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Evolutionary Medicine

Evolutionary medicine

Evolutionary medicine or Darwinian medicine is a perspective on medicine derived through applying evolutionary theory. Humans, (as well as any other species) are adapted by evolution to live in particular environments. In other words, we thrive best under certain conditions as to a variety of environmental factors, including social and nutritional factors. There are many differences between the Stone Age environment we are adapted to and the industrialized environment of today. While many of these differences may have a positive impact on health and quality of life, some have a negative impact. At the same time, our parasites and pathogens have co-evolved with our bodies and immune systems. Evolutionary medicine views the evolutionary arms races between the body and disease from a Darwinian point of view, and proposes treatments and public health policies based on that analysis. A major developer of this field is Dr. Paul W. Ewald.

Bibliography

- Randolph M. Nesse and George C. Williams (1996) Why we get sick: The new science of Darwinian medicine ISBN 0679746749
- Wenda Trevathan, James J. McKenna, and Euclid O. Smith Evolutionary medicine ISBN 0195103564
- LeGrand EK, Brown CC. Darwinian medicine: applications of evolutionary biology for veterinarians. Can Vet J. 2002 Jul;43(7):556-9. PMID 12125190 [http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=12125190 full text]

External links

- http://www.people.virginia.edu/~rjh9u/darwmed.html
- http://www.chester.ac.uk/~sjlewis/DM/
- Smith JG Jr. Darwinian (evolutionary) medicine. editorial, South Med J. 1996 Oct;89(10):1028-30. [http://www.sma.org/smj/invoke.cfm?component=smj&objectid=1796CE44-BCD4-FF25-50819E5D213C879D&method=display&pageid=51A70215-BCD4-FF25-5270B8828847ED71 TOC] PMID 8865805 Category:Evolutionary biology Category:Medical research

Medicine

Medicine is a branch of health science concerned with maintaining human health and restoring it by treating disease and injury; it is both an area of knowledge, a science of body systems and diseases and their treatment, and the applied practice of that knowledge. The practice of medical care is shared between the medical profession—physicians or doctors—and other groups of professionals, such as nurses or pharmacists (sometimes called allied health professions). Historically, only members of the medical profession proper have been considered to actually practice medicine in the strictest sense, in contrast to the allied fields of health care professionals. Clinicians can be physicians, nurses, or physician assistants -- those who provide health care or otherwise tend to their patients. The medical profession is the social and occupational structure of the group of people formally trained and authorized to apply medical knowledge. Many countries and legal jurisdictions have legal limitations on who may practice medicine or the allied medical fields. Medicine is typically seen as composed of various specialized sub-branches, such as pediatrics, gynecology, neurology, dealing with particular body systems, diseases, or areas of health. Systems of medical and healthcare practices have existed among human societies since at least the dawn of recorded history. These systems have developed in various ways in different cultures and regions. Medicine as understood in the modern period has historically been considered to be the mainstream tradition which developed in the Western world since the early modern age. Many other traditions of medicine and healthcare are still widely practiced throughout the world, most of which are still considered to be separate and distinct from Western medicine, also called biomedicine or the Hippocratic tradition. The most highly developed systems of medicine outside the Western system are the Ayurvedic tradition of India and traditional Chinese medicine. Various non-mainstream traditions of health care have also developed in the Western world distinct from mainstream medicine. The various other systems practiced among various cultures are sometimes practiced alongside or in cooperation with Western medicine, while sometimes being seen as competing traditions. Medicine is also often used amongst medical professionals as shorthand for Internal Medicine. Veterinary medicine is the practice of health care specialized for other animal species.

History of medicine

Medicine as it is practiced now is rooted in various traditions, but developed mainly in the late 18th and early 19th century in Germany (Rudolf Virchow) and France (Jean-Martin Charcot, Claude Bernard and others). The new, "scientific" medicine replaced earlier Western traditions of medicine, mostly based on the "four humours" and other pre-modern theories. The focal points of development of clinical medicine shifted to the United Kingdom and the USA by the early 1900s (Sir William Osler, Harvey Cushing). Evidence-based medicine is the recent movement to link the practice and the science of medicine more closely through the use of the scientific method and modern information science. Genomics and knowledge of human genetics is already having a large influence on medicine, as the causative genes of most monogenic genetic disorders have now identified, and the development of techniques in molecular biology and genetics are influencing medical practice and decision-making.

Practice of medicine

The practice of medicine combines both science and art. Science and technology are the evidence base for many clinical problems for the general population at large. The art of medicine is the application of this medical knowledge in combination with intuition and clinical judgment to determine the proper diagnoses and treatment plan for this unique patient and to treat the patient accordingly. Central to medicine is the patient-doctor relationship established when a person with a health concern or problem seeks the help of a physician (i.e. the medical encounter). Other health professionals similarly establish a relationship with a patient and may perform interventions from their perspective, e.g. nurses, radiographers and therapists. As part of the medical encounter, the doctor needs to:
- develop a relationship with the patient
- gather data (medical history and physical examination combined with laboratory or imaging studies)
- analyze and synthesize that data (assessment and/or differential diagnosis), and then
- develop a treatment plan (further testing, therapy, watchful observation, referral and follow-up)
- treat the patient accordingly
- assess the progress of treatment and alter the plan as necessary. The medical encounter is documented in a medical record, which is a legal document in many jurisdictions. One method that is used is called the problem-oriented medical record (POMR), which includes a problem list of diagnoses and a "SOAP" method of documentation for each visit:
- S - Subjective, the medical history of the problem from the point-of-view of the patient.
- O - Objective, the physical examination and any laboratory or imaging studies.
- A - Assessment, is the medical decision-making process including the differential diagnoses and most probable diagnoses.
- P - Plan, the way resolve the problem and monitor progress

Medical systems

Medicine is practiced within the medical system of a particular culture or government. Leaving aside tribal cultures, the most significant divide in developed countries is that between universal health care and the market based health care (such as practiced in the U.S.).

