Wikipedia:Reference desk/Archives/Science/2019 January 4

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January 4

Is there any evidence that biology is reducible to physics

Reductionism has worked very well for technology but why do so many people assume everything can be reduced to subatomic particles? There are intractable problems like how the first cell formed, consciousness, free will, if reductionism is to be believed. Is there any research along the lines of "strongly emergent" behaviours of complex systems? By strongly emergent i mean something that's not predicted to exist given the laws governing the constituents, i.e. something completely new comes into existence at sufficient complexity. Have people tried to calculate how the simplest bacterium behaves according to laws governing atoms? — Preceding unsigned comment added by Money is tight (talk • contribs) 04:25, 4 January 2019 (UTC)

As mentioned in this talk, for simple microbes there does exist a complete description. But, with hundreds of thousands of different enzymes, the "flow chart" of a microbe is huge, it fills tens of thousands of pages. Count Iblis (talk) 04:49, 4 January 2019 (UTC)

Bear in mind that reductionism is not necessarily about arriving at the most efficient description of a given phenomenon--it's just an attempt to isolate and definite its constituent features, ideally in terms of universals that can be used for all other like phenomena, or (when it comes to physical reductionism, potentially all phenomena). So, to answer the query of your first sentence, the effort is based not so much in an "assumption" that everything can be reduced to a discussion of such constituents--no sensible empiricist working from first principles would operate their inquiry in that way--but rather upon a testing of that hypothesis. And so far, with one deeply perplexing exception, all biological functions have proven amenable to description in terms of physics. The one exception, which you allude to in your inquiry, is something we have such a difficult problem even conceptualizing, that we can;t reliably say whether it is a property (emergent or otherwise) of biology or physics--although we have a profound propensity/bias to frame it in those terms. I am, of course, talking about consciousness. Because it is (not just in terms of biology or psychology, but indeed the entirety of science and empirical human inquiry) the one phenomena that has never been captured or explained by a physical model in any concrete fashion, at any level, this quandry has been given (rather appropriately, I feel) the forbiding title of the the hard problem. And it is indeed something so incredibly different and alien to the empirical method, that some philosophers and cognitive scientists surmise that it is in some sense illusory (whatever Descartes would say to that) or something so far beyond the parameters of what our mental organs are designed to grapple with, that we will never understand it in even a rudimentary fashion. But as to everything else, reductionism works as well for biology as for any other physical system--the complexities simply require a broader canvas to orient and make sense of, with a lot of work still to be done to fill in the gaps--a task which may realistically span eons, if it is resolvable at all. Snow ^{let's rap} 05:41, 4 January 2019 (UTC)

Just as an addendum, OP, despite my comments above, which might reasonably be received as a full-throated defense of reductionism, I do not mean to suggest it is the only (or even the most effective) empirical model for physical systems, only that there is not fundamental reason why, as a per se matter, it cannot describe all biological phenomena. However, for an alternative model, you might consider looking into systems theory, which is very much in the vein of describing emergent properties of complex systems. Fritjof Capra, one the populizers of this field of thought, wrote a number of popular science works surveying its development, and one of them is focused on biology in particular. Alas, we have no article for it (perhaps I should fix that), but the title is Web of Life; it could be a good place to start regarding your interests in this area. Snow ^{let's rap} 05:55, 4 January 2019 (UTC)

Really? There has been calculation of the trajectories of each atom in a cell and it agrees with the observed movement? May I see a reference? — Preceding unsigned comment added by Money is tight (talk • contribs) 09:23, 4 January 2019 (UTC)

You're confusing the question of whether a model is in principle capable of describing a phenomena with the question of whether one has the ability to perform a given calculation--two very different matters. From the start through the finish of your original post, you framed the biological question as fundamentally different from other physical phenomena in terms of whether or not they could be reduced into fundamental constituents governed by the same basic physical laws as the rest of matter. And unless you are looking for some sort of answer steeped in quasi-mysticism, there's just no reason to believe that's so, and there's nothing in modern theoretical physics (whether it is reductionist or systems based) which suggests as much. The only difference between the only two examples of application you raise--the vaguely defined "technology" and a human cell--is the orders of complexity involved in the specific object or process observed. Again, that's a matter of calculation restraints, not any flaw of the model itself, and I believe I made it pretty clear in my first response that the distinction is between efficiencies when one compares more or less reductive methods of description of a given closed system against others. But more to the point, friend, if you want to be snidely dismissive of an answer that isn't the one you wanted, seconding your opinion of how limited a fundamental ontological branch of physics is, I'll just leave you to the assistance of all of the other people who have rushed to take some time out of their day to give you a considered answer and point you to some resources.... Snow ^{let's rap} 10:50, 4 January 2019 (UTC)

