Domen
Misico dux Vandalorum
According to new scientific publications concerning fossil DNA of prehistoric Scandinavians (Malmström et al. 2009, Skoglund et al. 2012, Lazaridis et al. 2014, Szécsényi-Nagy et al. 2014, Skoglund & Malmström et al. 2014), prehistoric population continuity in Scandinavia was broken by new large waves of immigrations. That most likely started taking place between 5,000 and 4,000 years ago, when the Pitted Ware Culture (pottery-making hunters) disappeared.
Analysis of prehistoric fossil Y-DNA from Scandinavian human remains shows that their haplogroups were different than haplogroups of modern Scandinavians. It appears that all of modern "typically Scandinavian" Y-DNA haplogroups came from continental Europe during the last few thousand years.
Haplogroup I1, for example, according to new discoveries (2014) was present among the inhabitants of what is now Hungary during the period in Hungary's history known as the Linear Pottery Culture Transdanubian (LBKT). And that was 2,000 - 3,000 years before this HG first came to Scandinavia.
Also analysis of mitochondrial haplogroups of prehistoric and modern Scandinavians suggested genetic discontinuity between these two populations.
Mitochondrial HGs of people who lived in Sweden between 7500 BC and 2000 BC (sample size: 28 people):
U - 1 -------------- 3,57%
U2e1 - 2 ------- 7,14%
U4 - 6 ------------ 21,43%
U4b1 - 1 -------- 3,57%
U4d - 3 ---------- 10,71%
U5a1 - 3 -------- 10,71%
U5a1a'g - 2 ---- 7,14%
U5a2 - 1 ------- 3,57%
U5a2d - 2 ------ 7,14%
U5b - 2 --------- 7,14%
U5b2b1a - 1 -- 3,57%
HV - 1 ---------- 3,57%
V - 1 ------------ 3,57%
T2b - 1 --------- 3,57%
K1a - 1 --------- 3,57%
Mitochondrial HGs of modern ethnic Swedish people, not including recent immigrants (sample size: 307 people):
1) Haplotypes completely not present in prehistoric Sweden (at least 63% of the population):
C: 0.3%
H: 8.1%
H1: 12.7%
H1a: 2.3%
H1b: 1.3%
H1f: 1%
H2a1: 9.1%
H2: 2%
H3: 3.9%
H5: 1.3%
H6: 3.9%
I: 3.3%
J: 2.3%
J1: 2.6%
J1a: 0.3%
J1b1: 0.3%
J2: 0.3%
T1: 2.9%
W: 1.3%
X: 0.3%
Z: 0.3%
Other haplogroups: 3.3%
2) Haplotypes present already in prehistoric Sweden (no more than 37% of the population):
K: 7.5%
T: 7.2%
U3: 1.3%
U: 3.3%
U2: 0.3%
U4: 2.9%
U5: 0.7%
U5a: 4.6%
U5a1: 2%
U5b: 3.9%
U5b1b: 2%
V: 1.3%
=======================================
As we can see only 37% of modern Swedes have maternal haplogroups of similar types as prehistoric inhabitants of Sweden. However, assuming that all of these 37% of modern Swedes are descendants of prehistoric population of Sweden would be wrong, because it would require an assumption that immigrants who came to Sweden during the last few thousand years did not bring any of these haplogroups with them. Immigrants brought with them to Sweden not only haplogroups which had not been present in prehistoric Sweden, but also some percent of those haplogroups which had been found among prehistoric Swedes (because those haplogroups - such as U4 or U5 - in prehistoric times were not limited just to Sweden, but were far more widespread).
Therefore 1/3 of mitochondrial gene pool would be the absolute maximum of possible prehistoric descent in modern Sweden. But the real amount of prehistoric Scandinavian ancestry in modern Scandinavians is almost certainly much lower this absolute possible maximum.
To demonstrate this, let's compare the frequencies of two mtDNA types most common in prehistoric Sweden - U5 and U4.
In samples from Sweden dating to 7500 BC - 2000 BC, almost 40% (39,27%) of all people had U5 (all of its variants) and almost 36% (35,71%) had U4 (all of its variants). By comparison just 13,2% of modern Swedes have U5 and just 2,9% of modern Swedes have U4.
