Friday, December 23, 2016

Is genetics still metaphysical? Part V. Examples of conditions that lead to transformative insights

A commenter on this series asked what I thought that "a theory of biology should (realistically) aspire to predict?" The series (part 1 here) has discussed aspects of life sciences in which we don't currently seem to have the kind of unifying underlying theory found in other physical sciences. I'm not convinced that many people even recognize the problem.

I couched the issues in the context of asking whether the 'gene' concept was metaphysical or was more demonstrably or rigorously concrete.  I don't think it is concrete, and I do think many areas of the life sciences are based on internal generic statistical or sampling comparison of one sort of data against another (e.g., genetic variants found in cases vs controls in a search for genetic causes of disease), rather than comparing data against some prior specific theory of causation other than vacuously true assertions like 'genes may contribute to risk of disease'.  I don't think there's an obvious current answer to my view that we need a better theory of biology, nor of course that I have that answer.   

I did suggest in this series that perhaps we should not expect biology to have the same kind of theory found in physics, because our current understanding doesn't (or at least shouldn't) lead us to expect the same kind of cause-effect replicability.  Evolution--which was one of the sort of basic revolutionary insights in the history of science, and is about life, specifically asserts that life got the way it is by not being replicable (e.g., in one process, by natural selection among different--non-replicate--individuals).  But that's also a very vanilla comment.

I'll try to answer the commenter's question in this and the next post.  I'll do it in a kind of 'meta' or very generic way, through the device of presenting examples of the kind of knowledge landscape that has stimulated new, deeply synthesizing insight in various areas of science.

1.  Relativity
History generally credits Galileo for the first modern understanding that some aspects of motion appear differently from different points of view.  A classic case was of a ship gliding into the port of Genoa: if someone inside the ship dropped a ball it would land at his feet, just as it would for someone on land.  But someone on land watching the sailor through a window would see the ball move not just down but also along an angled path toward the port, the hypotenuse of a right triangle, which is longer than the straight-down distance.  But if the two observations of the same event were quantitatively different, which was 'true'?  Eventually, Einstein extended this question using images such as trains and railroad stations: a passenger who switched on two lightbulbs, one each at opposite ends of a train, would see both flashes at the same time.  But a person at a station the train was passing through would see the rearmost flash before the frontward one.  So what does this say about simultaneity?

These and many other examples showed that, unlike Isaac Newton's view of space and time as existing in an absolute sense, they depend on one's point of view, in the sense that if you adjust for that, all observers will see the same laws of Nature at work.  Einstein was working in the Swiss patent office and at the time there were problems inventors were trying to solve in keeping coordinated time--this affected European railroads, but also telecommunication, marine transport and so on. Thinking synthetically about various aspects of the problem led Einstein later to show that a similar answer applied to acceleration and a fundamentally different, viewpoint-dependent, understanding of gravity as curvature in space and time itself, a deeply powerfully deeper understanding of the inherent structure of the universe.  A relativisitic viewpoint helped account for the nature and speed of light, aspects of both motion and momentum, of electromagnetism, the relationship between matter and energy, the composition of 'space', the nature of gravity, of time and space as a unified matrix of existence, the dynamics of the cosmos, and so on, all essentially in one go.

The mathematics is very complex (and beyond my understanding!).   But the idea itself was mainly based on rather simple observations (or thought experiments), and did not require extensive data or exotically remote theory, though it has been shown to fit very diverse phenomena better than former non-relativisitc views, and are required for aspects of modern life, as well as our wish to understand the cosmos and our place in it.  That's how we should think of a unifying synthesis. 

The insight that led to relativity as a modern concept, and that there is no one 'true' viewpoint ('reference frame'), is a logically simple one, but that united many different well-known facts and observations that had not been accounted for by the same underlying aspect of Nature.

2.  Geology and Plate Techtonics (Continental Drift)
Physics is very precise from a mathematical point of view, but transformative synthesis in human thinking does not require that sort of precision.  Two evolutionary examples will show this, and that principles or 'laws' of Nature can take various forms.  

The prevailing western view until the last couple of centuries, even among scientists, was that the cosmos had a point Creation, basically in its present form, a few thousand years ago.  But the age of exploration occasioned by better seagoing technology and a spirit of global investigation, found oddities, such as sea shells at high elevations, and fossils.  The orderly geographical nature of coral atolls, Pacific island chains, volcanic and earthquake-prone regions was discovered.  Remnants of very different climates than present ones in some locations were found.  Similarly looking biological species (and fossils) were found in disjoint parts of the world, such as South Africa, South America, and eventually Antarctica.  These were given various local, ad hoc one-off explanations.  There were hints in previous work, but an influential author was Alfred Wegener who wrote (e.g., from 1912--see Wikipedia: Alfred Wegener) about the global map, showing evidence of continental drift, the continents being remnants of a separating jigsaw puzzle, as shown in the first image here; the second shows additional evidence of what were strange similarities in distantly separated lands.  This knowledge had accumulated by the many world collectors and travelers during the Age of Exploration. Better maps showed that continents seemed sometimes to be 'fitted' to each other like pieces of a jigsaw puzzle.  

Geological ages and continental movement (from Hallam, A Revolution in the Earth Sciences, 1973; see text)

Evidence for the continental jigsaw puzzle (source Wikipedia: Alfred Wegener, see text)

Also, if the world were young and static since some 'creation' event, these individual findings were hard to account for. This complemented ideas by early geologists like Hutton and Lyell around the turn of the 19th century. They noticed that deep time also was consistent with the idea of (pardon the pun) glacially slow observable changes in glaciers, river banks, and coastlines that had been documented since by geologists  Their idea of 'uniformitarianism' was that processes observable today occurred as well during the deep past, meaning that extrapolation was a valid way to make inferences.  Ad hoc isolated and unrelated explanations had generally been offered piecemeal for these sorts of facts.  Similar plants or animals on oceanically separated continents must have gotten there by rafting on detritus from rivers that had been borne to the sea.

