Climate shaped the Neolithic Advance

Angela

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Lia Betti et al:

"Climate shaped how Neolithic farmers and European hunter-gatherers interacted after a major slowdown from 6,100 BCE to 4,500 BCE"

https://www.nature.com/articles/s41562-020-0897-7

"Abstract

The Neolithic transition in Europe was driven by the rapid dispersal of Near Eastern farmers who, over a period of 3,500 years, brought food production to the furthest corners of the continent. However, this wave of expansion was far from homogeneous, and climatic factors may have driven a marked slowdown observed at higher latitudes. Here, we test this hypothesis by assembling a large database of archaeological dates of first arrival of farming to quantify the expansion dynamics. We identify four axes of expansion and observe a slowdown along three axes when crossing the same climatic threshold. This threshold reflects the quality of the growing season, suggesting that Near Eastern crops might have struggled under more challenging climatic conditions. This same threshold also predicts the mixing of farmers and hunter-gatherers as estimated from ancient DNA, suggesting that unreliable yields in these regions might have favoured the contact between the two groups."



There's some nice figures, but difficult to see.
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This study is best summarised by this video in the supplements.

41562_2020_897_MOESM2_ESM.gif
 
Well, if they're correct, Cardial were just an offshoot of the original group, not a separate one genetically.

Also, the early spread to Cyprus would appear to have been a dead end.
 
The pauses took place at specific times along each track: 6200 BCE for Central Europe, 5400 BCE for Scandinavia, and 5700 BCE for northeastern Europe, and were all linked to the fact that the climate in those places at those times were not appropriate for the Middle Eastern crops the farmers brought with them. It had to do with the number of summer "growing days" over 5 degrees celsius and overall summer temperatures, not the severity of winter temperatures per se.

I think we all suspected this, but it's nice to see it documented.

Also interesting, these pauses show more admixture with local hunter-gatherers at the times and places of the "pause". Makes sense. They weren't forging ahead, but staying put for a few hundred years, and knowing where the best hunting and fishing were located to make up for less crop production would have been helpful.

There's no evidence that the increased admixture was because there was a greater density of hunter-gatherers in those areas.

The climate seems to have been so bad, that in the British Isles and most of Scandinavia cereal production nearly ceased. They must have relied completely on animal husbandry. In those places where it didn't cease, like some Scottish Islands and some parts of Scandinavia they turned to barley.

Crop growing came back to the British Isles in the Bronze Age because new varieties of wheat had been developed which could be planted in spring and harvested in fall, unlike the original varieties which were planted in autumn and harvested in the spring. Those varieties couldn't grow in the cold, wet winters of the Isles.
 
Well, if they're correct, Cardial were just an offshoot of the original group, not a separate one genetically.

It's a shame that they did not document the Neolithic progression in North Africa, as there is no way to know from their data points if the Cardial farmers in Southwest Europe really came straight from Greece (apparently bypassing Italy completely) or came via North Africa. The fact that the oldest Neolithic settlements in Southwest Europe are in Andalusia (La Almagra) seem to suggest a diffusion along the North African coast.
 
It's a shame that they did not document the Neolithic progression in North Africa, as there is no way to know from their data points if the Cardial farmers in Southwest Europe really came straight from Greece (apparently bypassing Italy completely) or came via North Africa. The fact that the oldest Neolithic settlements in Southwest Europe are in Andalusia (La Almagra) seem to suggest a diffusion along the North African coast.

Sorry. I'm not following.

They clearly show a split off in Greece and then across into Italy and eventually to Spain. They mention in the paper some of it was a sea based diffusion. The dates seem to leave no doubt, with the earliest in the eastern regions.
 
Sorry. I'm not following.

They clearly show a split off in Greece and then across into Italy and eventually to Spain. They mention in the paper some of it was a sea based diffusion. The dates seem to leave no doubt, with the earliest in the eastern regions.

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What was the population before agriculture in Europe, is there an estimation as to the population density?
 
What was the population before agriculture in Europe, is there an estimation as to the population density?

In one of our recent threads a paper was quoted as saying that the population levels of the Mesolithic hunter-gatherers in southern, central, western, and even northern Europe were extremely low. What the case was on the steppe with the EHG I don't know.

I've been saying that for ten years. The only settlements we've found with any appreciable numbers of people were around fishing areas. It's extremely difficult to support a population on hunting/fishing and gathering. It's been speculated they must have practiced not only long weaning to decrease fertility, but infanticide in order to keep their numbers low.

The paper to which I'm referring mentioned the high runs of homozygocity even in widely scattered people. Unfortunately, I can't remember the thread in which it appeared. I'll try to use the search engine to see if I can find it.
 
Sorry. I'm not following.
They clearly show a split off in Greece and then across into Italy and eventually to Spain. They mention in the paper some of it was a sea based diffusion. The dates seem to leave no doubt, with the earliest in the eastern regions.
You can see that the blue line goes straight from Greece to Aquitaine in SW France. The data points in the supplements confirm it. The sites of La Lede du Gurp in Aquitaine and La Roche aux Fées in Brittany are both dated 7360 BP. The only contemporary point in Italy at the time is Torrente Cervaro (province of Taranto, Apulia). There is a complete gap between Apulia and western France.
Looking at Italy, France and Iberia, the next data points are:
- Scamuso in Apulia : 7290 BP
- Terragne in Manduria, Apulia : 7260 BP
- Mendandia near the border of Castille & Leon and the Basque country : 7210 BP
- La Revilla del Campo near Burgos, Castille & Leon : 7165 BP
- La Lampara, Castille & Leon : 7136 BP
- Pulo di Molfetta, near Bari, Apulia : 7134 BP
- Masseria Giuffreda near Foggia, Apulia : 7125 BP
- Rendina, border Apulia-Basilicata : 7110 BP
- Pontcharaud in Clermont-Ferrand, Auvergne : 7095 BP (oldest sample listed as Epicardial)
- Scaramella near Foggia, Apulia : 7000 BP
- Abri de la Poujade near Millau, border of Languedoc and Auvergne : 6990 BP
- Defensola, Gargano, Apulia : 6990 BP
and so on...
So we see Neolithic sites popping up a bit all around central and western France and in central and northern Spain. But in the meantime all Italian sites are confined to Apulia, opposite Albania and Greece. For many centuries there is just no link between the two that passes through the rest of Italy or Southeast France. It's only later that the gaps in between start to fill little by little. Curious, isn't it?
 
^^I don't find it curious because I don't interpret the data points in that way. We can't ignore the light blue dots along the lines through Italy and France. That would be giving the graphic a far too literal interpretation, imo.

Those were the seeding areas, which as they mentioned in the paper backfilled through time.

There's nothing really new about what this paper is telling us, other than tying it in with admixture between farmers and HG and explaining the pauses we knew took place with more precise climate data.

These maps, some with more precise dates per area, may be more helpful.

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The Neolithic Advance didn't pass Italy by; it still went through Italy, but there seems to have been a pause even in the Mediterranean route, reflected in the difference between Impressa and Cardial perhaps.

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