For much of the 20th century, biology adopted a reductionist framework, borrowing heavily from physics. In physics, reductionism works well. Complex systems like the orbit of planets or the behaviour of particles can be reduced to mathematical laws and simple rules. This success inspired the same approach in biology, especially in the study of genetics, where scientists believed that by breaking life down into its most basic components—DNA/genes—they could explain everything from development to disease.
However, biology is fundamentally different from physics. Life is not just a series of isolated mechanisms but a dynamic, self-organising system. While genes play a crucial role in our life, they are not the sole drivers of health or disease. Increasingly, we are realising that a gene-centric view is not enough to understand the complexity of living organisms. Instead, we must consider the larger networks of interactions within the body and the environment—especially when it comes to metabolic diseases and mental health.
Picking from the the earlier blog, in this blog (7), we’ll explore the dynamic nature of biology, why the reductionist approach borrowed from physics falls short, and how epigenetics has reshaped our understanding of health, showing that factors beyond our genetic code play a major role in influencing physiology and disease outcomes.
The Limitations of a Physics-Centric View
Biological systems are not simply machines made up of parts. They are dynamic, self-organizing systems that exhibit emergent properties that cannot be fully explained by the interactions of individual molecules. The reductionist approach, which attempts to break down complex systems into simpler components, may overlook the essential properties that emerge at higher levels of organisation.
One of the most significant issues with applying a purely physics-based approach to biology, especially in the context of health and well-being, is that it tends to oversimplify complex biological systems. While the laws of physics offer foundational truths about energy and matter, the reductionist "calories in, calories out" or "input-output" models fail to capture the nuanced interactions between various biological processes.
Image Credit: Fritz Kahn
In biology, context matters. A calorie is not simply a unit of energy that the body burns in a vacuum. Hormonal fluctuations, the body's circadian rhythm, genetic predispositions, stress levels, and even the gut microbiome all play roles in determining how energy is utilized, stored, or even wasted.
The Dynamic Nature of Biology
Unlike the fixed laws of physics, biological systems are constantly adapting and evolving. Our genomes are not static entities; they are subject to epigenetic modifications that can alter gene expression without changing the underlying DNA sequence. This dynamic nature of biology highlights the importance of considering the context and interactions within biological systems.
In physics, the reductionist approach works because physical systems can often be boiled down to simple, unchanging laws. The mass of an object or the charge of a particle is fixed, and these constants determine how they interact with each other.
In contrast, biology is in constant flux. Living systems are made up of thousands of interacting components—proteins, cells, organs, and external environmental factors—that continuously communicate with each other. The behaviour of these components is dynamic and can change depending on the state of the organism or its environment. This means that you can’t just isolate one element, like a gene, and understand its role fully without considering the broader context.
For instance, while a gene may encode a protein, whether or not that protein is expressed, how much of it is produced, and when it is active are all influenced by external and internal factors, such as signals from other cells or changes in the environment.
The static, reductionist view of genetics as the "blueprint for life" overlooks this dynamic interplay, leading to an incomplete understanding of how life works.
The following video, which might seem unrelated, however encapsulates this whole dynamic nature of our cells, rather perfectly!
Enter Epigenetics: A Bridge Between Genes and Environment
If genes are not the full story, then what is? Enter epigenetics—a field that studies how gene expression is influenced by external factors without changing the underlying DNA sequence. Epigenetics acts as a bridge between our genetic makeup and the environment, revealing that while our genes are important, they are also highly responsive to the world around us.
Epigenetic modifications—such as the addition of chemical groups to DNA or to the proteins that help package DNA—can turn genes on or off, making certain proteins more or less likely to be produced. These changes are influenced by diet, stress, exercise, and exposure to toxins, and can even be passed down from one generation to the next.
This is a paradigm shift from the old view, where DNA was seen as a static, unchangeable blueprint. Now we understand that our genetic expression is fluid, constantly adapting to our internal and external environments.
Epigenetics and Metabolic Diseases
The role of epigenetics is particularly important when we look at metabolic diseases like obesity, diabetes, and cardiovascular disease. These conditions are influenced not just by genetics but also by lifestyle factors such as diet, physical activity, and stress.
For instance, studies have shown that poor diet of the mother, while she is carrying, can lead to epigenetic changes that promote insulin resistance, a precursor to type 2 diabetes. These changes can be passed down to offspring, meaning that the consequences of a poor diet could affect future generations.
Similarly, obesity is not just a matter of consuming too many calories; epigenetic modifications can alter how the body stores and uses fat, making it easier for some individuals to gain weight than others. Even if someone is genetically predisposed to obesity, the expression of these genes can be modified by lifestyle interventions such as exercise and a healthy diet.
Image Credit: http://dx.doi.org/10.1038/s41576-020-0270-8
Epigenetics and Mental Health
Epigenetics also plays a crucial role in mental health. Conditions like depression, anxiety, and schizophrenia are not caused by any single gene but by a combination of genetic predispositions and environmental triggers. Epigenetic mechanisms help explain how early life stress, trauma, or chronic stress in adulthood can lead to long-lasting changes in brain function, increasing the risk of mental health problems.
