There is no need to resort to exaggerated claims about species loss to realize that the decline of global biodiversity has been proceeding at rates that, on geological time scales, may already amount to the Earth’s sixth mass extinction wave (Barnosky et al. 2011). I have calculated that during the 20th century the mass of wild mammals was halved (and the mass of elephants was reduced by 90%), while the mass of domesticated animals more than tripled and the global mass of humanity more than quadrupled (Smil 2013a). People and their animals have been steadily marginalizing all wild
