What homeostasis is not

Homeostasis is a notion that is accepted uncritically and without a full appreciation of all it implies. Thus, the word ‘homeostasis’ is often used rather loosely. It is often used synonymously with ‘balance’. I question whether ‘homeostasis’ and ‘balance’ are interchangeable terms.

Another name for a set of scales is a balance. Balance implies equality between two opposing sides. However, the body does not have two sides. While it does have an input and an output, what goes on in between is more important. There is a myriad of interconnected processes. To maintain a steady internal state, often input and output must be out of balance.

We should, I believe, try to avoid ideas of ‘balance’. Such thinking is a remnant of the past. The ancients believed that a healthy body consisted of four balanced humours. The four humours have been banished from science. The tendency to think in terms of balance has not.

The Body's Internal Economy

Advice often given to students is to cite only the most recently published academic work. Anything more than a few years old is out of date. I must disagree. Many helpful ideas are lurking in dusty old tomes.

I recently read some things written over two hundred years ago. An early reference to what is now ecology described the Earth as having an internal economy. The idea of an internal economy is also applicable to the human body. Whole-body physiology is equivalent to an internal economy.

The impression conveyed is more meaningful than that conveyed by the word homeostasis. There is considerable discussion about the nation’s economy in the media. The use of the word economy always refers to something active. It implies something with an input and an output and much going on in between. What economies do, our bodies do, too. Thinking of our bodies as economies gives a better impression of what they are and how they are.

Quotations (101)

For some people, quotations hold a certain appeal. I suspect that I am one such person. Such is the appeal that there have been countless collections of quotations published. I certainly possess some of them. We rarely, if ever, ask how publishers find these books to be commercially viable, yet they do. A market for them must exist. Now mobile apps and even whole websites are devoted exclusively to brief excerpts of what other people - not least those now dead - have said. A quotation is typically little more than the verbatim repetition of what somebody else has uttered. Attached is the name of the person who wrote or spoke this gem. Even if we have never heard of that person, we assume they have a reputation for wisdom or some other commendable human attribute. Rarely does one encounter a quotation from a notoriously bad or incompetent person. In this respect, a quotation is trading upon that person’s reputation. Because of this, a quotation becomes more than the words alone.

Extensive blocks of text expressing a carefully crafted argument are almost unheard of as quotations. Yet, reputations result from such work. Significantly, the emphasis is very much on briefness. The reader wants a quick dose of instant wisdom. Thus, quotations are typically pithy comments or sayings.

Although knowing who made a specific remark helps check accuracy and context, what the quotation is about - not the person who said it - is what matters. A quotation typically contains a single idea expressed clearly and concisely. Here, I am concerned first and foremost with those ideas. What makes a given quotation particularly appealing is the idea contained and its expression. What I then seek to do is dissect the words and the idea. If an idea is worth having, it is worth dwelling upon meticulously, looking at its implications and what may follow. That usually means seeking to express it in different ways, paraphrasing and re-wording it, expanding it and trying to make it more concise, all at the same time. It may also mean trying to express it diagrammatically instead of verbally. Given all that, does the person to whom the quotation is attributed matter? The simple answer is no - apart from giving them the credit courtesy dictates. The idea and its usefulness are what matters most.

No quotation, however elegantly put, should ever be taken at face value. We often hear somebody use a quotation with ‘As so-and-so said…’ or ‘So-and-so once said that…’ As a result, a quotation is given a certain authority because of who said it. To say that ‘so-and-so’ said it makes it definitive in some way; there is no arguing against it. (Those using quotations in this way are usually only pontificating.) Statements always require critical evaluation. (Even that one!) None of the quotations I will be using here are definitive. The person to whom the quotation is attributed is simply the person who happened to have said it. Given the time or opportunity, somebody else could have had the same idea. Somebody else may even have had the idea but never have expressed it. It is just that the person to whom the quotation is attributed happened to have said it first or more memorably. We should consider quotations as things that certain named persons have ‘suggested’, ‘proposed’, ‘pointed out’ etc. They have provided us with food for thought. They have provided brief and concise encapsulations of ideas upon which we can dwell. We can then go on to combine those ideas with our own. Finally, it is not beyond the realm of possibility that what somebody has said is so wrong that it may prompt us to think of something much better!

Thinking for oneself

Today, Aristotle (384–322 BC) has a reputation as a philosopher. However, he was also a natural historian. He had much to say about living things and the universe in general. Formerly, his views formed the basis of much thinking about the universe. His philosophical ideas are still pertinent, but his scientific ideas are less so. They are of more interest to historians of science than to scientists. How Aristotle lost this seemingly unimpeachable reputation is particularly interesting (and perhaps less well-known to scientists). How he fell out of favour influenced how modern science operates.