For example, research has shown that chronic stress can lead to epigenetic changes in genes related to the brain’s stress response, making individuals more susceptible to anxiety and depression. These epigenetic marks can alter the function of key brain regions involved in emotion regulation, such as the hippocampus and amygdala, leading to changes in mood and behavior.
The rising incidence of mental health disorders may be linked, in part, to the modern environment—constant stress, poor diet, and lack of sleep can all influence the epigenetic regulation of genes involved in brain function.
The Immune System: A Testament to Biological Adaptability
The immune system is a prime example of the dynamic nature of biology. It is constantly adapting to new challenges, such as pathogens and environmental changes. This adaptability is essential for survival and is not something that can be fully explained by the laws of physics alone.
The Microbiome and Human Health
While genetics play some role in shaping our traits and behaviours, it is becoming increasingly evident that our health is also influenced by the vast array of microorganisms that inhabit our bodies. These microorganisms, collectively known as the microbiome, have a profound impact on various aspects of our physiology and mental health.
The human microbiome consists of trillions of bacteria, viruses, fungi, and other microorganisms that live on and inside our bodies. These microorganisms play a crucial role in digestion, nutrient absorption, immune function, and even brain development.
The gut microbiome, in particular, has been extensively studied and has been shown to have a significant impact on human health. It can influence our metabolism, weight, immune function, and even our mood and behaviour.
The Role of the Microbiome in Health and Disease
Digestion: The gut microbiome plays a vital role in breaking down food and absorbing nutrients. Imbalances in the gut microbiome can lead to digestive disorders, such as irritable bowel syndrome and inflammatory bowel disease.
Immune Function: The gut microbiome helps to train and regulate the immune system. Disruptions in the microbiome can increase the risk of autoimmune diseases and allergies.
Mental Health: Emerging research suggests that the gut microbiome may also influence mental health. Studies have found links between the gut microbiome and conditions such as depression, anxiety, and autism spectrum disorder.
Moving Beyond the Reductionist Approach: A Holistic View of Health
A reductionist approach, which focuses on the individual components of a system, may overlook the emergent properties that arise from the interactions between these components. For example, while we may understand the individual molecules involved in metabolism, we may not fully understand the complex metabolic pathways that emerge from these interactions.
The reductionist, gene-centric approach to biology is being replaced by a more holistic view that recognises the complexity and dynamism of living systems. While genes are important, they are not destiny. The interactions between genes, epigenetics, and environmental factors are what ultimately determine health outcomes.
For diseases like obesity, diabetes, heart disease, and mental health disorders, this means that we need to look beyond genetic predispositions and focus on how lifestyle and environment interact with our biology. Understanding the dynamic nature of biology offers new avenues for treatment—epigenetic therapies, for example, aim to "reprogram" the epigenome to reverse harmful changes and restore healthy gene expression.
The Importance of Context
Biological systems are highly context-dependent. The behaviour of a molecule or cell can vary depending on its environment and interactions with other molecules and cells. This highlights the importance of considering the broader context when studying biological systems.
For example, in the context of biology, the concept of calories is not as straightforward as in physics. The energy derived from food is influenced by various factors, including:
Individual variations: Metabolic rates and individual factors can affect how calories are burned and utilised.
Nutrient composition: The type and quality of nutrients in food can influence how calories are metabolised.
Hormonal factors: Hormones play a crucial role in regulating metabolism and energy expenditure.
Physical activity: Exercise and muscle mass can significantly impact calorie expenditure and overall energy balance.
Image Credit: TattooProjects
The Role of Systems Biology in Health and Well-being
The Future of Health Lies in Systems Biology. The pursuit of understanding the natural world has long been driven by a reductionist approach, focusing on the individual components of complex systems. However, when it comes to the intricacies of biological systems, a more holistic perspective is essential.
To fully understand biological systems, we need to adopt a systems biology approach that considers the interactions between various components of the system. This approach recognises that biological systems are complex networks of interconnected molecules and processes, and that understanding the behaviour of the system as a whole is essential.
Systems biology has the potential to revolutionise our understanding of health and disease. By considering the interactions between genes, proteins, and environmental factors, systems biology can provide insights into the underlying causes of complex diseases and identify potential therapeutic targets.
Some of the key benefits of a systems biology approach to health and well-being include:
Personalised medicine: Systems biology can help identify personalised treatment plans based on an individual's unique genetic makeup and environmental factors.
Disease prevention: By understanding the underlying causes of diseases, we can develop more effective prevention strategies.
Understanding the microbiome: The microbiome plays a crucial role in human health, and systems biology can help us understand how it interacts with our genes and environment.
Conclusion
While physics provides a valuable framework for understanding the natural world, it is important to recognise its limitations when applied to biological systems. Biological systems are complex, dynamic, and constantly evolving. A more holistic approach that considers the interactions between various components of biological systems is necessary to gain a deeper understanding of life.
The dynamic, interconnected nature of biology requires a shift in how we approach health and disease. Instead of viewing genes as the ultimate blueprint, we must recognise that they are part of a larger system influenced by epigenetics and the environment. By adopting a systems biology approach, we can better understand the root causes of complex diseases and develop more effective treatments.
By embracing the dynamic nature of biology and recognising the limitations of a purely reductionist perspective, we can unlock new insights into the complexities of life and develop innovative solutions to pressing biological challenges.
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