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Essay / Decoded

Ancient Pollen Is Hiding in a Surprising Place

A paleoecologist explains what pollen in fossilized mammal urine can reveal about past ecosystems and environmental change.
Against a blurry background of grass blades, a close-up image features a white flower with a cloud of small white particles floating in the air around it.

Pollen can record millions of years of environmental change.

Alex Jones/Unsplash

This article was originally published at The Conversation and has been republished under Creative Commons.

IF YOU ARE ALLERGIC to pollen, you are likely to curse the existence of these microscopic particles. You’re not alone: Up to 30 percent of the world’s population suffers from hay fever, which is often driven by pollen allergies. Shifting global climates are likely to push that figure even higher.

However, pollen represents one of the most powerful tools to uncover the nature of past environmental change.

I am the head of the Palaeoecology Laboratory at Nelson Mandela University in South Africa. My research focuses on unraveling the secrets of ancient environments and ecosystems by examining fossil pollen grains. These tiny time capsules hold a wealth of information about the Earth’s past. They help scientists reconstruct ecosystems, track climate change, and understand the evolution of plant life.

But it can be difficult to source pollen deposits in arid regions. That’s because such deposits are often found in large lakes, which are in short supply in Southern Africa. That’s where an unlikely scientific ally enters the picture: the fossilized urine of a small mammal, the rock hyrax. (South Africans call them “dassies.”)

LOOKING BACK

Pollen grains are incredibly durable because they are made of an organic substance (called sporopollenin) that is very resistant to decay. Pollen is released into the air, often in large quantities, and can settle on surfaces like lakes and become preserved in sediment deposits over thousands, or even millions, of years.

In the lab, we examine the pollen found in these deposits using a microscope. By identifying the different types of pollen grains found within the different layers (representing different time slices), we can reconstruct the area’s vegetation history. Plants grow under specific climatic conditions: For instance, desert plants can grow under low rainfall conditions, whereas forest plants need high amounts of rainfall. So we can make inferences about the climate at the time that the pollen was incorporated into the deposit.

A small mammal with brown fur sits on a grassy field with few blades of grass sticking out of its mouth.

Scientists have found ways to study pollen trapped in the fossilized urine of rock hyraxes.

Jason Shallcross/Flickr

As I’ve said, Southern Africa’s arid climates mean there are very few large lakes in the region. This makes it a challenge to source deposits that adequately preserve pollen within them over long periods of time. That’s where fossilized dassie urine comes in.

These sticky deposits, called “rock hyrax middens,” accumulate in rock crevices in mountainous areas over thousands to tens of thousands of years and contain beautifully preserved pollen grains. As they also contain various other types of evidence (such as geochemical data) and can be accurately dated, they represent the most valuable archive of past climate data in Southern Africa. The oldest middens we’ve worked with date back 50,000 years.

ANCIENT SITES

The research my lab conducts, focusing on harnessing the power of the humble pollen grain and utilizing unique archives such as hyrax middens, is strongly multidisciplinary. It draws together elements from botany, geography, geology, climatology, and archaeology.

We are currently generating fossil pollen records from several sites within the Cape Fold Belt mountains of South Africa. For example, we have a midden sequence that covers the last 6,000 years from the Baviaanskloof in the Eastern Cape province. The fossil pollen from this sequence shows there was a dramatic shift in vegetation about 3,300 years ago driven by a large fire event and increased temperatures. We’re hoping to publish this research soon.

A bumpy, terracotta-colored rock face with green shrubs scattered over it fills a photograph with only a bit of blue sky visible beyond its horizon.

The author is studying pollen records from South Africa’s Cape Fold Belt mountains.

Winfried Bruenken/Wikimedia Commons

This information provides baselines of variability in natural systems and can help inform current conservation efforts within the Baviaanskloof, which is a biodiversity hotspot.

Another project we are involved in is centered on an archaeological excavation within South Africa’s southern Cape region at a site called Boomplaas Cave. By using the fossil pollen within hyrax middens found within the vicinity of Boomplaas Cave, we hope to provide the environmental context to the archaeological record that can help decipher how early humans responded to climate change.

LOOKING FORWARD

We are not only working within the realm of the past: Since pollen is one of the main sources of allergies, it is important to monitor the types and amounts of pollen currently present in the air we breathe. My lab is part of the South African Pollen Monitoring network, and we generate pollen data for the city of Gqeberha in the Eastern Cape province.

This initiative focuses on analyzing pollen captured in the air across several different parts of South Africa and ensuring that this information is publicly available. This project is particularly important as, due to climate change, pollen seasons are lengthening and allergenic pollen is increasing.

A smiling person with shoulder-length blonde hair wearing a necklace, black shirt, and sunglasses perched atop their head is in front of a background of green leaves.

Lynne Quick is a senior research fellow associated with the African Centre for Coastal Palaeoscience at Nelson Mandela University in South Africa. She is a paleoecologist, specifically a palynologist who runs the Palaeoecology Laboratory at the university’s Gqeberha campus in the Eastern Cape. Quick’s research relates to reconstructing Southern African paleoenvironments, with a key focus on the vegetation history and past climate dynamics of the highly biodiverse Cape Floristic Region.

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