Dairying enabled Early Bronze Age Yamnaya steppe expansions

Abstract

During the Early Bronze Age, populations of the western Eurasian steppe expanded across an immense area of northern Eurasia. Combined archaeological and genetic evidence supports widespread Early Bronze Age population movements out of the Pontic–Caspian steppe that resulted in gene flow across vast distances, linking populations of Yamnaya pastoralists in Scandinavia with pastoral populations (known as the Afanasievo) far to the east in the Altai Mountains1,2 and Mongolia3. Although some models hold that this expansion was the outcome of a newly mobile pastoral economy characterized by horse traction, bulk wagon transport4–6 and regular dietary dependence on meat and milk5, hard evidence for these economic features has not been found. Here we draw on proteomic analysis of dental calculus from individuals from the western Eurasian steppe to demonstrate a major transition in dairying at the start of the Bronze Age. The rapid onset of ubiquitous dairying at a point in time when steppe populations are known to have begun dispersing offers critical insight into a key catalyst of steppe mobility. The identification of horse milk proteins also indicates horse domestication by the Early Bronze Age, which provides support for its role in steppe dispersals. Our results point to a potential epicentre for horse domestication in the Pontic–Caspian steppe by the third millennium bc, and offer strong support for the notion that the novel exploitation of secondary animal products was a key driver of the expansions of Eurasian steppe pastoralists by the Early Bronze Age.

Leveraging palaeoproteomics to address conservation and restoration agendas

“…Shotgun proteomics provides the opportunity to examine phylogenetic relationships in materials that are too old or poorly preserved to yield aDNA ( Rybczynski et al., 2013 ; Welker et al., 2015a ). It can also be used to identify the sex of prehistoric individuals ( Stewart et al., 2017 ), the presence of particular fauna, and to explore human-animal relationships from indirect sources such as dental calculus (e.g., Wilkin et al., 2021 ). With shotgun proteomics, it is also possible, as it is not with ZooMS, to detect posttranslational modifications of individual amino acids, allowing insight into the degradation patterns and authenticity of ancient proteins ( Van Doorn et al., 2012 ; Cleland et al., 2015 , 2021 ).…”

“…Protein-based methods are not new in archaeology ( Abelsen, 1954 ; Hare and Abelsen, 1968 ; Newman and Julig, 1989 ; Johnson and Miller, 1997 ; Ostrom et al., 2000 ; Kooyman et al., 2001 ; Buckley et al., 2009 , 2011 ; Cappellini et al., 2014 ); however, methodological improvements over the past decade ( Van Doorn et al., 2011 ; Van der Sluis et al., 2014 ; McGrath et al., 2019 ) have seen their increasing application to a wide range of archaeological, human evolutionary, and art historical questions (for a more in-depth review about the historical perspective of ancient protein-based methods and their applications, please see Buckley (2018) ; Welker (2018) ; Villanova and Porcar (2019) ; Hendy (2021) , and references therein). Critically, a broad array of materials are suitable for palaeoproteomic analysis, including bone ( Buckley et al., 2009 ; Cappellini et al., 2012 ; Cleland et al., 2015 , 2016 ; Welker et al., 2015b ), antler ( Von Holstein et al., 2014 ; Ashby et al., 2015 ), mollusc shell ( Sakalauskaite et al., 2020 ), eggshell ( Demarchi et al., 2019 ), ivory ( Coutu et al., 2016 ), dentine and enamel ( Cappellini et al., 2019 ; Welker et al., 2019 ), dental calculus ( Warinner et al., 2014 ; Bleasdale et al., 2021 ; Wilkin et al., 2021 ), leather ( Brandt et al., 2014 ), parchment ( Fiddyment et al., 2015 ), hair ( Solazzo et al., 2013 ), textiles ( Gong et al., 2016 ), ceramic residues ( Solazzo et al., 2008 ), and preserved food remains ( Yang et al., 2014 ).…”

“…Peptide mass fingerprinting is also increasingly being used to directly track the spread of a broad range of domesticated species, including in eastern Africa ( Culley et al., 2021 ; Janzen et al., 2021 ), southern Africa ( Le Meillour et al., 2020 ; Coutu et al., 2021 ) and central and eastern Asia ( Taylor et al., 2018 , 2020 ). Species-specific palaeoproteomic identification of milk proteins in human dental calculus ( Wilkin et al., 2020 , 2021 ; Bleasdale et al., 2021 ) has further contributed to this effort and is particularly useful in regions where zooarchaeological evidence is lacking for taphonomic or cultural reasons. Studying the introduction of domesticated species is critical to conservation efforts as many have played a significant role in transforming local ecosystems ( Boivin et al., 2016 ; Hofman and Rick, 2018 ).…”

The spread of herds and horses into the Altai: How livestock and dairying drove social complexity in Mongolia

“…Prior to ~3500 BCE, hunter-gatherer-fisher (HGF) groups were separated, both geographically and genetically, by the Altai Mountains [ 2 ], whereas in the Bronze Age (c. 3500 to 900 BCE), populations moved into and across the mountain range in multiple waves, from regions to the west and southwest [ 2 – 4 ]. Recent studies on the arrival of human population waves, and transmission of cultivated species, are beginning to shed new light on the Holocene prehistory of the Altai [ 2 , 5 – 14 ], however more work is needed to understand this region as a transmitter of economic and cultural adaptations.…”

Mitochondrial DNA Footprints from Western Eurasia in Modern Mongolia

“…Archaeological evidence ( Kovalev and Erdenebaatar, 2009 ; Wilkin et al, 2021 ) and genetic studies provided the first information on the complex Mongolian past ( Cavalli-Sforza et al, 1994 ; Comas et al, 1998 ; Yao et al, 2004 ; Yang et al, 2008 ; Yunusbayev et al, 2015 ; Pugach et al, 2016 ; Bai et al, 2018 ). As in another population context ( Achilli et al, 2018 ), archaeogenomics unveiled further details on the emerging scenario of admixture between Eastern and Western Eurasians for the origin of the Central Asian populations, with distinct west-east genetic gradients between different western and eastern Eurasian groups ( Jeong et al, 2019 ; Narasimhan et al, 2019 ; Ning et al, 2021 ).…”