The ancient Egyptian civilization flourished along the banks of the Nile River, which supplied the waters that ensured a prosperous and lengthy agricultural vitality over the course of thousands of years. On the strength provided by this rich agricultural productivity, the Egyptian civilization was able to develop into one of the foremost and notable ancient empires, excelling in architecture (including the use of the ramp and the lever in construction), science, medicine (including the art of mummification), mathematics, writing (hieroglyphic script), art, engineering, stone masonry, irrigation techniques, and commerce. See also: Africa; Agricultural science (animal); Agricultural science (plant); Agriculture; Anthropology; Archeology; Architectural engineering; Inclined plane; Irrigation (agriculture); Lever; Masonry; Mathematics; Medicine; River; River engineering; Science; Scientific methods; Stone and stone products

The Aztecs were an indigenous group of Mesoamerican tribal peoples whose influence dominated that region between the fourteenth and early sixteenth centuries. They predominantly spoke a native language called Nahuatl, and they lived a nomadic existence prior to the twelfth century. See also: Agricultural science (plant); Agriculture; Bean; Corn; Domestication (anthropology); North America

The Babylonian civilization flourished from approximately 1900 to 539 BC in the central and southern regions of Mesopotamia (present-day Iraq), predominantly between the Euphrates and Tigris rivers. Before the rise of the Babylonians, the area was inhabited by the Sumerians in southeast Mesopotamia and the Akkadians in northwest Mesopotamia. Through a series of expansions and conquests undertaken by various dynastic kings, these two cultures were incorporated into the Babylonian empire, which eventually established control over many other kingdoms from ancient Persia to Syria and Palestine. Along with this political and geographical dominance, the cities of the Babylonian empire became rich centers of learning, especially in the areas of astronomy, astrology (including the division of the night sky into a zodiac of constellations), mathematics, and medicine. The most important city was Babylon, which was situated 88 kilometers (55 miles) southwest of modern-day Baghdad. Once famous for its impressive architectural marvels, including massive walls, ziggurats (pyramid-shaped temples built on platforms), and the Hanging Gardens of Babylon (considered to be one of the Seven Wonders of the Ancient World), few remains of this ancient city can be found today. In addition, it is likely that the biblical story of the Tower of Babel was based on an ancient Babylonian structure. See also: Anthropology; Archeoastronomy; Archeology; Architectural engineering; Astronomy; Mathematics; Medicine; Science; Scientific methods; Zodiac

Scientists have suggested a possible connection between ancient Neandertals (Homo neanderthalensis) and the severity of disease in patients affected by COVID-19. In short, certain genes acquired from Neandertals during instances of interbreeding with ancestors of modern humans (Homo sapiens) approximately 60,000 years ago may be involved in the susceptibility of individuals to severe disease from the virus that causes COVID-19. Specifically, researchers have identified a region on human chromosome 3 that possibly influences whether a person infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) will become seriously ill and require artificial ventilation. This chromosomal region is almost identical to a segment found in the DNA of Neandertals from Croatia and Siberia, and present-day carriers of the Neandertal-derived gene variant on human chromosome 3 have an increased likelihood of developing life-threatening forms of COVID-19. See also: Chromosome; Coronavirus; Deoxyribonucleic acid (DNA); Gene; Neandertal DNA; Neandertals; Novel coronavirus is declared a global pandemic

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 until dating and other analyses were completed in 2019, the well-preserved fossil is the first skull of this particular species to be found. Paleoanthropologists expect that this discovery will reshape the ancient timeline of human evolutionary history because it reveals the previously unknown facial features of A. anamensis, which now can be compared to the facial morphologies of other ancient hominins. The fossil evidence also opens up the possibility of the coexistence of two early hominins—A. anamensis and A. afarensis—in the same area of Ethiopia. Prior to this cranium discovery, these two species were assumed to have emerged consecutively along a more linear chronology. See also: Anthropology; Australopith; Dating methods; Earliest hominins; Fossil; Fossil humans; Paleontology; Physical anthropology

The evolutionary ancestry of the modern human race became even more complicated in 2012 with the results of studies on DNA extracted from bits of 50,000-year-old bone from Siberia. The analysis confirmed that an archaic species of people called Denisovans—contemporaries of Neandertals who were unknown to science until 20120—are indeed ancestors of many people living today. See also: Denisovans; DNA unveils enigmatic Denisovans; Neandertals

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 been provisionally assigned to a new species of the genus Homo. The location in which these numerous fossils were found is a highly inaccessible chamber known as the Dinaledi ("Star") Chamber; hence, this previously unknown offshoot of the hominin family has been given the name Homo naledi. This discovery has provided the largest morphologically homogeneous assemblage of a single species of ancient hominins yet found in Africa. See also: Anthropology; Fossil; Physical anthropology

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 (or locations) and time (or times) of origin for canine domestication are contentious topics. Southeast Asia and Europe have often been noted as early centers for the domestication of dogs, with most researchers assigning a probable range of dates between 15,000 and 32,000 years ago as the time for dog domestication. However, a recent study pinpoints northern Siberia as the origin of the domestication of dogs and estimates that domestication took place approximately 23,000 years ago. Early domesticated dogs later dispersed eastward to the Americas and westward to Eurasia as ancient Siberian peoples migrated away from their original geographic homes. See also: Anthropology; Dogs; Domestication; Fossil; Phylogeny; Zooarcheology

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 expanded. In some cases, modern humans may have admixed with local archaic human populations; in other cases, they completely displaced archaic peoples. Then, about 70,000 to 60,000 years ago, H. sapiens dispersed from Africa in significant numbers, first spreading eastward into Asia. However, a portion of the population roamed northward into central Asia and then westward into Europe. Now, investigators in present-day Bulgaria have found the earliest evidence of H. sapiens in Europe, including a fossilized molar, six bone fragments, and various stone tools and ornaments that date back as early as 44,000–46,000 years ago. See also: Anthropology; Archeology; Bone; Dental anthropology; Early modern humans; Europe; Fossil; Physical anthropology; Tooth

In the Afar region of Ethiopia, paleoanthropologists unearthed a 2.8 million-year-old jawbone (mandible) that was provisionally assigned to the genus Homo [the genus of human beings, including modern humans (Homo sapiens) and other extinct species]. This fossil discovery, announced in the journal Science in 2015, is extremely important because it fills in a notable gap in the ancient timeline of human evolutionary history. See also: Anthropology; Fossil; Physical anthropology