The scales of life
A scientific meditation (4 minute preview, 7 minute read)
Before I begin, I’d like to offer an act of solidarity to scientists and others working in the science and health fields in the USA, as well as New Zealand. I’ve had the pleasure to meet or correspond with a number of the wonderful people doing amazing science supported by the US federal government in the course of my work. I follow a lot of people working in the sciences on social media and to see so many losing their jobs is heartbreaking. I don’t have much to offer right now, but if you are working in these areas in the USA or New Zealand and have lost your job, I’m offering you a year’s paid subscription for free. Just reply to this post if you receive it by email, or send me a direct message on the Substack app. I’m thinking of you all. Kia kaha.
I was a student long before the days of smartphones. When I stood at a bus stop, or stood in a queue – enrolling took a whole day of queueing in different places around the university – I couldn’t pass the time scrolling through social media and horrifying myself with the disintegration of US democracy. So I used to turn inward and entertain myself with my imagination.
For the first couple of years at university, I studied both chemistry and biology, and I was struck by the way the different disciplines looked at the world on different scales. I began trying to visualise what life looked like at these different scales. It turned into a kind of meditation where I contemplated the complexity of the natural world.
I began writing this as an introduction to an article, but I realised it was far too long to serve as an introduction and might be better as something to stand alone. So here it is, along with my attempt at illustration – but the version in my mind is much more magnificent.
When I look around me, I see a natural world described by ecology, which looks at the interactions of living things, on the scale of whole communities. One important representation of these communities is a food web – what is eating what. As children, we might learn about a food chain, where a plant is eaten by a prey animal, which is then eaten by a predator. But reality is much more complex, and a web is a much better representation than a chain.
In a forest, such as in the small reserve where I’m doing restoration work, we might start with a tree, perhaps a common species such as māhoe. There are wētā which eat the leaves and when there are fruit, as there are right now, these are eaten by tūī and kererū. Ruru (also known as the morepork, a native owl) are predators and will eat wētā. There are no native predators remaining which would eat a tūī or kererū, but the eggs and chicks may be eaten by rats. The māhoe will drop old leaves, which are decayed by fungi on the forest floor. Māhoe probably also has fungi living in association with its roots, with both tree and fungi benefitting. Then there are droppings from the animals, as well as any dead animals, which will be decomposed by microbes, various insects, worms and other small animals which contribute to decay. It’s incredibly complex and interlinked, and it’s also resilient. The forest of this reserve was almost completely destroyed, and although it isn’t what it once was, it is making a strong recovery. Although there are numerous introduced weeds, very few will have a long-term impact.
I could keep going with this, listing all the species which can be found in the reserve, but I’m going to shift the scale now, and get closer. Or rather, I’m going to imagine myself getting smaller.
When I look at the wētā at my normal size, it appears to be a single organism, but as I imagine myself shrinking I see it’s a community in itself. Like humans and other animals, the wētā carries many microbes in its gut which are important for digestion. It can also have parasites, such as a horrifying worm which eats the weta from the inside then compels it to jump into the water so the worm can escape. I’m going to supress a shudder and move quickly past that to the microscopic level.
Every living thing is made up of one or more cells – from the māhoe tree, to the wētā, to the rat, to the microbes breaking down dead plant and animal material. Close-up, they are extraordinary, constantly active, humming along like little machines. I find the idea wondrous, that there is such complexity beyond our sight. Today, I’m going to steer clear of bacteria, because they are a little different, and look at a cell in the wētā. Although an insect doesn’t seem much like a human, once we get to the size of a cell, the similarities are remarkable.
I don’t know how many cells a wētā has, but small insects such as mosquitoes can have 200,000 brain cells alone. There are many different kinds of cell, but each has certain things in common. Just as the wētā has shell around its body and various organs inside, each individual cell has a membrane around it, with organs inside, known as organelles. These organelles include the nucleus, which contains the DNA, and structures which turn DNA into the proteins which are used to make the wētā’s body. There are also small structures which act as energy factories – the chemical reactions which happen inside them fuel all the other functions of the cell. The cell even has hollow tubes which act as a kind of skeleton.
I try to imagine myself shrunk down until I can fit inside a cell, watching all of that activity – the process from DNA to protein, the cell membrane letting chemicals in and out of the cell, the energy production. Then I make myself smaller again.