Many very different kinds of evidence were then assembled and a profound insight was the result, which we today refer to by terms such as 'plate techtonics' or 'continental drift'.   There are now countless sources for the details, but one that I think is interesting is A Revolution in the Earth Sciences, by A. Hallam, published by Oxford Press in 1973, only a few years after what is basically the modern view had been convincingly accepted.  His account is interesting because we now know so much more that reinforces the idea, but it was as stunning a thought-change as was biological evolution in Darwin's time.  I was a graduate student at the time, and we experienced the Aha! realization that was taking place was that, before our very observational eyes so to speak, diverse facts were being fit under the same synthesizing explanation (even some of our faculty were still teaching old, forced, stable-earth explanations).

Among much else, magnetic orientation of geological formations, including symmetric stripes of magnetic reversals flanking the Mid-Atlantic Trench documented the sea-floor spreading that separated the broken-off continental fragments--the pieces of the jigsaw puzzle.  Mountain height and sea depth patterns gained new explanations on a geologic (and very deep time) scale, because the earth was accepted as being older than biblical accounts).  Atolls and the volcanic ring of fire are accounted for by continental motions.  

This was not a sudden one-factor brilliant finding, but rather the accumulation of centuries of slowly collected global data from the age of sail (corresponding to today's fervor for 'Big Data'?).  A key is that the local facts were not really accounted for by locally specific explanations, but were globally united as instances of the same general, globally underlying processes.  Coastlines, river gorges, mountain building, fossil-site locations, current evidence of very different past climates and so on were brought under the umbrella of one powerful, unifying theory.  It was the recognition of very disparate facts that could be synthesized that led to the general acceptance of the theory.  Indeed, subsequent and extensive global data, continue to this day to make the hypothesis of early advocates like Wegener pay off.

3.  Evolution itself
It is a 100% irrefutable explanation for life's diversity to say that God created all the species on Earth. But that is of no use in understanding the world, especially if we believe, as is quite obvious, that the world and the cosmos more broadly follows regular patterns or 'laws'.  Creationist views of life's diversity, of fossils, and so on, are all post hoc, special explanations for each instance. Each living species can be credited to a separate divine reason or event of creation.  But when world traveling became more common and practicable, many facts and patterns were observed that seemed to make such explanations lame and tautological at best.  For example, fossils resembled crude forms of species present today in the same area.  Groups of similar species are found living in a given region, with clusters of somewhat less similar species elsewhere. The structures of species, such as of vertebrates, or insects, showed similar organization, and one could extend this to deeper if more different patterns in other groups (e.g., that we now would call genera, phyla, and so on).  Basic aspects of inheritance seemed to apply to species, plant and animal alike.  If all species had been, say, on the same Ark, why were similar species so geographically clustered?

It dawned on investigators scanning the Victorian Age's global collections, and in particular Darwin and Wallace, that because offspring resemble their parents, though are not identical to them, and individuals and species have to feed on each other or compete for resources, that those that did better would proliferate more.  If they became isolated, they could diverge in form, and not only that but the traits of each species were suited to its circumstances, even if species fed off each other.  Over time this would also produce different, but related species in a given area.  New species were not seen directly to arise, but precedents from breeders' history showed the effects of selective reproduction, and geologists like Lyell had made biologists aware of the slow but steady nature of geological change.  If one accepted the idea that rather than the short history implied by biblical reading, life on earth instead had been here for a very long time, these otherwise very disparate facts about the nature of life and the reasons for its diversity might have a common 'uniformitarian' explanation--a real scientific explanation in terms of a shared causative process, rather than a series of unrelated creations: the synthesis of a world's worth of very diverse facts made the global pattern of life make causal and explanatory sense, in a way that it had never had before.

Of course the fact of evolution does not directly inform us about genetic causation, which has been the motivating topic of this series of posts.  We'll deal with this in our next post in the series.

Insight comes from facing a problem by synthesis related to pattern recognition
The common feature of these examples of scientific insight is that they involve synthesis derived from pattern recognition. There is a problem to be solved or something to be explained, and multiple facts that may not have seemed related and have been given local, ad hoc, one-off 'explanations'. Often the latter are forced or far-fetched, or 'lazy' (as in Creationism, because it required no understanding of the birds and the beasts). Or because the explanations are not based on any sort of real-world process, they cannot be tested and tempered, and improved.  And, unlike Creationist accounts, scientific accounts can be shown to be wrong, and hence our understanding improved.

In our examples of the conditions in which major scientific insights have occurred, someone or some few, looking at a wealth of disparate facts, or perhaps finding some new fact that is relevant to them, saw through the thicket of 'data', and found meaning.  The more a truly new idea strikes home, in each case, the more facts it incorporates, even facts not considered to be relevant.

Well!  If we don't have diverse, often seemingly disparate facts in genetics then nobody does!  But the situation now seems somewhat different from the above examples: indeed, with the precedents like those above, and several others including historic advances in chemistry, quantum physics, and astronomy, we seem to hasten to generalize, and claim our own synthesizing 'laws'.  But how well are we actually doing, and have we identified the right primary units of causation on which to do the same sort of synthesizing?  Or do we need to?

 I'll do my feeble best to offer some thoughts on this in the final part of this series.

1 comment:

Ken Weiss said...

I'll aim for the final part on Monday (after Christmas).