While U5 is only 3-times less common today than in prehistoric times, U4 is as much as 12-times less common (!) in modern Sweden than in prehistoric Sweden. Thus we can assume that immigrants to post-prehistoric Sweden brought some U5 with them, but not much or none of U4.
All in all a reasonable estimate is that just between 10% (or slightly less) and 20% (at the most) of modern Swedish mitochondrial lineages date back to prehistoric Scandinavia. The rest are descendants of people who immigrated to Sweden during the last 4000 or 5000 years, in several major migration events. In case of paternal lineages (Y-DNA) the % of prehistoric Swedish ancestry is even smaller - MUCH smaller - than in case of mitochondrial lineages (however, sample sizes of fossil Y-DNA are smaller, so this assertion is less certain than in case of mtDNA).
=========================================
Finally, let's also compare autosomal DNA (genes responsible for physical appearance, etc.) of modern and ancient populations of Sweden.
It is shown by this two-dimensional graph showing genetic distances between populations:
As we can see hunter-gatherers from prehistoric Sweden were not similar to any modern European population, including the Swedes themselves.
On the other hand, the earliest groups of Late Neolithic and Early Chalcolithic farmers who immigrated to Sweden were pretty similar in terms of autosomal DNA (overal physical appearance, etc.) to people such as modern Basques, Tuscans, Sardinians, etc., but again NOT to modern Swedes.
So the question "when did Swedes come to Sweden" remains open to discussion, but it was probably happening from the Copper or Bronze Age onwards.
And when it comes to Denmark:
This 2010 publication suggests the Iron Age and the Viking Age (!) as times when major immigrations (!) to Denmark took place:
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011898
During the Iron Age and the Viking Age, % frequency of mtDNA haplogroups U4 and U5 was significantly declining in Denmark. This implies large immigrations of foreigners to Denmark in those perods - and those foreigners had either no or much less of U4 and U5:
===========================================
What is interesting, the Sami minority in Sweden are also NOT similar to prehistoric "Swedes" in terms of autosomal DNA.
Quite the contrary - the Sami are much different in terms of DNA than most of Europeans, and show some similarities to East Asians.
The conclusion that the Sami are late BC / early CE immigrants to Europe from North-Eastern Asia will not be far from the truth.
Analysis of prehistoric fossil Y-DNA from Scandinavian human remains shows that their haplogroups were different than haplogroups of modern Scandinavians. It appears that all of modern "typically Scandinavian" Y-DNA haplogroups came from continental Europe during the last few thousand years.
Haplogroup I1, for example, according to new discoveries (2014) was present among the inhabitants of what is now Hungary during the period in Hungary's history known as the Linear Pottery Culture Transdanubian (LBKT). And that was 2,000 - 3,000 years before this HG first came to Scandinavia.
Also analysis of mitochondrial haplogroups of prehistoric and modern Scandinavians suggested genetic discontinuity between these two populations.
Mitochondrial HGs of people who lived in Sweden between 7500 BC and 2000 BC (sample size: 28 people):
U - 1 -------------- 3,57%
U2e1 - 2 ------- 7,14%
U4 - 6 ------------ 21,43%
U4b1 - 1 -------- 3,57%
U4d - 3 ---------- 10,71%
U5a1 - 3 -------- 10,71%
U5a1a'g - 2 ---- 7,14%
U5a2 - 1 ------- 3,57%
U5a2d - 2 ------ 7,14%
U5b - 2 --------- 7,14%
U5b2b1a - 1 -- 3,57%
HV - 1 ---------- 3,57%
V - 1 ------------ 3,57%
T2b - 1 --------- 3,57%
K1a - 1 --------- 3,57%
Mitochondrial HGs of modern ethnic Swedish people, not including recent immigrants (sample size: 307 people):
1) Haplotypes completely not present in prehistoric Sweden (at least 63% of the population):
C: 0.3%
H: 8.1%
H1: 12.7%
H1a: 2.3%
H1b: 1.3%
H1f: 1%
H2a1: 9.1%
H2: 2%
H3: 3.9%
H5: 1.3%
H6: 3.9%
I: 3.3%
J: 2.3%
J1: 2.6%
J1a: 0.3%
J1b1: 0.3%
J2: 0.3%
T1: 2.9%
W: 1.3%
X: 0.3%
Z: 0.3%
Other haplogroups: 3.3%
2) Haplotypes present already in prehistoric Sweden (no more than 37% of the population):
K: 7.5%
T: 7.2%
U3: 1.3%
U: 3.3%
U2: 0.3%
U4: 2.9%
U5: 0.7%
U5a: 4.6%
U5a1: 2%
U5b: 3.9%
U5b1b: 2%
V: 1.3%
=======================================
As we can see only 37% of modern Swedes have maternal haplogroups of similar types as prehistoric inhabitants of Sweden. However, assuming that all of these 37% of modern Swedes are descendants of prehistoric population of Sweden would be wrong, because it would require an assumption that immigrants who came to Sweden during the last few thousand years did not bring any of these haplogroups with them. Immigrants brought with them to Sweden not only haplogroups which had not been present in prehistoric Sweden, but also some percent of those haplogroups which had been found among prehistoric Swedes (because those haplogroups - such as U4 or U5 - in prehistoric times were not limited just to Sweden, but were far more widespread).
