Viral Shockwave 2: Gift from the Neanderthals

Where did all the dogs go?

When Europeans first reached the New World, the Native Americans didn’t have horses but they had dogs. Those dogs had come along with their masters from Siberia and had been on the continent for 9,000 years.

They’re all gone now. A study showed that looked for genes from Native American dogs in dogs from all over the the globe found almost no traces of their DNA. Where did they go? Why? This post may explain where and why.

Viral Shockwave

This is a continuation of my Viral Shockwave Theory, which states that pathogens play a major, and perhaps the primary role, in evolution, and that populations that can harbor pathogens benign to themselves but fatal to other populations have a major survival advantage.

Furthermore, I posit that clash of such populations, one armed with a co-evolved virus or pathogen, and one defenseless against it, has occurred multiple times in the past and has had an enormous impact on evolution, populations, and genetic makeup of organisms.

In fact, in the Red King Theory, I attribute evolution of aging and mortality itself to evolutionary pressure from pathogens.

One example I talked about was the holocaust visited upon Native American populations upon contact with Europeans. The virtual eradication of Native Americans by European diseases was a terrible tragedy. But if my theory is correct, there should be other examples of one group of people taking over a large swarth of territory formerly held by another group. And there should be evidence that pathogens and immunity played an important role. Is there evidence for that?

Yes.

All across the Old World, there is evidence that something big happened about five thousand years ago. Certain populations of people came and replaced the indigenous populations. It used to be thought that the new group assimilated or were assimilated into the pre-existing populations. That the newcomers mingled and mixed with the new group.

But DNA analysis is making it clear there was little mixing–the newcomers replaced the original inhabitants. Here is one example:

Here are some quotes from that article.

About 5,000 years ago, a “relatively sudden” mass migration of nomadic herders from the east — the steppes of eastern Ukraine and southern Russia — swept in and almost entirely replaced the continent’s existing communities of hunter-gatherers and early farmers.

After Europe and India, there were similar mass migrations identified in Africa, the Middle East and Southeast Asia.

People who live in a place today often bear no genetic resemblance to people who lived there thousands of years ago

Another example is Australia. In this paper, The origin and expansion of Pama–Nyungan languages across Australia, the authors document that the current dominant family language spread across Australia very quickly and displaced any previous ones.

So, the evidence says that often, entire populations of people in an area or continent periodically get replaced by an entirely different populations. That what happened with Native Americans might have happened in other places.

But are those wholesale replacements due to disease? Maybe it’s because of superior technology, like guns, steel, horses. Or back further, Inuit dogsleds, Mongol recursive bows, or Roman phalanx.

We can argue back and forth about the importance of technology, and certainly they playe da role. But consider several facts:

  • Even as recently as World War I, disease killed more soldiers than combat. Historically, that has overwhelmingly been the case in wars.
  • Until disease eradicated much of the Native Americans, Europeans settlements couldn’t find purchase in the New World, despite the superior technology.
  • Until quinine was discovered, Europeans couldn’t penetrate and conquer the malaria-infested African continent. (Ironically, quinine was discovered as result of European conquest of the New World, which was made possible by Viral Shockwave eliminating much of the native human society.)

But we don’t have to argue to resolve this. There is scientific data. Let’s look at when modern humans clashed with Neanderthals.

We Absorbed Neanderthal Immune Genes

It appears that Neanderthals were very successful, and spread out over huge swathes of Europe. They were very well-adapted group. For a long time, they faced little encroachment from us. Then they disappeared.

For a long time, things like climate change was thought to have been the reason for a highly successful population suddenly disappearing.

I don’t think so. My theory is that either 1) we evolved a new virus or pathogen that we were adapted to but Neanderthals weren’t. The virus swept the way clear for us, who were not nearly as adapted to Northern climates as the Neanderthals, to step into the vacated areas (like we did when we spread out over North America) or 2) Neanderthals had diseases to which we didn’t have immunity, but we eventually gained immunity to them.