Oh, but I see from reviewing your contrib history that this is not a topic you were looking for information on, but in fact a topic you are persistently trying to create a debate around, across numerous spaces on this project over the course of years. Please understand that the RefDesk, and Wikipedia broadly, are WP:NOTAFORUM for you try to use to argue your metaphysical perspectives on. This desk is for genuine inquiries, not your efforts to set up someone to espouse a perspective you disagree with, so you can attempt to score a discursive victory. This has already been explained to you previously, I now see. Please respect the scope and purpose of this space. There are plenty of forums online for you to advance and argue your beliefs at length--this is not one of them. Snow ^{let's rap} 11:10, 4 January 2019 (UTC)

I was genuinely asking for a link about any strongly emergent process, after watching this https://www.youtube.com/watch?v=GVL2Y5z2jLU and knowing the severe problems with reductionism. All you did is link me to biophysics article and claim all of biology except for consciousness has already been proven to be derivable from interactions between atoms. I ask for link then you get so hurt that you spend the time to go through my posts just to cook up some insults so you can feel better about yourself... All I can do is lol. — Preceding unsigned comment added by Money is tight (talk • contribs) 11:54, 4 January 2019 (UTC)

There is an article "Reductionism in Biology" in the Stanford Encyclopedia of Philosophy. There is no proof that biology can be reduced to physics but there is no proof it cannot. I suppose the reason that people assume reductionism is possible is that organic objects have been observed to respond to physical actions in the same way as inorganic ones. It requires the same effort for example to transport organic and inorganic cargo of the same weight. There seems to be implicit in your question whether a resolution of this issue would have any metaphysical implications, specifically whether it could prove or disprove religious claims. The answer is no. (PS - please sign your posts.) TFD (talk) 13:43, 4 January 2019 (UTC)

The point is, this space is for people seeking information, while your previous history of getting into fights about the nature of an immaterial existence beyond the body all across the project as basically your only activity here for years makes it clear that that you are actually here to find opponents/a debate--and you're not going to get either here. You very clearly were asking about something you expected responders not to be able to provide to your satisfaction: you ask your queries with the vague "Have people tried to calculate how the simplest bacterium behaves according to laws governing atoms?", to which the obvious answer is "yes, of course" at which point you get to swoop in with "Oh come on, obviously no one has tracked the motion of every subatomic particle in a cell", which is something you clearly already knew and just wanted an excuse to say. Again, this space is for people who are requesting new information on a topic, not an excuse to argue about spiritual or philosophical beliefs for which they already know the standard arguments, which they want to engage in a WP:BATTLEGROUND over.

Your question was disingenuous and you're just trying to re-engineer the same debate you apparently have everywhere you go on Wikipedia--on talk pages for articles about near-death experiences to those about metaphysics and indeed, on this very page previously--despite being told this project isn't the place for that kind of engagement. It is WP:disruptive to the point of being a form of WP:NOTAFORUM trolling, since you clearly know this is, under our policies, not an acceptable use for a talk space and yet it is all you are here to do. Please desist. Snow ^{let's rap} 17:14, 4 January 2019 (UTC)

If this isn't a forum, this isn't a moot court either. There are some good answers here but please, take the nastiness and WP:SILLYTERMS to talk or something. Wnt (talk) 22:03, 4 January 2019 (UTC)

Wnt, this isn't about nastiness, it's about WP:NOTHERE and WP:DENY. And why would I take this talk; I'm not trying to give an opening to any guideline skeptics to open that TP's five-hundreth tedious, no-consensus debate about liberalizing our WP:NOTAFORUM standards. I commented here because this is where this user is engaged (for the moment) and therefore this is the appropriate place to tell him this is not what the RefDesks are for. Aside from that, I'd said what I intend to say on the matter, but I'll add this: I really suggest you look through the diffs before you consider feeding this user's behaviour--you'll not be doing the desks any favour and you'll be steering them that much closer to a block or topic ban. Snow ^{let's rap} 01:24, 5 January 2019 (UTC)

I think an answer to the OP's question that was not yet given is that - the question is wrong. The passage I know of that best expresses this meaning is:

In our own days, Einstein and others have sought unification of scientific concepts in the form of principles of increasing generality. The goal is a connected body of theory that might ultimately be completely general in the sense of applying to all material phenomena.

The goal is certainly a worthy one and the search for it has been fruitful. Nevertheless, the tendency to think of it as the goal of science or the basis of the unification of sciences has been unfortunate. It is essentially a search for the least common denominator in science. It necessarily and purposely omits much the greatest part of science, hence can only falsify the nature of science and can hardly be the best basis for unifying the sciences. I suggest that both the characterization of science as a whole and the unification of all the various sciences can most meaningfully be sought in quite the opposite direction, not through principles that apply to all phenomena but through a phenomena to which all principles apply. Even in this necessarily summary discussion, I have, I believe, sufficiently indicated what those latter phenomena are: they are the phenomena of life.

