I am becoming more and more fascinated by the microbial world. Had to happen, they have billions of years of experience and hold vast secrets. And like any field with growth potential – the more we think we know the smaller we become in a vast universe.
So I’m going to take yet another sideline here. You know the familiar adage – Which came first? The chicken or the egg?” This is a question almost as old as our species. Although the answer lies in the question, it actually highlights the poignancy of dilemma in questioning — which came first? Movement or the mechanism to move? Is it that the circular nature of water molecules led to concentric movement of microbes, influenced the circular patterning of cilia movement, or perhaps even the evolutionary development of flagella on a cell? Dilemmas have been and continue to face biological studies and the natural sciences and surroundings affect change in varying degrees in different species. But in the microbial world, early life shaped and was shaped so intimately that co-creation and co-speciation surely must have occurred. I’ve been impressed by scientists involved in the study of bacteria evolution and co-speciation and co-evolutionary processes are pretty astonishing in the research and analysis. While I am more interested as you know in movement patterning in the evolution of microbes and multi-cellular creatures, I’d like to share a couple of interesting bits of research with you.
In studies of the microbiome of the human stomach gut there is an exciting new frontier in genetic profiling and bacteria symbiosis research. Which came first? The human gut or the jumble of bacteria which lives competes, morphs, co-operates, maintains and evolves to serve and function in our gut survival, health and evolution? Does the mammalian gut shape its microbiota by offering a closed-circuit environment of steady conditions with a flow of nutrients to live on and warm even temperatures to grow in or did microbes shape the functioning efficiency of our gut and even possibly our immune system along the way in the co-evolution of a near perfect interior substrate? There is speculation it’s likely both. I think that simply the fact that most of the microbiota in our stomachs are beneficial and not harmful supports the theory that together we evolved dependent on each other as co-species. That does not mean to say that bacteria evolution is not dominated by the first microbial goal to compete and persist. Survival to the fittest has been the name of the game for billions of years on earth. But warmth and steadiness of nurturing is likely to generate co-operation and symbiotic methodologies to take advantage of those gentile conditions between species, right?
Researchers have found that the mammalian gut likewise has evolved mechanisms that encourage beneficial traits in hosting the bacterial complexitiy, such as -immune suppression of harmful microbes and preferential feeding of beneficial ones. So perhaps both the mammal and mammalian microbiota species conversely invest in each other to evolve an efficient steady-state mutualism. And with that knowledge… we just have to consciously feed both as nutritionally as possible.
That is one, here’s another interesting factoid. Bacteria evolves very quickly comparatively to multi-cellular animals. Microbes are the ultimate in effecting creative molecular morphing, movement, defense and co-operation tactics and techniques. Granted they’ve had a few billions of years, but also bacteria microbes are damn persistent. Just to give you an idea of it. A man over 30 years ago set out to test the evolution of twelve identical populations of e. coli bacteria to see how they might evolve. The e. coli bacteria each day received fresh nutrients to enable cell division and growth. Same temperature, same everything – in order to affect little or no change in population growth by outside influences. The bacteria underwent 60,000 generations over 30 years. During that time samples were taken from the 12 populations no less than 500 generations apart and frozen for analyses of their evolutionary processes. Even under these controlled conditions mutations in all of the populations occurred in many different ways. The researchers reconstructed the trajectories of all of the mutations that reached a threshold frequency. In other words, if a mutation caught hold and began to change the population that mutation would then be tracked to find out if the mutation became extinct or changed the entire population. Interesting, huh?
What they found has changed thinking in the current approach to the processes of evolution. We have all too easily thought of evolution as linear, as coupled with earth’s timeline. While species evolution often do have timelines influenced by earth changes such as cataclysmic events and we know that traits come and go according to environmental pressures and changes, this recent research into the evolution of bacteria in a controlled environment modifies that. Research analyses of bacteria evolution shows that mutations often occur time and time again – sometimes successful and adopted, sometimes go extinct, sometimes mutations persist for a while but cannot gain a foothold but re-appear later. What was thought as evolutionary traits moving forward as the earth evolved actually re-occurs with regularity, again and again. So shall we find that mammalian whales did not return from life on land to live in the water but actually never left the ocean? That perhaps their unused and non-functioning ears were developed when hunting shores long ago.
The dynamics of molecular evolution over 60,000 generations, B.J. Good, MJ McDonald, JE Barrick, RE Lenski, MM Desai, Nature Journal 2 November 2017, Vol. 551, Pg 45. Doi:10.1038/nature24287
No Escape from the Tangled Bank, Joshua B. Plotkin, 2017, published online Nature 18 October 2017.
The evolution of the host microbiome as an ecosystem on a leash, K.R Foster, J. Schluter, K.Z. Coyte, S.Rakoff-Nahoum, Nature Journal 3 August 2017, Vol. 548, Pg 43. DOI:10.1038/nature23292