Eastern Hunter-Gatherer

In archaeogenetics, the term Eastern Hunter-Gatherer, East European Hunter-Gatherer, or Eastern European Hunter-Gatherer, is the name given to a distinct ancestral component that represents descent from Mesolithic hunter-gatherers of Eastern Europe. The term is abbreviated as EHG. During the Mesolithic, the EHGs inhabited an area stretching from the Baltic Sea to the Urals and downwards to the Pontic-Caspian steppe.
Along with Scandinavian Hunter-Gatherers (SHG) and Western Hunter-Gatherers (WHG), the EHGs constituted one of the three main genetic groups in the postglacial period of early Holocene Europe. The border between WHGs and EHGs ran roughly from the lower Danube, northward along the western forests of the Dnieper towards the western Baltic Sea.
According to a study by Haak et al. (2015), EHGs have about 75% Ancient North Eurasian (ANE) and 25% WHG descent, and to have contributed significantly to the ancestry of the WHGs and SHGs (a mixture of WHG and EHG). Wang et al. (2018) models EHGs as 9% ANE and 91% descended from a group more closely related to but distinct from WHGs. During the Neolithic and early Eneolithic, EHGs on the Pontic-Caspian steppe formed the Yamnaya culture, after some admixture with Caucasus hunter-gatherers (CHGs). The genetic cluster formed from this admixture is known as Western Steppe Herder (WSH). The Yamnaya culture and its descendants are supposed to have embarked on a massive migration leading to the spread of Indo-European languages throughout large parts of Eurasia.
Research.
Haak et al. (2015) identified the Eastern Hunter-Gatherers (EHG) as a distinct genetic cluster in two males only. The EHG male of Samara (dated to ca. 5650-5550 BC) carried Y-haplogroup R1b11a1a* and mt-haplogroup U5a1d. The other EHG male, buried in Karelia (dated to ca. 5500-5000 BC) carried Y-haplogroup R1a1 and mt-haplogoup C1g. The authors of the study also identified a Western Hunter-Gatherer (WHG) cluster and a Scandinavian Hunter-Gatherer (SHG) cluster, intermediate between WHG and EHG. 
Also Lazaridis et al. (2016) confirmed SHGs to be a mix of EHGs and WHGs.
They suggested that EHGs harbored mixed ancestry from Ancient North Eurasians (ANEs) and WHGs. The people of the Yamnaya culture were found to be a mix of EHG and a "Near Eastern related population". During the 3rd millennium BC, the Yamnaya people embarked on a massive expansion throughout Europe, which significantly altered the genetic landscape of the continent. The expansion gave rise to cultures such as Corded Ware, and was possibly the source of the distribution of Indo-European languages in Europe.
EHGs may have mixed with "an Armenian-like Near Eastern source", which formed the Yamnaya culture, as early as the Eneolithic (5200-4000 BC). Researchers have found that EHGs may have derived 75% of their ancestry from ANEs. WHGs were in turn a mix of EHGs and the Upper Paleolithic people (Cro-Magnon) of the Grotte du Bichon in Switzerland. 
The people of the Mesolithic Kunda culture and the Narva culture of the eastern Baltic were a mix of WHG and EHG, showing the closest affinity with WHG. Samples from the Ukrainian Mesolithic and Neolithic were found to cluster tightly together between WHG and EHG, suggesting genetic continuity in the Dnieper Rapids for a period of 4,000 years. The Ukrainian samples belonged exclusively to the maternal haplogroup U, which is found in around 80% of all European hunter-gatherer samples.
The people of the Pit–Comb Ware culture (PCW/CCC) of the eastern Baltic bear 65 % EHG ancestry. This is in contrast to earlier hunter-gatherers in the area, who were more closely related to WHG. This was demonstrated using a sample of Y-DNA extracted from a Pit–Comb Ware individual. This belonged to R1a15-YP172. The four samples of mtDNA extracted constituted two samples of U5b1d1, one sample of U5a2d, and one sample of U4a.
Bünther et al. (2018) analyzed 13 SHGs and found all of them to be of EHG ancestry. Generally, SHGs from western and northern Scandinavia had more EHG ancestry (ca 49%) than individuals from eastern Scandinavia (ca. 38%). The authors suggested that the SHGs were a mix of WHGs who had migrated into Scandinavia from the south, and EHGs who had later migrated into Scandinavia from the northeast along the Norwegian coast. EHGs and WHGs displayed lower allele frequences of SLC45A2 and SLC24A5, which cause depigmentation, and OCA/Herc2, which causes light eye color, than SHGs.
Members of the Kunda culture and Narva culture were also found to be more closely related with WHG, while the Pit–Comb Ware culture was more closely related to EHG. Northern and eastern areas of the eastern Baltic were found to be more closely related to EHG than southern areas. The study noted that EHGs, like SHGs and Baltic hunter-gatherers, carried high frequencies of the derived alleles for SLC24A5 and SLC45A2, which are codings for light skin.
The Genomic History of Southeastern Europe.
Mathieson et al. (2018) analyzed the genetics of a large number of skeletons of prehistoric Eastern Europe. Thirty-seven samples were from Mesolithic and Neolithic Ukraine (9500-6000 BC). These were classified as intermediate between EHG and SHG. The males belonged exclusively to R haplotypes (particularly subclades of R1b1 and R1a) and I haplotypes (particularly subclades of I2). mtDNA belonged almost exclusively to U (particularly subclades of U5 and U4). 
A large number of individuals from the Zvejnieki burial ground, which mostly belonged to the Kunda culture and Narva culture in the eastern Baltic, were analyzed. These individuals were mostly of WHG descent in the earlier phases, but over time EHG ancestry became predominant. The Y-DNA of this site belonged almost exclusively to haplotypes of haplogroup R1b1a1a and I2a1. The mtDNA belonged exclusively to haplogroup U (particularly subclades of U2, U4 and U5). 
Forty individuals from three sites of the Iron Gates Mesolithic in the Balkans were also analyzed. These individuals were estimated to be of 85% WHG and 15% EHG descent. The males at these sites carried exclusively R1b1a and I (mostly subclades of I2a) haplotypes. mtDNA belonged mostly to U (particularly subclades of U5 and U4). 
People of the Cucuteni–Trypillia culture were found to harbor about 20% hunter-gatherer ancestry, which was intermediate between EHG and WHG.
The Genomic Formation of South and Central Asia.
Narasimshan (2019) coined a new ancestral component, West Siberian Hunter-Gatherer (WSHG). WSHGs contained about 30% EHG ancestry, 50% ANE ancestry, and 20% East Asian ancestry.
Physical appearance.
Some of the EHGs are believed to have been light-skinned and brown eyed.