and meet nutrient needs from their host.
The history of biology traces the study of the living world from ancient to modern times. Although the concept of biology as a single coherent field arose in the 19th century, the biological sciences emerged from traditions of medicine and natural history reaching back to Ayurveda, ancient Egyptian medicine and the works of Aristotle, Theophrastus and Galen in the ancient Greco-Roman world. This ancient work was further developed in the Middle Ages by Muslim physicians and scholars such as Avicenna. During the European Renaissance and early modern period, biological thought was revolutionized in Europe by a renewed interest in empiricism and the discovery of many novel organisms. Prominent in this movement were Vesalius and Harvey, who used experimentation and careful observation in physiology, and naturalists such as Linnaeus and Buffon who began to classify the diversity of life and the fossil record, as well as the development and behavior of organisms. Antonie van Leeuwenhoek revealed by means of microscopy the previously unknown world of microorganisms, laying the groundwork for cell theory. The growing importance of natural theology, partly a response to the rise of mechanical philosophy, encouraged the growth of natural history.
An endotherm is an organism that maintains its body at a metabolically favorable temperature, largely by the use of heat released by its internal bodily functions instead of relying almost purely on ambient heat. Such internally generated heat is mainly an incidental product of the animal's routine metabolism, but under conditions of excessive cold or low activity an endotherm might apply special mechanisms adapted specifically to heat production. Examples include special-function muscular exertion such as shivering, and uncoupled oxidative metabolism, such as within brown adipose tissue.
Cat food is food specifically formulated and designed for consumption by cats. As obligate carnivores, cats have specific requirements for their dietary nutrients, namely nutrients found only in meat or synthesized, such as taurine and Vitamin A. Certain nutrients, including many vitamins and amino acids, are degraded by the temperatures, pressures and chemical treatments used during manufacture, and hence must be added after manufacture to avoid nutritional deficiency. Cat food is typically sold as dry kibble, or as wet food in cans and pouches.
L-Gulonolactone oxidase is an enzyme that produces vitamin C. It is expressed in most mammals, but is non-functional in Haplorrhini, in some bats, and in guinea pigs. It catalyzes the reaction of L-gulono-1,4-lactone with oxygen to form L-xylo-hex-3-gulonolactone (2-keto-gulono-γ-lactone) and hydrogen peroxide. It uses FAD as a cofactor. The L-xylo-hex-3-gulonolactone then converts to ascorbic acid spontaneously, without enzymatic action. The structure of L-gulonolactone oxidase in rats helps identify characteristics of this enzyme.
A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual cell, a multicellular organism, or a community of interacting populations. They usually specialize in a particular branch of biology and have a specific research focus.
Biological value (BV) is a measure of the proportion of absorbed protein from a food which becomes incorporated into the proteins of the organism's body. It captures how readily the digested protein can be used in protein synthesis in the cells of the organism. Proteins are the major source of nitrogen in food. BV assumes protein is the only source of nitrogen and measures the amount of nitrogen ingested in relation to the amount which is subsequently excreted. The remainder must have been incorporated into the proteins of the organisms body. A ratio of nitrogen incorporated into the body over nitrogen absorbed gives a measure of protein "usability" – the BV.
In the study of the biological sciences, biocommunication is any specific type of communication within (intraspecific) or between (interspecific) species of plants, animals, fungi, protozoa and microorganisms. Communication means sign-mediated interactions following three levels of rules. Signs in most cases are chemical molecules (semiochemicals), but also tactile, or as in animals also visual and auditive. Biocommunication of animals may include vocalizations, or pheromone production, chemical signals between plants and animals, and chemically mediated communication between plants and within plants.
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary information encoded in genes, which can be transmitted to future generations. Another major theme is evolution, which explains the unity and diversity of life. Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms are able to regulate their own internal environments.
An organism's sex is female if it produces the ovum, the type of gamete that fuses with the male gamete during sexual reproduction.
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms. It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology, Glossary of environmental science and Glossary of scientific naming, or any of the organism-specific glossaries in Category:Glossaries of biology.
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