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Map of early human migrations based on the Out of Africa theory; figures are in thousands of years ago (kya). [1]The peopling of the Americas began when Paleolithic hunter-gatherers (Paleo-Indians) entered North America from the North Asian Mammoth steppe via the Beringia land bridge, which had formed between northeastern Siberia and western Alaska due to the lowering of sea level during the ...
A troglobite (or, formally, troglobiont) is an animal species, or population of a species, strictly bound to underground habitats, such as caves.These are separate from species that mainly live in above-ground habitats but are also able to live underground (eutroglophiles), and species that are only cave visitors (subtroglophiles and trogloxenes). [1]
Troglomorphism is the morphological adaptation of an animal to living in the constant darkness of caves, characterised by features such as loss of pigment, reduced eyesight or blindness, and frequently with attenuated bodies or appendages.
Other trogloxenic animals include vertebrates such as bears, hyenas, other predators, reptiles, oilbirds, cave swiftlets and even humans, that enter for short term shelter or for hibernation. Most of them contribute organic matter rather than consuming it, and are important resources for troglobitic insects, many of which actually specialise in ...
Schematic illustration of maternal (mtDNA) gene-flow in and out of Beringia, from 25,000 years ago to present. The genetic history of the Indigenous peoples of the Americas is divided into two distinct periods: the initial peopling of the Americas from about 20,000 to 14,000 years ago (20–14 kya), and European contact, after about 500 years ago.
In Pennsylvania caves were used by newcomers as homes for a long time, certainly half a century. They generally were formed by digging into the ground about four feet in depth on the banks or low cliffs near the river front. The walls were then built up of sods or earth laid on poles or brush; thus half only of the chamber was really under ground.
The oldest human skeletal remains are the 40ky old Lake Mungo remains in New South Wales, but human ornaments discovered at Devil's Lair in Western Australia have been dated to 48 kya and artifacts at Madjedbebe in Northern Territory are dated to at least 50 kya, and to 62.1 ± 2.9 ka in one 2017 study. [26] [27] [28] [29]
The American Nation: A History of the United States: AP Edition (2008) Egerton, Douglas R. et al. The Atlantic World: A History, 1400–1888 (2007), college textbook; 530pp; Elliott, John H. Empires of the Atlantic World: Britain and Spain in America 1492–1830 (2007), 608pp excerpt and text search, advanced synthesis