One of the realisations one makes when continuing to study a subject beyond one’s initial formal education is that things you were once told in all honesty are sometimes not quite right. There are many reasons for this although one thing is sure. No teacher or lecturer ever deliberately provides their students with false information. (Or if they do, it is to make a point that is immediately made clear.)
When it comes to models of the atom, the situation is perhaps a little greyer. I was taught the Bohr model of the atom at school—although it was not given that name. It was ‘the atom’. When I went to university we were taught something quite different. The flaw in what I was taught at school was not some much the inaccuracies as the fact that we were not told that it was only a model. We thought that it was what the atom was really like.
As a model, the Bohr model serves many useful purposes—but not as a description of what the structure atom is really like. What we were taught at university was also a model—albeit a better one—but a model nonetheless.
As undergraduates, when studying the nervous control of movement, we were told by an old professor that reptile movement was slower and deliberate because they had to ‘think’ about each movement. That is because their cerebella are much simpler than that in higher animals. The input the reptile cerebellum makes to locomotion is limited. The missing input had to come from elsewhere. That was from the brain, which had to divert what it was doing to ‘thinking’ about locomotion.
This description is not wrong but not a complete description.
Firstly, it overlooks the fact that reptiles are ectothermic animals and have a particular way of life. Indeed, when sufficiently warm, ectotherms can move quite quickly. They demonstrate a ‘sprint-and-pause’ style of movement which is, in fact, a highly efficient way for them to conserve energy. Furthermore, that plays a key part of their survival and hunting strategies.
Secondly, and very easily overlooked, is how in animals with side-to-side movement, walking and breathing at the same time is difficult. There is a need to stop every so often in order to breath. This is now known as Carrier's constraint after the American biologist David R. Carrier.
And about which a limerick has been penned by the English paleontologist Richard Cowen.
The reptilian idea of fun
Is to bask all day in the sun.
A physiological barrier,
Discovered by Carrier,
Says they can't breathe, if they run.
The realisation that walking and breathing at the same time was difficult for animals with side-to-side movement, only came to prominence in the late 1980s, after my old professor has retired. So he could not have known about it. However, when discussing organisms, it must be remembered that many different factors are in play at the same time. To do otherwise is, in a quite literal sense, not organismal thinking.
And there is always the caveat that something we haven’t thought of (yet) might apply too.