Therefore 1/3 of mitochondrial gene pool would be the absolute maximum of possible prehistoric descent in modern Sweden. But the real amount of prehistoric Scandinavian ancestry in modern Scandinavians is almost certainly much lower this absolute possible maximum.
To demonstrate this, let's compare the frequencies of two mtDNA types most common in prehistoric Sweden - U5 and U4.
In samples from Sweden dating to 7500 BC - 2000 BC, almost 40% (39,27%) of all people had U5 (all of its variants) and almost 36% (35,71%) had U4 (all of its variants). By comparison just 13,2% of modern Swedes have U5 and just 2,9% of modern Swedes have U4.
While U5 is only 3-times less common today than in prehistoric times, U4 is as much as 12-times less common (!) in modern Sweden than in prehistoric Sweden. Thus we can assume that immigrants to post-prehistoric Sweden brought some U5 with them, but not much or none of U4.
All in all a reasonable estimate is that just between 10% (or slightly less) and 20% (at the most) of modern Swedish mitochondrial lineages date back to prehistoric Scandinavia. The rest are descendants of people who immigrated to Sweden during the last 4000 or 5000 years, in several major migration events. In case of paternal lineages (Y-DNA) the % of prehistoric Swedish ancestry is even smaller - MUCH smaller - than in case of mitochondrial lineages (however, sample sizes of fossil Y-DNA are smaller, so this assertion is less certain than in case of mtDNA).
=========================================
Finally, let's also compare autosomal DNA (genes responsible for physical appearance, etc.) of modern and ancient populations of Sweden.
It is shown by this two-dimensional graph showing genetic distances between populations:
As we can see hunter-gatherers from prehistoric Sweden were not similar to any modern European population, including the Swedes themselves.
On the other hand, the earliest groups of Late Neolithic and Early Chalcolithic farmers who immigrated to Sweden were pretty similar in terms of autosomal DNA (overal physical appearance, etc.) to people such as modern Basques, Tuscans, Sardinians, etc., but again NOT to modern Swedes.
So the question "when did Swedes come to Sweden" remains open to discussion, but it was probably happening from the Copper or Bronze Age onwards.
And when it comes to Denmark:
This 2010 publication suggests the Iron Age and the Viking Age (!) as times when major immigrations (!) to Denmark took place:
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011898
During the Iron Age and the Viking Age, % frequency of mtDNA haplogroups U4 and U5 was significantly declining in Denmark. This implies large immigrations of foreigners to Denmark in those perods - and those foreigners had either no or much less of U4 and U5:
"However, the frequency of Hg U4 and U5 declines significantly among our more recent Iron Age and Viking Age Danish population samples to the level observed among the extant Danish population. Our study therefore would point to the Early Iron Age and not the Neolithic Funnel Beaker Culture as suggested by Malmström et al. (2009) [14], as the time period when the mtDNA haplogroup frequency pattern, which is characteristic to the presently living population of Southern Scandinavia, emerged and remained by and large unaltered by the subsequent effects of genetic drift."
===========================================
What is interesting, the Sami minority in Sweden are also NOT similar to prehistoric "Swedes" in terms of autosomal DNA.
Quite the contrary - the Sami are much different in terms of DNA than most of Europeans, and show some similarities to East Asians.
The conclusion that the Sami are late BC / early CE immigrants to Europe from North-Eastern Asia will not be far from the truth.