Patient-doctor relationship

The doctor-patient relationship and interaction is a central process in the practice of medicine. There are many perspectives from which to understand and describe it. An idealized physician's perspective, such as is taught in medical school, sees the core aspects of the process as the physician learning from the patient his symptoms, concerns and values; in response the physician examines the patient, interprets the symptoms, and formulates a diagnosis to explain the symptoms and their cause to the patient and to propose a treatment. In more detail, the patient presents a set of complaints or concerns about his health to the doctor, who then obtains further information about the patient's symptoms, previous state of health, living conditions, and so forth, and then formulates a diagnosis and enlists the patient's agreement to a treatment plan. Importantly, during this process the doctor educates the patient about the causes, progression, outcomes, and possible treatments of his ailments, as well as often providing advice for maintaining health. This teaching relationship is the basis of calling the physician doctor, which originally meant "teacher" in Latin. The patient-doctor relationship is additionally complicated by the patient's suffering (patient derives from the Latin patiens, "suffering") and limited ability to relieve it on his own. The doctor's expertise comes from his knowledge about, or experience with, other people who have suffered similar symptoms, and his presumed ability to relieve it with medicines or other therapies about which the patient may initially have little knowledge. The doctor-patient relationship can be analyzed from the perspective of ethical concerns, in terms of how well the goals of non-maleficence, beneficence, autonomy, and justice are achieved. Many other values and ethical issues can be added to these. In different societies, periods, and cultures, different values may be assigned different priorities. For example, in the last 30 years medical care in the Western World has increasingly emphasized patient autonomy in decision making. The relationship and process can also be analyzed in terms of social power relationships (e.g., by Michel Foucault), or economic transactions. Physicians have been accorded gradually higher status and respect over the last century, and they have been entrusted with control of access to prescription medicines as a public health measure. This represents a concentration of power and carries both advantages and disadvantages to particular kinds of patients with particular kinds of conditions. A further twist has occurred in the last 25 years as costs of medical care have risen, and a third party (an insurance company or government agency) now often insists upon a share of decision-making power for a variety of reasons, reducing freedom of choice of both doctors and patients in many ways. The quality of the patient-doctor relationship is important to both parties. The better the relationship in terms of mutual respect, knowledge, trust, shared values and perspectives about disease and life, and time available, the better will be the amount and quality of information about the patient's disease transferred in both directions, enhancing accuracy of diagnosis and increasing the patient's knowledge about the disease. In some settings, e.g. the hospital ward, the patient-doctor relationship is much more complex, and many other people are involved when somebody is ill: relatives, neighbors, rescue specialists, nurses, technical personnel, social workers and others.

Clinical skills

Main articles: Medical history, Physical examination. A complete medical evaluation includes a medical history, a physical examination, appropriate laboratory or imaging studies, analysis of data and medical decision making to obtain diagnoses, and treatment plan. The components of the medical history are:
- Chief complaint (CC) - the reason for the current medical visit.
- History of present illness (HPI) - the chronological order of events of symptoms. A mnemonic PQRST is sometimes helpful in obtaining the history:
- Provocative-palliative factors - what makes a symptom worse or better.
- Quality - description of the symptom
- Region - which part of the body is affected
- Severity - what is the intensity of the symptom; using a scale of 0-10 (10 worst)
- Timing - what is the course of the symptom
- Current activity - occupation, hobbies, what the patient actually does.
- Medications - what drugs including OTCs, and home remedies, as well as herbal remedies such as St. John's Wort. Allergies are recorded.
- Past medical history (PMH/PMHx) - other medical diagnoses, past hospitalizations and operations, injuries, past infectious diseases and/or vaccinations, history of known allergies.
- Review of systems (ROS) - an outline of additional symptoms to ask which may be missed on HPI, generally following the body's main organ systems (heart, lungs, digestive tract, urinary tract, etc).
- Social history (SH) - birthplace, residences, marital history, social and economic status, habits (including diet, medications, tobacco, alcohol).
- Family history (FH) - listing of diseases in the family that may impact the patient. A family tree is sometimes used. The physical examination is the examination of the patient looking for signs of disease. The doctor uses his senses of sight, hearing, touch, and sometimes smell (taste has been made redundant by the availability of modern lab tests). Four chief methods are used: inspection, palpation, percussion, and auscultation; smelling may be useful (e.g. infection, uremia, diabetic ketoacidosis). The clinical examination involves study of:
- Vital signs include height, weight, body temperature, blood pressure, pulse, respiration rate, hemoglobin oxygen saturation
- General appearance of the patient
- Skin
- Head, eye, ear, nose, and throat (HEENT)
- Cardiovascular - heart and blood vessels
- Respiratory - lungs
- Abdomen and rectosigmoid
- Genitalia
- Spine and extremities - musculoskeletal
- Neurological and psychiatric Laboratory and imaging studies results may be obtained, if ncessary. The medical decision-making (MDM) process involves analysis and synthesis of all the above data to come up with a list of possible diagnoses (the differential diagnoses), along with an idea of what needs to be done to obtain a definitive diagnosis that would explain the patient's problem. The treatment plan may include ordering additional laboratory tests and studies, starting therapy, referral to a specialist, or watchful observation. Follow-up may be advised. This process is used by primary care providers as well as specialists. It may take only a few minutes if the problem is simple and straightforward. On the other hand, it may take weeks in a patient who has been hospitalized with multi-system problems, with involvement by several specialists. On subsequent visits, the process may be repeated in an abbreviated manner to obtain any new history, symptoms, physical findings, and lab or imaging results or specialist consultations.

Settings where medical care is delivered

See also clinic, hospital, and hospice Medicine is a diverse field and the provision of medical care is therefore provided in a variety of locations. Primary care medical services are provided by physicians or other health professionals who has first contact with a patient seeking medical treatment or care. These occur in physician's office, clinics, nursing homes, schools, home visits and other places close to patients. About 90% of medical visits can be treated by the primary care provider. These include treatment of acute and chronic illnesses, preventive care and health education for all ages and both sex. Secondary care medical services are provided by medical specialists in their offices or clinics or at local community hospitals for a patient referred by a primary care provider who first diagnosed or treated the patient. Referrals are made for those patients who required the expertise or procedures performed by specialists. These include both ambulatory care and inpatient services, emergency rooms, intensive care medicine, surgery services, physical therapy, labor and delivery, endoscopy units, diagnostic laboratory and medical imaging services, hospice centers, etc. Some primary care providers may also take care of hospitalized patients and deliver babies in a secondary care setting. Tertiary care medical services are provided by specialist hospitals or regional centers equipped with diagnostic and treatment facilities not generally available at local hospitals. These include trauma centers, burn treatment centers, advanced neonatology unit services, organ transplants, high-risk pregnancy, radiation oncology, etc. Modern medical care also depends on information - still delivered in many health care settings on paper records, but increasingly nowadays by electronic means.

Branches of medicine

Working together as an interdisciplinary team, many highly trained health professionals besides medical practitioners are involved in the delivery of modern health care. Some examples include: nurses, laboratory scientists, pharmacists, physiotherapists, speech therapists, occupational therapists, dietitians and bioengineers. The scope and sciences underpinning human medicine overlap many other fields. Dentistry and psychology, while separate disciplines from medicine, are sometimes also considered medical fields. Physician assistants, nurse practitioners and midwives treat patients and prescribe medication in many legal jurisdictions. Veterinary medicine applies similar techniques to the care of animals. Medical doctors have many specializations and subspecializations which are listed below.

