Faculty of Mathematics and Natural Sciences

Unlocking human history through pollen

A new paper in Nature Scientific Data offer a comprehensive exploration of food plants and human indicators found in fossil pollen records. This new paper developed by Suzette Flantua (researcher and CESAM member at Dept. of Biological Sciences) creates an invaluable resource for interdisciplinary research aiming to reconstruct human history over long time scales.

Primary regions of diversity of major agricultural crops worldwide
Figure 1. Primary regions of diversity of major agricultural crops worldwide (Khoury et al. 2016), https://doi.org/10.1098/rspb.2016.0792)
Khoury et al. 2016

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Piecing together the past is like assembling a vast jigsaw puzzle. Paleoecologists extract information from diverse sources, examining many proxies in sediment cores like diatoms, phytoliths, charcoal, and pollen. This meticulous process helps uncover a detailed picture of our past environment across millennia and revealing the profound impact humans have had on it.

Central to this endeavor are anthropogenic pollen indicators. These invaluable tools in paleoecology depict the historical interplay between humans and their surroundings. For instance, traces of cereal pollen might hint at ancient agricultural practices, while pollen from certain weedy plants could signify past disturbances or shifts in land use. Around the world, many different food plants are known (Fig. 1).

However, the vastness of data on anthropogenic pollen indicators, especially the morphological details of their pollen grains, remains scattered across numerous publications. This poses a challenge: without the right knowledge, researchers might overlook pivotal evidence of human activity.

Addressing this, Suzette Flantua and Henry Hooghiemstra's study serves as a valuable guide, guiding researchers through the vastness of information. They present a global overview of 354 pivotal food plants, providing details on the ornamentation on their pollen grains, historical usage, environmental affinities, and geographical distributions. For Latin America, a continent rich in history and biodiversity, the authors dove deeper. Reviewing over 750 publications, they catalogued all human indicators from across the continent, highlighting 212 individual pollen types and pinpointing 95 combinations essential as "human indices".

Pollen through a microscope

Figure 2. Pollen from Zea mays (corn) - Capsicum annuum (paprika) - Cucurbita maxima (pumpkin) - Ipomoea batatas (sweet potato) (from left to right).


A deep dive into their Latin American fossil pollen records reveals a fascinating diversity of human indicators. While some indicators, like Zea mays (corn, Figure 2), are frequently cited, an unexpected high diversity of rare indicators was uncovered, often mentioned in less than 1% of reviewed papers. This discovery not only emphasizes the intricate diversity of human interaction with the environment but also underscores the importance of exploring these seldom-mentioned indicators. Their research often found human indicators intertwined with other signals such as increased fire occurrences or changes in sedimentation rates, showcasing the depth of interdisciplinary work undertaken by paleoecologists.

Flantua & Hooghiemstra provide the much-needed datasets to be able to do continental-scale reconstructions unveiling the prehistorical dynamics of deforestation, dietary shifts, cultural exchanges, and the interplay of climate change and human activities. Integrating their findings with vast open-access databases such as the Neotoma Paleoecology Database has the potential to provide even more detailed narratives of human history.  Their syntheses, when paired with the pollen standardization guidelines from Flantua et al. 2023 and the harmonization methods proposed by Birks et al. 2023, promises research that can bridge a significant gap in our understanding of global and continental-scale human interactions with the environment.