Biology Popular Science

Sexual preference refers to an animal's tendency to choose either males or females as partners for courtship or mating. Although sexual preference is closely related to sexual attraction, sexual motivation, and the actual performance of sexual behavior, these aspects of sexuality do not necessarily coincide. For example, an animal may actively seek sexual stimulation without showing a clear preference for either sex. Conversely, an animal may prefer partners of a particular s

When faced with a wide variety of products, many people have experienced difficulty making a choice. As the number of options increases, making a decision can become more difficult, requiring more time to consider the alternatives and sometimes even leading people to abandon the purchase altogether. This phenomenon is known as choice overload. Schematic Diagram of the Experimental Setup（Image source：Hemingway, C. T et al. (2026).， CC BY 4.0 。） In the past, this phenomenon was

Body size often influences the outcome of competition among animals. Larger species may monopolize food, occupy preferred habitats or directly attack smaller competitors. In the Negev Desert of southern Israel, Rüppell's fox (Vulpes rueppellii) shares its habitat with just such a neighbour: the red fox (Vulpes vulpes). In this region, red foxes weigh about 3.5 kg on average, whereas Rüppell's foxes weigh only about 1.7 kg, making the red fox roughly twice as heavy. Under such

Feathers found in the nests of spotless starlings (Sturnus unicolor) may convey information that other members of the same species can interpret. A recent study found that nests containing feathers experienced lower rates of conspecific brood parasitism. Conspecific brood parasitism is a reproductive tactic in which some females lay eggs in the nests of other females of the same species, leaving the hosts to incubate the eggs and rear the resulting nestlings. Because spotless

South America is home to a group of small, spotted and rosetted cats in the genus Leopardus whose taxonomy has puzzled researchers for decades. These cats are remarkably similar in appearance, with differences among populations often limited to subtle variations in body proportions, coat color, and marking patterns. The northern tiger cat (Leopardus tigrinus) has been particularly difficult to classify. The species was named as early as 1775, yet its original description was

Every New Year's Eve, fireworks fill the night with intense noise and light for only a few hours, yet their effects on roosting birds may persist far longer. Urban birds routinely encounter vehicles, human activity and a wide range of background noise, but sudden explosive sounds can still represent a very different form of disturbance. One study followed birds along the River Rhine in Basel, Switzerland, over three consecutive winters. The study site contained a long-establi

Ciliates (Ciliophora) are unicellular organisms, most of which can live freely in aquatic environments. Mobilid ciliates, however, have tied their life histories closely to animal hosts. They commonly inhabit the body surface or gills of aquatic animals, including fishes, mollusks, annelids, and crustaceans, attaching themselves to host tissues by means of an adhesive disc on the aboral side. At the center of the adhesive disc is a ring of specialized denticles that helps anc

Sloths spend much of their day in trees, often moving with their bodies suspended beneath branches while alternately hooking their limbs onto supports ahead of them. In most quadrupedal animals, the limbs primarily bear the forces generated as body weight presses downward against the ground. Sloths frequently experience a very different mechanical situation: their limbs must support the body's weight while it hangs below the point of attachment for prolonged periods. What fea

Nestlings confined to a nest, unable to fly or make a rapid escape, have very few options when a predator enters. Eurasian roller (Coracias garrulus) nestlings, however, have developed an unusual response. When strongly disturbed, they regurgitate an odorous orange liquid from their mouths. Ornithologists had observed this behavior before, but it remained unclear whether the vomit was simply a physiological response to distress or served a specific function. Eurasian roller (

For patients with respiratory failure, maintaining adequate oxygen levels in the blood is one of the most urgent priorities in life-saving care. Mechanical ventilation can be used to support pulmonary gas exchange, while patients with extremely severe respiratory failure may require extracorporeal membrane oxygenation (ECMO). Yet some animals have evolved an unusual survival strategy: when oxygen becomes scarce, they can absorb oxygen through their intestines. This led a Japa

