The Fatyanovo were swarthy & not lactose tolerant

 https://www.science.org/doi/10.1126/sciadv.abd6535

The presented genome-wide data are derived from 3 Stone Age HGs (WeRuHG; 10,800 to 4250 cal BCE, BER001, KAR001, PES001) and 26 Bronze Age Fatyanovo Culture farmers from western Russia (Fatyanovo; 2900 to 2050 cal BCE) and 1 Corded Ware Culture individual from Estonia (EstCWC; 2850 to 2500 cal BCE)

In the case of radiocarbon dating, it is possible that fish from rivers and lakes consumed by Stone Age fisher-hunter-gatherers may cause a notable reservoir effect. This means that the radiocarbon dates obtained from the human bones and teeth can be hundreds but not thousands of years older than the actual time these people lived (33). Unfortunately, we do not yet have data to estimate the size of the reservoir effect for each specific case. Then, we turned to the Bronze Age Fatyanovo Culture individuals and determined that they carry maternal (subclades of mtDNA hg U5, U4, U2e, H, T, W, J, K, I, and N1a) and paternal (chrY hg R1a-M417) lineages (Table 1, fig. S1, and tables S2 to S4) that have also been found in CWC individuals elsewhere in Europe (14–16, 18, 27). In all individuals for which the chrY hg could be determined with sufficient depth (n = 6), it is R1a2-Z93. 

The Fatyanovo are the most likely candidates for pre-Proto-Indo-Iranians, representing the earliest stage Pre-Proto-IIr splitting up from what would be Proto-Balto-Slavic. 

We estimated the time of admixture for Yamnaya and EF populations to form the Fatyanovo Culture population using DATES (37) as 13 ± 2 generations for Yamnaya Samara + Globular Amphora and 19 ± 5 generations for Yamnaya Samara + Trypillia. If a generation time of 25 years and the average calibrated date of the Fatyanovo individuals (~2600 cal BCE) are used, this equates to the admixture happening ~3100 to 2900 BCE. 

The confidence intervals (CIs) were extremely wide with Trypillia, but the chrX data showed 40 to 53% Globular Amphora ancestry in Fatyanovo, in contrast with the 32 to 36% estimated using autosomal data. The sex-biased admixture is also supported by the presence of mtDNA hg N1a in two Fatyanovo individuals—an hg frequent in Linear Pottery Culture (LBK) EFs but not found in Yamnaya individuals so far 

The Fatyanovo were formed as a result of the process of Yamnaya male invaders taking European farmer women as wives, resultant genome being 2/3 Yamnaya and 1/3 EEF. The chrX data is based on a horribly low 45k snps so I will take it with a grain of salt, but the Y-DNA makes it somewhat clear still.

From the phenotype prediction results, we see that only 4% of Fatyanovo samples had blonde/dark blonde hair, while 96% had dark hair and 80% had brown eyes. 60% of the samples had an intermediate skin tone, and the remaining 40% had a combination of mixed skin tone, unpredictable intermediate and just straight up dark skin. Lactase persistence was only 17%, clearly showing that it had already undergone selection from Steppe EMBA times. A gene for high serum cholesterol was 83% but drops to barely 13% by the Estonian Middle Ages, showing strong negative selection for serum cholesterol possibly.

Outgroups used in the study:  Mota, Ust-Ishim, Kostenki14, GoyetQ116, Vestonice16, MA1, AfontovaGora3, ElMiron, Villabruna, WHG, EHG, CHG, Iran_N, Natufian, Levant_N, and Anatolia_N