Basic sciences

- Anatomy is the study of the physical structure of organisms. In contrast to macroscopic or gross anatomy, cytology and histology are concerned with microscopic structures.
- Biochemistry is the study of the chemistry taking place in living organisms, especially the structure and function of their chemical components.
- Biostatistics is the application of statistics to biological fields in the broadest sense. A knowledge of biostatistics is essential in the planning, evaluation, and interpretation of medical research. It is also fundamental to epidemiology and evidence-based medicine.
- Cytology is the microscopic study of individual cells.
- Embryology is the study of the early development of organisms.
- Epidemiology is the study of the demographics of disease processes, and includes, but is not limited to, the study of epidemics.
- Genetics is the study of genes, and their role in biological inheritance.
- Histology is the study of the structures of biological tissues by light microscopy, electron microscopy and immunohistochemistry.
- Immunology is the study of the immune system, which includes the innate and adaptive immune system in human, for example.
- Microbiology is the study of microorganisms, including protozoa, bacteria, fungi, and viruses.
- Neuroscience is a comprehensive term for those disciplines of science that are related to the study of the nervous system. A main focus of neuroscience is the biology and physiology of the human brain.
- Nutrition is the study of the relationship of food and drink to health and disease, especially in determining an optimal diet. Medical nutrition therapy is done by dietitians and is prescribed for diabetes, cardiovascular diseases, weight and eating disorders, allergies, malnutrition and neoplastic diseases.
- Pathology is the study of disease - the causes, course, progression and resolution thereof.
- Pharmacology is the study of drugs and their actions.
- Physiology is the study of the normal functioning of the body and the underlying regulatory mechanisms.
- Toxicology is the study of hazardous effects of drugs and poisons.

Diagnostic specialties

- Clinical laboratory sciences are the clinical diagnostic services which apply laboratory techniques to diagnosis and management of patients. In the United States these services are supervised by a Pathologist. The personnel that work in these medical laboratory departments are technically trained staff, each of whom usually hold a medical technology degree, who actually perform the tests, assays, and procedures needed for providing the specific services.
- Transfusion medicine is concerned with the transfusion of blood and blood component, including the maintenance of a "blood bank".
- Cellular pathology is concerned with diagnosis using samples from patients taken as tissues and cells using histology and cytology.
- Clinical chemistry is concerned with diagnosis by making biochemical analysis of blood, body fluids and tissues.
- Hematology is concerned with diagnosis by looking at changes in the cellular composition of the blood and bone marrow as well as the coagulation system in the blood.
- Clinical microbiology is concerned with the in vitro diagnosis of diseases caused by bacteria, viruses, fungi, and parasites.
- Clinical immunology is concerned with disorders of the immune system and related body defenses. It also deals with diagnosis of allergy.
- Radiology is concerned with imaging of the human body, e.g. by x-rays, x-ray computed tomography, ultrasonography, and nuclear magnetic resonance tomography.
- Interventional radiology is concerned with using imaging of the human body, usually from CT, ultrasound, or fluoroscopy, to do biopsies, place certain tubes, and perform intravascular procedures.
- Nuclear Medicine uses radioactive substances for in vivo and in vitro diagnosis using either imaging of the location of radioactive substances placed into a patient, or using in vitro diagnostic tests utilizing radioactive substances.

