Over at Gene Expression, Razib Khan has up an interesting post that compares and contrasts the genetics of South Africa’s Afrikaner population with New England whites:
Afrikaner ancestry is overwhelmingly Northern European. But as you see in the PCA above they are notably African and Asian shifted when compared to their potential ancestral populations (I used Dutch and German individuals above). For me this is the part [of the study] that is important, if not surprising:
The individual with the most non-European admixture had 24.9% non-European admixture, and only a single Afrikaner individual (out of 77) had no evidence of non-European admixture…Amongst the 77 Afrikaners investigated, 6.5% had above 10% non-European admixture, 27.3% between 5 and 10%, 59.7% between 1 and 5% and 6.5% below 1%.
So about 87% of Afrikaners in their sample had between 1 to 10 percent non-European ancestry. As suggested by genealogical evidence, genetics indicates this is a relatively recent admixture, occurring during the 17th and 18th-century. The early decades of the Cape Colony. It’s a mix of diverse Asian and African components. In some ways, it seems that the non-European ancestry in modern Afrikaners is just the same phenomenon which gave rise to the Cape Coloured population, which is a mix of European, Asian (Indian and Austronesian) and African (Bantu and Khoisan).
But, this result is more interesting in light of how it contrasts with another case. Also in the 17th-century, there emerged another European settler society on the edge of a vast ocean rooted in a deeply Calvinist faith. By this, I mean the colonies of New England. Though New England has been reshaped by later migrations, between 1640 and 1790 30,000 English settlers expanded and grew into a region with 750,000 Americans. In the early 19th-century, New England spilled out over much of the northern swath of the United States of America, in part due to the fact that the fertility of New Englanders was quite high (the early Mormons were fundamentally a New England-derived subculture).
And yet unlike the Afrikaners or the whites of Latin America, the scions of New England have no non-European ancestry. One might argue here that this is due to the lack of opportunity, as the number of slaves in New England was always very low, and there were no native peoples. King Philip’s War falsifies the latter contention. There were numerous native people. At least initially. But the New Englanders were very efficient and effective at marginalizing and exterminating the native peoples of the region. To a far greater extent than occurred in the South.
Razib suggests that the almost nonexistent level of admixture between the English settlers in New England and their counterparts in Africa can be attributed to two things:
- The New Englanders came over from England as families and congregations, with a favorable male to female ratio
- The New Englanders had a confident culture ready to assert itself as itself from the beginning (or as Razib puts it, “by the latter portion of the 18th-century New England was unique because it was beginning to see itself as not just a complement of the metropole, but a potential rival”).
While Razib takes an angle informed by population genetics, the general observation that the English colonists in general and the New England settlers in particular had much lower intermarriage rates with indigenous peoples than colonists from other places is not new. One of the most interesting hypotheses for why this is so put forward in Alfred Crosby’s Ecological Imperialism: The Biological Expansion of Europe, 900-1900. If you have never read this book before I strongly recommend it—Crosby was a talented prose writer and a thoughtful historian. I blame the lack of attention the book has received outside of historical circles on its wordy and political sounding title. This is a shame. Most of the good ideas you find in Jared Diamond’s Guns, Germs, and Steel actually come from Crosby, though Crosby is both the better historian and the finer writer.
The question Crosby sets out to answer in Ecological Imperialism is this: why did European colonists almost completely displace native cultures and populations in Australia, New Zealand, North America, and Argentina, create mestizo populations and cultures in Central America, the Caribbean, the Andes, and coastal Brazil, but fail to even make a dent in most of Africa, interior Brazil, or Asia? For Crosby, the answer to all of these questions can be found by looking at the weeds.
A wild fact: the majority of the wild flora in the San Joaquin Valley did not exist in California two centuries ago. For most of temperate Canada and the United States, Australia, New Zealand, and Argentina the ratio of invasive to indigenous flora is similar, ranging from 30-60% of the flora in the places most of the population lives. The spread of disease from the Old World to the New is now quite famous: less famous is the spread of European weeds (dandelions, Kentucky bluegrass, nettles, white clover, etc.), pests (rats, roaches, houseflys, etc), and other disruptive species (earthworms, pigs, peach trees, and so forth) that transformed the landscape into something decidedly more European. Most interesting of all for the original question: the displacement of entire local biomes by European biota happened only in those places where the colonists displaced the local people.
Crosby suggests the first caused the second. The Europeans’ biological footprint in Africa—outside of the Mediterranean climate of the Cape—is near non-existent. African diseases killed European crops, animals, and colonists. European weeds, which had an advantage in North American biomes whose plants had not faced grazing herds since the ice age, were outclassed by African grasses that evolved next to an even larger contingent of grazers than found in Europe. In Mexico and the Andes the environment was not hostile to the Europeans entirely—but the climate was different enough from Europe, and the local biota resilient enough in face of European imports, that Spanish colonists could not transplant their entire mode of agriculture to Mexico whole-sale (as they did in Argentina). The colonists in these areas needed indigenous crops and styles of farming to survive. They depended on the indigenous farmers for those crops. Eventually, they would intermarry with them. 
