If you have a Western Atlantic Modal Haplotype Match badge in the Badges section of your dashboard, it means that you match or are close to the historic Western Atlantic Modal Haplotype (WAMH) that has been reported in Y-chromosome population genetics studies.
The first studies referencing the WAMH were published in 2001. Based on six STR (short tandem repeat) markers, they noted a distinctive motif (haplotype) that along with its near matches represented an overwhelming number of European and even Western Asian Y-chromosome lineages. The motif has since been noted for its presence in or absence from populations in many journal articles.
Today we know, thanks to superior levels of STR testing and advances in haplogroup testing, that this motif, even at 12 STR markers, does not represent a single founder dating to the last ice age but many different lineages within haplogroup R-M269. Due to the rapid population expansion that took place at the end of the last ice age, these lineages at low levels of testing have experienced convergence. That is, they have mutated to look alike even though they do not share even middling deep ancestry.
Relevant to our customers, this 12-marker haplotype represents about 1.3% of European male lines. This is why we recommend that those who have the WAMH use the Y-67 or Y-111 test to confirm genealogical relationships unless they have a rare surname.
Sources:
McEvoy, B., M. Richards, P. Forster, and D. Bradley (2004, October). The longue durée of genetic ancestry: Multiple genetic marker systems and celtic origins on the atlantic facade of europe. The American Journal of Human Genetics 75 (4), 693-702.
Morelli, L., D. Contu, F. Santoni, M. B. Whalen, P. Francalacci, and F. Cucca (2010). A comparison of y-chromosome variation in sardinia and anatolia is more consistent with cultural rather than demic diffusion of agriculture. PloS one 5 (4).
Novelletto, A. (2007). Y chromosome variation in europe: Continental and local processes in the formation of the extant gene pool. Annals of Human Biology 34 (2), 139-172.
Pichler, I., J. C. Mueller, S. A. Stefanov, A. D. Grandi, C. B. Volpato, G. K. Pinggera, A. Mayr, M. Ogriseg, F. Ploner, T. Meitinger, and P. P. Pramstaller (2006). Genetic structure in contemporary south tyrolean isolated populations revealed by analysis of y-chromosome, mtdna, and alu polymorphisms. Human Biology 78 (4), 441-464.
Renfrew, C. (2001, April). From molecular genetics to archaeogenetics. Proceedings of the National Academy of Sciences of the United States of America 98 (9), 4830-4832
Weale, M., L. Yepiskoposyan, R. Jager, N. Hovhannisyan, A. Khudoyan, O. Burbage-Hall, N. Bradman, and M. Thomas (2001, December). Armenian y chromosome haplotypes reveal strong regional structure within a single ethno-national group. Human Genetics 109 (6), 659-674.
Wilson, J. F., D. A. Weiss, M. Richards, M. G. Thomas, N. Bradman, and D. B. Goldstein (2001, April). Genetic evidence for different male and female roles during cultural transitions in the british isles. Proceedings of the National Academy of Sciences of the United States of America 98 (9), 5078-5083.
Yepiskoposian, L., A. Harutyunian, and A. Khudoyan (2006). Genetic testing of language replacement hypothesis in southwest asia. Iran and the Caucasus 10 (2), 191-208.