Clinical disciplines

- Anesthesiology (AE), Anaesthesia (BE), is the clinical discipline concerned with providing anesthesia. Pain medicine is often practiced by specialised anesthesiologists.
- Dermatology is concerned with the skin and its diseases.
- Emergency medicine is concerned with the diagnosis and treatment of acute or life-threatening conditions, including trauma, surgical, medical, pediatric, and psychiatric emergencies.
- General practice, Family practice, family medicine or primary care is, in many countries, the first port-of-call for patients with non-emergency medical problems. Family doctors are usually able to treat over 90% of all complaints without referring to specialists.
- Hospital medicine is the general medical care of hospitalized patients. Doctors whose primary professional focus is hospital medicine are called hospitalists.
- Internal medicine is concerned with systemic diseases of adults, i.e. those diseases that affect the body as a whole , (restrictive ,current meaning) or with all adult non-operative somatic medicine (traditional , inclusive meaning) , thus excluding pediatrics , surgery , gynaecology & obstetrics and psychiatry. There are several subdisciplines of internal medicine:
- Cardiology is concerned with the heart and cardiovascular system and their diseases.
- Critical care medicine is concerned with the therapy of patients with serious and life-threatening disease or injury. Intensive care medicine employs invasive diagnostic techniques and (temporary) replacement of organ functions by technical means. Also known as Intensive care medicine. This field is often associated with Pulmonology.
- Endocrinology is concerned with the endocrine system, i.e. endocrine glands and hormones, usually Diabetes or Thyroid diseases.
- Gastroenterology is concerned with the alimentary tract.
- Geriatrics is concerned with medical care of the elderly.
- Hematology (or haematology) is concerned with the blood and its diseases.
- Hepatology is concerned with the liver and biliary tract, and is usually a part of Gastroenterology
- Infectious diseases is concerned with the study, diagnosis and treatment of diseases caused by biological agents.
- Nephrology is concerned with diseases of the kidneys.
- Oncology is devoted to the study, diagnosis and treatment of cancer and other malignant diseases, and is often grouped with Hematology.
- Pulmonology (or chest medicine, respiratory medicine or lung medicine) is concerned with diseases of the lungs and the respiratory system.
- Rheumatology is devoted to the diagnosis and treatment of inflammatory diseases of the joints and other organ systems, such as arthritis.
- Neurology is concerned with the diagnosis and treatment of nervous system diseases.
- Obstetrics and Gynecology (often abbreviated as Ob/Gyn) are concerned respectively with childbirth and the female reproductive and associated organs. Reproductive medicine and fertility medicine are generally practiced by gynecological specialists.
- Palliative care is a relatively modern branch of clinical medicine that deals with pain and symptom relief and emotional support in patients with terminal diseases (cancer, heart failure).
- Pediatrics (or paediatrics) is devoted to the care of infants, children, and adolescents. Like internal medicine, there are many pediatric subspecialities for specific age ranges, organ systems, disease classes and sites of care delivery. Most subspecialities of adult medicine have a pediatric equivalent such as pediatric cardiology, pediatric endocrinology, pediatric gastroenterology, pediatric hematology, and pediatric oncology, pediatric ophthalmology, and neonatology.
- Physical medicine and rehabilitation (or physiatry) is concerned with functional improvement after injury, illness, or congenital abnormality.
- Preventive medicine is the branch of medicine concerned with preventing disease.
- Community health care or public health is an aspect of health services concerned with threats to the overall health of a community based on population health analysis.
- Occupational medicines principal role is the provision of health advice to organisations and individuals to ensure that the highest standards of health and safety at work can be achieved and maintained.
- Psychiatry is a branch of medicine that studies and treats mental disorders. Related non-medical fields are psychotherapy and clinical psychology. There are several subdisciplines of Psychiatry:
- Child & adolescent psychiatry focuses on the care of children and adolescents with mental/emotional/learning problems (i.e., ADHD, Autism, family conflicts).
- Geriatric psychiatry focuses on the care of elderly people with mental illnesses (i.e., dementias, post stroke cognitive changes, depression).
- Addiction psychiatry focuses on substance abuse and its treatment.
- Forensic psychiatry focuses on the interface of psychiatry and the Law.
- Radiation therapy is concerned with the therapeutic use of ionizing radiation and high energy elementary particle beams in patient treatment.
- Surgical specialties - there are many medical disciplines that employ operative treatment. Some of these are highly specialized and are often not considered subdisciplines of surgery, although their naming might suggest so.
- General surgery is traditionally defined as the specialty of surgery of the skin, endocrine glands, and abdomen (and, sometimes, the mammary glands). In some countries, it is still deemed a pre-requisite training prior to progression to training in certain sub-specialties, but lately has evolved into its own sub-specialty.
- Cardiovascular surgery is the surgical specialty that is concerned with the heart and major blood vessels of the chest.
- Neurosurgery is concerned with the operative treatment of diseases of the nervous system.
- Maxillofacial surgery (technically a subspeciality of dentistry)
- Ophthalmology deals with the diseases of the eyes and their treatment.
- Orthopedic surgery consists on surgery of the locomotor system.
- Otolaryngology (or otorhinolaryngology or ENT/ear-nose-throat) is concerned with treatment of ear, nose and throat disorders. The term head and neck surgery defines a closely related specialty which is concerned mainly with the surgical management of cancer of the same anatomical structures.
- Pediatric surgery treats a wide variety of thoracic and abdominal (and sometimes urologic) diseases of childhood.
- Plastic surgery includes aesthetic surgery (operations that are done for other than medical purposes) as well as reconstructive surgery (operations to restore function and/or appearance after traumatic or operative mutilation).
- Surgical oncology is concerned with curative and palliative surgical approaches to cancer treatment.
- Urology focuses on the urinary tracts of males and females, and on the male reproductive system. It is often practiced together with andrology ("men's health").
- Vascular surgery is surgery of "peripheral" blood vessels, i.e. those outside of the chest (usually operated on by cardiovascular surgeons) and of the central nervous system (treated by neurosurgery).
- Urgent Care focuses on delivery of unscheduled, walk-in care outside of the hospital emergency department for injuries and illnesses that are not severe enough to require care in an emergency department.
Interdisciplinary fields
Interdisciplinary sub-specialties of medicine are:
- Aerospace medicine deals with medical problems related to flying and space travel.
- Bioethics is a field of study which concerns the relationship between biology, science, medicine and ethics, philosophy and theology.
- Clinical pharmacology is concerned with how systems of therapeutics interact with patients.
- Conservation medicine studies the relationship between human and animal health, and environmental conditions. Also known as ecological medicine, environmental medicine, or medical geology.
- Diving medicine (or hyperbaric medicine) is the prevention and treatment of diving-related problems.
- Evolutionary medicine is a perspective on medicine derived through applying evolutionary theory.
- Forensic medicine deals with medical questions in legal context, such as determination of the time and cause of death.
- Medical humanities includes the humanities (literature, philosophy, ethics, history and religion), social science (anthropology, cultural studies, psychology, sociology), and the arts (literature, theater, film, and visual arts) and their application to medical education and practice.
- Medical informatics and medical computer science are relatively recent fields that deal with the application of computers and information technology to medicine.
- Nosology is the classification of diseases for various purposes.
- Sports medicine deals with the treatment and preventive care of athletics, amateur and professional. The team includes specialty physicians and surgeons, athletic trainers, physical therapists, coaches, other personnel, and, of course, the athlete.
- Therapeutics is the field, more commonly referenced in earlier periods of history, of the various remedies that can be used to treat disease and promote health [http://2.1911encyclopedia.org/T/TH/THERAPEUTICS.htm] [http://www.britannica.com/eb/article-9106176?query=Therapeutics&ct=].
- Travel medicine or emporiatrics deals with health problems of international travelers or travelers across highly different evironments.
Medical education
See also Medical doctor (BE), Physician (AE), and Medical school. Medical training involves several years of university study followed by several more years of residential practice at a hospital. Entry to a medical degree in some countries (such as the United States) requires the completion of another degree first, while in other countries (such as the United Kingdom, Australia and New Zealand) medical training can be commenced as an undergraduate degree immediately after secondary education. The name of the medical degree gained at the end varies: some countries (e.g. the US) call it "Doctor of Medicine" (abbreviated 'M.D.'), while other countries (mostly following the British Oxbridge system) call it "Medicinæ Baccalaureus & Baccalaureus Chirurgiæ" (Latin for "Bachelor of Medicine/Bachelor of Surgery", Old English: "Chirurgie"); this is technically a double degree, frequently abbreviated 'MB BChir', 'MB ChB', 'MB BS' (or variations thereof), dependent on the medical school. In either case, graduates of a medical degree may call themselves physician. In the US and some other countries there is a parallel system of medicine which is equal in all aspects of education, legality, and practice to M.D.'s. It is called osteopathic medicine (generic term: "osteopathy") which awards the degree of "Doctor of Osteopathic Medicine" (abbreviated 'D.O.'). In many countries, a doctorate of medicine does not involve original research as does, in distinction, a Ph.D.. Once graduated from medical school most physicians (both M.D.'s and D.O.'s) begin their residency/house post training, where skills in a speciality of medicine are learned, supervised by more experienced doctors. The first year of residency is known as the "intern" year (USA) or "junior/pre-registration house officer" year (UK). The duration of residency training depends on the speciality. A medical graduate can then enter general practice and become a general practitioner (or primary care internist in the USA); training for these is generally shorter, while specialist training is typically longer. Medical education is a never ending endeavor. In addition to continually reading relevant medical journals, physicians require a number of continuing medical education (CME)credits annually to be recertified. These can be acquired by attending conferences, lectures, online, and through other sources.
Medical devices
See also the main articles: implant, artificial limbs, corrective lenses, cochlear implants, ocular prosthetics, facial prosthetics, somato prosthetics, surgical prosthetics, maxillo-facial prosthetics and dental implants Medical devices are devices used by health professionals as tools in diagnosis, treatment, or other aspects of patient care.
Legal restrictions
In most countries, it is a legal requirement for medical doctors to be licensed or registered. In general, this entails a medical degree from a university and accreditation by a medical board or an equivalent national organization, which may ask the applicant to pass exams. This restricts the considerable legal authority of the medical profession to doctors that are trained and qualified by national standards. It is also intended as an assurance to patients and as a safeguard against charlatans that practice inadequate medicine for personal gain. While the laws generally require medical doctors to be trained in "evidence based", Western, or Hippocratic Medicine, they are not intended to discourage different paradigms of health and healing, such as alternative medicine or faith healing.
Criticism
Criticism of medicine has a long history. In the Middle Ages, it was not considered a profession suitable for Christians, as disease was considered Godsent, and interfering with the process a form of blasphemy. Barber-surgeons generally had a bad reputation that was not to improve until the development of academic surgery as a speciality of medicine, rather than an accessory field. Through the course of the twentieth century, doctors focused increasingly on the technology that was enabling them to make dramatic improvements in patients' health. The ensuing development of a more mechanistic, detached practice, with the perception of an attendent loss of patient-focused care led to further criticisms. This issue started to reach collective professional consciousness in the 1970s and the profession had begun to respond by the 1980s and 1990s. Perhaps the most devastating criticism of modern medicine came from Ivan Illich, in his 1976 work Medical Nemesis. In his view, modern medicine only medicalises disease, causing loss of health and wellness, while generally failing to restore health by eliminating disease. The human being thus becomes a lifelong patient. Other less radical philosophers have voiced similar views, but none were as virulent as Illich. (Another example can be found in Technopoly: The Surrender of Culture to Technology by Neil Postman, 1992, which criticises overreliance on technological means in medicine.) Criticism of modern medicine has led to some improvements in the curricula of medical schools, which now teach students systematically on medical ethics, holistic approaches to medicine, the biopsychosocial model and similar concepts. The inability of modern medicine to properly address many common complaints continues to prompt many people to seek support from alternative medicine. Although most alternative approaches lack scientific validation, some report improvement of symptoms after obtaining alternative therapies. The bioscience medical paradigm and the alternative / complementary healthcare paradigms may differ to such an extent that what constitutes scientific evidence is contested. Many medical doctors also practice alternative medicine alongside the orthodox. Medical errors are also the focus of many complaints and negative coverage. Practitioners of human factors engineering believe that there is much that medicine may usefully gain by emulating concepts in aviation safety, where it was long ago realized that it is dangerous to place too much responsibility on one "superhuman" individual and expect him or her not to make errors. Reporting systems and checking mechanisms are becoming more common in identifying sources of error and improving practice. Radical critics of certain medical traditions may hold that whole fields or traditions of medicine are intrinsically harmful or ineffective. They would reject any use or support of practices belonging to that tradition. However, generally, there is spectrum of efficacy on which all traditions lie; some are more effective, some are less effective, but nearly all contain some harmful practices and some effective ones. Naturally, though, most individuals or groups seeking a healthcare practice to improve their own health would seek a tradition with the maximum degree of efficacy.
See also

