alternatehistory.com

Tentatively, my scenario features a POD of the native's across both continents having more diverse haplogroups. To tl;dr as much as possible - haplogroups are groupings of mitochondrial DNA. Minute (.2-.3%) mutations happen in mDNA every ten thousand years or so. Since mDNA is only passed down via the mother's line, and never recombines with the Y-DNA of the Y-chromosome that passes down the father's lines, its possible to track population movements and divergences by a population's haplogroup.

Across all of the native populations of both American continents, there are only four haplogroups, three of which are commonly found throughout Siberia and parts of Eurasia. However, the unimaginatively named Haplogroup A has a clear majority in populations of the Americas, but it is not found anywhere else on the planet.

Here I'm going to jump tracks slightly, and make an important distinction before continuing. There are two types of susceptibility to disease; the first is from lack of acquired immunity - immunity gained from an individual's previous exposure to a pathogen. To take a well known example think of chicken pox; people who have never been exposed to chicken pox are readily infected by it, but those that have been previously exposed to it almost never become (re-)infected. Since native Americans had never been exposed to European diseases, and vice-versa, both groups were easily susceptible to each others' diseases.

The second type of susceptibility is genetic in nature. Research has shown that native populations as a whole had more restricted immune systems due to only having a limited number of haplogroups within the population. A quirk of this is that nine of ten native americans, even today, have Type O blood, whereas Europeans are fairly evenly split between Type O and Type A.

Speaking purely from an evolutionary stand point, genetic homogeneity by itself is neither a positive nor a negative trait. It can be beneficial; according to most earlier reports combined with modern day research and genetics, we now know that almost all native populations prior to European contact were totally devoid of cystic fibrosis, Huntington's chorea, newborn anemia, schizophrenia, asthma, and juvenile diabetes - all because they had a limited gene pool which did not include the necessary keys for those diseases.

However, when combining genetic homogeneity with the sudden appearance of previously unknown pathogens..

Human leukocyte antigens (HLAs) are molecules inside most human cells that are key to our bodies defenses. HLAs basically (and again, I'm simplifying this a lot) transport recycled material from inside cells, including bits of foreign invaders that a cell might pick up and use, to the surface of the cell. From there passing white blood cells scan the cell walls. If they detect something that shouldn't be there, they destroy the cell in question immediately. Of course this means that if an HLA doesn't bring that bit of virus within the cell to the cell wall, the white blood cell doesn't see it, doesn't destroy it, and the virus is allowed to run its course.

The way HLAs work is that they fit their loads to carry by fitting them into a kind of 'slot.' If a snippet of material within the cell doesn't fit into an HLA's slot, it can't carry it.

All people have multiple types of HLAs, which means they can bring almost every potential problem to the attention of their white blood cells. However, no matter what his/her genetic endowment, no one person immune system has enough different HLAs, or even the capability to have enough different HLAs, to catch every single problem that might arise. If a man sneezes in a crowded elevator, releasing ten variants of the cold-causing rhinovirus, the other man next to him might be lucky enough to have the exact ten HLAs to prevent him from getting sick. Not so lucky is the woman on the other side who only has eight, or even nine, of the HLAs needed to block the disease; she gets sick. So even missing out on one potentially dangerous pathogen can have large effects.

Most human groups are a real scattershot of HLA profiles, meaning of course that while several individuals might come down with a particular sickness, the group itself will survive. Unsurprisingly, thanks to the lack of diverse haplogroups, native populations have lesser HLA diversity than Afro-Eurasias do. Europeans alone as a group have thirty-five main HLA groups; native south americans have less than seventeen. This means that in South America the minimum probability that one particular strand of a particular pathogen in one host will encounter a host with a similar (lack) of immune spectrum is 28%. To contrast that, in Europe the probability is less than 2%.

My POD would posit that the other haplogroups within native populations would have a higher representation in the population, thus leading to more genetic diversity even within such a narrow genetic field. Instead of seeing a death-rate from initial exposure to diseases such as smallpox well in excess of 50% (in some areas, particularly the highly urbanized areas of Mesoamerica and the Andes, research has shown death-rates reached 96%!), under this AH we might see a death-rate of only 50%, or less. As a comparison, the Black Plague has been estimated to have a had a median death-rate of 45%.

Of course this still means a large society-wide upheaval, but it doesn't mean complete and total collapse. To point out a fairly obvious example, look at the Triple Alliance ('Aztecs').

Even after allying themselves with the neighboring Tlaxcala, killing Moctezuma, burning and/destroying via cannon-fire much of Tenochtitlan, cutting of the drawbridges leading to the city and destroying the aqueduct feeding it freshwater, the Spanish under Cortes were still almost destroyed during the final eight-month Siege of Tenochtitlan. To quote from 1491:
[Following La Noche Triste] Because the Mexica did not view the goal of warfare as wiping out enemies to the last man, they did not hunt down the last Spaniards. A costly mistake: Cortes was among the escapees.

A man of unfathomable determination, Cortes never thought of giving up. He persuaded several other vassal states to join his anti-Alliance alliance with Tlaxcala. Negotiating furiously, he assembled a force of as many as 200,000 men and built thirteen big ships (brigantines) in an audacious plan to assault Tenochititlan from the water. He followed this plan and ever after has been identified by history as the city's conquer. But all of his bold resolve would have come to nothing without the vast indigenous army whose leaders believed that they could use the Spanish presence to catalyze the destruction of the Triple Alliance (by this point Cortes had lost well over 1/2 of his men, and was down to only 20 horses). And even this enormous force might not have overcome the Empire (remember that the Triple Alliance completely surrounded the Tlaxcala and other vassal states and ruled over populations in the millions) if while Cortes was building his ships Tenochtitla had not been swept by smallpox. Without any apparent volition by Cortes, the great city lost at least a third of its population to the epidemic, including the new emperor Cuitlahuac.

When Cortes and his Indian allies finally attacked, the Mexica resisted so fiercely that despite their weakness (due to smallpox) that the siege has often been described as the costliest battle in history - casualty estimates range up to 100,000. Absent smallpox, it seems likely that Cortes would have been lost.
Emphasis added in parenthesis ()'s is mine.

Sorry to drop all this on you but it kinda takes a lot to explain, and honestly I haven't been able to think of any other ways to posit a realistic way for the natives to survive initial European contact and colonization without fundamentally changing either the natives or Afro-Eurasians :eek:.

So, anyone got any thoughts, comments, critiques?
Top