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As social animals, humans tend to form groups that can range in size from a few individual members to entire nation-states. Historically and through the present day, human groups frequently come into conflict. A noted feature of human intergroup…

Food packaging prevents contamination and extends the shelf-life of food products, making food safe and available to the public. Common food-packaging materials include metals, glass, paper, and plastics. Of these, metals, glass, and recyclable…

Bats are members of the order Chiroptera, which is the second-largest order of living mammals. The geographic distribution of these flying mammals is tremendous as well, ranging from the limit of trees in the Northern Hemisphere to the southern tips…

Monarch butterflies (Danaus plexippus) exclusively consume milkweed plants (genus Asclepia) both for nutrition and to help deter predators. Milkweed plants contain toxins that accumulate in the butterfly larva, or caterpillars, as the insects feed;…

Genealogists and anthropologists have long disputed the provenance of domestic dogs (Canis lupus familiaris). Although genetic analyses and fossil evidence indicate that the domestic dog descended from the gray wolf (Canis lupus), the exact location…

Food waste occurs at all levels of the supply chain and beyond, from farm to table, for reasons ranging from spoilage to over-buying. The U.S. Department of Agriculture’s (USDA) Economic Research Service defines food waste as “the edible amount of…

Approximately 75% of flowering plants—including about a third of agricultural food crops—depend on the distribution of pollen by an array of animals known collectively as pollinators. These animals include insects such as bees and wasps…

The Antarctic ice sheet is the largest remnant of previous ice-age glaciations. Glaciers flow out from this ice sheet and feed into floating ice shelves along one-third of the Antarctic coastline. One of the largest ice shelves is the Filchner-Ronne…

Pasta comes in various sizes and shapes, ranging from long and flat (such as linguine and spaghetti) to short types in the shape of shells (conchiglie), corkscrews (fusilli), and many others. Shaped pastas contain a larger volume of air, resulting…

The Hudson River estuary in the United States experiences a tide from New York Harbor (river kilometer 0/river mile 0) to Troy, New York (river kilometer 244/river mile 152). In the lower 60 kilometers (37 miles) of the Hudson River, the water is…

The spotted hyena (Crocuta crocuta)—one of three species of hyenas found in Africa—is a highly social mammal that lives in large groups, or clans, containing at least 90 individuals. The social organization of spotted hyenas is more complex than the…

In the future, will global demand for coffee outstrip supply? The International Coffee Organization thinks so, based on droughts in Central America, crop-destroying freezing weather in Brazil, and global climate change. In general, coffee is a very…

The American bald eagle (Haliaeetus leucocephalus) was once on the brink of extinction in North America. As a result of concerted conservation efforts, including the elimination of use of the pesticide DDT in the United States in 1972, the bald…

Peatlands, also known as bogs and fens, are a type of wetland in which, over the course of hundreds to thousands of years, vegetation—mosses, sedges, trees, and other plants—have accumulated as partially decomposed organic matter. Peat itself covers…

The fossil record of sharks (members of the subclass Elasmobranchii within the class Chondrichthyes, or cartilaginous fishes) dates back more than 420 million years. Over the course of this time, sharks have been among the top predators found in the…

An investigation of 890-million-year-old limestone rocks excavated from the mountains of Canada's Northwest Territories has revealed possible evidence of the oldest animal life on Earth. Prior to this study, the oldest undisputed fossils of animal…

There is a growing body of evidence that many of the thousands of prescription and over-the-counter medications ultimately make their way into water bodies and drinking-water supplies. Typical wastewater treatment plants may not be effective at…

Microplastics are raining down on national parks and other protected areas in the western United States at the rate of about 132 pieces of microplastic per square meter every day, according to a report in the journal Science (June 2020).…

Wildfires, also termed bushfires or forest fires, are currently devastating large swaths of land in Australia. Detrimental ecologic consequences of these uncontrolled combustions of forest fuels and vegetation are numerous. One of the most serious…

The world’s oceans and coasts provide a natural sink for excess carbon in the atmosphere. Scientists refer to carbon that is captured and stored this way as blue carbon. Well-known blue-carbon examples include mangroves and salt marshes—wetland…