- Academic conference
- Big killers
- Complementary and alternative medicine
- Health profession
- Healthcare system
- Iatrogenesis (ill health caused by medical treatment)
- List of diseases
- List of medical abbreviations
- List of medical schools
- Important publications in medicine
- Medical equipment
- Rare diseases
External links

- [http://home.planet.nl/~hend2438/MOTW/index.htm Medicine on the Web]
- [http://www.nlm.nih.gov NLM] (National Library of Medicine, contains resources for patients and healthcare professionals)
- [http://www.vh.org Virtual Hospital] (digital health sciences library by the University of Iowa)
- [http://cancerweb.ncl.ac.uk/omd/index.html Online Medical Information]- medical news, links and resources.
- [http://www.medmark.org Online Medical Directory]
- [http://www.wikimd.org/index.php?title=Free_Medical_Resources Collection of links to free medical resources] fiu-vro:Arstitiidüs als:Medizin zh-min-nan:I-ha̍k ko:의학 ja:医学 simple:Medicine th:แพทยศาสตร์

Human

Humans or human beings define themselves in biological, social, and spiritual terms. Biologically, humans are classified as the species Homo sapiens (Latin for "wise man" or "thinking man"): a bipedal primate of the superfamily Hominoidea, together with the other apes: chimpanzees, gorillas, orangutans, and gibbons. Humans have an erect body carriage that frees their upper limbs for manipulating objects and a highly developed brain capable of abstract reasoning, speech, language, and introspection. Bipedal locomotion appears to have evolved before the development of a large brain. The origins of bipedal locomotion and of its role in the evolution of the human brain are topics of ongoing research. The human mind has several distinct attributes. It is responsible for complex behaviour, especially language. Curiosity and observation have led to a variety of explanations for consciousness and the relation between mind and body. Psychology attempts to study behaviour from a scientific point of view. Religious perspectives emphasise a soul, qi or atman as the essence of being, and are often characterised by the belief in and worship of God, gods, spirits, or other people. Philosophy, especially philosophy of mind, attempts to fathom the depths of each of these perspectives. Art, music and literature are often used in expressing these concepts and feelings. Like all primates, humans are inherently social. They create complex social structures composed of co-operating and competing groups. These range from nations and states down to families. Seeking to understand and manipulate the world around them has led to the development of technology and science. Artifacts, beliefs, myths, rituals, values, and social norms have all helped to form humanity's culture.

Terminology

In general, the word "people" is a collective or plural term for any specific group of individual persons. However, when used to refer to a group of humans possessing a common ethnic, cultural or national unitary characteristic or identity, "people" is a singular count noun, and as such takes an "s" in the plural (examples: "the English-speaking peoples of the world", "the indigenous peoples of Brazil"). ethnic Juvenile males are called boys, adult males men, juvenile females girls, and adult females women. Humans are commonly referred to as persons or people, and collectively as Man (capital M), mankind, humankind, humanity, or the human race. Until the 20th century, "human" was only used adjectivally ("pertaining to mankind"). Nominal use of "human" (plural "humans") is short for "human being", and not considered good style in traditional English grammar. As an adjective, "human" is used neutrally (as in "human race"), but "human" and especially "humane" may also emphasise positive aspects of human nature, and can be synonymous with "benevolent" (versus "inhumane"; cf. humanitarian). A distinction is maintained in philosophy and law between the notions "human being", or "man", and "person". The former refers to the species, while the latter refers to a rational agent (see, for example, John Locke's Essay concerning Human Understanding II 27 and Immanuel Kant's Introduction to the Metaphysic of Morals). The term "person" is thus used of non-human animals, and could be used of a mythical being, an artificial intelligence, or an extraterrestrial. An important question in theology and the philosophy of religion concerns whether God is a person. In Latin, "humanus" is the adjectival form of the noun "homo", translated as "man" (to include males and females). The Old English word "man" could also have this generic meaning, as demonstrated by such compounds as "wifman" ("female person") → "wiman" → "woman". For the etymology of "man" see mannaz.

Biology

Anatomy and physiology

mannaz] Humans exhibit fully bipedal locomotion. This leaves the forelimbs available for manipulating objects using opposable thumbs. Humans vary substantially around the mean height and mean weight. Some of this variation is explained by locality and historical factors. Although body size is largely determined by genes, it is also significantly influenced by diet and exercise. The mean height of a North American adult female is 162 centimetres (5 feet 4 inches) and the mean weight is 62 kilograms (137 pounds). North American adult males are typically larger: 175 centimetres (5 feet 9 inches) and 78 kilograms (172 pounds). Human skin appears to be relatively hairless in comparison to other primates; however, most humans have a larger number of hairs on their body than a chimpanzee. The main difference is that human hairs are shorter, finer, and less coloured then the average chimpanzee's, thus rendering them harder to see. The colour of human hair and skin is determined by the presence of coloured pigments called melanins. Most researchers believe that skin darkening was an adaptation that evolved as a defence against UV solar radiation; melanin is an effective sunblock. The skin colour of contemporary humans can range from very dark brown to very pale pink. It is geographically stratified and in general correlates with the environmental level of UV. Human skin and hair colour is controlled in part by the MC1R gene. For example, the red hair and pale skin of some Europeans is the result of mutations in MC1R. Human skin has a capacity to darken (sun tanning) in response to UV exposure. Variation in the ability to sun tan is also controlled in part by MC1R. sun tanning] Because humans are bipedal, the pelvic region and spinal column tend to become worn, creating locomotion difficulties in old age. The individual need for regular intake of food and drink is prominently reflected in human culture, and has led to the development of food science. Failure to obtain food leads to hunger and eventually starvation, while failure to obtain water leads to dehydration and thirst. Both starvation and dehydration cause death if not alleviated. In modern times, obesity amongst humans has increased to almost epidemic proportions, leading to health complications and increased mortality in some developed countries, and is becoming problematic elsewhere. The average sleep requirement is between seven and eight hours a day for an adult and nine to ten hours for a child. Elderly people usually sleep for six to seven hours. It is common, however, in modern societies for people to get less sleep than they need, leading to a state of sleep deprivation. The human body is subject to an ageing process and to illness. Medicine is the science that explores methods of preserving bodily health.