I think #1 is more likely, with some help from #2. Until recently, we thought we didn’t interbreed with Neanderthals. But in 2010, that assumption was turned on its head, and two groups published evidece that in fact, we have some of their genes. If you look in our genome, 1%-4% percent of our genes are from Neanderthals. Some of those genes are for things like red hair, or light skin,  But guess what. A lot of those genes we copped from Neanderthals, perhaps up to about half of those genes, are immune-related, as noted in multiple articles:

Adaptively introgressed Neandertal haplotype at the OAS locus functionally impacts innate immune responses in humans

Preserving Immune Diversity Through Ancient Inheritance and Admixture

The Contribution of Neanderthals to Phenotypic Variation in Modern Humans

Introgression of Neandertal- and Denisovan-like Haplotypes Contributes to Adaptive Variation in Human Toll-like Receptors

Genomic Signatures of Selective Pressures and Introgression from Archaic Hominins at Human Innate Immunity Genes

 

Commentary by Nature on the last two articles says:

Immunity boosted by archaic humans

Genes inherited from ancient hominins have improved the human immune system.

Homo sapiens interbred with Neanderthals and other ancient humans called Denisovans less than 100,000 years ago. Janet Kelso and her team at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, looked for Neanderthal and Denisovan genetic ancestry that has benefited humans by analysing the genomes of hundreds of people from around the world. They found a cluster of three Toll-like receptor (TLR) genes, which are involved in rapidly sensing and responding to infections as part of the innate immune response. Two Neanderthal versions of this cluster and one from Denisovans are common in different human populations. The archaic TLR genes are linked to reduced susceptibility to a bacterial infection of the stomach, but also to higher rates of allergies.

In a separate study, a team led by Lluis Quintana-Murci at the Pasteur Institute in Paris identified innate immunity genes that Europeans and Asians seem to have inherited from Neanderthals, including the same cluster of TLR genes.

Let me repeat that. We kept less than 4% of the Neanderthal genes, and about half of those appear to be related to immune function. Generally, in cases like this, only the really important genes, and superior genes, are retained. For example, Nepalese kept the Denisovian gene that allows them to function well in low oxygen environment.

Now let’s look at another piece of evidence. Biological warfare. It’s terrible. It’s terribly effective. And used over and over. Here is a quote from the article, History of biological warfare and bioterrorism.

The Hittites might have produced the first documented example of biowarfare by sending diseased rams (possibly infected with tularaemia) to their enemies to weaken them. In the fourth century BC, the Greek historian Herodotus relates that Scythian archers used to infect their arrows by dipping them in a mixture of decomposing cadavers of adders and human blood.

And below are some historical examples.

Year Event
~1400 BC The Hittites send rams infected with tularaemia to their enemies
~400 BC According to Herodotus, Scythian archers infect their arrows by dipping them into decomposing cadavers
1155 Barba rossa poisons water wells with human bodies, Tortona (Italy)
1346 Mongols hurl bodies of plague victims over the walls of the besieged city of Caffa (Crimea)
1422 Lithuanian army hurls manure made of infected victims into the town of Carolstein (Bohemia)
1495 Spanish mix wine with blood of leprosy patients to sell to their French foes, Naples (Italy)
1650 Polish army fires saliva from rabid dogs towards their enemies
1710 Russian army catapult plague cadavers over the Swedish troops in Reval (Estonia)
1763 British officers distribute blankets from smallpox hospital to Native Americans
1797 The Napoleonic armies flood the plains around Mantua (Italy), to enhance the spread of malaria among the enemy
1863 Confederates sell clothing from yellow fever and smallpox patients to Union troops during the American Civil War

 

In fact, some Neanderthal genes are so important that they were brought back to Africa and spread. As you might expect, many of those genes are related to the immune response. The other is to UV resistance.

So now we return to the dogs.

Most likely, the Native American dogs suffered the same fate as Native Americans. I think that the Old World canine diseases probably wiped out the New World dogs.

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