Domestic horses likely did not originate in Anatolia as previously suspected, according to a new study of ancient horse remains dating as far back as 9000 BCE. Instead, they may have been introduced to the peninsula - which makes up most of modern-day Turkey - and the nearby Caucasus region from the Eurasian Steppe by about 2000 BCE, during the Bronze Age. The findings also suggest imported domestic horses were bred with local wild Anatolian horses and donkeys and provide the earliest genomic evidence for a mule in southwest Asia, dating to between 1100 and 800 BCE. Domestication of horses about 5,500 years ago forever changed transportation, trade, warfare, and migration. But despite their transformative role in human history, it remains unclear where, when, and how many times horses were domesticated. In recent years, careful recovery of horse remains from well-preserved archaeological sites in Anatolia and neighboring areas together with progress in paleogenetic approaches has made it possible to specifically address the processes responsible for the origins of domestic horses in this part of western Asia. To explore whether Anatolia might have been this mysterious point of origin, Silvia Guimaraes and colleagues analyzed more than 100 equid remains from 8 sites in central Anatolia and 6 sites in the Caucasus dating mostly from the Early Neolithic to the Iron Age (from 9000 to 500 BCE). The researchers performed both morphological and paleogenetic analyses, scrutinizing mitochondrial DNA, Y chromosome DNA, and DNA markers related to coat color. They found that nonlocal genetic lineages still present in domestic horses today suddenly appeared in about 2000 BCE rather than developing gradually over time, as would be expected if these changes emerged within Anatolia. This directs attention to nearby Black Sea regions as a more likely origin for domesticated horses, the authors say.