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Written by Lotta Raitanen, Early Childhood Teacher Education Student, Tampere University, Finland
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When we talk about children’s lives today, screen time, global influences, and rapid technological growth often dominate the conversation. However, children’s bodies no longer develop solely on nature’s terms. They are built in a world where chemicals, air quality, and industrial processes have already changed the basic characteristics of the environment.
Zsuzsa Millei, a researcher at the University of Tampere, reminds us that childhood should not be viewed solely as a social and educational phenomenon. Children are also biological beings whose bodies are built and in constant interaction with their environment, for example through microbes.
Why does the environment shape children’s bodies?
Millei’s research highlights how waste, such as pollution, toxins, plastics, and other by‑products of industrial production, urban lifestyles, and common hygiene and health practices, change children’s biology at the micro level. The consequences of human activity do not remain in the environment—they travel into the body and shape the child’s immune system and metabolism. These wide changes can be seen in children’s health and wellbeing.
A child’s body does not develop in isolation; it is intensively shaped by the surrounding environment. A child who grows up in the city encounters very different microbes than one raised in the countryside, but today these differences are no longer only natural. As children move through the world and consume products, the chemicals and pollutants ultimately enter children’s bodies and interact with their microbiome. The human-induced changes in the environment have thus quite literally gone “under the skin”.
Children are holobionts – what does that mean?
According to Millei, one of the biggest misconceptions is seeing children as individual, independent beings, because biologically that is not true. Billions of microbes live inside each child and on their skin: bacteria, viruses, yeasts, and other invisible companions that help build the immune system, digestion, hormone function, and metabolism. A child’s body is not only human, but rather a constantly changing ecosystem. The cooperation between microbes and the child’s own cells forms a whole that develops and adapts to the environment. When a child runs around in the forest, plays in the dirt, or pets a pet, the microbial community in their body diversifies and strengthens. By studying children’s microbiota, we can see how global environmental changes affect ”under the skin.”
What does this mean in a child’s everyday life?
- Pollutants and chemicals
Road traffic emissions, barbecue smoke, and other PAH compounds enter the body through breathing, skin, and food. They alter a child’s gut microbiota, weaken the immune system, and increase the risk of allergies and asthma.
- An overly clean home – a familiar idea?
Many of us want to create the cleanest and safest environment possible for our children, but excessive use of disinfectants can also destroy beneficial microbes, affect hormone function, and increase susceptibility to inflammation. Safety does not come from a sterile environment, but from balance.
- The importance of animals and nature
Being close to animals and spending time in nature enriches children’s microbiota and strengthens their immune system. It is therefore important to involve children in gardening and forest outings. All of this supports children’s development in ways we may not always even think about.
What does this mean for the future of childhood?
This perspective challenges us to look at childhood in a new way. We no longer view childhood solely as a social phenomenon, but now also as an ecological phenomenon, where childhood is affected by industrial and chemical changes. Children are living, breathing creatures teeming with microbes, who are both fragile and wonderfully connected to all living things.
Changes are already taking place “under the skin”. Industrial and chemical changes have irreversibly changed children’s microbiota. This is precisely why it is our responsibility to protect what remains of the good. Our task now is to safeguard what is still healthy and possible, and to ensure that children can grow up with a good enough childhood in a biologically altered world.
This blog was written in relation to the following article:
Millei, Z. (2026). Childhood in a bacterial world: Anthropogenic biology for the global studies of childhood. SageJournals, 16(1), 76–89. https://journals.sagepub.com/doi/epub/10.1177/20436106251398515