#398 Soil Microbiomes, Plant Genetics, and Groundswell with Nikki Reed and Rebecca Harrell Tickell

What if the future of human health doesn’t just begin in the clinic, but in the soil?

In this episode of DNA Today, we explore the new documentary Groundswell, the final chapter in the regenerative agriculture documentary trilogy that began with Kiss the Ground and continued with Common Ground. Narrated by Demi Moore and Woody Harrelson, Groundswell follows regenerative agriculture solutions across five continents, showing how restoring soil health can support biodiversity, food systems, local economies, climate resilience, and human health.

This episode takes DNA Today into a different but deeply relevant corner of genetics and genomics. While we often focus on human genetics, Groundswell broadens the lens to show how genetics is embedded in entire ecosystems.

Soil is alive with microbial diversity. Plants depend on complex relationships with bacteria, fungi, insects, and the environment around them. Crop diversity and seed diversity can influence resilience to drought, pests, disease, and changing climate conditions. Human health is also shaped not only by our DNA, but by the environments we live in, the food we eat, the water we drink, the chemicals we are exposed to, and the microbes we encounter.

Joining us are Nikki Reed, co-producer of Groundswell, and Rebecca Harrell Tickell, co-director of the film. 

About Nikki Reed

Many listeners will know Nikki from her role as Rosalie Hale in The Twilight Saga, as well as her work in Thirteen, which she co-wrote and starred in, and her role in The O.C. Beyond acting, Nikki is also a filmmaker, farmer, entrepreneur, and environmental advocate.

About Rebecca Harrell Tickell

Rebecca Harrell Tickell is an award-winning filmmaker, producer, and environmental activist whose work includes Kiss the Ground, Common Ground, and now Groundswell. Through this trilogy, Rebecca and her collaborators have helped bring regenerative agriculture into mainstream conversations about climate, food, health, and the future of farming.

In This Episode, We Discuss

• How Nikki Reed’s experience in Twilight shaped the way she thinks about storytelling, cultural influence, and using her platform for impact
• Why Nikki became involved in regenerative agriculture and how her connection to food, farming, and environmental advocacy became personal
• What regenerative agriculture means and how it differs from conventional agriculture
• Why healthy soil is not just “dirt,” but a living ecosystem filled with microbes, fungi, roots, insects, and organic matter
• How soil health connects to plant health, nutrient cycling, water retention, and ecosystem resilience
• Why biodiversity matters above and below ground, from soil microbial communities to crops, pollinators, insects, animals, and humans
• How regenerative agriculture reframes food systems as regionally specific, community-based, and connected to local ecosystems
• The connection between food, chemical exposures, the environment, and gene-environment interactions
• Why the guests see regenerative agriculture as both a practical solution and a hopeful movement
• How storytelling can help make complex topics like soil science, microbes, farming systems, and climate resilience more accessible

Fact Check & Context

This episode includes a passionate discussion about regenerative agriculture, pesticides, cancer, fertility, carbon, and soil health. As with many topics at the intersection of environment and health, the science is complex. Here are a few important clarifications and sources for our audience members who want to dig deeper.

Cancer Rates

The episode references concern about rising cancer rates, including pediatric cancer and cancers in younger adults. The most accurate summary is nuanced. For childhood and adolescent cancers in the U.S., a 2025 analysis found that age-standardized cancer incidence increased from 2001 to 2016, then decreased from 2016 to 2022. Cancer death rates among U.S. youth ages 0–19 also declined 24% from 2001 to 2021, according to CDC/NCHS data. Read the study in Cancer Discovery.

At the same time, early-onset colorectal cancer has clearly been increasing. The American Cancer Society reports that colorectal cancer death rates in adults under 50 have increased by about 1% per year since 2004, even as rates have declined among many older adults. Researchers are actively studying potential contributors, including diet, obesity, sedentary behavior, environmental exposures, microbiome changes, and other factors, but there is not one single proven cause. Read more from the American Cancer Society.

Pesticides, Epigenetics, and Fertility

The episode discusses pesticides and their potential effects on human health. A careful way to frame this is that some pesticide exposures have been associated with biological effects, including possible epigenetic changes and reproductive health concerns, especially at higher or occupational exposure levels. 

Risk depends on the specific chemical, dose, route of exposure, timing, and individual susceptibility. For glyphosate specifically, there is disagreement among major scientific and regulatory bodies. The U.S. Environmental Protection Agency states that it does not agree with the International Agency for Research on Cancer’s conclusion that glyphosate is “probably carcinogenic to humans.” EPA’s position is that glyphosate is not likely to be carcinogenic to humans when used according to current labeling, while IARC classified glyphosate as “probably carcinogenic to humans” in 2015. Read EPA’s glyphosate overview.

There is also research connecting some pesticide exposures with male fertility markers. A 2022 review found epidemiological evidence supporting associations between pesticide exposure and male fertility outcomes, including semen quality, particularly among workers and exposed populations. Read the review in Toxics.

Soil Carbon and Climate

Regenerative agriculture and improved soil health can play an important role in carbon storage, water retention, and climate resilience. However, soil carbon sequestration should be understood as one climate tool, not a complete solution on its own. Fossil fuel emissions remain the dominant driver of human-caused carbon dioxide emissions.

The Global Carbon Project projected total anthropogenic CO₂ emissions from fossil fuels and land-use change at about 41.6 GtCO₂ in 2024, with fossil CO₂ emissions alone projected at 37.4 GtCO₂. This means land management matters, but reducing fossil fuel emissions remains essential. Read the Global Carbon Budget 2024.

Soil Degradation

The episode discusses major global soil loss and degradation. A commonly cited estimate from the Food and Agriculture Organization of the United Nations is that nearly one-third of the world’s soils are degraded, posing a serious threat to food security. Soil degradation can include erosion, loss of organic matter, nutrient depletion, contamination, salinization, compaction, and reduced biodiversity. Because estimates vary depending on definitions and measurement methods, overly specific claims about the exact amount of topsoil lost should be interpreted with caution unless tied to a specific source. Read more from FAO.

Nutrient Density and Food Quality

The film and episode discuss the idea that regenerative agriculture can support more nutrient-dense food. There is emerging research suggesting that soil health, microbial diversity, plant biodiversity, and farming practices may influence nutrient profiles in food. However, this is still an active area of research, and outcomes likely vary by crop, region, soil type, farming system, and measurement method.

A 2025 review in Frontiers in Nutrition describes regenerative agriculture as a promising pathway for producing nutrient-dense crops while also noting significant gaps in quantifiable research and policy needed for broader adoption. Read the review in Frontiers in Nutrition.

Watch Docuseries 

• Watch Kiss the Ground on Prime Video (First in Doc Series)
• Watch Common Ground on Prime Video (Second in Doc Series)
• Watch Groundswell on Prime Video (Third in Doc Series)

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