question: Why would Homo sapiens ever migrate north into colder climate?
comment: Well, back when we were migratory creatures, we wouldn't. Head north during the warner months and south fir the cooler months. But once we decided that settling down was better. The amount of fertile land and other natural resources was tempting enough for the settlers to brave a few cold months.
passages: Humans colonised the environment west of the Urals, hunting reindeer especially, but were faced with adaptive challenges; winter temperatures averaged from with fuel and shelter scarce. They travelled on foot and relied on hunting highly mobile herds for food. These challenges were overcome through technological innovations: tailored clothing from the pelts of fur-bearing animals; construction of shelters with hearths using bones as fuel; and digging “ice cellars” into the permafrost to store meat and bones.
   Section::::Human ecology in the Arctic.
  
  Evidence has been found of early humans in the early Würm-Weichsel period hunting large Arctic mammals in the Ice Age steppes of northern Europe. However, it is still unclear whether these humans were just temporary migrants or inhabitants of Arctic colonies at the time.
   An important difference between Europe and other parts of the inhabited world was the northern latitude. Archaeological evidence suggests humans, whether Neanderthal or Cro-Magnon, reached sites in Arctic Russia by 40,000 years ago.
   Since Tukudika were aware migratory patterns of deer and elk and bighorn sheep, they likely migrated out of high elevations to spend winter at the mouth of mountain canyons where they spill out to the plains, or in the basins themselves. Some big game wintering areas, such as Sunlight Basin and the upper Wind River Valley, are nearly snow-free in winter. Other recent excavations have suggested that certain snow-free areas within the Wind River Range may have been used by Indians in mid-winter for up to 12,000 years.
  
  Section::::Technology.
   According to mitochondrial timing techniques, modern humans migrated from Africa after the Riss glaciation in the Middle Palaeolithic during the Eemian Stage, spreading all over the ice-free world during the late Pleistocene. A 2005 study posits that humans in this migration interbred with archaic human forms already outside of Africa by the late Pleistocene, incorporating archaic human genetic material into the modern human gene pool.
  
  Section::::Deposits.
   Groups such as the inhabitants of northern Peru and central Chile, the Saqqaq in Greenland, nomadic Eurasian tribes in Historical China, and the Natufian culture in the Levant all display migration reactions due to climactic change.
  
  Section::::Role in human migration and agriculture.:Further descriptions of specific cases.
   BULLET::::- Migration patterns of certain animals seemed to suggest that the polar region was a hospitable place for them to live.
  
  Section::::Disproof and re-emergence.
   The continuity of the northern parts of the holarctic results from their shared glacial history. During the Pleistocene, these areas were subjected to repeated glaciations. Icecaps expanded, scouring the land of life and reshaping its topography. During glacial periods, species survived in refugia, small areas that maintained a suitable climate due to local geography. These areas are believed to have been primarily in southern regions, but some genetic and paleontological evidence points to additional refugia in the sheltered areas of the north (Stewart and Lister 2001).
   Glacial survival hypothesis
  
  According to the northern cryptic glacial refugial hypothesis (or glacial survival hypothesis), during the last ice age cold tolerant plant and animal species (e.g. Norway spruce and Norwegian lemmings) persisted in ice-free microrefugia north of the Alps in Europe. The alternative hypothesis of no persistence and postglacial immigration of plants and animals from southern refugia in Europe (southern refugia paradigm) is sometimes also called the tabula rasa hypothesis.
   The last region to be permanently settled by human migrations is the Arctic.
  
  The earliest inhabitants of North America's central and eastern Arctic are referred to as the Arctic small tool tradition (AST) and existed c. 2500 BCE. AST consisted of several Paleo-Eskimo cultures, including the Independence cultures and Pre-Dorset culture.
  
  The Inuit are the descendants of the Thule culture, which emerged from western Alaska around AD 1000 and gradually displaced the Dorset culture.
  
  Section::::See also.
  