Of all the “New Europe” zones discussed, the New England colonists had the least number of hiccups in setting up an Old World society somewhere in the New. The New Englanders famously faced far lower rates of disease than settlers in other parts of the Americas, and within a generation of the founding were living generally healthier lives than the English at home. They were also one of the most resistant to adopting local sources of food. Explains David Hackett Fisher:
“The Puritans of Massachusetts created one of the more austere food ways in the Western world, For three centuries, New England families gave thanks to their Calvinist God for cold baked beans and stale brown bread, while lobsters abounded in the waters of Massachusetts Bay and succulent game birds orbited slowly overhead… the coastal waters of New England teemed with mussels, oysters, lobsters, and clams. The rivers were choked with salmon and shad. Wild fowl flourished in abundance. Native delicacies such as glasswort sprouted along the seashore and fiddleheads carpeted the woodlands.
The Puritans showed little interest in these delights except when driven by hunger to consume them. Shellfish was regarded with grave suspicion. Shad roe, a gourmet’s delight, was used as a fertilizer. In the first year John Winthrop complained when he was compelled to eat oysters and wild duck instead of the staples of old England. “My dear wife,” he wrote, “we are here in paradise though we have not beef and mutton.“
That was true in 1630, when Winthrop wrote those words. It was not true in thirty years later, when the New Englanders had successfully transplanted the entirety of their agricultural system to their new home. Their success here is my favored explanation for why their marriages with non-colonists were so few.
 Razib Khan, “Afrikaner Genetics Show How Unique New England Culture Is,” Gene Expression (27 February 2019).
 This question is posed most clearly in Alfred Crosby, Ecological Imperialism: The Biological Expansion of Europe, 900-1900 (Cambridge: Cambridge University Press, 1986), 145-148; for his answers see 148-195; 269-304. Another famous book that I have not read is also relevant here: William Cronon, Changes in the Land Indians Colonists and the Ecology of New England (New York: Hill and Wang, 1985).
 Bernard Bailyn, The Barbarous Years: The Peopling of British North America: The Conflict of Civilizations, 1600-1675 (New York: Random House, 2012), 425-226.
 David Hackett Fisher, Albion’s Seed: Four British Folkways in America (Oxford: Oxford University Press, 1989), 135-137.
Perhaps Crosby digs deeper into this–I haven't read him and need to pick him up–but although the correlation between flora displacement and human displacement is strong, I'm not seeing a silver bullet of causation. The agricultural packages of the Native Americans of the East Coast *themselves* weren't disrupted–the Mayflower English got through their first winter on Wampanoag maize, as every schoolchild knows.
I don't know that it's necessarily correct that the Native population of the South necessarily fared better than that of New England. We know, for example, the linguistic identity of virtually the entirety of New York and New England at contact–most of upstate New York was Iroquoian-speaking, while the NYC area and Albany-area Hudson Valley were Algonquian-speaking (the closely-related Delaware and Mahican, respectively), with a second Algonquian dialect continuum in modern CT/RI/MA ("Southern New England Algonquian") and a third Algonquian subgroup in VT, NH and up to Nova Scotia (Abenaki, Passamaquoddy-Malecite, and Mi'gmaq). Except for Southern New England Algonquian, most of these languages survived into the 20th century, when modern linguists were able to document most of them–and the Puritans were unusually good field linguists by the standards of the time, at least for Massachusett.
By contrast, the linguistic patchwork of the South is spotty–much spottier than that of the North. Here is a map of language groups of North America at contact, to the best of our knowledge, adapted from Ives Goddard's breathtaking and more detailed version in vol. 17 of Handbook of North American Indians, which divides the families into their constituent languages. Note all that blank space in the South. We are pretty sure based on place-names that most of it must have been home to speakers of Iroquoian and Siouan languages (some of which did survive long enough to be documented decently, such as Catawba and Tutelo and Tuscarora), but we are really in the dark about much of the South, and even for some of the non-dark space the language in question is only well-known enough to us for us to place it with a family–we have a grand total of two words of Saponi, for example, but one of those is mąnį́ 'water' (cf. Lakota mnį 'water' or Minnesota 'cloudy water'), so we can place it with its cousins.
Also, doesn't Southern cuisine use more American ingredients than that of New England? Certainly the preponderance of cornmeal–but then cornmeal is a key ingredient of anadama bread. I will have to read Crosby.
"The agricultural packages of the Native Americans of the East Coast *themselves* weren't disrupted"
But they were! He describes this in depth. The pigs and the rats and the weeds and all that disrupted much of the indigenous farming systems and all of their hunting/gathering ones.
But the real argument I am making is that the non-reliance of the New Englanders on native resources meant they could afford genocidal conflict in a way that the Spaniards in Mexico could not.
National Geographic had one issue discussing that back in 2000s. But it was talk of Virginia
I've picked up a copy and will start sometime this week. Point taken about Mexico–I am curious to see what he says about Brazil, which is emphatically /not/ like Portugal at all but which did not fare as well as Mexico (though there was more syncretism than in the US).
