Monday 29 July 2024

The Weird Case of Space Lettuce

There's a fascinating paper that's recently been published on the challenges of growing lettuce in space (Simulated microgravity facilitates stomatal ingression by Salmonella in lettuce and suppresses a biocontrol agent | Scientific Reports (nature.com)). Space lettuce (and space-grown food more generally) is very important if we are ever to get to Mars, so there are numerous ongoing experiments to explore what micro-gravity does to cellular development. Unfortunately, it turns out that a lack of gravity leads to "space lettuce" becoming poisonous.



Not only does this give weight to the assertion by Torday and others that gravity is critically important in the evolution of life (Torday's 2003 experiment is important here: Parathyroid hormone-related protein is a gravisensor in lung and bone cell biology - PubMed (nih.gov)), it is a powerful reminder of the importance of initial conditions on evolutionary development and ecology. Cellular development is relational - and relations with the environment (and the physics of the environment) are causal in ongoing long-term development that affects ecological relations down the track. 

Poison space lettuce will produce very different relations between humans and the plant. Instead of putting it in our sandwiches, we would probably destroy it, and find something else to eat. Of course, in microgravity, our own cells would develop differently over time, so the ecological dynamics are very hard to predict. It does make me think about the relation humans have to plants and how those relations are framed by the physical environment: many plants, for example, have medicinal value. In microgravity would that be the same? I doubt it. 

All relationships have an evolutionary context. Bad human relationships are a bit like poison space lettuce: the emergent pathology results from initial conditions. But the pathological symptoms are often the same irrespective of the individuals involved: injunctions imposed as to who one can and can't communicate with; a loss of close friends; monitoring and surveillance of communications; threats; emotional blackmail; financial pressure, etc. Any objective assessment would say "get out" - but the move is difficult and painful.

One of the really fascinating things about the space lettuce is that the emergent properties of the lettuce are the result of cellular selection in microgravity. Cells "cognitively" choose to develop in a poisonous way in order to survive. It is also the same in human relations. Humans as biological systems adapt to all kinds of inhospitable environments, and the adaptation can make leaving difficult. 

The interesting thing is where a cell might decide to develop differently. In effect a cell will develop to "escape" so as to give itself more options for free development. Escape comes through what Stephen Jay Gould calls exaptation - the repurposing of absorbed but discarded adaptations from the past to create to evolutionary options in the future. This is all about a cell seeing the world differently, which is the result of reconfiguring its components and exploiting some feature of the environment which provides new opportunities for development. It is a reassessment of all the resources available and a "strategy" (do cells have strategy? well, possibly - it is anticipation). We also see in the natural world the importance of deception: cellular reorganisation only reveals itself at the last minute and new developments can be very unexpected: always a crucial strategy if one is trying to break free and do something new. 

What was it like for the first organisms to make the transition from water to land? Hypoxia had contributed to mechanisms producing new bone formation which provided new options (A Central Theory of Biology - PMC (nih.gov)), but probably the move was very painful. But necessary. Breaking free and striking a new path is never easy. But sometimes the pathology of constraints and lack of freedom actually makes the move easier. At some point any organism will decide that there is no way forward in the present direction, and they have to reorganise and do something new. 

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