Using an artificial intelligence technique known as deep learning and high-resolution remote sensing, scientists have counted and mapped the location of trees in 11,000 satellite images covering more than 1.3 million square kilometers (500,000…

The earliest representatives of modern humans—those belonging to Homo sapiens—evolved from more archaic humans approximately 150,000–300,000 years ago in eastern Africa. During succeeding years, the geographical range of anatomically modern humans…

Life on Earth has been punctuated by a number of catastrophic mass extinctions throughout history. During these events, diverse taxonomic groups collapsed from the relatively rapid and widespread extinction of large numbers of species. Precipitated…

Conservationists are alarmed by significant reductions in insect populations worldwide. Based on recent biodiversity surveys and entomological studies, scientists estimate that more than 40% of the world's insect species (class Insecta, phylum…

Of the three extant elephant species, two inhabit Africa: the African bush or savanna elephant, Loxodonta africana; and the smaller African forest elephant, L. cyclotis. The African bush elephant is the largest living land mammal and is primarily…

All of the many diverse breeds of dogs, including both domestic and wild dogs (wolves, coyotes, foxes, jackals, and dingoes), belong to the genus Canis in the mammalian family Canidae. One intriguing example of an obscure wild dog is the New Guinea…

Scientists have identified the earliest known fossil of a modern bird. The fossil remains—comprising an almost-complete skull and a few limb bones embedded in rock—were discovered in a limestone quarry in Belgium. Estimated to be approximately 66.7…

Overwhelming fossil evidence of dinosaurs indicates that these reptiles inhabited terrestrial environments and were initially bipedal (two-footed). Then, as dinosaurs evolved, some became quadrupedal, walking on four legs. Other ancient nondinosaur…

The Tasmanian devil (Sarcophilus harrisii) is the world's largest living marsupial carnivore. For tens of thousands of years, this fierce animal could be found throughout the continent of Australia, as well as inhabiting the island of Tasmania.…

Many trees in forests worldwide rely on natural fires to create growing conditions necessary to perpetuate the ecosystem, or to stimulate germination. However, for more than 100 years, humans have been suppressing frequent natural low-intensity…

Persistent changes in the Earth's climate that have been occurring primarily as a result of human-caused greenhouse-gas emissions since the mid-twentieth century have led to significant increases in infectious diseases in wildlife, both in terms of…

The Joshua tree (Yucca brevifolia) is a remarkable evergreen, treelike plant found only in the southwestern United States. It was named by Mormon settlers in the early 1800s. Upon seeing the limbs of this plant branching upwards to heaven, the…

Collectively, members of the class Amphibia are facing massive reductions in total numbers, and the overall biodiversity of amphibians across the globe is under threat. Scientists have determined that global climate change and habitat destruction…

Charles Robert Darwin (February 12, 1809 – April 19, 1882) is one of the most celebrated and eminent scientists of the past few centuries, with his broadest and most notable influence arising from his theory of evolution by means of natural…

It has been a long-held belief that, as a result of hunting habits, early humans were partly or even primarily responsible for the decline and eventual extinction of most of the largest mammalian species that inhabited ancient Africa. These large…

The critically endangered northern white rhinoceros (Ceratotherium simum cottoni) is a subspecies of white rhino that is on the brink of complete extinction, with only two individuals left in captivity and no known members reported in the wild. The…

The International Union for Conservation of Nature (IUCN)—the global authority on the status of the natural world—estimates that approximately 5–10% of the world's insect species (class Insecta, phylum Arthropoda) are threatened and facing…

At the Woranso-Mille paleontological site in northern Ethiopia, researchers have discovered a 3.8 million-year-old cranium (skull) belonging to a primitive hominin known as Australopithecus anamensis. Initially unearthed in 2016, but not reported…

All freshwater comes from precipitation over land, which is distributed on Earth as blue and green water. Blue water—that is, surface and groundwater—is stored as freshwater in lakes, streams, ice, and snow, as well as below ground. Green water is…

A report by a team of conservation biologists concludes that the total number of birds in North America has dropped precipitously since 1970. Annual surveys monitoring the biodiversity and abundance of bird populations across the North American…

