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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.
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.
This allowed land animals, followed by humans, to migrate south into the interior of the continent. The people went on foot or used boats along the coastline. The dates and routes of the peopling of the Americas remain subjects of ongoing debate. [3] It is likely there were three waves of ancient settlers from the Bering Sea to the America ...
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
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]
Humans also pose a threat to troglofauna. Mismanagement of contaminants (e.g. pesticides and sewage) may poison troglofaunal communities, [ 6 ] whilst removal of habitat, either directly or indirectly (e.g. rising watertable) is also a major threat.