Recent reports have once again raised concerns about food contaminated with Cyclospora cayetanensis in the United States. Looking beyond the latest incident, however, it becomes clear that this parasite has repeatedly entered the U.S. fresh produce supply chain. In 2019, the United States reported 2,408 cases of cyclosporiasis, with some outbreaks linked to imported basil. Another 1,241 cases were reported in 2020, including a large cluster associated with bagged salad mixes

Beginning in 2012, large numbers of brown bullheads (Ameiurus nebulosus) with dark skin lesions were observed in Lake Memphremagog, which straddles the border between Vermont in the United States and Quebec in Canada. Some lesions appeared as flat, darkly pigmented patches, while others developed into conspicuous raised masses, including lesions around the eyes, opercula and mouth. Histopathological examination confirmed that the raised lesions were malignant melanomas. Among

Human upright walking depends on the coordinated action of the legs, spine and pelvis, with the pelvis playing a central role in maintaining balance during every step. Compared with other primates, including chimpanzees (Pan troglodytes), the human pelvis is bowl-shaped. Its upper component, the ilium, is short and broad and curves around the sides of the body. This configuration stabilizes the trunk during single-leg stance, supports the internal organs and provides sufficie

Reptiles have long been shown to exhibit responses such as anxiety, stress, and preference when handled, exposed to novel environments, or choosing preferred foods. However, compared with mammals and birds, research on reptile emotions remains limited. As a result, whether reptiles possess emotional capacities similar to those of other vertebrates remains an important question in animal behaviour research. Researchers often use cognitive judgement bias tests to assess animals

Vomiting is unpleasant, but it serves as an important protective mechanism. When toxic substances, gastrointestinal irritation, or certain drugs threaten the body, the nervous system coordinates the esophagus, stomach, diaphragm, abdominal muscles, and respiratory muscles to expel gastric contents through the mouth. Cats, dogs, ferrets, primates, and shrews are all capable of vomiting. Laboratory mice, however, have rarely, if ever, been observed to vomit. It was therefore un

Reptiles have become increasingly popular pets around the world. Many people believe that reptiles rely primarily on instinct rather than possessing the rich emotional lives often associated with cats and dogs. As a result, they are often assumed to require little space and only simple enclosures. However, growing research suggests that these assumptions may underestimate the abilities of reptiles. Sentience is generally understood as the capacity to experience both positive

The pursuit between bats and moths takes place in an ultrasonic world beyond the range of human hearing. Nocturnal bats emit high-frequency sounds and use the returning echoes to determine the location, size, and flight direction of their prey. In response, many moths have evolved ultrasound-sensitive hearing organs that allow them to turn sharply, dive, or stop flying when a bat approaches. Some species also produce ultrasonic clicks that interfere with a bat's ability to tr

In the Andes along the border between northern Chile and northwestern Argentina, towering volcanoes, salt flats, and arid grasslands form the Puna de Atacama. Cold, severely hypoxic, and extremely dry, this region was long considered incapable of supporting mammals year-round. Yet the Andean leaf-eared mouse (Phyllotis vaccarum) ranges from the coastal lowlands of northern Chile to volcanic summits above 6,700 meters. Individuals have even been found on the 6,739-meter summit

By the 1870s, the cell theory had established that plants and animals were composed of cells, and some researchers already knew that cells could multiply by division. Yet there was still no reliable account of how a cell completed this process. The theory of "free-cell formation" had not entirely disappeared from scientific thought, and some scholars continued to believe that new cells might arise directly from an unidentified substance between existing cells. Against this ba

Anyone seeing a pigeon or dove nest for the first time might easily mistake it for a few dead twigs that happened to become lodged in a tree or on a windowsill. Several slender sticks are loosely laid across one another, with only a shallow depression in the center. Sometimes the white eggs or nestlings can be seen directly through the nest from below. The nests of many members of the family Columbidae do indeed look remarkably flimsy, but this apparent crudity reflects a con