Pesticides—including insecticides and herbicides—are chemical products used to control, reduce, or eliminate organisms that are harmful to cultivated plants. However, the use of pesticides on plants that provide foods for human consumption is often…

The bacteria that live in the gut (gastrointestinal tract) constitute a large part of an individual's microbiome (also known as microbiota). In general, gut bacteria, also referred to as the microbial flora of the gut, are harbored by normal,…

Psychedelic drugs, also termed hallucinogenic or psychotomimetic drugs, induce transient states of altered perception resembling or mimicking the symptoms of psychosis and are characterized by profound alterations in mood. Because psychedelic drugs…

The golden jackal (Canis aureus) is the most widely distributed jackal in the world, populating widely diverse habitats across extensive ranges. In particular, this canine predator occupies large areas of northern and eastern Africa, the Middle…

Reusable sponge-like (foam) sorbent materials for cleaning up oil spills may soon become available, as a result of promising research from multiple groups. Oil spills damage ecosystems and habitats, harm and kill wildlife and plants, contaminate…

The Asian longhorned tick (Haemaphysalis longicornis), also known as the bush tick, is a troublesome parasitic species and is an important vector of disease agents. (Note that vectors are capable of biologically transferring a pathogen from one…

Colony collapse disorder (CCD) is a baffling detrimental condition in colonies of honeybees (Apis mellifera). It is characterized by a rapid loss of the adult bee population, with an absence of dead bees in and around affected colonies. No single…

Crown-of-thorns starfish or sea stars (Acanthaster planci; order Valvatida) are predatory marine invertebrates that feed on phytoplankton found on coral. They are native inhabitants of coral reefs in both the Indian Ocean and Pacific Ocean and are…

Conservationists have determined that the Bornean orangutan (Pongo pygmaeus) is disappearing much more rapidly than previously thought. Since 1999, the total number of Bornean orangutans declined by at least 148,000 individuals. The chief culprits…

The warming temperatures attributed to global climate change are making it more difficult for sea turtle populations to survive. As a result of the unusual developmental processes found in many reptiles, including some species of turtles, the sex of…

Sunscreens are polluting the ocean, and increasing evidence points toward some ultraviolet-light–absorbing chemicals found in sunscreens as being harmful to marine life—particularly corals at popular tourist destinations. While working toward…

The World Health Organization (WHO) is planning to recognize gaming disorder as a mental health disease in 2018. The 11th revision of the WHO's International Classification of Diseases (ICD), which is a major worldwide reference for epidemiological,…

The evolutionary transition of certain dinosaurs into modern birds has long been an active area of paleontological research. Because the members of the class Aves are living representatives of theropod dinosaurs, paleontologists have sought fossil…

In the fall of 2014 and early winter of 2015, an estimated 250,000 to 500,000 seabirds known as Cassin's auklets (Ptychoramphus aleuticus) died along the Pacific Coast from California to British Columbia, Canada. Researchers have now reported the…

Neonicotinoids (also termed neonics) comprise a class of insecticides and pesticides that chemically resemble nicotine. They are the most widely used insecticides in the world and are deployed by plant and crop farmers because these chemical…

Mammals possess a certain gene, termed PON1, which encodes a protein enzyme (paraoxonase) that is used to process the cholesterol lipids and fatty acids found in food. This gene evolved millions of years ago and is functionally active in terrestrial…

The Northern white rhinoceros (Ceratotherium simum cottoni)—one of two white rhino subspecies—is functionally extinct. Officially, this subspecies is classified by the International Union for Conservation of Nature and Natural Resources (IUCN) as…

Humans' contributions to global warming through burning fossil fuels and other actions (for example, detrimental land-use practices) have resulted in sharp increases in the levels of atmospheric carbon dioxide (CO2). These rising levels of CO2 also…

A newly identified reptilian fossil has pushed back the phylogenetic (evolutionary) family tree of Squamata [the dominant order of living reptiles, comprising lizards, snakes, and amphisbaenians (mostly limbless lizards that resemble worms)] by 75…

Autism, also known as autism spectrum disorder (ASD), is a complex neurodevelopmental condition that impairs the way that a person relates to and communicates with other people. In addition, autism is characterized by restricted, repetitive, or…

