Complex adaptive system in the context of "Complex system"

Societal collapse (also known as civilizational collapse or systems collapse) is the fall of a complex human society characterized by the loss of cultural identity and of social complexity as an adaptive system, the downfall of government, and the rise of violence. Possible causes of a societal collapse include natural catastrophe, war, pestilence, famine, economic collapse, population decline or overshoot, mass migration, incompetent leaders, and sabotage by rival civilizations. A collapsed society may revert to a more primitive state, be absorbed into a stronger society, or completely disappear.

Virtually all civilizations have suffered such a fate, regardless of their size or complexity. Most never recovered, such as the Western and Eastern Roman Empires, the Maya civilization, and the Easter Island civilization. However, some of them later revived and transformed, such as China, Greece, and Egypt.

In sociology, social complexity is a conceptual framework used in the analysis of society. In the sciences, contemporary definitions of complexity are found in systems theory, wherein the phenomenon being studied has many parts and many possible arrangements of the parts; simultaneously, what is complex and what is simple are relative and change in time.

Contemporary usage of the term complexity specifically refers to sociologic theories of society as a complex adaptive system, however, social complexity and its emergent properties are recurring subjects throughout the historical development of social philosophy and the study of social change.

In excitotoxicity, nerve cells suffer damage or death when the levels of otherwise necessary and safe neurotransmitters such as glutamate become pathologically high, resulting in excessive stimulation of receptors. For example, when glutamate receptors such as NMDA receptors or AMPA receptors encounter excessive levels of the excitatory neurotransmitter, glutamate, significant neuronal damage might ensue. Different mechanisms might lead to increased extracellular glutamate concentrations, e.g. reduced uptake by glutamate transporters (EAATs), synaptic hyperactivity, or abnormal release from different neural cell types. Excess glutamate allows high levels of calcium ions (Ca) to enter the cell. Ca influx into cells activates a number of enzymes, including phospholipases, endonucleases, and proteases such as calpain. These enzymes go on to damage cell structures such as components of the cytoskeleton, membrane, and DNA. In evolved, complex adaptive systems such as biological life it must be understood that mechanisms are rarely, if ever, simplistically direct. For example, NMDA, in subtoxic amounts, can block glutamate toxicity and induce neuronal survival. In addition to abnormally high neurotransmitter concentrations, also elevation of the extracellular potassium concentration, acidification and other mechanisms may contribute to excitotoxicity.

Excitotoxicity may be involved in cancers, spinal cord injury, stroke, traumatic brain injury, hearing loss (through noise overexposure or ototoxicity), and in neurodegenerative diseases of the central nervous system such as multiple sclerosis, Alzheimer's disease, amyotrophic lateral sclerosis (ALS), Parkinson's disease, alcoholism, alcohol withdrawal or hyperammonemia and especially over-rapid benzodiazepine withdrawal, and also Huntington's disease. Other common conditions that cause excessive glutamate concentrations around neurons are hypoglycemia. Blood sugars are the primary energy source for glutamate removal from inter-synaptic spaces at the NMDA and AMPA receptor site. Persons in excitotoxic shock must never fall into hypoglycemia. Patients should be given 5% glucose (dextrose) IV drip during excitotoxic shock to avoid a dangerous build up of glutamate. When 5% glucose (dextrose) IV drip is not available high levels of fructose are given orally. Treatment is administered during the acute stages of excitotoxic shock along with glutamate receptor antagonists. Dehydration should be avoided as this also contributes to the concentrations of glutamate in the inter-synaptic cleft and "status epilepticus can also be triggered by a build up of glutamate around inter-synaptic neurons."

Collective intelligence (CI) or group intelligence (GI) is the emergent ability of groups, whether composed of humans alone, animals, or networks of humans and artificial agents, to solve problems, make decisions, or generate knowledge more effectively than individuals alone, through either cooperation or by aggregation of diverse information, perspectives, and behaviors. The term swarm intelligence (SI) is sometimes used interchangeably with collective intelligence but is simply one instance of it.

Collective intelligence encompasses not only complex adaptive systems, which self-organize and adapt in dynamic environments, but also creative and cognitive processes observed in social groups, which are often referred to as the wisdom of crowds. In this context, collective judgments, sometimes from non-experts, often exceed the accuracy of expert predictions, as illustrated by Francis Galton's famous experiment on estimating the weight of an ox. Contemporary theorists have posited that intelligence can be interpreted as an emergent collective process that manifests across various biological and social scales, including neural, organismal, and group levels.