Some old papers are just like the old pictures you get to find if you rummage in the garret during a rainy afternoon. Cluttered in a trunk just to be forgotten, they tell you about days gone by, but sometimes they can reveal facts you just couldn’t suspect. In the last decade, the research on the symbiotic interactions between mammals and bacteria made impressive steps forward. The so-called microbiota has been extensively studied, revealing his fundamental role in immunity, aging and several pathogenesis events. The last intriguing hypotesis links the composition of microbiota with autism, stating how can be crucial the role of microbes in our body.

For my very last exam, I had to study the composition of microbiota and his role in pathogenesis and immunity. We have been committed to choose a paper to make a small presentation. And as in the rainy afternoon in the old garret in front of a fucking trunk, I have found a picture from the past, a paper healing from the 90s, when no one had a clear idea on what those bacteria were doing around our body’s external surface. So, let me show you this old, but still very interesting picture.

The title immediately caught my attention:

Nonlinear dynamics, chaos-theory, and the” sciences of complexity”: their relevance to the study of the interaction between host and microflora

The article (PDF), dating 1997, is written by M.H.F. Wilkinson, a computer scientist from the University of Groningen, in Holland. After a concise and really clear explanation of non-linear dynamics, chaos theory and complex systems, the paper propose that gut and microbiota constitute a pseudo-chaotic complex system, thus showing a non-linear dynamic. With this assumption, a computer model of microflora has been built. The “organisms” are divided into aerobians and anaerobians and brought to compete for space and nutrients. IMHO, the result is quite striking. Several simulations of gut colonization confirm the interdependency between anaerobes and facultative anaerobes, but the most intriguing result is presented here:

chaos

If you check out the recently proposed dynamics for gut colonization of microbiota, from the birth till the very first weeks of life, you will find a very similar path. Facultative anaerobes, such as Firmicutes, take the stage as first to prepare the ground to strict anaerobes, such as Bacteroides, which overcome later to become the biggest population. Intriguingly, the theoretical modeling forecasted this years before the experimental approaches.

There is another important fact to highlight. This work gets the point when it remarks the semi-chaotic behavior of the system constituted by the intestine and the microbial community. As mentioned by the author, a semi-chaotic organization is really suitable for those systems who need a compromise between plasticity and stability, such as biological systems undergoing to evolutionary constraints.

An old picture, but still really interesting. A memory from a past in wich there were no mass sequencing, big data, proteomics and systems biology. To understand the complexity of biological systems, scholars made use of theoretical models developed in physics and math, such as chaos theory or fractal geometry. A theoretical modeling step that is quite often underestimated by genomic scientists and systems biologists, and wrongly forgotten in the post-genomic era.

Old pictures can be interesting.

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