For over a thousand years, the writings of the ancients - in particular, Aristotle - were the ultimate authorities in scientific matters. In the sphere of anatomy and physiology, for example, the works of Galen (129-c216) were adhered to strictly. Human dissections at medical schools were demonstrations of what Galen had stated centuries before. They were not a means of discovery. A professor - seated above proceedings - would read from Galen while a junior colleague under his direction would perform the dissection.*

In the thirteenth century, the Roman Catholic church in Paris, keen to counter - what it considered - heretical teachings, published a list of 219 propositions whose discussion was forbidden. Neither could these be read about - even in private! Prohibition was not limited to theological ideas. An ecclesiastical condemnation published in 1210 prohibited Aristotle’s books on natural philosophy (i.e. physics) from being read. Even reading commentaries was forbidden. (His philosophical works were not directly affected.) The penalty was excommunication. (Excommunication implied eternal damnation to hell fire.)

Initially, that condemnation only applied in Paris. Other cities in France were unaffected. Aimed at attracting students, some universities even advertised that they allowed the reading of things forbidden in Paris!

An unforeseen consequence of the condemnation was that without the authority of Aristotle upon which to rely, the only option was to find out for oneself. Thus, an intellectual shift away from the reliance on ancient authority began.

Simple reflection must recognise how relying on authority must result in intellectual stagnation. Often, a plurality of possible positions exists. No authority can advocate a plurality of positions. Authorities can hold only a single position. By definition, that position must be the right one. There is no need to develop ideas if they are right. Hence stasis. Only a revolution in thinking can change this. An authoritative position presupposes perfect knowledge of all relevant facts. Nobody can genuinely claim this. Thus, there can be no authoritative positions in science.

Later, Hegel (1770-1831) proposed that knowledge could progress via dialectic between a thesis and an antithesis. There can be no completely authoritative positions. Every position is provisional, dependent on the current state of our knowledge.

Note

* There are two approaches that one can take when dissecting a human body.

(a) One takes a dissecting guide and follows its instructions closely. When I was teaching medical students, this was the approach prescribed. Classes of this type have something in common with those of old. Professors no longer sit directing proceedings, but dissection is still strictly guided.

(b) One opens the body to see what is inside. It is helpful to know what to expect in advance. However, this is not essential. One then identifies the findings. When I was a (non-medical) undergraduate on a course that permitted human dissection, we adopted this approach. We knew what we were looking for, but we went about it in our own way.

Reality (and alcohol)

My first day as an undergraduate student was on Monday, 9th October 1978. I remember it well. At 11:00 am, we had our first lecture from our head of department. It was the first in a series he gave entitled The Biological Basis of Human Action. Affectionately known as Prof, our head of department was not an unpleasant fellow. However, he could exude considerable gravitas. Nobody wanted to upset him.

Upon entering the room, the first thing he said - while also writing it on the blackboard - was, Reality is a state of mind brought about by low blood alcohol concentration. It was a light-hearted comment, no doubt meant as an ice-breaker. Not knowing at that time what to expect, it certainly got us all relaxed. He did not go on to elaborate at length. It was something left open-ended.

Perhaps it was his usual opening gambit with a group of new students. 

Perhaps it was an off-the-cuff remark for only that occasion. I do not know.

However, this statement has frequently come to mind over the intervening decades. Most often, I remember it after having had a pint (or two) of beer!

After some beer, the world does seem a little different. Alcohol affects one’s mood. For the better or worse, reality does take on a different feel.

The changeability of mood raises questions about the world - at least as we perceive it. If my perception of reality is changeable, how do I know which perceived reality is the real reality?

One might answer that it is one unaffected by alcohol. But how do I know that my alcohol-free state reality is being perceived accurately? Does not being hungry or thirsty also have an effect? Or any number of other influences?

Prof’s opening statement has posed for me a lasting question. To this question, I do not have an answer. However, pondering the question continues to provide much pleasure. (Which also has an effect on my sense of reality.)

Adults Only

There are a few characteristics of textbooks on anatomy and physiology that need to be recognised lest they go unnoticed. Recognising what is missing from teaching, why it is missing and how, despite its absence, it may still be important must be identified.

Including everything pertinent to the anatomy and physiology of the human body in one textbook is unfeasible. Thus, one reason why something is missing is lack of space. Another reason is to do with the approach textbooks habitually adopt. Textbooks on anatomy and physiology have a typical style and approach.