Biology, then, is the science that stands at the center of all science. It is the science most directly aimed at science's major goal and most definitive of that goal. And it is here, in the field where all the principles of all the sciences are embodied, that science can truly become unified.

This is from an essay published in Science by George Gaylord Simpson and reprinted in Robert T. Blackburn- Interrelations_ The Biological & Physical Sciences- Scott, Foresman (1966) and George Gaylord Simpson- This View of Life_ The World of an Evolutionist- Harcourt, Brace & World (1964) (this book has additional notes). I recommend all the essays in both books.

Ernst Mayr also liked this passage and had a similar view, as have some modern philosophers of science and biology in the vein of Simpson or Mayr. Overall, it is something of a reabsorbtion of an Aristotelian or Hegelian point of view into modern science.John Z (talk) 02:42, 16 January 2019 (UTC)

Can blood vessels damaged by hypertension repair themselves?

I personally think the damaged inner lining of artery in which inducers like hypertension left cracks on the vessel wall that later allowed buildup of plaque (lipids) can eventually heal on their own if the inducer such as hypertension is no longer present just like how a bleeding-wound healing works when we don't rub it or irritate it. If a cut or damaged vessel can't be regenerated, then those bleeding wounds on the skin involving much broken vessels we have all ever had in childhood shouldn't have been able to heal.

I wonder which article to read in Wikipedia that gives in-depth introduction to damaged blood vessel wall recovery? Thanks! --It's gonna be awesome!✎Talk♬ 13:52, 4 January 2019 (UTC)

I would try to start at wound healing or Regeneration in humans and check out ongoing links there. For more specific Information you may have to search the WWW.

Anyway, since the exact cause of Atherosclerosis (plaque builds up inside your arteries) is still considered to be unknown to science, some answers to that part of your questions may be more speculation than science. --Kharon (talk) 15:33, 4 January 2019 (UTC)

Thank you for the productive response! --It's gonna be awesome!✎Talk♬ 16:11, 4 January 2019 (UTC)

Everything in your body, including your arteries are constantly being repaired in response to damage done. Biological systems are dynamic systems not static systems that gradually wear down. Any long term degradation of a system in your body is the result of the net balance between wear and tear and the repairs being slightly negative. So, if you remove a source of wear and tear in your body then usually the system will improve. E.g. atherosclerosis is not simply the result of a long term deposition of plaque on artery walls, it is the dynamic equilibrium between plaque buildup and plaque removal being shifted too much toward plaque buildup. Under normal circumstances both processes occur at quite high rates, but plaque removal is more effective so arteries of animals tend to not have any plaque. When the first heart-lung machine was invented, the medical scientists were surprised to find that blood circulating in the pipes of the machines had a large amount of blood clots in them after just a few minutes. This shows that the blood vessels in your body are not simply inert pipes. This is why people who get angioplasty and are fitted stents need to get anti-platelet medication for the rest of their lives. Count Iblis (talk) 19:43, 4 January 2019 (UTC)

Yes, but the process of wounding and healing is inefficient, which is why scaring is a thing. The repair the body makes in response to stress, damage, injury, etc. is almost always inferior to what would have been there had the damage not occured in the first place. In general, the microscopic accumulation of these processes of damage and repair is senescence, and most living multi-cellular organisms undergo these problems to one extent or another. The body cannot go one forever, because the processes that created the body are not the same processes that repair the body. --Jayron32 20:38, 4 January 2019 (UTC)

Thanks both of you for the informative replies. --It's gonna be awesome!✎Talk♬ 09:27, 5 January 2019 (UTC)

Australian Snakes - Origin ?

How did the ancestors of modern Australian snakes get to Australia across Wallace's Line? It is my understanding that snakes are thought to be a monophyletic clade, so that the ancestral reptiles either evolved elsewhere and went to Australia or evolved in Australia and went elsewhere. Wallace's Line has been a barrier to placental mammals since before the evolution of placental mammals. (When Europeans "discovered" Australia, it had two placental species, C. dingo and H. sapiens, and we know which of them built boats.)

