Haplogroup D1b (Y-DNA)

Haplogroup D-M55
Possible time of origin	35,000-40,000YBP
Possible place of origin	Japanese archipelago
Ancestor	(Grandparent) D
Defining mutations	M55, M57, M64.1, M179, P37.1, P41.1, P190, 12f2b
Highest frequencies	Japan（Ainu people、Ryukyuan people、Yamato people）

Haplogroup D-M55 also known as Haplogroup D1b is a Y-chromosome haplogroup. It is one of two branches of Haplogroup D1, one of the descendants of Haplogroup D. The other is D1a.

Haplogroup D-M55 is found about 32% -39% in Japanese people and more than 80% in Ainu people. It occupies the majority in Japan. It is considered that Hapologroup D-M55 was born in Japan 38,000-37,000 years before present.

More than 40,000 years distinction exists between Haplogroup D-M55 and other subgroups of Haplogroup D.

Among the subgroups of Hologroup D, the ancestor of D1b went eastward to reach the Japanese archipelago. Michael F. Hammer of the University of Arizona said: "The ancestors of the Jomon people were in Central Asia about 50,000 years ago. They continued to migrate eastwards and arrived in Hokkaido by the northern Okhotsk route about 30,000 ago and D1b was born in the Japanese archipelago." said that Haplogroup D arrived to northern Kyusyu via Northern China and Korean Peninsula about 35,000 years before present, and Haplogroup D1b was born in Japanese archipelago.

Haplogroup D1b prospered as the majority of the Japanese archipelago for about 35,000 years before Yayoi people arrived.

High frequency in various places in Japan. Especially high in East Japan and Okinawa.

（Hammer et al. 2006）

Outside Japan, discovered in Micronesia and Timor Island. They were both former Japanese territory, so it was possibly carried during World War II.

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