Life is not strictly part of the biosphere, which is technically the regions of the Earth which support life. However, as mentioned in Chapter 3, I have chosen to include non-human life in these chapters on the biosphere.
I’ve already referred to the sixth mass extinction, and don’t want to belabour the point. But it does need some elaboration.
Rachel Carson’s “Silent Spring”, published in 1962, is often cited as marking the birth of the modern environmental movement. In it, she drew attention to the serious impact of heavy use of pesticides on the environment, and in particular birdlife – hence the book’s title. She also accused the corporations concerned of spreading disinformation about the effects of their products – a type of action which continues, and which I will return to in some detail later.
Carson’s book can also be seen as another canary in the coal mine of life on earth.
The extinction of the dodo in Mauritius in the mid-seventeenth century was one of the earlier canaries. The dodo now has iconic status as a defenceless, allegedly stupid, and apparently pointless (and therefore obsolescent) flightless bird. It became flightless, and grew large (to about a metre tall) because there were no predators on Mauritius, which is a recently formed volcanic island (10 million years or so is “recent” in geological terms).
As soon as humans introduced predators (dogs, cats and rats, for example) to Mauritius, the dodo’s survival was put under severe threat. And, although the process of extinction will have started earlier, it was only 70 years between the first and the last recorded sightings of a living dodo.
Here’s a thing. While we have learned something about the dodo’s feeding and other habits, and its place in the food chain, we will never know the exact place it had in its environment, or the other forms of life which were interdependent with it, and may have died along with or after it. The dodo and its immediate ancestors had been around, developing their own ecologies, for some millions of years. And who knows what we’ve lost along with the dodo – a new drug? Another form of edible plant life? An insect or bacterium which might change our world?
And these were wiped out – very rapidly – by the arrival of new and more rapacious forms of life.
This wasn’t just in Mauritius, of course. Most large animals and birds in the world (known as “megafauna”) have been wiped out or are perilously close to extinction, almost exclusively as a result of human activity. Bill Bryson[i] notes that 30 genera[ii] of large and very large animals were wiped out soon after humans arrived on the American continent, and that, world-wide, only four types of really large land animals survive today (elephants, rhinos, hippos and giraffes) out of hundreds (perhaps thousands) which existed before humans.
In New Zealand, many flightless birds had developed as a result of its millions of years of isolation. All the larger species of these were wiped out by the Maori, who arrived in the 13th century, before the Pakeha (Europeans) first arrived in the 17th century, and continued and accelerated the elimination of smaller birds and other species[iii]. And so it has gone on around the world.
That’s Darwinism, I hear you say. The survival of the fittest.
Well, not really. Evolution of species operates by genetic selection, based on survival traits, over multiple generations. It results in many more dead-ends than it does success stories. But conscious manipulation of the environment on any large scale is not contemplated by Darwinism.
Richard Dawkins and other “deep” Darwinists argue that everything humans do is driven by genetic survival imperatives. But I’m a humanist. Even if I’m wrong, I prefer to believe that humans can make choices of their own free will which change things. Yes, we’re limited by our genes and conditioned by our environments, and rewarded more by luck than by merit. But if we don’t give ourselves even the illusion of free will to make choices within these constraints, we can never be more than instruments of something else.
Humans manipulate the environment consciously, and on huge and never-before-seen scales. Their actions are not an expression of “natural selection”, but of conscious will. They remake landscapes, move plant and animal life round indiscriminately, and pump new chemicals into the land, air and water.
The point is that, in the world of Darwinian evolution, it is NOT inevitable that the predator wipes out the defenceless. In natural ecology, if a natural predator wipes out its natural prey, then it too is doomed to extinction. Populations of predators and prey usually grow and shrink in cycles – more prey means more new predators as more are born and survive, leading to less prey and more starving predators and less predator births – and so the great circle of life continues! Perhaps for millions of years, until something disturbs the situation.
Yes, “survival of the fittest” does mean that species need to change to survive. But, if they don’t, they take out other species or environmental characteristics with them.
Humans are very very good at wiping out other species (not to mention culling their own). Only a very few of those other species can be classed as “prey”, in the sense that they’re immediately necessary for human survival. Many species have been exterminated or brought to the brink of extinction for sport, or for profitable sale of some small part of them (antler velvet!? rhinoceros horn?! elephant tusks?!), or because they’re in the way of something humans want to do. And most of the time, for smaller life forms, we don’t even know we’re wiping them out.
“A Short History of Progress”[iv] suggests that early hunting societies, when they became too efficient, wiped out their local populations of prey and had to move on. From the stone to the spear to driving whole herds of animals off cliffs, we humans got more efficient at killing other species. Until recently, there was usually somewhere else to move to, and hopefully more of that species, or useful substitutes, to hunt. But there aren’t nearly enough large wild mammals left to feed humanity any more. We’ve either wiped them out completely, or so few are left that they are to all intents and purposes extinct.
And so all we have left are domesticated animals and birds, such as cattle, pigs, sheep, and chickens, which can provide meat and other protein products. However, the environmental risks and real costs of industrial production from these sources are increasing.
So then we have grains and protein from plants such as soybeans, which can feed us all. The Green revolution worked, right?
Well, yes and no. The development of higher yielding crops from the mid 20th century was probably a great boon, and, in the short term, has enabled us to feed most of a population which has doubled in less than 50 years to seven billion. The crop yields from arable lands have nearly tripled since 1960, according to at least one study[v]. But I have already referred to the negative effects of the industrial agriculture that this all entailed in chapter 7.
We seem to have come a very long way from the dodo. But it’s not that far, actually. Not only have humans wiped out most of the large animals by mass slaughter, but they’re also busy wiping out the smaller ones, and the birds and insects, by recklessly demolishing natural environments that developed over thousands and millions of years, in the interests of industrial food production – to which there are perfectly viable alternatives, as I’ll discuss later.
And this loss of species not only directly affects us, by removing food from our mouths and interest from our environment, but also affects the long-term viability of life on Earth, through loss of diversity. The Planetary Boundary framework recognises this risk, and I will also expand on it further in chapter 28.
Planetary Boundary 2 – change in biosphere integrity – red zone: Back at the beginning, I wrote that species extinction rates were currently 10 to 100 times higher than is safe for sustaining human life on Earth. This was taken straight from the Planetary Boundaries framework.
This Boundary uses two variables. One is an interim measure, the “Biodiversity Intactness Index”, which is very tentative and only partially measured so far. It attempts to assess change in population abundance across a wide range of functional groups compared with pre-industrial levels as result of human impacts.
The other is extinction rate of species. The “background” rate (ie without human intervention) is about 1 species per million species-years (MSY). The assessed safe Boundary is 10 species per MSY, and the current rate is somewhere between 100 and 1,000 species per MSY. This variable is far into the red zone.
And our transgression of this Boundary profoundly threatens our own future as a species.
[i] In “A Short History of Everything”, pages 41 and 54
[ii] A genus (pl genera) is a biological classification of type of life which is above “species” and below “family”. For example, the species “lion” is part of the genus “panthera” (which also includes tigers, panthers, and other large wild cats which can roar but not purr), which is part of the cat family “felidae”.
[iv] “A Short History of Progress”, Kindle edn Loc 350ff