Life cycle

health] The human life cycle is similar to that of other placental mammals. New human life develops from conception. An egg is usually fertilised inside the female by sperm from the male through sexual intercourse, though in vitro fertilisation methods are also used. The fertilised egg is called a zygote. The zygote divides inside the female's uterus to become an embryo which over a period of thirty-eight weeks becomes the fetus. At birth, the fully grown fetus is expelled from the female's body and breathes independently as a baby for the first time. At this point, most modern cultures recognise the baby as a person entitled to the full protection of the law, though some jurisdictions extend personhood to human fetuses while they remain in the uterus. Compared with that of other species, human childbirth is relatively complicated. Painful labours lasting twenty-four hours or more are not uncommon, and may result in injury to the child or the death of the mother, although the chances of a successful labour increased significantly during the twentieth century in wealthier countries. Natural childbirth remains an arguably more dangerous ordeal in remote, underdeveloped regions of the world, though the women who live in these regions have argued that their natural childbirth methods are safer and less traumatic for mother and child. Natural childbirth Human children are born after a nine-month gestation period, with typically 3–4 kilograms (6–9 pounds) in weight and 50–60 centimetres (20–24 inches) in height in developed countries. [http://www.childinfo.org/eddb/lbw] Helpless at birth, they continue to grow for some years, typically reaching sexual maturity at twelve to fifteen years of age. Boys continue growing for some time after this, reaching their maximum height around the age of eighteen. These values vary too, depending on genes and environment. The human lifespan can be split into a number of stages: infancy, childhood, adolescence, young adulthood, maturity and old age, though the lengths of these stages, especially the later ones, are not fixed. There are striking differences in life expectancy around the world. The developed world is quickly getting older, with the median age around 40 years (highest in Monaco at 45.1 years), while in the developing world, the median age is 15–20 years (the lowest in Uganda at 14.8 years). Life expectancy at birth is 77.2 years in the U.S. as of 2001. [http://www.cdc.gov/nchs/fastats/lifexpec.htm] The expected life span at birth in Singapore is 84.29 years for a female and 78.96 years for a male, while in Botswana, due largely to AIDS, it is 30.99 years for a male and 30.53 years for a female. One in five Europeans, but one in twenty Africans, is 60 years or older, according to The World Factbook. [http://www.cia.gov/cia/publications/factbook] African.]] The number of centenarians in the world was estimated by the United Nations [http://www.un.org/ageing/note5713.doc.htm] at 210,000 in 2002. The maximum life span for humans is thought to be over 120 years. Worldwide, there are 81 men aged 60 or over for every 100 women, and among the oldest, there are 53 men for every 100 women. The philosophical questions of when human personhood begins and whether it persists after death are the subject of considerable debate. The prospect of death may cause unease or fear. People who are near death sometimes have a near-death experience, in which they have visions. Burial ceremonies are characteristic of human societies, often inspired by beliefs in an afterlife. Institutions of inheritance or ancestor worship may extend an individual's presence beyond his physical lifespan (see immortality).

Genetics

Humans are a eukaryotic species. Each diploid cell has two sets of 23 chromosomes, each set received from one parent. There are 22 pairs of autosomes and one pair of sex chromosomes. At present estimate, humans have approximately 20,000–25,000 genes and share 95% of their DNA with their closest living evolutionary relatives, the two species of chimpanzees. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12368483] Like other mammals, humans have an XY sex determination system, so that females have the sex chromosomes XX and males have XY. The X chromosome is larger and carries many genes not on the Y chromosome, which means that recessive diseases associated with X-linked genes affect men more often than women. For example, genes that control the clotting of blood reside on the X chromosome. Women have a blood-clotting gene on each X chromosome so that one normal blood-clotting gene can compensate for a flaw in the gene on the other X chromosome. But men are hemizygous for the blood-clotting gene, since there is no gene on the Y chromosome to control blood clotting. As a result, men will suffer from haemophilia more often than women.

Race and ethnicity

haemophilia, Black, White (Hispanic), and Asian. Top row males, bottom row females.]] Humans often categorise themselves and others in terms of race or ethnicity. In the United States, racial categories are primarily based on language and ethnicity, although biological qualities, such as skin colour, blood type, facial features, ancestry, and other genetic variances are also key factors. Self identification with an ethnic group is usually based on kinship and descent, as well as presumed advantage. When race and ethnicity lead to variant treatment it is thought to impact social identity, giving rise to the theory of identity politics. Although most humans recognise that variances occur within a species, it is often a point of dispute as to what these differences entail, and if discrimination based on race (racism) is acceptable in the early twenty-first century. Race and intelligence, scientific racism, xenophobia and ethnocentrism are just a few of the many basis' for such practices.

Habitat

The view most widely accepted by the anthropological community is that the human species originated in the African savanna between 100 and 200 thousand years BCE, colonised the rest of the Old World and Oceania by 40,000 years BCE, and finally colonised the Americas by 10,000 years BCE. Homo sapiens displaced groups such as Neanderthals and Homo floresiensis through more successful reproduction and competition for resources, and/or extermination. (See Human evolution, Vagina gentium, and Environment of Evolutionary Adaptedness.) Technology has allowed humans to colonise all of the continents and adapt to all climates. Within the last few decades, humans have been able to explore Antarctica, the ocean depths, and space, although long-term habitation of these environments are not yet possible. Humans, with a population of about six thousand million, are one of the most numerous mammals on Earth. Most humans (61%) live in the Asian region. The vast majority of the remainder live in the Americas (14%), Africa (13%) and Europe (12%), with 5% in Oceania. (See list of countries by population and list of countries by population density.) list of countries by population density (The arctic is at the centre of the map and the numbers are millennia before present).]] The original human lifestyle is hunting-gathering, which is adapted to the savanna. Other human lifestyles are nomadism (often linked to animal herding) and permanent settlements made possible by the development of agriculture. Humans have a great capacity for altering their habitats by various methods, such as agriculture, irrigation, urban planning, construction, transport, and manufacturing goods. Permanent human settlements are dependent on proximity to water and, depending on the lifestyle, other natural resources such as fertile land for growing crops and grazing livestock, or seasonally by populations of prey. With the advent of large-scale trade and transport infrastructure, immediate proximity to these resources has become unnecessary, and in many places these factors are no longer the driving force behind growth and decline of population. Human habitation within closed ecological systems in hostile environments (Antarctica, outer space) is expensive, typically limited in duration, and restricted to scientific, military, or industrial expeditions. Life in space has been very sporadic, with a maximum of thirteen humans in space at any given time, starting with Yuri Gagarin's space flight in 1961. Between 1969 and 1974, up to two humans at a time spent brief intervals on the Moon. As of 2005, no other celestial body has been visited by human beings, although there has been a continuous human presence in space since the launch of the initial crew to inhabit the International Space Station on October 31, 2000.

