Humans have been altering the natural world for millennia, and today our impact is felt in every corner of the globe. Due to our disconnection with nature, the devastation of “the environment” is often seen as a price to pay for continued economic growth and human progress. However, in reality the erasure of biological diversity threatens not only our physical and mental wellbeing, but also undermines the sustainability of our civilisation.
The loss of biological diversity inflicts irreparable damage on the tree of life. The mind boggling diversity of species present on the earth today is the result of 3.5 billion years of evolution, and as an intelligent and self-aware species with an unrivalled impact on the planet, we have a moral duty to preserve other species. Rolston (1985) described eradicating species as like “tearing pages out of an unread book, written in a language humans hardly know how to read”. However, it is debatable whether a species can actually have inherent value, other than simply being useful or aesthetically desirable from a human perspective. From a utilitarian viewpoint, “the preservation of species is to be aimed at and commended only in so far as human beings are emotionally and sentimentally interested” (Hampshire 1972). It is widely agreed that we have a moral duty to not harm other human beings, so arguably we also have a moral duty to not harm other species, because there is no fundamental reason to prioritise our own species over others. However, since it is inevitable that we have to kill and displace many organisms in order to survive (and that there is not enough conservation funding to save every species), it is impossible to escape the fact that some species must be prioritised over others. In answering the question of which species to prioritise, we inevitably make a subjective judgement of which species are most important to us, rather than which have a greater inherent value. Furthermore, the flaws of the Biological Species Concept make it harder to justify which groups of organisms we choose to protect. For example, in my opinion, the vast amount of money spent on attempting to save northern white rhinos through IVF would be better spent on other conservation projects. Given that the northern and southern subspecies are very similar physiologically and fill the same ecological niche, southern white rhinos could simply be introduced to the northern white rhino’s former range. The distinction between the subspecies is probably more an arbitrary division than anything ecologically meaningful. If our aim is simply to preserve biodiversity, should this be extended to preserving genetic diversity within common species as well as saving rare species from extinction? On the other hand, if different species with similar ecological functions are seen as interchangeable, we risk homogenising the planet’s ecosystems.
On a more practical level, the loss of biodiversity threatens economic prosperity. Biodiverse ecosystems provide countless benefits such as flood mitigation, pollination of crops, carbon sequestration, and raw materials, which would otherwise be costly to produce. Beavers, by creating leaky dams and spongy wetlands, slow the flow of floodwaters though upland streams and so reduce the likelihood of flash flooding downstream, which in 2000 cost £600 million in England and Wales. Not only would building flood defences be more costly than reintroducing beavers, but beavers also create wonderful diverse habitats full of life such as frogs, water voles, and black storks, and could benefit rural economies by boosting tourism. On a global scale, Costanza et al (1997) estimated the total value of the world’s ecosystem services to be roughly 33 trillion USD. However, the implicit suggestion of this statement is that the loss of these services could be redeemed by 33 trillion USD of money. Although some services may be replaceable, for example crops can be hand pollinated if the insect pollinators have been exterminated, many ecosystem services are simply irreplaceable, so assigning them a monetary value is misleading. This is especially true of the provision of raw materials. Soil erosion in England and Wales is estimated to cost around £1 billion per year, but the consequence of soil erosion is not just a loss of money, it is the end of the food production on which we all depend. The Knepp rewilding project has shown that biodiverse plant communities arising from low intensity mixed grazing increase the nutrient availability and carbon content of the soil far better than monocultures. Furthermore, a greater diversity of mycorrhizae increases nutrient and water uptake by crops. It has been suggested that, by reducing the diversity of pollinating insects and mycorrhizae, pesticides and herbicides make no significant net contribution to increasing overall yields.
As well as the measurable economic impacts, the loss of biodiversity also threatens our physical and mental wellbeing. Children who spend time learning in green space “perform better in reading, mathematics, science and social studies” according to a report commissioned by Natural England, and patients recovering from surgery had shorter hospital stays if they were allocated a room with a view of foliage than those looking out over a brick wall (Ulrich 1984). What is more interesting and amazing is that it is not just the exposure to any green space which benefits our health, but we are even able to subconsciously assess the level of biodiversity in an area. Fuller et al (2007) found that, among visitors to green spaces in Sheffield, there was a correlation between species richness and number of habitats, and various measures of people’s wellbeing. This is fascinating because, if the study population was representative of the UK population as a whole, their knowledge of natural history was probably very low, yet still they rated the more biodiverse systems as more appealing. A possible explanation is that, in our evolutionary history, a propensity to seek out more biodiverse areas would have been rewarded by the larger numbers of plant food sources and prey species living there. As Darwin stated in The Origin of Species, more biodiverse meadows attain a greater biomass of herbage. In general, more biodiverse ecosystems have greater plant and animal biomass (explained by the adaptation of each species to specific conditions, and the insurance hypothesis), so would have provided more food for our hunter gatherer ancestors. Perhaps this explains our innate attraction to more biodiverse systems.
The loss of biodiversity is probably the biggest problem facing humanity today. Not only does it threaten the sustainability of our economy, but also undermines the very foundations of our existence. Even if we could survive a massive loss of biodiversity, our lives would be unbelievably diminished. In the words of Attenborough, “The natural world is the greatest source of excitement, the greatest source of visual beauty, the greatest source of intellectual interest. It is the greatest source of so much in life that makes life worth living.”
Ethics of conserving species: https://www.pdcnet.org/collection/authorizedshow?id=enviroethics_1981_0003_0002_0101_0112&file_type=pdf and https://www.jstor.org/stable/1310053?seq=4#metadata_info_tab_contents