Indo-Europeans caused Y-chromosome bottleneck during Neolithic period?

[Brian G Turner]

An interesting study suggests that severe tribal warfare may have been responsible for a serious lack of diversity in male genes after 5,000 BC - an event term the Neolithic Y-chromosome bottleneck: Wars and clan structure may explain a strange biological event 7,000 years ago

However, I find myself speculating on how this may be directly related to the expansion of Indo-Europeans, around 4,500 BC.

While the dates don't exactly align, this isn't uncommon when comparing archaeology and molecular biology - especially when the Indo-European entry into Europe saw the almost complete destruction of the original Western Europe genetic lines:

Beaker People replaced original Britons
Indo-Europeans brought plague to Europe?

This is especially after a recent suggestion that - before the Indo-European invasion - Britons were black: First modern Britons had 'dark to black' skin, Cheddar Man DNA analysis reveals

 

[Brian G Turner]

Updating this thread, as recent research in Sweden suggests the arrival of plague in the Neolithic might have actually preceded the Indo-Aryan migration: Ancient, Unknown Strain of Plague Found in 5,000-Year-Old Tomb in Sweden

The new findings contradict an older theory about how plague spread, according to the researchers. About 5,000 years ago, humans migrated from the Eurasian steppe down into Europe in major waves, replacing the Neolithic farmers who lived in Europe at that time. Previous research had suggested the steppe folk brought the plague with them, wiping out pre-existing settlements upon their arrival. However, if the plague specimen from the Swedish grave diverged from other strains 5,700 years ago, it likely evolved before the steppe migrations began — suggesting it was already there.

Rather, the researchers suggested that the plague emerged in so-called mega settlements of 10,000 to 20,000 inhabitants that existed in Europe between 6,100 and 5,400 years ago. These mega settlements — up to 10 times larger than previous European settlements — "had people, animals, and stored food close together, and, likely, very poor sanitation. That's the textbook example of what you need to evolve new pathogens," senior study author Simon Rasmussen, a computational biologist at the University of Copenhagen, said in a statement.

If plague evolved in these mega settlements, "then when people started dying from it, the settlements would have been abandoned and destroyed. This is exactly what was observed in these settlements after 5,500 years ago," Rasmussen said. Plague then could have spread across trade networks made possible by wheeled transport, which had expanded rapidly throughout Europe by that time, Rascovan said. Eventually, it would have made its way even to relatively distant sites like Frälsegården in Sweden, where the woman the researchers analyzed died. That woman's DNA revealed she was not genetically related to steppe folk, supporting the idea that this ancient strain of plague arrived before the migrants came from the steppe.