This would seem to imply either that snakes are older than placental mammals and crossed to Australia when there was a land bridge across what is now Wallace's Line, or that there is some alternate explanation. The alternate explanations that come to my mind are that aquatic snakes crossed to (or from) Australia and evolved back to terrestrial life, or that snakes arrived by rafting or similar accidental transport. Robert McClenon (talk) 20:58, 4 January 2019 (UTC)

• Rafting. Abductive (reasoning) 21:13, 4 January 2019 (UTC)
• (ec) The argument is not conclusive - it may be that placental mammals did not migrate to Australia for some other reasons (e.g. unsuitable climate, or origin in a very different location and not having spread there before the Wallace Line became a barrier). Indeed, Wallace Line says that the deep water channel has been a barrier for "over 50 million years", while "true placentals may have originated in the Late Cretaceous around 90 MYA, but the earliest undisputed fossils are from the early Paleocene, 66 MYA, following the Cretaceous–Paleogene extinction event" (from Placentalia#Evolution). Snakes go back at least 90 million years, so probably could have spread to Australia long before the Wallace Line became a barrier. Indeed, a lot of interesting continental movement happened during the time snakes have been around - it's hard to imagine 1e8 years... --Stephan Schulz (talk) 21:19, 4 January 2019 (UTC)

• Naw, just rafting. Abductive (reasoning) 21:48, 4 January 2019 (UTC)

As I said, either rafting or a land bridge. No suggestion of swimming. Robert McClenon (talk) 23:39, 4 January 2019 (UTC)

There are variety of families, but none endemic to Australia. This means it can only, only, only be rafting. Abductive (reasoning) 01:44, 5 January 2019 (UTC)

This paper may be of interest, although it deals with all snakes, rather than just Australian ones. The "biogeographic reconstruction" section on page 19 discusses the likelihoods of snakes crossing water barriers of various different sizes. Mikenorton (talk) 21:52, 4 January 2019 (UTC)

Thanks. Robert McClenon (talk) 23:39, 4 January 2019 (UTC)

Robert McClenon, "two placental species", and the rest. cygnis insignis 22:26, 4 January 2019 (UTC)

User:Cygnis insignis? What do the two placental species have to do with the snakes? The snakes were already there. If you mean that how H. sapiens arrived is just another oceanic dispersal, that is one way of viewing things. Robert McClenon (talk) 23:39, 4 January 2019 (UTC)

Robert McClenon, excuse me being unclear, there are many placental mammals (Placentalia). Lots of them, the statement at the outset is incorrect. cygnis insignis 23:44, 4 January 2019 (UTC)

What other placental mammals were there in Australia at the time of its "discovery" by Europeans? Robert McClenon (talk) 01:42, 5 January 2019 (UTC)

I assume bats would have made it to Australia, as they did to more remote NZ.-gadfium 03:04, 5 January 2019 (UTC)

Okay, thank you. Two land placental species, then. Robert McClenon (talk) 04:51, 5 January 2019 (UTC)

According to Fauna of Australia#Placental mammals, there were at least two families of bats (it's a little unclear from the article how many were present prior to European influence), and many species of rodents, with 14 genera from five million+ years ago, and another seven species of rats from only one million years ago.-gadfium 05:17, 5 January 2019 (UTC)

Then the rodents presumably arrived by rafting. Robert McClenon (talk) 08:32, 5 January 2019 (UTC)

Robert McClenon, inside snakes being carried by bats between rafts during the Eocene (sometime before Europeons arrived) cygnis insignis 21:21, 5 January 2019 (UTC)

I haven't put in the effort to answer this properly, but for example Elapidae has members in and out of Australia. The genus also includes sea snakes, but I don't know how rapidly ancestral forms might have developed the ability to cross the ocean. This list of "ten deadly snakes" [1] are all venomous elapids; I haven't figure out, but if the continent was colonized by something akin to a sea snake I suppose it would explain why so many of its snakes are deadly. Wnt (talk) 15:07, 6 January 2019 (UTC)

Flightless Birds - Origin?

Now that we have discussed the arrival of snakes in Australia, I will ask about the arrival of the emu in Australia. There are large flightless birds known as ratite birds in Africa, South America, and Australia. Did the emu arrive in Australia by rafting, or by land bridge, or are the flightless birds paraphyletic, so that their ancestors flew, and they then evolved species that were too large to fly? Robert McClenon (talk) 23:44, 4 January 2019 (UTC)

• The ratite article seems to cover this. Abductive (reasoning) 01:42, 5 January 2019 (UTC)
• Robert McClenon I would recommend this article by zoologist Darren Naish [2]. To directly answer your question, their ancestors are thought to have flown there and then evolved into emus and cassowaries. Now, the ratite lineage (moas, kiwis, emus, ostriches, cassowaries, rheas, and elephant birds) is a monophyletic group, with the exception of tinamous being deeply nested within them, sister to moas, but almost all of these lineages seemed to have independently evolved flightlessness (including kiwis and moas - the former are closest to elephant birds). Lusotitan (Talk | Contributions) 22:30, 6 January 2019 (UTC)