Population

2000 From 1800 to 2000, the human population increased from one to six billion. It is expected to crest at around ten billion during the 21st century. In 2004, around 2.5 billion out of 6.3 billion people lived in urban centres, and this is expected to rise during the 21st century. Problems for humans living in cities include various forms of pollution, crime, and poverty, especially in inner city and suburban slums. Geneticists Lynn Jorde and Henry Harpending of the University of Utah have concluded that the variation in the total stock of human DNA is minute compared to that of other species; and that around 74,000 years ago, human population was reduced to a small number of breeding pairs, possibly as small as 1000, resulting in a very small residual gene pool. Various reasons for this bottleneck have been postulated, the most popular, called the Toba catastrophe theory, being the eruption of a volcano at Lake Toba.

Human evolution

The study of human evolution encompasses many scientific disciplines, but most notably physical anthropology and genetics. The term "human", in the context of human evolution, refers to the genus Homo, but studies of human evolution usually include other hominids and hominines, such as the australopithecines. Biologically, humans are defined as hominids of the species Homo sapiens, of which the only extant subspecies is Homo sapiens sapiens (Latin for "very wise man"); Homo sapiens idaltu (roughly translated as "elderly wise man") is the extinct subspecies. Modern humans are usually considered the only surviving species in the genus Homo, although some argue that the two species of chimpanzees should be reclassified from Pan troglodytes (Common Chimpanzee) and Pan paniscus (Bonobo/Pygmy Chimpanzee) to Homo troglodytes and Homo paniscus respectively, given that they share a recent ancestor with man. [http://news.nationalgeographic.com/news/2003/05/0520_030520_chimpanzees.html] Full genome sequencing resulted in these conclusions: "After 6 [million] years of separate evolution, the differences between chimp and human are just 10 times greater than those between two unrelated people and 10 times less than those between rats and mice." [http://news.ft.com/cms/s/43445728-1a44-11da-b279-00000e2511c8.html Chimp and human DNA is 96% identical] It has been estimated that the human lineage diverged from that of chimpanzees about five million years ago, and from gorillas about eight million years ago. However, in 2001 a hominine skull approximately seven million years old, classified as Sahelanthropus tchadensis, was discovered in Chad and seems to indicate an earlier divergence. Two prominent scientific theories of the origins of contemporary humans exist. They concern the relationship between modern humans and other hominids: The single-origin or "out of Africa" hypothesis proposes that modern humans evolved in Africa and later replaced hominids in other parts of the world. The multiregional hypothesis proposes that modern humans evolved at least in part from independent hominid populations. Human evolution is characterised by a number of important physiological trends:
- expansion of the brain cavity and brain itself, which is typically 1,400 cm³ in volume, over twice that of a chimpanzee or gorilla. The pattern of human postnatal brain growth differs from that of other apes (heterochrony), allowing for an extended period of social learning in juvenile humans. Physical anthropologists argue that a reorganisation of the structure of the brain is more important than cranial expansion itself;
- canine tooth reduction;
- bipedal locomotion;
- descent of the larynx, which makes speech possible. Humans are classified as Homo sapiens sapiens. A camp of physical anthropologists see neanderthalensis as a subspecies and classify the neanderthals as Homo sapiens neanderthalensis. A second camp of physical anthropologists see the neanderthals as a distinct species diverging from the modern human lineage over 500,000 years ago. Under this classification, neaderthals are Homo neanderthalensis. Recent DNA analysis suggests that neanderthalensis were not a subspecies. How these trends are related and what their role is in the evolution of complex social organisation and culture are matters of ongoing debate. larynx]]

Intelligence

Most humans consider their species to be the most intelligent in the animal kingdom. Certainly, humans are the only technologically advanced animal. Along with the brain's internal complexity, the brain to body mass ratio is generally assumed to be a good indicator of relative intelligence. Humans have the second highest ratio, with the tree shrew having the highest [http://www.hindustantimes.com/news/181_935198,00300006.htm], and the bottlenose dolphin very similar to humans. The human ability to abstract may be unparalleled in the animal kingdom. Human beings are one of five species to pass the mirror test — which tests whether an animal recognises its reflection as an image of itself — along with chimpanzees or bonobos, orangutans, and dolphins. Human beings under the age of four usually fail the test.

Culture

dolphin]] Culture is defined here as a set of distinctive material, intellectual, emotional, and spiritual features of a social group, including art, literature, lifestyles, value systems, traditions, rituals, and beliefs. Culture consists of at least three elements: values, social norms, and artifacts. A culture's values define what it holds to be important. Norms are expectations of how people ought to behave. Artifacts — things, or material culture — derive from the culture's values and norms together with its understanding of the way the world functions.

Origins

Essentially every culture has its characteristic origin beliefs. Creationism or creation theology is the belief that humans, the Earth, the universe and the multiverse were created by a supreme being or deity. The event itself may be seen either as an act of creation (ex nihilo) or the emergence of order from preexisting chaos (demiurge). Many who hold "creation" beliefs consider such belief to be a part of religious faith, and hence compatible with, or otherwise unaffected by scientific views while others maintain the scientific data is compatible with creationism. Proponents of evolutionary creationism may claim that understood scientific mechanisms are simply aspects of supreme creation. Otherwise, science-oriented believers may consider the scriptural account of creation as simply a metaphor.

Language

metaphor, Chinese, Korean, Hebrew and Greek]] Values, norms and technology are dependent on the capacity for humans to share ideas. The faculty of speech may be a defining feature of humanity, probably predating phylogenetic separation of the modern population. (See Proto-World language, Origins of language.) Language is central to the communication between humans. Some scientists argue that non-human animals are able to use some form of language too, and that non-human primates are able to learn human sign language [http://www.mnsu.edu/emuseum/cultural/language/chimpanzee.html] [http://www.msubillings.edu/asc/PDF-WritingLab/3-Minute%20Spr05/APA%20sample%20paper.pdf] (pdf). Language is central to the sense of identity that unites cultures and ethnicities. The invention of writing systems some 5000 years ago, allowing the preservation of speech, was a major step in cultural evolution. Language, especially written language, is sometimes thought to have supernatural status or powers. (See Magic, Mantra, Vac.) The science of linguistics describes the structure of language and the relationship between languages. There are estimated to be some 6,000 different languages, including sign languages, used today.