Firstly, these textbooks concentrate on adults. There is little or no content relating to how adults come about. There is little or no content relating to embryology, prenatal or postnatal development. If these subjects receive any attention, it is necessarily limited.

Teaching embryology comes after adult anatomy. That is not surprising. Embryology can be rather intricate. However, teaching anatomy from an embryological perspective is a potentially creative approach. It adopts a synthetic rather than analytic approach. It builds the body rather than dismantling it.

Life history is divisible into three phases (rather than the seven ages in Shakespeare's As You Like It). These can be called pre-adult, adult and post-adult. Roughly, they are the pre-reproductive, reproductive, and post-reproductive phases of our lives. Just as the pre-reproductive phase is missing, so is the post-reproductive phase. The bodily changes that occur with ageing are also largely ignored. These changes are not necessarily pathological or associated with disease. These changes are not abnormal. They are changes experienced by all.

The adult bodies in textbooks are always healthy. Significantly, textbooks on anatomy and physiology are primarily concerned with normal, non-pathological and healthy adult bodies. But what that is is not clear. There is no single simple agreed definition of what constitutes healthy. (Similarly, there is no single simple agreed definition of what constitutes diseased.) Normal and healthy are terms used loosely. They are used synonymously and even interchangeably. What a standard or 'normal' body is is never stated.

Anatomically, there is considerable scope for variation - even anomalies - without adverse effects on the individual. What textbooks represent is an accepted canon. They overlook variations and anomalies. A tradition has built up about what is considered standard. Textbooks are written based on textbooks that have preceded them. The body depicted is what is now deemed canonical.

Similarly, there is little or no reference to evolution in textbooks on anatomy and physiology. As noted elsewhere, the theory of evolution makes all of biology intelligible. Evolution accounts for how we got to be how we are. It also provides the conceptual framework for understanding all biology. Variation is a feature of evolution. Without variation, there would be no anatomical or physiological change.

I mentioned above how there is often little or no reference to certain things that still need mentioning. A passing mention or brief paragraph noting these things does not necessarily qualify as sufficient attention. It is impossible to include everything that has a bearing on the body. To reiterate, recognising what is missing from teaching, why it is missing and how, despite its absence, it may still be important must be identified. We have only a partial picture of our bodies. That must not be forgotten.

Nothing in biology makes sense...

Academic articles rarely have catchy titles. One that has - and that is also frequently cited - is Nothing in Biology Makes Sense Except in the Light of Evolution.

Its full citation is:

Dobzhansky, Th. (1973). Nothing in Biology Makes Sense Except in the Light of Evolution. The American Biology Teacher. 35 (3): 125–129.

A transcript of the article is on biologie-lernprogramme.de. An article about it is on Wikipedia.

The article was written by the eminent Ukrainian-born evolutionary biologist Theodosius Dobzhansky (1900-1975) when living and working in the USA. Significantly, it is an essay that argues that Christianity and evolutionary biology are compatible. Furthermore, it argues in support of theistic evolution. Irrespective of their personal religious beliefs, few biologists would advocate theistic evolution professionally. Most keep their scientific work and their religious views separate. That being the case, it is open to question how widely this essay has been read by those citing it.

The citations the article continues to receive could be more for its title than its content. What the essay title encapsulates is a statement of how evolution pervades and relates to every aspect of biology. The phrase states vividly and concisely something all informed biologists recognise - that evolution is at the very heart of all of the life sciences. It is in this sense that the article is sure to continue to be cited.

What is easy to overlook is what the essay title implies. The implication is that without evolution, biology, in fact, makes no sense.

In their book Evolution and Healing (published in the US as Why We Get Sick), Randy Nesse and George Williams modified the essay title to make specific reference to medicine. They proposed that nothing in medicine makes sense except in the light of evolution. Upon this notion, evolutionary (Darwinian) medicine rests.

Fun fact

I once set a multiple-choice exam question for a biology paper that read...

According to Theodosius Dobzhansky (1973), ‘Nothing in biology makes sense...’

(A) ...at all

(B) ...except in the light of evolution

(C) ...

(D) ... I have forgotten the other incorrect choices I offered.

How many students got it right, I do not remember (although it was the majority - if not all of them). I remember very clearly how relieved I was when I found that nobody had chosen (A), implying that nothing in biology makes sense... at all.

[Full citation for the above:

Nesse, R. and Williams, G. (1995). Evolution and Healing. London, Weidenfeld and Nicolson.]