Reconstructed setting· The columns of time
Mammoth steppe
45 ka → 11.7 ka
A cold land of grass and flowers that no longer exists anywhere: dry, treeless, and grazed by mammoth, horse and steppe bison. It covered much of the northern hemisphere until the end of the last ice age.
What the evidence shows
Fifty thousand years of ancient DNA show what grew there, and the answer surprised the people who asked: not a grass-dominated tundra but a dry steppe in which the dominant plants were forbs, flowering herbs that are neither grasses nor shrubs. Sedimentary DNA records mammoth, horse and steppe bison among its grazers. Shrubs are absent from this backdrop on purpose, because the spread of birch and willow scrub is precisely what marks the collapse of the biome, between 13,900 and 13,200 years ago.
Bounds and conventions
No modern landscape is a good analogue, which makes this the hardest backdrop on the timeline to draw honestly. The plant record behind it is circumpolar, but the timing of the collapse comes from pollen and sedimentary DNA in eastern Beringia, where the change was uneven: steppe plants held on where slope and exposure kept the ground dry. The same biome stretched to western Europe, where it need not have looked identical.
Sources
- Monteath, A. et al. (2021), PNAS, doi:10.1073/pnas.2107977118
- Monteath, A. et al. (2023), Quaternary Science Reviews, doi:10.1016/j.quascirev.2022.107878
- Cocker, S. L. et al. (2026), Quaternary Science Reviews, doi:10.1016/j.quascirev.2026.110081
- Willerslev, E., et al. (2014), Nature, doi:10.1038/nature12921. PMID 24499916, résumé lu.