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Xenobots and living machines

Started by tacf, January 02, 2023, 12:57:12 PM

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Recently ran across an article about xenobots, and the amount of sensationalism made me a bit angry, so I though I would give my opinions on the topic.

Xenobots have been described as "synthetic, living machines". They are aggregates of cells taken from an organism which are artificially arranged so that they perform a function not performed by the cells in the donor organism.

The example given by the research team is that of cells taken from frogs: skin and muscle cells, which attach to each other naturally, are arranged in such a way that aggregates are formed which are capable of locomotion, and when placed in a dish with small particles, will push those particles into small clumps. ( As the aggregates have no means of acquiring nutrition, the cells die after running out of the food stores which were present internally at the moment of separation from the donor organism.

Comparisons can be helpful for determining what is happening. Let us consider a renal transplant. Here, living tissue is taken from a donor, implanted in another, and performs a determined task - filtering blood. How is this different from the xenobots? In both instances, a specified task is performed which was determined to be useful by an external agent. In fact an obvious difference which gives credit to the transplant is that it is able to acquire nutrition (through the blood it also filters). But no one calls a kidney transplant a machine. The distinction which makes a xenobot a machine is implied to be that the xenobot has a function which the tissue would not have performed in the parent organism. This has been described as an "emergent outcome" or function. Let us examine this.

Contractility is a known power of muscle cells. That a muscle cell is or is not locomotive is dependent upon its relations with its external environment. So Thomistically speaking, locomotion is always present for a muscle cell at least virtually ("by way of active potentiality or efficacy, after the manner of a cause" Bernard Wuellner, SJ, Dictionary of Scholastic Philosophy.)- i.e., in its causes, although not necessarily manifestly. We do not have to refuse the term "emergent" as long as we are aware of what this actually means. And this is currently found in nature and art everywhere, and has been known for over a millenia - real things are often constituted of a plurality of principles, and the combination can effect a new manifestation. St Thomas uses this in his discussion qualities, pointing out that sweetness is a combination of other qualities effecting a sense of taste. (Cf. St. Thomas, On Being and Essence, Paragraph 21.)

Let us consider another example: If someone sat near a cow on a hot day, waiting patiently for it to swing its tail for the small breeze it would generate, we would think him foolish - as there are much better ways to make a fan. But if he anesthetized the tail, and slowly over months with surgical tissue expanders formed a tail with a fan shape, we may still think he is wrong and possibly mad, but would have to admit his "living machine" is now twice as effective based on the amount of wind current generated per tail swing. But if the xenobots where used for the same purpose, we would say the man has scientifically removed the muscle and skin and awaits the wind generated by the spontaneous contractions of the cells - we can admit it is industrious and ingenious, but still point out nothing categorically has changed in his manipulation of nature.

Some may think the aggregation of muscle and skin in entirely new ways meets the criteria for a "living robot" - but they are held together by the same means they held to other cells in nature - an extracellular matrix and membrane proteins, generated during growth and maintenance. And what if they were connected by some gel entirely artificial? If one tied the tails of two cows together with a string, that would be an artificial aggregation of the parts of a fan in our example, and yet no one would say the still hot man generated a "living robot", although he did through art unite two organisms for an external purpose determined by him. Now when one cow swings its tail it will pull the other with it, and the pulled tail will be having its parts used for a purpose entirely different than what we would say the natural purpose to be: It is now serving as a blade for a fan to cool a separate organism (the man); its purpose by nature would be to swat insects (or to cool the cow itself if you allow it).

This is not to say that manipulating living tissue to serve for external purposes is intrinsically wrong - many cells have been manipulated to produce antibiotics, for example. It is just to protest against claiming a new category of manipulation of nature has been achieved - that we must now "Meet the Xenobots: Virtual Creatures Brought to Life". (Sokol, Joshua (2020-04-03). "Meet the Xenobots: Virtual Creatures Brought to Life". The New York Times.) A machine is defined as "an apparatus using or applying mechanical power and having several parts, each with a definite function and together performing a particular task." Here we have tissue removed from an animal which through careful manipulation is able to function for an external goal for a period of time before dying. So it is a machine with living tissue as its material cause, which we have seen before. The newness is that the particular task it was designed to do was seemingly unrelated to the natural tasks we imagine for the tissue, but this can be explained by considering the base functions of the tissue and being creative in what relationships we have that tissue form with its surroundings (including other tissues). It is interesting because it sparks our imagination on what is the actual limits on "emergent functions". But it does not threaten the traditional understanding of what a soul is, what it means to be alive, or what nature is.

On another note, the fact that some of these have now been able to form clumps of cell aggregates which then perform the same function Joshua Brown, Nov 29, 2021.), "replicating" themselves, in the broad sense of the term, does not change the discussion. Having a machine build more of itself is clearly within the possibilities of art. Doing so with a machine having living tissue as its material cause is novel, but almost expected given enough time and human effort.

We can even make some predictions on what other powers are possible. Since transplants can continue to acquire nutrients given the right environment, I would not be surprised if future "living machines" expand upon this. If the nutrient material, incorporated into the xenobot, would then be used to give rise to another xenobot of the same kind, we could call it generation or reproduction in a sense. If the living tissue was manipulated to provide inputs to a more traditional computer, and that computer was then able to manipulate the living tissue, the system could become exponentially more complex. Already there are programs capable of simulating animal behavior, which is governed by instinct - Thomistically, the estimative power (The estimative power is the "power in the intellect of an animal which has the capacity to make associations." Fr. Chad Ripperger, Introduction to the Science of Mental Health. ) - we could then have self-replication machines capable of nutrition with instincts programmable by art - and that indeed could become nearly indistinguishable from a "natural organism's" powers and behaviors to most observation. Finally, it is already observed that some tissues have achieved what is to us indistinguishable from immortality - namely, unending replication of cells within a tissue which preserves the tissue. This is the case for cancer cells, and HeLa cells obtained in 1951 are still viable (Batts DW (2010-05-10). "Cancer cells killed Henrietta Lacks – then made her immortal". The Virginian-Pilot. pp. 1, 12–14.). Whether this persists indefinitely has yet to be seen - and whether the collection of tissue should be considered a whole versus an aggregate of individually living beings is another question. (The individual cells die but are replaced; if they do not function as a whole calling the result "immortal" would be like calling a beehive "immortal".) But if the cells can be manipulated to perform a function determined by an external agent, the continuous replacement of the cells would give the appearance of immortality. So we can imagine someone in the future claiming to have achieved "immortal life in self-willed machines capable of self-generation". And yet we can already say this would actually challenge nothing of our traditional understanding.