Scientists have long thought that dinosaur eggs were white in color and that the evolution of colored eggs in birds was strictly an avian innovation that occurred after the demise of the nonavian dinosaurs. However, technical advancements in the…

One notable study of predator-prey relationships, specifically between wolves and moose, has been conducted on Isle Royale since the late 1950s. Isle Royale is the largest island in Lake Superior. It was established as a national park in the United…

In early 2018, NASA announced that it had demonstrated a new type of celestial navigation for the first time. Called XNAV, for x-ray pulsar-based navigation, it relies on beams of radiation from pulsars—the cinders of exploded, massive stars. As…

Quorum sensing is a process by which bacteria monitor their own population density by detecting the levels of signal molecules that are released by the bacteria. It is a unique phenomenon of cell-to-cell communication, enabling microorganisms to…

The Iberian lynx (Lynx pardinus; also known as the Spanish lynx), which inhabits the shrublands of southwestern Spain and Portugal, was on the verge of extinction at the beginning of the twenty-first century. At that time, this wild cat species was…

By July 6, 2018, beaches on the eastern coast of St. Vincent—an island located in the southeastern Caribbean Sea (Lesser Antilles)—were covered nearly one-meter deep with rotting brown algae (seaweed), known as Sargassum, posing multiple problems…

To better understand the nutritional effects (health benefits), chemical composition, growing conditions, and shelf life of microgreens, a team of researchers reviewed the science behind them in the Journal of Agricultural and Food Chemistry…

On October 9, 2018, the U.S. Food and Drug Administration (FDA) banned the use of seven synthetic food flavoring additives: benzophenone, ethyl acrylate, eugenyl methyl ether, myrcene, pulegone, pyridine, and styrene. The use of benzophenone as a…

Destructive blooms of Karenia brevis, a dinoflagellate species of algae that imparts a red color to ocean waters when the microorganisms grow and accumulate to unusually high quantities, are causing unprecedented environmental and ecosystem damage…

Trophic ecology is the general study of the structure of feeding relationships among organisms in an ecosystem. These feeding or trophic relationships are often represented as food webs or food chains. One very important phenomenon of trophic…

Biocontrol, or biological control, is the natural or applied regulation of populations of pest organisms—especially insects—through the role or use of natural enemies. In other words, biocontrol uses living organisms to reduce and eliminate pest…

People consider visual perception to be one of the most trustworthy means of gathering information about the world. However, striking limitations in visual processing occur daily, distorting the precision and completeness of the visual experience…

Recent excavations in Asia unearthed a pristine, three-dimensional fossil of a tiny dinosaur tail with preserved feathers and soft tissues (presumably skin). In 2016, investigators in northern Myanmar (Burma) recovered a piece of Cretaceous-era…

In 2016, animal researchers and geneticists concluded that the giraffe (genus Giraffa), once thought to consist of a single extant species (Giraffa camelopardalis), comprises four distinct species: the northern giraffe (Giraffa camelopardalis),…

Global climate change affects all areas of the Earth, with some regions experiencing greater impacts than others. In particular, the Arctic treeline—that is, the southern limit of the Arctic Bioclimate Zone—is being affected to various degrees by…

Survival prospects for the honeybee (Apis mellifera) look increasingly promising as entomologists and beekeepers have reported a dramatic increase in the population numbers of these essential insects in North America and Europe. Honeybees, which are…

Forests absorb and store carbon. If this ability is hampered, then levels of atmospheric carbon will increase and global temperatures will rise, leading to potentially drastic climatic changes. In particular, deforestation (the permanent elimination…

Through study of the fossil record, paleontologists can frequently identify when an ancient species or taxon (a grouping of related organisms) first emerged in evolutionary history. (Paleontologists often prefer the term taxon over species because…

Mangrove forests are taxonomically diverse assemblages of trees and shrubs that form the dominant plant communities in tidal, saline wetlands along sheltered tropical and subtropical coasts. They have several ecological and physical functions that…

Traditionally, the lowest-pitched (bass) instruments have provided the rhythmic foundation in musical ensembles. Researchers from McMaster University, Hamilton, Ontario, Canada, reporting in the Proceedings of the National Academy of Sciences (June…

