“ohbird after their kind,” the Lord said to Noah, “and livestock according to their kind, of everything that creeps on the ground according to their kind, two of each kind will come to you. Cooperation from the animal kingdom helped make the biblical patriarch the best conservationist in history, saving all animals on earth, including humans, from a wave of divine extinction .
Unlike Noah, today’s conservationists have limitations: they cannot save everything. The patriarch could fit a breeding pair of each of the 5.6m or so terrestrial species on his 300 cubit ark. If he had to ration his space, faced with the traditional economic problem of scarce resources and unlimited desire, which animals should Noah have prioritized and kept safe from the flood for the future generations?
This was the dilemma posed by Martin Weitzman, an economist, in a paper published in 1998, and it is one that carries lasting lessons. Weitzman’s goal, beyond biblical interpretation, was to create an economic theory of conservation, devising a strategy that a rational conservationist could follow to maximize both human welfare and natural biodiversity. . He wanted to find a way to rank conservation projects; how to measure what the Lord called the crawling things of the Earth against each other with how little funding there is to keep them alive.
Animals have two sources of value in Weitzman’s model. The first is the resource they provide to humanity: economists now call this “ecosystem services”. They vary from the pleasure that megafauna brings to those who visit a safari park to the more prosaic: pollinators fertilizing crops; earthworms keep the soil healthy. A forthcoming paper by Eyal Frank of the University of Chicago and Anant Sudarshan of the University of Warwick looks at the economic benefits of “keystone species”. They find that the accidental poisoning of vultures in India led to a dramatic increase in human mortality, with more than 100,000 extra deaths in an average year, because the birds did not consumption of waterway poisoning further (see graphic details). Despite their bad reputation, such vultures could earn a place on an ark with limited resources.
The second part of the calculation directly values biodiversity. Imagine, now, that you are not Noah trying to save the natural world from a flood, but a scholar trying to save texts from the Library of Alexandria. All the scrolls may be valuable, but many have information about them that is in other libraries. The aim would be to save those whose information has not been recorded elsewhere. Weitzman applies the same logic to animals: biodiversity has both aesthetic and informational value, with content rooted in animal genetics. The selection for the ark should try to preserve as much of this information, even if the animals themselves do little for human welfare.
That led to what some conservationists might consider a questionable conclusion: on purpose, the best way to conserve biodiversity for the resource-limited ark is to choose a genre and squeeze in as many as they can. By preventing just one type of animal from becoming extinct, not only what is different about that animal, but everything it shares genetically with its every other animal too. Trying to keep two species alive, and failing, means losing everything. The effect of this on the world is that using conservation money on critically endangered species risks throwing good money after bad. Pandas, for example, are cute but require a lot of effort to survive. Perhaps Noah would have preferred to fill the ark with smart cockroaches instead, ensuring that at least one creature makes it through the flood.
To reach that counterintuitive conclusion, Weitzman assumed that people should value biodiversity for its own sake. Some boat builders may want to focus only on the benefits that animals bring to people. Some creatures may give a low enough value or even a negative value to be excluded entirely. Wasps are one candidate, but picnickers play a vital role, eating other pests and pollinating flowers. Another is mosquitoes, the biggest natural killer of humans, responsible for over half a million deaths a year. Some scientists have proposed releasing customized, sterilized versions of the insects that would completely eradicate the species; others warn that eliminating both a pollinator and a food source for other animals could have unintended consequences.
Deliberate elimination is sometimes successful. Every week the us Department of Agriculture (usda) and the Panamanian government drops sterilized shrews, the larvae of a parasitic flesh-eating fly that eats livestock, out of a plane on the Panama-Colombia border to stop the creatures from breeding. This helps maintain a biological barrier that prevents the creature from moving north, thus protecting a program that spans decades and countries. got rid of the fly from North America. The usda estimates that the project will bring economic benefits worth around $3.1bn a year.
Be fruitful and multiply
There is reason to be cautious, however. Even when animals are valued solely for their benefits to humanity, biodiversity still has something to offer: insurance. Genetic diversity reduces the vulnerability of any part of an ecosystem to pests and diseases, helping to avoid a catastrophic extinction of a species critical to human survival. If Noah had filled his ark with cockroaches – or pandas, for that matter – one virus could have wiped out the lot.
Weitzmann himself applied such an approach to climate change, creating his “painful theorem”, which states that in the presence of sufficiently large risks with a small chance of significant harm, cost analysis is not -a very useful regular benefit. The same may be true of biodiversity. Extinction cannot be done on purpose and will reduce humanity’s options, so they should be used sparingly. Playing at being Noah is one thing, playing at being God is quite another. ■
Read more from Free Exchange, our economics column:
Democracy and the price of a vote (August 17)
Elon Musk’s plans could disrupt Twitternomics (August 7)
Depression hampers China’s economic growth (July 27)
