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Haplogroup H1a

H-M82

Macro-haplogroup
H
Parent clade
H1
Formed (estimate)
c. 12,000–15,000 years before present
TMRCA (estimate)
c. 6,000–8,000 years ago

Overview

H1a (M82) is the most demographically and historically significant branch of haplogroup H. It forms the core of the South Asian H radiation and includes lineages that played major roles in the genetic history of India, Pakistan, Iran and the Romani diaspora of Europe. H1a likely emerged in northwest India or the western Indus region during the early to mid Holocene, expanding across diverse cultural and linguistic populations. Within H1, H1a displays the richest internal structure, containing multiple downstream branches that trace distinct demographic histories. Some clusters are tied to northern and northwestern India, others to the Deccan plateau and Sri Lanka, while key downstream lineages such as H1a1a form the primary paternal lineage among the Romani people of Europe. This makes H1a a crucial clade for connecting South Asian and European population histories.

Geographic distribution

H1a is widespread across South Asia, with high frequencies in northwest India, central India, Pakistan and Sri Lanka. Tribal populations, scheduled castes and pastoralist groups show some of the highest concentrations. The lineage extends westward into Iran and the Caucasus, reflecting early mobility between the Indus region and the Iranian plateau. In Europe, H1a is best known from the Romani diaspora. The dominant Romani Y chromosome lineage originates from a downstream branch of H1a, specifically H1a1a, which left the Indian subcontinent around one millennium ago and spread through the Middle East and Balkans into Europe.

Ancient DNA

  • Neolithic and Chalcolithic South Asian samples frequently show M52 and M82 upstream signals, supporting an early presence of H1a.
  • Romani associated medieval European remains match downstream H1a1a signatures.
  • Iranian Chalcolithic individuals sometimes show lineages compatible with early H1a expansions.

Phylogeny & subclades

H1a is internally structured into several well defined branches. H1a1 is the primary trunk connecting South Asia to Iran and Europe, while H1a1a is the Romani associated subbranch. Additional branches include H1a2 and regionally anchored microclades found in southern India and Sri Lanka. This internal branching illustrates both ancient local expansions and more recent historical movements.

  • H1a1
  • H1a1a
  • H1a2
  • regional H1a microclades

Notes & context

H1a is arguably the most historically impactful branch of haplogroup H. Its role in linking South Asia with the Romani diaspora, combined with its widespread presence across Indian cultural regions, makes it indispensable for any comprehensive Y chromosome atlas.