It appears Blogger's comment function doesn't like URL tags: here's the URL of the map I mentioned. https://upload.wikimedia.org/wikipedia/commons/a/a5/Langs_N.Amer.png
Speed-read through Crosby.
An important point that is worth considering, particularly with regards to New England, is the time lag between ecological (mostly epidemiological) contact and colonization itself. In Peru and Mexico, there was relatively little time lag between first epidemiological contact and European colonization: Tenochtitlan was the capital of New Spain within three decades of Columbus's first landfall in the Caribbean, and Pizarro exploited a civil war whose proximate cause was a smallpox epidemic cutting through the ranks of the Inca ruling dynasty. Because Cortés and Pizarro conquered empires, they also inherited an entire state and social apparatus. The Spaniards ruled Peru in much the same way the Inca did, by organizing peasant households into larger estates and taxing them for their labor, and there were similar continuities in Mexico.
North of the Rio Grande, however, the time lag grows much more considerable. The earliest Spanish reports of the American Southeast report large chiefdoms and settlement; in 1500, Louisiana and Mississippi were densely packed with farmers, and we have every reason to believe this was true of the entire US east of about the longitude of Dallas or Omaha. But when the French return to the Mississippi valley in the early 17th century, they report a primeval landscape of buffalo herds roaming across great prairies.
The consensus conclusion these days–I don't know whether it was when Crosby first wrote in 1986–is that the colonists of North America, unlike those of Mexico or Peru, had the advantage that their diseases, plants and animals did much of their dirty work for them in the century before they settled for good. Crosby does note (pg. 147 of the 2004 edition) that at first contact the eastern US was probably more densely populated than sub-Saharan Africa. That was certainly true at first ecological contact around 1500, but between then and the first successful European colonies in the early 17th century, successive waves of epidemics destroyed huge numbers of settlements and created the illusion that eastern North America was an idyllic paradise sparsely populated here and there by simple corn-farming villages and chiefdoms.
So, in answer to your closing paragraph: to the extent that New England looked like a paradise of wildfowl and seafood in 1630 and not in 1660, I wouldn't be certain that it would have looked just as Edenic in 1490.
Doesn't seem so plausible to me. Admixture in Utah is not really greater than in New England, though the biome is much less similar to the European Old World. If it were about mastering local agricultural systems, and so needing to recruit locals, then there would be?
I would guess rather than culture or biome, beyond raw population size and relative death rates from disease and hypoxia (which surely explains most of the facts), the colonial economy matters. The Spanish Empire was largely an empire of silver, and the colonisation of the Cape a colonisation of gold. Men came for gold and silver. They made a place in those societies for local people they needed in that economic structure (to the most extent largely as wives).
For settler colonies based on agriculture, whether those in dry and more different biomes, or verdant and more similar biomes, whatever the talk of conversion to the Christian faith, there was no real drive to economically integrate locals in any sense, compared to the drives to employ cousins and nephews and nieces and countrymen.
(Of course there is also the problem, as Razib alludes to, of New England being a first port of call for later turnover, and not so much early ancestry left.)
Crosby sees the great basin, colorado plateau and the great plains as naturally more hostile to the European package, and part of the reason they were the last places settled. The Europeans won out there by sheer demographic weight–there are some similarities here to Pekka Hämäläinen's discussion of how the Comanche were able to fight off the Spanish for two centuries but fell to the Americans fairly quickly–but even in Utah the win was not complete. Demographic displacement in Utah and Arizona is one of the smallest in the nation–the Navajo nation still exists in great numbers!
"The consensus conclusion these days–I don't know whether it was when Crosby first wrote in 1986–is that the colonists of North America, unlike those of Mexico or Peru, had the advantage that their diseases, plants and animals did much of their dirty work for them in the century before they settled for good"
Crosby does discuss this. See especially his section on peach trees and pigs
The ratio of indigenous people to colonizers is the most important single factor, and the suitability of a European ecological-agricultural package to the local environment certainly played a big role in that. But indigenous population density is at least as important.
This is masked by the fact that the higher-latitude areas that were conducive to European settlement also tended to have lower population densities than the colonized tropics. Northeast American cultures were so hard hit by the early plagues that an entire civilization vanished before a single army of conquest could see it – there just weren't enough people left to support that kind of social complexity. But enough indigenous people remained in Mexico and Peru, even after the apocalyptic plagues, for Nahuatl and Quechua to remain relevant administrative languages for over a century after the conquests.
Australia, New Zealand, Argentina, and the Cape are similar to NE America – temperate and suitable to European settlement, and with relatively sparse indigenous populations, even before conquest.
The only non-European temperate zone with a large, dense population was Northeast Asia, which was never fully colonized. But even if some European country had been able to conquer China at the same time that New England was colonized, do we really think the North China Plain would be similarly European? And this is despite the fact that the Northeast Asian climate is very similar to that Northeast America, with a lot of familiar European staple crops and animals already being used locally.
I'm rather sceptical of how "European" Argentina is, at least genetically. Some studies have shown that most Argentinians have non-trivial amounts of Native ancestry.
Weren't there "grazing herds" of bison in North America?