Music

Music is a natural intuitive phenomenon operating in the three worlds of time, pitch, and energy, and under the three distinct and interrelated organisation structures of rhythm, harmony, and melody. Composing, improvising and performing music are all art forms. Listening to music is perhaps the most common form of entertainment, while learning and understanding it are popular disciplines. There are a wide variety of music genres and ethnic musics.

Emotion and sexuality

Human emotion has a significant influence on, or can even be said to control, human behaviour. Emotional experiences perceived as pleasant, like love, admiration, or joy, contrast with those perceived as unpleasant, like hate, envy, or sorrow. There is often a distinction seen between refined emotions, which are socially learned, and survival oriented emotions, which are thought to be innate. Human exploration of emotions as separate from other neurological phenomena is worth note, particularly in those cultures were emotion is considered separate from physiological state. In some cultural medical theories, to provide an example, emotion is considered so synonymous with certain forms of physical health that no difference is thought to exist. The Stoics believed excessive emotion was harmful, while some Sufi teachers (in particular, the poet and astronomer Omar Khayyám) felt certain extreme emotions could yield a conceptual perfection, what is often translated as ecstasy. ecstasy"]] In modern scientific thought, certain refined emotions are considered to be a complex neural trait of many domesticated and a few non-domesticated mammals, developed commonly in reaction to superior survival mechanisms and intelligent interaction with each other and the environment; as such, refined emotion is not in all cases as discrete and separate from natural neural function as was once assumed. Still, when humans function in civilised tandem, it has been noted that uninhibited acting on extreme emotion can lead to social disorder and crime. Human sexuality, besides ensuring reproduction, has important social functions, creating physical intimacy, bonds and hierarchies among individuals, and that may be directed to spiritual transcendence, and/or to the enjoyment of activity involving sexual gratification. Sexual desire, libido, is experienced as a bodily urge, often accompanied by strong emotions, both positive (such as love or ecstasy) and negative (such as jealousy). As with other human self-descriptions, humans propose it is high intelligence and complex societies of humans that have produced the most complex sexual behaviors of any animal. Human sexual choices are usually made in reference to cultural norms, which vary widely. Restrictions are largely determined by religious beliefs.

Body image

norms, Japan]]The physical appearance of the human body is central to culture and art. In every human culture, people adorn their bodies with tattoos, cosmetics, clothing, and jewellery. Hairstyles and hair colour also have important cultural implications. The perception of an individual as physically beautiful or ugly can have profound implications for their lives. This is particularly true of women, whose external appearance is highly valued in most, if not all, human societies. Anthropologists believe this to be an important factor in the development of personality and social relations in particular physical attractiveness. There is a relatively low sexual dimorphism between human males and females in comparison with other mammals.

Trade and economics

sexual dimorphism.]] Trade is the voluntary exchange of goods, services, or both, and a form of economics. A mechanism that allows trade is called a market. The original form of trade was barter, the direct exchange of goods and services. Modern traders instead generally negotiate through a medium of exchange, such as money. As a result, buying can be separated from selling, or earning. The invention of money (and later credit, paper money and non-physical money) greatly simplified and promoted trade. Trade exists for many reasons. Due to specialisation and division of labor, most people concentrate on a small aspect of manufacturing or service, trading their labour for products. Trade exists between regions because different regions have an absolute or comparative advantage in the production of some tradable commodity, or because different regions' size allows for the benefits of mass production. As such, trade between locations benefits both locations. Economics is a social science that studies the production, distribution, trade and consumption of goods and services. Economics, which focuses on measurable variables, is broadly divided into two main branches: microeconomics, which deals with individual agents, such as households and businesses, and macroeconomics, which considers the economy as a whole, in which case it considers aggregate supply and demand for money, capital and commodities. Aspects receiving particular attention in economics are resource allocation, production, distribution, trade, and competition. Economic logic is increasingly applied to any problem that involves choice under scarcity or determining economic value. Mainstream economics focuses on how prices reflect supply and demand, and uses equations to predict consequences of decisions.

Artifacts, technology, and science

supply and demand.]] Human cultures are both characterised and differentiated by the objects that they make and use. Archaeology attempts to tell the story of past or lost cultures in part by close examination of the artifacts they produced. Early humans left stone tools, pottery and jewellery that are particular to various regions and times. Improvements in technology are passed from one culture to another. For instance, the cultivation of crops arose in several different locations, but quickly spread to be an almost ubiquitous feature of human life. Similarly, advances in weapons, architecture and metallurgy are quickly disseminated. Such techniques can be passed on by oral tradition. The development of writing, itself a type of artifact, made it possible to pass information from generation to generation and from region to region with greater accuracy. Together, these developments made possible the commencement of civilisation and urbanisation, with their inherently complex social arrangements. Eventually this led to the institutionalisation of the development of new technology, and the associated understanding of the way the world functions. This science now forms a central part of human culture. In recent times, physics and astrophysics have come to play a central role in shaping what is now known as physical cosmology, that is, the understanding of the universe through scientific observation and experiment. This discipline, which focuses on the universe as it exists on the largest scales and at the earliest times, begins by arguing for the big bang, a sort of cosmic explosion from which the universe itself is said to have erupted ~13.7 ± 0.2 billion (10⁹) years ago. After its violent beginnings and until its very end, scientists then propose that the entire history of the universe has been an orderly progression governed by physical laws.

Mind

physical laws Consciousness is a state of mind, said to possess qualities such as, self-awareness, sentience, sapience, and the ability to perceive the relationship between oneself and one's environment. The way in which the world is experienced is the subject of much debate and research in philosophy of mind, psychology, brain biology, neurology, and cognitive science. Humans (and often others as well) are variously said to possess consciousness, self-awareness, and a mind, the fruition of being our senses and perceptions. Each of us has a subjective view of existence, the passage of time, and free will. There are many debates about the extent to which the mind constructs or experiences the outer world, and regarding the definitions and validity of many of the terms used above. Cognitive scientist Daniel Dennett, for example, argues that there is no such thing as a narrative centre called mind, but that instead there is simply a collection of sensory inputs and outputs: different kinds of software running in parallel (Dennett, 1991).

Psychology and human ethology

Psychology (Classical Greek: psyche = "soul" or "mind", logos = "study of") is the study of behaviour, mind and thought and the neurological basis for them. Psychoanalysis, the examination of the subconscious was, devised by Sigmund Freud and expanded and refined by the Swiss psychiatrist Carl Gustav Jung (initially one of Freud's followers and friends) and others. Carl Gustav Jung Freud divided the mind into the id (an individual's basic needs and instincts), the superego (personal and cultural values and norms), and the ego (the central, organising self, whose job it is to satisfy the id but not upset the superego). [http://allpsych.com/psychology101/ego.html] C. G. Jung founded the school of analytical psychology and introduced the notion of the collective unconscious, a term taken from philosophy and used by Jung to describe symbols or archetypes that he believed might be common to all cultures. There are also the Conscious, Subconscious, and Superconsciousness, a related but not identical set of categories. The behaviour and mental processes of animals (human and non-human) can be described through animal cognition, ethology, and comparative psychology as well. Human ecology is an academic discipline that investigates how humans and human societies interact with their environment, nature and the human social environment.