Over the past year, on and off, I’ve been building computer simulation models of multiplying plant cell populations. Implicit in these models is the fact that the cells grow and divide. And, although it didn’t really matter too much, at the back of my mind I was wondering all the time: How do cells grow and divide? How can something grow bigger and then all of a sudden split in half? Pretty much nothing else behaves that way. If I heap up a pile of sand or earth, it doesn’t break in two at some point. Same if I mix flour and water to create a ball of dough: that doesn’t break in two either.
Pretty much the only things that do it are dripping taps. A drop of water forms on the underside of the tap, and gets bigger, and finally detaches itself, and falls off. As best I understand the process, the drop falls when the weight of the drop exceeds the surface tension around the drop.
But living cells aren’t just drops of water. They have a membrane surround (and sometimes quite a thick one). So a cell is more like a polythene bag that’s filled with water than just a simple drop of water. So how could a polythene bag filled with water grow and divide in two?
Back at the end of March, I at last came up with a solution to the problem. Subject to one or two other constraints, a polythene bag full of water would divide in two if the surface area of the bag (polythene) was kept in constant proportion to the cell volume (water) as the bag grew. I produced a demonstration of how it could do it. But the geometry was maybe a bit too complicated for people to understand.
Yesterday, however, I produced a much simpler model, of a cubical cell forming a furrow, and finally dividing in two. I worked it out with a pencil. The cubical cell has side length a, and so has volume a3 and surface area 6a2, and so the initial ratio of area to volume is 6/a. When the cell starts growing, it lengthens one side (c), and forms a furrow of width h and depth (a-b). When h = 0, the volume of half the growing cell at any point is c.a2 and the surface area is a2 + 4.a.c + a(a-b). If the ratio of these two values is equated to 6/a, a simple equation drops out: c = a – b/2.
As the cell grows, and always keeps surface area to volume ratio equal to 6/r, the notch gradually extends right down from the top of the cell to the bottom. And when that happens, the cell divides. And what’s more, the two new cells that have been created are exactly the same size as the parent cell: a cube with side length a.
What’s so interesting about this? Well, it means that a cell doesn’t have to do anything complicated to grow and divide in two to produce perfect replicas of itself. All it has to do is manufacture surface membrane and internal material in the same constant ratio. If it does that, and grows in just one direction, it will fall in half. It’s very, very simple.
So? Well, the thing is that this isn’t the standard explanation for cell division. According to the standard explanation, the way it works is that cells just swell up (and the cubical cell becomes a larger cubical cell, say of side length 2a), and the ratio of the surface area to the cell volume falls as it does so (which is true, because area is now 24.a2 and volume is 8.a3 and so ratio of area to volume has fallen to 3/a), and this results in the cell getting starved of nutrients it absorbs through its surface, and so the cell divides in order to restore a better ratio of surface area to volume. Cell division is a sort of emergency measure that the cell takes.
This isn’t an irrational explanation. But is it plausible? For a start, in order to just swell up bigger, and remain cubical (or spherical), the cell has to continually modulate its production of surface membrane and internal matter. Also, it has (as noted) to starve. And finally (which isn’t noted) it’ll have to dispose of a third of its internal material to squeeze into two new cells. This is a really tall order for any cell to accomplish. It’s a bit like landing an airplane on the deck of a turning aircraft carrier while running out of fuel.
But, in the standard explanation of cells, they are very, very clever things. They can do almost anything, because everything they do is under tight control (just like a jet fighter coming in to land on the deck of an aircraft carrier). In descriptions of what goes on inside cells, you keep finding things described as “beautifully orchestrated”, as if there was a score with a conductor waving a baton to keep the horns in sync with the violins.
But in my explanation of cell growth and division, cells are very stupid things, and they aren’t ‘controlling’ anything, let alone ‘orchestrating’ anything. In my model, the cells just crank out surface membrane and internal material at a steady rate, and they fall in half without even noticing that they’ve done it. They divide because their geometry requires it, not because they’re starving.
So which is it? Are the experts right? Or am I right?
Well, I think I’m right and the experts are wrong. The experts’ explanation is just too damn complicated. It requires a super-smart cell to carry out a death-defying manoeuvre, and to do it every day. Just because they’re the experts doesn’t mean they’re right. And my explanation only needs a dumb cell to crank a handle, all day every day, to keep on dividing perfectly time after time.
And theirs is a top-down explanation, while mine is a bottom-up explanation. In my explanation, something that’s quite complicated (cell division) is the result of something very simple (keeping surface area and volume in a constant ratio). In their explanation, something that’s quite complicated (cell division) is the result of something even more complicated (the cell that conducts an orchestra). Furthermore, their explanation could be used to explain absolutely anything, including a cell dividing into 12 and re-uniting again upside-down like the Red Arrows.
I’m getting more and more sceptical about more and more of the ‘science’ generated by the ‘experts’. Anti-smoking ‘science’ isn’t science at all, in my view. And climate science is at best incomplete science, if it’s not actually outright, politically-motivated fraud. But now I’m wondering: Do biologists know how cells divide?
And I don’t think they do. And if they don’t know how cells divide, then they don’t understand the first thing about biology. And since cancer cells are cells that keep on growing and dividing, it would be kinda helpful to have a good fundamental understanding of how cells divide, wouldn’t it? Is it any wonder that cancer research is getting nowhere? Or that it’s all blamed on smoking?
We are, I increasingly believe, still living in a dark age. And we still understand fuck all about anything. The doctors who treat our maladies are the same old witch doctors we thought we’d left behind, and the cures they offer us are the same old bones and blood and prayers, dressed in miniskirts and the latest statistical mumbo-jumbo.
If so, there’s nothing to be angry about. It’s not a crime to be ignorant. It’s really only a crime to pretend to be knowledgeable when in fact you’re completely ignorant.