A new species of orangutan has been identified in the Batang Toru forest ecosystem in northern Sumatra, Indonesia. Genetic and morphological evidence, as well as behavioral data, have confirmed that the Tapanuli orangutan (Pongo tapanuliensis) is…

In an attempt to quantify the amount of plastics ever produced and what has happened to them, researchers produced the first global analysis using data collected from plastic industry sources. As reported in Science Advances (July 2017), 8300…

Research into the depleted state of the Great Barrier Reef, one of the great wonders of the natural world, provides a vivid case study of the extreme harm that the warming climate and the affliction called coral bleaching cause globally. In March…

Although the survival of the snow leopard (Panthera uncia; formerly, Uncia uncia), also known as the ounce, is precarious, the International Union for Conservation of Nature and Natural Resources (IUCN) has assigned an upgraded…

Surface water from streams across the United States contain a diverse mixture of synthetic organic pollutants, according to a joint U.S. Geological Survey (USGS) and U.S. Environmental Protection Agency (EPA) study reported in the journal…

Wildfires are known to emit large amounts of gaseous and particulate pollutants. In an effort to identify and quantify these pollutants, researchers took their instruments to the skies where they sampled and analyzed smoke plumes from aircraft…

The dance language of honeybees (Apis mellifera) is a unique form of animal behavior and communication that was discovered by the zoologist Karl von Frisch (1886–1982) in the 1920s, which he continued to study through the 1960s and for which he was…

Cafestol, C20H28O3, is a compound, specifically a diterpene alcohol, found in coffee beans. It is extracted during the coffee-brewing process and may be present in coffee beverages, depending on the preparation method. Consumption of cafestol in…

High within the coldest and driest continent, Antarctica, lies what may be an environment too hostile to support life, according to a team of scientists from Canada and the United States. They reported finding no evidence of microbial life in the…

In 2016, the eastern lowland gorilla (Gorilla beringei graueri), also known as Grauer's gorilla, was identified as critically endangered because of the precipitous drop in its population by more than 77% over the past few decades. The critically…

Landfill mining is a method for recovering valuable materials, reclaiming land, and mitigating air and water pollution. It is similar to surface mining, in which valuable minerals are recovered from the earth by removing (excavating) soil and ore,…

The study of the neural basis of animal behavior is known as neuroethology. It is a combination of two disciplines: neurobiology, the study of the nervous system, and ethology, the study of animal behavior. Neurobiology describes how the nervous…

Between 2004 and 2014, the total phosphorus content of lakes and streams in the contiguous (lower 48) United States rose, according to surveys by the U.S. Environmental Protection Agency (EPA) reported in the journal Environmental Science &…

Organic micropollutants are synthetic chemicals found in water sources and treated wastewater at concentrations in the range of micrograms per liter or lower. Micropollutants tend to be resistant to biodegradation and many are bioactive. Most…

The species diversity and ultimate survival of amphibians, one of the major groupings of vertebrate animals, face tremendous challenges today for reasons that are still not entirely understood. Since the 1980s, the pace of amphibian extinction has…

For over fifty years, heat stabilizers, light stabilizers, and antioxidants have been added to polymers to maintain their material properties by preventing their degradation. This chemical adjustment is necessary to extend the life of products such…

In the Rising Star cave system in South Africa, located about 48 kilometers (30 miles) north of Johannesburg, paleoanthropologists have unearthed an extensive collection of more than 1550 skeletal elements from at least 15 individuals that have…

Since 1975, approximately 1200 dams have been removed from rivers in the United States, including 72 in 2014. Some of these dams were in danger of failure, others had become functionally obsolete because their reservoirs had filled with sediment,…

In humans, taste buds on the tongue have sensory receptors that detect the qualities of water-soluble chemicals in food and convert (or transduce) those stimuli to electrical signals. Nerves then carry the signals to the brain, which processes them…

Lobsters are bottom-dwelling decapod crustaceans making up the family Nephropidae (also called Homaridae). The most familiar and commercially important lobsters are large-clawed ones possessing a hard protective exoskeleton and belonging to the…