  BULLET::::- Historical migration
  
  BULLET::::- Human migrations
  
  BULLET::::- List of countries and islands by first human settlement
  
  BULLET::::- Middle Paleolithic
  
  BULLET::::- Timeline of human evolution
   The earliest inhabitants of the polar regions were the Neanderthals, or "Homo neanderthalensis", who are considered to be an intermediate stage between "Homo erectus" and "Homo sapiens sapiens". The Neanderthals made advances in the basic production of stone, bone antler and flint tools, which archaeologists call a Mousterian industry. About 40,000 years ago, the Neanderthals quickly disappeared and were replaced by modern humans, "Homo sapiens sapiens". Just a few thousand years after the sudden disappearance of the Neanderthals, modern humans occupied all the land that their predecessors had occupied. Some scientists believe that the Neanderthals were overcome by the incoming modern race, commonly called Cro-Magnon people, while others believe the race disappeared by integrating itself within the new population.
   The Yamnaya horizon was an adaptation to a climate change which occurred between 3500 and 3000 BCE, in which the steppes became drier and cooler. Herds needed to be moved frequently to feed them sufficiently, and the use of wagons and horse-back riding made this possible, leading to "a new, more mobile form of pastoralism".
   Rust, through his discoveries in the field excavations at Meiendorf, showed that reindeer hunters belonging to the Hamburg culture in the late Paleolithic were hunting in this region about 15000 years ago. During a period of warmer climate, about 13400 years ago, hunters belonging to the Magdalenian culture also lived at the foot of glaciers until a new cold period, 12,700 years ago, after which appeared the reindeer huntering Ahrensburg culture.
   These colonization entailed successive bottlenecks phenomena that led to a loss of genetic diversity in northern populations.
  
  Therefore, based on the data of numerous phylogeographic research, the high genetic diversity of populations of southern regions can often be an indication for positioning a Pleistocene refugium, while the geographical distributions of the northern populations are dictated by the colonization patterns of the refugia populations.
  
  While these southern refugia have been found for many other species of flora and fauna, there may have been high altitude refugia on the coast of northern Norway.
   In Grant's view, Nordics probably evolved in a climate that "must have been such as to impose a rigid elimination of defectives through the agency of hard winters and the necessity of industry and foresight in providing the year's food, clothing, and shelter during the short summer. Such demands on energy, if long continued, would produce a strong, virile, and self-contained race which would inevitably overwhelm in battle nations whose weaker elements had not been purged by the conditions of an equally severe environment." The "Proto-Nordic" human, Grant reasoned, probably evolved in eastern Germany, Poland and Russia, before migrating northward to Scandinavia.
   According to the essay, after this cataclysm, a tribe of primitive humans were at a technological level hardly above the Neanderthal. They fled to the northern areas of what was left of the Thurian continent to escape destruction. They discovered the region to be safe, but covered with snow and already inhabited by a race of vicious apes. The apes were large with white fur and apparently native to their land. The Stone Age invaders engaged in a territorial war with them and eventually managed to drive them off, past the Arctic Circle. Believing their enemies were destined to perish and no longer interested in them, the recently arrived group adapted to their new, harsh environment and its population increased.
   The final region to be permanently settled by humans was the Arctic, reached by the Dorset culture during about 500 BC to AD 1500. The Inuit are the descendants of the Thule culture, which emerged from western Alaska around AD 1000 and gradually displaced the Dorset culture.
  
  Section::::Proto-historical and early historical migration.
  
  The German term "Landnahme" ("land-taking") is sometimes used in historiography
  
  for a migration event associated with a founding legend, e.g. of the 
  
  conquest of Canaan in the Hebrew Bible,
   Transhumance was practised in Europe in prehistoric times. Isotope studies of the bones of livestock show that animals were sometimes moved seasonally.
  
  Section::::Europe.
  
  Section::::Europe.:The Balkans.
   BULLET::::- The close of the Pliocene and the whole of the Pleistocene period were marked by violent changes of climate bringing on what is called the Glacial and Inter-Glacial epochs. A succession of cold and warm climates must have characterized these Glacial and Inter-Glacial periods which were also accompanied by extensive movements of depression and elevation of land, the depression taking place after the land was weighed down with the enormous mass of ice.
   Around 20,000 years ago, approximately 5,000 years after the Neanderthal extinction, the Last Glacial Maximum forced northern hemisphere inhabitants to migrate to several shelters (refugia) until the end of this period. The resulting populations are presumed to have resided in such refuges during the LGM to ultimately reoccupy Europe, where archaic historical populations are considered their descendants. The composition of European populations was later altered by further migrations, notably the Neolithic expansion from the Middle East, and still later the Chalcolithic population movements associated with Indo-European expansion. A Paleolithic site on the Yana River, Siberia, at 71°N, lies well above the Arctic Circle and dates to 27,000 radiocarbon years before present, during glacial times. This site shows that people adapted to this harsh, high-latitude, Late Pleistocene environment much earlier than previously thought.
   During the period of maximum glaciation, ancient man (Homo heidelbergensis – later the Neanderthals) retreated behind the permafrost boundary and, in the warmer periods, spread beyond it to the north and northeast. Not until the Weichsel-Würm ice age did modern Cro-Magnon man settle these regions, in about 40,000 BC.
  
