FOR more than a decade, scientists have been warning of an impending collapse of global biodiversity – the sixth great extinction. Averting this massive species loss and the resulting pauperisation of ecosystems demands immediate action, they urge.
What they don’t realise is that this “extinction crisis” is no more preventable than previous extinctions caused by asteroid impacts or the detonation of tens of thousands of volcanoes. In the century ahead, upwards of half of all species will functionally, if not literally, vanish. In this respect, the crisis is over.
The cause of the sixth extinction is well known: human selection (what might be termed unintelligent design) is systematically replacing natural selection as the engine of evolution. “Weedy species” (those organisms that thrive on the disturbances we create) are experiencing rapid population growth, accelerated dispersal and maybe augmented speciation – the development of additional species from an existing one. The great many “relic species” – those not equipped to live alongside us, or which we are not prepared to have living alongside us – are being shoved to the margins of existence. Many of these have become “ghost species”: they are on the brink of extinction. The net effect is global biologic homogenisation and ecosystem simplification – the end of the wild.
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Human selection is particularly insidious for two reasons. First, it is driven by the otherwise innocuous aspirations, actions and choices of ordinary people pursuing a better life. You might wonder how my taste for swordfish for tonight’s dinner could affect the trophic balance of sea life, let alone drive the species to the brink of extinction. Yet hundreds of published studies document how the cumulative pressure of over 6 billion people systematically transforms the landscape, alters global biogeochemical processes, demolishes geophysical barriers thereby facilitating the free flow of alien species, consumes natural resources beyond their capacity for regeneration, and motivates us to intentionally eliminate those organisms we deem inconvenient. For weedy species, such as the English house sparrow and the Asian tiger mosquito, we are building paradise. For relics and ghosts like the polar bear and the Chilean monkey puzzle tree, the new world is a graveyard.
“Restoring natural selection to its dominant place is impossible in the world as it is now”
Second, the very actions we take to forestall the “extinction crisis” and blunt the force of human selection serve to amplify its distorting effects. Species-based regulatory regimes such as the Endangered Species Act in the US preferentially allocate protective resources to organisms that are charismatic, symbolically important, and do not pose serious social or economic conflicts. Conservation goals are set by social carrying capacity – what people will tolerate – rather than what is of ecological or evolutionary value.
Human considerations are equally decisive in the design and operation of bio-reserves and refuges, which become agents of human selection. Bio-reserves are isolated islands of landscape, or marine-scape, embedded in a sea of human activity – remnants of what were once expansive ecosystems. Often a country’s last undeveloped places, these areas are ripe for economic development, natural resource exploitation and homesteading, as in Mexico’s Montes Azules Biosphere Reserve, where 25 per cent of jungle habitat has disappeared. As human activity seeps in, weedy species crowd out relics and ghosts. The resulting balance among the menagerie of what remains is neither ecological nor self-sustaining. Similarly, experiments in sustainable development are fundamentally about human needs. Ecosystem tolerance is a residual concern.
Restoring natural selection to its dominant place – bringing back “the wild” – requires unprecedented changes in human aspirations and societal organisation. Lacking a global spiritual epiphany of unimaginable proportions, this is simply not possible in the world as it is now. The grossly mistaken belief that we can halt – if not reverse – the ongoing extinction fuels our preoccupation with saving relics and ghosts and steers us further away from preservation strategies based on ecological and evolutionary value.
We need a new approach. We must turn our attention to the new assemblages of organisms that are emerging as a result of “unintelligent design”. The huge losses in global biomass caused by previous great extinctions will not happen this time; the Earth will continue to teem with life as the expansion of weedy species occurs simultaneously with the decline of relics and ghosts. Net biomass might actually increase. What will change is the complexity of how life is organised and how the biotic and abiotic worlds interact. Understanding and engaging this transformation should be the focus of conservation efforts in the years ahead.
