Exosomatic Energy
Exosomatic energy is energy sourced from outside the body — principally fossil fuels — as distinct from the metabolic energy the body extracts from food. It is the enabling condition for the Neurobiological/Fitness Gap: humanity's access to dense exosomatic energy let it evade the negative feedbacks (resource depletion, disease, conflict) that previously kept population, consumption and waste in check.
The scale of the shift
In roughly 200 years, fossil fuel use increased 1,300-fold, fuelling a 100-fold increase in real gross world product. It took H. sapiens about 350,000 years to reach a global population of 1 billion (1820), and just over 200 years to go from 1 billion to 8 billion — a trajectory made possible by mechanised agriculture, irrigation, scientific plant breeding, synthetic fertilisers, pesticides, and improved sanitation and healthcare, all underwritten by exosomatic energy.
Distancing, not decoupling
The paper is explicit that this is not a genuine decoupling of the human enterprise from biophysical limits: growth is being financed by drawing down cumulative natural capital (fish stocks, forests, soils, fossil fuels, rare minerals), and contemporary civilisation is in fact more deeply embedded in ecosystems and the lithosphere than ever. High-income populations use financial wealth — itself a product of energy access — to distance themselves temporally and spatially from the worst effects of this drawdown; the poor have no equivalent recourse.
See also
Neurobiological/Fitness Gap · Discounting · Ecological Overshoot · Maximum Power Principle