This is the subject of one of my reviews of cranial materials that I did at college, any one of which COULD have been a doctoral thesis. It was a review of the varieties of Native crania in both of the Americas with an eye to determining whether or not the variations indicated separate migrations into the New World. This is a longstanding theory popularized in such sources as the book Men Out Of Asia
by Harold T. Gladwin in the WWII era.
The map at Left illustrates a recent attempt to mark out the migrations and I have it as a reprint, not from the original source. It is interesting that while most other maps indicating mtDNA groups in the New World indicate the presence of group X, this map does not and indicates its ancestor group N in its place. This is if anything worse for the theorists that want to keep the Europeans out of the early Americas, because mtDNA group N is ancestral to ALL of the European mtDNA lineages.
Group 1 on the map is the same as the "Australoid" migration of Gladwin and other authors, as indicated by such groups as the Pericu of Baja California and the similar skulls from Lagoa Santos in South America, illustrated in the photo montage at left here. This group was presumably already in place before the Clovis peoples arrived and possibly even before 25000 years ago, and they originated in SouthEast Asia, the same place as the actual Australian Aboriginals came from. They are actually later in date than the colonization of Australia and somewhat more gracile, in that the brow ridges are not so heavy, but the cranium is long and has a high peaked ridge down its top medially placed.
The main group of the ancestors of later Amerinds were the Clovis wave, initially tall longheads with prominent noses, only later populations tended to become rounder-headed over time. The skulls at left are the Spirit Cave skull in pencil drawing and a photograph of the corresponding South American type. More recently these two populations have tended to center at opposite poles of the Americas, at Argentina and in Canada
The Archaic or Arawak type of skull is basically a smaller-sized variant of the tall longheads and similarly tended to become more rounder-headed as time went on. These skulls are common in the Southern USA after the end of the Ice Age, Central America and the Andes region, and eventually intio the West Indies when they were colonised some time around 4000 BC. There used to be a South American language classification called "Andean-Equatorial" which admirably corresponded to the distribution of this type of skulls, but it has since fallen into disfavor. In the Southeastern USA the earliest peoples that built mounds continued to be of this type. Since this type is found in warmer climates and at the time agriculture was being introduced, we can see it as the more "Civilized" reduction (Smaller, frailer) of the Tall Longheads.
This time at left we have the Small Longheads, drawings (credited to Charles Darwin) from Argentina (Patagonia) and the coloured center artwork done by an artist from Brazil. At one time this was the predominant type in South America just as the Tall Longheads predominated in North America before the Dene peoples came in from the West. However, the same type was also present in the US Southwest and in Central America at an early age, and it is also referred to as the "Basketmaker" type because it is characteristic of that Archaic ("PrePueblo") peoples in the Southwest. In the past there has been confusion about this type which has been said to have odd affinities including with African natives, Pygmies and Bushmen. Most more recent authorities have dismissed those suggestions as unlikely. However in a reivew of the types of skulls corresponding to those illustrated on this page, Neumann said that both of the shorter populations were probably related to one another because of some anatomical similarities and they had separated from one another in different Geiographical locations. Neumann did allow migrations into the Americas corresponding to 1 and 2 on the map above during the Ice age and migrations 3 and 4 after the end of the Ice Age. That would be consistent with most other authorities. The other, shorter types he was not so certain of but he suggested that either one or both could have arisen in the New World out of members of migration 2, the Clovis one. Neumann also identified a Plains type corresponding to the Sioux (Lakotid) but he said it came from a mixing of the newer Dene populations (Athabascans, including Navajos ans Apaches) with the older American lineages derived from migration 2. And he also recognised the Adena type as distinctive but was also uncertain as to its place of origin. It was definitely intrusive into the Eastern USA when it appeared.