Why did the snail cross the road?

Why indeed? A snail has no notion of roads, what they are made of or what they are used for or even that it is lousy habitat for a gastropod. So what, you might ask…

On my morning walk, I see a snail crossing a tarmac road. This snail is unusual. I’ve never seen one quite like this one before. Snails are not that common on the sandstone derived soils of the Blue Mountains that lack calcium and are exposed to volatile moisture conditions. Conditions that don’t suit gastropods.

This particular snail was small and had only just started on what for it was an epic journey across the tarmac. I’m tempted to pick it up and return the errant creature to the bush for a better chance of survival. 

The question is, should I move it? 

Should I save this individual organism from death under a passing car or from dehydration by returning it to its natural habitat? Or should I leave it to its marathon crossing? 

This is the conundrum we face since humanity altered the face of the planet. There are literally hundreds of thousands of species whose habitats are disrupted as a result of our presence. Change that alters behaviours and survival probability. 

I’m tempted to save that individual snail but the reality is that the survival probability of that snail species is determined by its adaptation to the new environment that humans have created. Not by any random act of a morning walker. 

A changed environment

This new environment created by humanity is not going away. 

Human activity is a massive disturbance to the natural systems of the world. Species that survive such a disturbance must have the ability to live with us. Anything that can’t manage has a very high probability of extinction. There are very few wild areas left and of those wild areas most of those are essentially non-livable in other words, most biodiversity struggles to live there too because these places are either too cold or too dry or bereft of nutrients. 

At some point, we have to accept this as a reality. Humans appropriating the planet have massively changed it. And the priority for those humans will always be themselves. Feeding ourselves to maintaining our health and well-being is always going to be the number one priority. We won’t sacrifice ourselves for other species. 

We may tell ourselves that we will but, when the push comes to shove, that’s not what’s going to happen. Humans will prioritize themselves over other species. 

Biodiversity is and will be lost.

small snail on a fern frond
Photo by Juli Kosolapova on Unsplash

Ecosystem services 

The huge challenge humanity has is that if too many species are lost it will endanger our own survival. 

The goods and services that humans need from nature are the consequence of other species. Some we eat. Some we use to build our homes or fuel our fires. There are those that we admire. 

Then there are all the species that must be present to clean the air, the water, and make life possible. These species moderate and deliver critical ecosystem services.

So, how many species can we lose?

Written in the research literature, sometimes with great vigour and huge catastrophe, other times more subtly is the reality that we don’t know exactly how many other species we need to maintain in landscapes in order for us to persist. 

Along with limited knowledge of how many species we need are policies or practices to make sure that a sufficient number of species survive in order to supply us with the goods and services we require. 

We don’t see that changing anytime soon either. 

The imperative still is to create commodities for sale. The food supply system prioritizes production and production efficiency over the services provided by organisms that as far as the farmer knows they don’t ever use. 

Profitability and production efficiency are much more easily understood with inputs of fertilizer, pesticides, and tillage. Rather than understanding the more subtle and more complex delivery of services from nature. 

A shift to looking long 

Humanity must make a fundamental shift in our food supply systems — services must become equal to profit.  

This will mean profitability must be curtailed in some places in favour of maintaining ecosystem services so that production can persist for a long period of time. 

Unfortunately, the long view is often in conflict with profitability, the imperative to convert natural capital into cash. Conversion of resources into financial returns is the fundamental premise of capitalism so any shift to give services equal weight is no small task.

It means a different way of producing food and fibre from the natural capital that’s not profit-driven. Or, at the very least, can make a profit but not at the expense of the organism’s supplying the critical long-term services. 

The way to achieve this is to understand what long-term means. At a minimum, it is the persistence of supporting and enabling ecosystem services way beyond the lifetime of the farmer or the farm business. 

But first, it means understanding what these services are and how they come about in each context. 

Initially, this is a job for the scientific literature, the mountain of human knowledge. Researchers have found out a great deal about how ecosystems work. Mining that information and collating it into practical solutions is one obvious first step. This would also identify gaps in our knowledge and enable us to work on research and fund programs that can fill those gaps. 

It’s actually surprising how much information you can gather if you know what you’re looking for and have the skills to filter evidence from opinion. 

The next step is to map the food production systems, the way that farmers farm to produce commodities for consumption or sale and establish if those mechanisms and approaches are the most efficient in that location. It’s not just efficient from the immediate turnover and transference, but also in the long term. 

Food production can’t be efficient by mining the carbon in the soil. It is efficient because production is in balance with the natural nutrient transfer capability of the location. Only most of our agricultural systems are subsidised by energy and nutrients. And so we have to manage that subsidy in a way that’s much more aligned to the natural capacity of the local ecosystem. 

Intensification is an essential part of food production globally. But we just assume it will deliver forever and not disrupt the core services. We have to know how production combines with the natural systems rather than against or as a substitute. 

Why did the snail cross the road?

This post began with a snail crossing the road. And from there you can see how easy it is to wander off into the much bigger picture of how and even if humans will persist on the planet. 

Whether to save that snail from near-certain death on the busy road by replacing it back into the natural habitat is a critical one. It is fundamental to how we have to operate now that we’ve altered every landscape on earth. Knowing how many species we need to survive and if the snail is among them is a determinant of our future. 

But we need to understand that the snail crossed the road because it had no choice.

Humanity took away its choice by building the road.

Hero image modified from photo by Juli Kosolapova on Unsplash


Mark is an ecology nerd who was cursed with an entrepreneurial gene and a big picture view making him a rare beast, uncomfortable in the ivory towers and the disconnected silos of the public service. Despite this he has made it through a 40+ year career as a scientist and for some unknown reason still likes to read scientific papers.

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