Post by Admin on Mar 27, 2023 21:56:40 GMT
Figure 5
Y chromosome phylogeny of all male samples tested
Y chromosome phylogeny containing all male samples tested, including Ludwig van Beethoven, the six closest known living Y chromosome relatives of Ludwig van Beethoven within the FamilyTreeDNA database (FT1–FT6), five living descendants of Aert van Beethoven (VB1–VB5), and the Cramolini-Brown Lock.
(A) Deep phylogenetic overview within the last 50,000 years of three major clades harboring Ludwig van Beethoven and his closest living Y chromosome relatives (I-Z139), the living Aert van Beethoven descendants (R-Z2565), and the Cramolini-Brown Lock (R-Z283).
(B) Detailed phylogeny within the last thousand years outlining Ludwig van Beethoven’s Y chromosome lineage (blue outline; haplogroup I-FT396000), the living Van Beethoven Y chromosome lineage (orange outline; haplogroup R-FT446200), and the approximate hypothesized location of an extra-pair paternity (EPP) event within the Van Beethoven Y chromosome tree (dotted line). In blue parentheses are the numbers of confidently ascertained private variants (for Ludwig van Beethoven, see those with a 3-star rating in Data S1E).
Considering the strong historical and genetic evidence for the authenticity of the five matching hair samples, and our Y chromosome evidence for the lack of discontinuity in the paternal lineage between Aert van Beethoven and the five living descendants, we conclude that the most plausible explanation for our observations entails that at least one extra-pair paternity (EPP) event occurred on Beethoven’s direct paternal line, between the conception of Aert van Beethoven’s son Hendrik in Kampenhout, Belgium, in c.1572, and the conception of Ludwig van Beethoven seven generations later in 1770, in Bonn, Germany.
In order to further investigate the details of an EPP scenario and possibly ascertain Beethoven's genetic patrilineage, we queried the FamilyTreeDNA Y chromosome database, including >52,500 user records at high sequence resolution.30 We identified five closely related profiles descending from the I-FT396000 lineage within I1a-Z139, with a mean time to most recent common ancestor (TMRCA) of 1,018 (95% CI 714–1,419) years before present (Figure 5; Methods S1Q; Table S6). However, all five of these participants carried dissimilar surnames, consistent with the fixation of surnames in many parts of Europe occurring several centuries after the most probable TMRCA for I-FT396000. We were therefore unable to establish Beethoven’s direct genetic patrilineage and the surname of the individual involved in an EPP event.
In addition to testing the Y chromosomes of living Van Beethovens, we tested for IBD segment sharing among three living descendants of Beethoven’s nephew, Karl van Beethoven, who are documented as 7th-degree genetic relatives to Beethoven.23 Using IBIS,31 which can accurately detect IBD segments ≥7 cM, we detected no IBD segments ≥7 cM shared between Beethoven and the three participants. The IBD-sharing and mitochondrial relatedness detected among the participants internally, however, was consistent with their documented genealogy.
In order to better interpret this result, we performed 100,000 simulations on a reconstructed pedigree using pedSIM,32 including the three living descendants of Karl van Beethoven, and including Ludwig and Karl’s father, Kaspar Anton Karl van Beethoven (1774–1815), as full siblings. These simulations estimated an average of 47.23 detectable cM among 2.46 IBD segments ≥7 cM shared with Beethoven per descendant. The simulated probability for detecting zero IBD segments ≥7 cM shared between Beethoven and each individual participant averaged 9.08% (95% CI 8.9%–9.26%), while the probability of detecting zero ≥7 cM IBD-segment sharing with Beethoven among all three participants combined was 0.851% (95% CI 0.79%–0.91%).
However, given the virtual certainty that an EPP event occurred in Beethoven’s direct paternal ancestry, we could not assume with confidence that Ludwig and Kaspar Anton Karl were full siblings. In the event that Ludwig and Kaspar Anton Karl were half-siblings, the probability of detecting zero ≥7 cM IBD-segment sharing with Beethoven among all three participants combined was 8.34% (95% CI 7.81%–8.9%). As a result, we are unable to conclusively prove or disprove relatedness between Beethoven and the descendants of Karl van Beethoven, and are unable to provide further verification of sample authenticity on this basis.