Pollen grains are telling the story of asteroids, dinosaurs, Mayans and others

To learn about past humans, scientists dig up regions, look at fossils, tree rings, and more. While these are commonly known ways that are used to unearth humanity's past, an unusual item also acts like a time capsule, The Conversation stated in a study. These tiny beings are pollen grains.

They encapsulate a lot of history, hinting at the make-up of the ecological system during different times. According to the report, pollen grains provide a plethora of data to "reconstruct ancient forests, track sea-level changes and identify the fingerprints of significant events, such as asteroid impacts or civilisations collapsing."

Story of asteroid that killed the dinosaurs

One of the most well-known incidents on Earth happened 65 million years ago when an asteroid crashed into the planet, killing the dinosaurs. Scientists have found fossilised pollen from the Late Cretaceous and Early Palaeocene periods that tells the story of everything that changed after the cosmic event.

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When the asteroid smashed into Earth, it hit what is now Mexico’s Yucatan Peninsula. This resulted in a tidal wave crashing onto North America, carrying marine animals and rocks with it. Millions of years later, scientists found marine fossils, rock fragments and fossilised pollen in southeastern Missouri.

Palynologists studied the pollen from gymnosperms, such as pines, ferns, flowering plants, grasses, herbs and palm trees. They found a clear pattern. After the impact, some forest pollen disappeared. This means that the regions’ vegetation changed. But they reemerged gradually when the environment stabilised.

Rising of sea levels 33.9 to 28 million years ago

They were also able to identify dramatic changes that occurred along the eastern Gulf Coast states of Mississippi and Alabama. "During the Early Oligocene, around 33.9 to 28 million years ago, sea levels rose and flooded low-lying conifer forests in the region," the report stated.

They noticed a distinct change in pollen released by Sequoia-type trees.

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The pollen records have been used to reconstruct how far the shoreline moved inland.

Story of Mayans and pollen

Lake Izabal in Guatemala shows the history of Mayans over the past 1,300 years. "This sediment record reflects both natural climate variation and the profound impact of human land use".

The report adds that around 1,125 to 1,200 years ago, pollen from maize and opportunistic herbs surged, while tree pollen dropped. This change hinted at widespread deforestation. Historical records show political centres in the region collapsed soon after.

The forests recovered after population pressure eased. Vegetation returned, even though rainfall declined during the Little Ice Age between the 14th and mid-19th centuries.