Bird anatomy Birds have a four-chambered heart, in common with mammals, and some reptiles (mainly the crocodilia). This adaptation allows for an efficient nutrient and oxygen transport throughout the body, providing birds with energy to fly and maintain high levels of activity. A ruby-throated hummingbird's heart beats up to 1200 times per minute (about 20 beats per second). Many birds possess a muscular pouch along the esophagus called a crop. The crop functions to both soften food and regulate its flow through the system by storing it temporarily. The size and shape of the crop is quite variable among the birds. Members
Names for the human species "animal capable of rationality", a term used in medieval scholasticism (with reference to Aristotle), and also used by e.g. Carl von Linné 1760, Immanuel Kant 1798. Based on the same pattern is "animal sociale" or "social animal" "animal laborans" "laboring animal" (Hannah Arendt 1958) and "animal symbolicum" "symbolizing animal" (Ernst Cassirer 1944). The binomial name "Homo sapiens" was coined by Carl Linnaeus (1758). Names for other human species were introduced beginning in the second half of the 19th century ("Homo neanderthalensis" 1864, "Homo erectus" 1892). There is no consensus on the taxonomic delineation between human species, human subspecies and the