  Section::::Sequence and extent of the Riss glaciation.
   The different inhabitants of Greenland, specifically in the west, migrated primarily in response to temperature change. The Saqqaq people arrived in Greenland around 4,500 B.P. and experienced moderate temperature variation for the first 1,100 years of occupation; near 3,400 B.P. a cooling period began that pushed the Saqqaq toward the west. A similar temperature fluctuation occurred around 2,800 B.P. that led to the abandonment of the inhabited Saqqaq region; this temperature shift was a decrease in temperature of about 4 °C over 200 years. Following the Saqqaq dominance, other groups such as the Dorset people inhabited west Greenland; the Dorset were sea-ice hunters that had tools adapted to the colder environment. The Dorset appeared to leave the region around 2,200 B.P. without clear connection to the changing environment. Following the Dorset occupation, the Norse began to appear around 1,100 B.P. in west Greenland during a significant warming period. However, a sharp decrease in temperature beginning in 850 B.P. of about 4 °C in 80 years is thought to contribute to the demise of initial Norse occupation in western Greenland.
   The wide dispersal of humans across varying environments with different evolutionary pressures, Wade contends, began to give rise to regional differentiation. He gives examples of variation in two genes related to brain development: an allele of microcephalin that appeared about 37,000 years ago and is common in Europeans and East Asians, but rare in sub-Saharan Africans; and an allele of ASPM that appeared about 6,000 years ago and is common in Europeans, Middle Easterners and to a lesser extent East Asians, but is nearly non-existent in sub-Saharan Africans. Wade believes that the rapid spread of these alleles conferred some cognitive advantage, and one that was enough to be favoured by natural selection. Wade continues to discuss the different human trajectories in chapter six, "Stasis"; he writes that while the humans across the Eurasian landmass were exposed to similarly harsh glacial conditions during the Upper Paleolithic, they gradually began to diverge between east and west. It was during this period that the dog was domesticated by humans living in Siberia, who in turn crossed the Bering land bridge and populated the Americas. Wade states that an adaptation in mitochondrial DNA for cold conditions possibly facilitated this migration. Furthermore, he theorises that the "mongoloid" skull and body type of East Asians and Native Americans were physical adaptations to the cold, and also partly the result of genetic drift, whereas light skin developed separately in East Asians and "caucasoid" Europeans to better enable them to synthesise vitamin D with sunlight.
   Local climate changes around 10,500 BCE, initiated both cultural changes and the first settling of the northern parts of Scandinavia. Initially, a thousand year long climate cooldown replaced the taiga with the former tundra and the local culture reverted to former times focus on the reindeer hunt. This culture is now referred to as the Ahrensburg culture. Around 9,500 BCE, the local climate warmed yet again, as the pre-Boreal era emerged, and this triggered the Ahrensburg to settle the emerging tundra of northern Scandinavia. For the next two thousand years, the climatic phase known as the Boreal reigned in the Scandinavian region.
   In Grant's view, Nordics probably evolved in a climate which "must have been such as to impose a rigid elimination of defectives through the agency of hard winters and the necessity of industry and foresight in providing the year's food, clothing, and shelter during the short summer. Such demands on energy, if long continued, would produce a strong, virile, and self-contained race which would inevitably overwhelm in battle nations whose weaker elements had not been purged by the conditions of an equally severe environment" (p. 170). The "Proto-Nordic" human, Grant reasoned, probably evolved in "forests and plains of eastern Germany, Poland and Russia" (p. 170).
  
presuppositions: Homo sapiens migrate north during colder climate. Humans had no reason to migrate north into colder climates.
corrections: We didn't do that when we were a migratory species.  Humans had a reason to migrate north into colder climates if the land was fertile enough and there were enough natural resources there.
raw_presuppositions: Homo sapiens migrate north during colder climate. Humans had no reason to migrate north into colder climates.
raw_corrections: We didn't do that when we were a migratory species.  Humans had a reason to migrate north into colder climates if the land was fertile enough and there were enough natural resources there.