Origins

by Lewis Dartnell

  The carbon dioxide released by the combustion of fossil fuels has been rapidly increasing its level in the atmosphere, which is now already 45 per cent higher than prior to the Industrial Revolution. Indeed, the current rate of greenhouse gas emissions from human civilisation is unprecedented in the geological history of at least the last 66 million years. Perhaps the closest natural analogue was the Palaeocene–Eocene Thermal Maximum42 that we explored in Chapter 3 and which saw a rapid increase in global temperature making the world 5–8 °C hotter than today.43 We’re currently doing our best (or worst) to yank our global climate back to that period.44

  The presence of such greenhouse gases in the atmosphere is not in itself a problem – indeed, it is their insulating effect that through our planet’s history has kept the Earth’s surface above freezing and so has been vital for supporting complex life.fn8 But the rapidly rising carbon dioxide level is shifting the current established equilibriums in the natural world, and impacting on how we support our civilisation. It has caused increasingly acidic oceans, threatening coral reefs as well as the fisheries we rely upon for food.45 Moreover, a warming global climate in turn drives rising sea levels that threaten our coastal cities, and shifts in the world’s rainfall patterns have significant implications for agriculture.

  But carbon dioxide is not the only form of pollution released by fossil fuels. As we saw, oxygen-poor conditions were required to prevent the decomposition of dead organisms and so allow the carbon to accumulate and become coal, oil and natural gas. These same conditions also favour the formation of sulphide compounds – this is why bogs today often have the distinctive rotten-egg smell of hydrogen sulphide – which are released when fossil fuel is burned and reacts with moisture in the air to create sulphuric acid. Thus the oxygen-poor soil of the Carboniferous coal swamps and the sediment of the Cretaceous sea floor also locked up future acid rain.46

  Burning fossil fuels has been like releasing a trapped genie: it granted us our seventeenth-century wish for virtually limitless energy, but has done so with mischievous malice for the unintended consequences further down the line.

  The challenge facing us now is to reverse the trend since the Industrial Revolution and once again decarbonise our economy. As we saw earlier in the chapter, throughout history, our intensification of agriculture and harvesting of woodland has enhanced the rate at which humanity could gather solar energy. This sunlight is transformed into nutrition for our bodies, as well as into the raw materials and fuel we need, and we learned how to harness mechanical power from the natural world with waterwheels and windmills. Part of the solution to our current carbon crisis will be to return to these age-old practices, but with technological updates. Farms of solar panels produce electricity directly, and hydroelectric dams and wind turbines are identical in principle to waterwheels and mills, although prodigiously more productive than their technological forebears.

  But perhaps the next revolution in humanity’s enduring efforts to marshal ever greater supplies of energy will be to crack nuclear fusion: to harness the power source of the stars themselves. We saw in Chapter 6 how nuclear fusion within stars fuses hydrogen atoms together to create helium, and releases a great deal of energy in the process. Several facilities around the world are already making good progress in scaling up experimental reactors for mainstream nuclear power stations. The fusion fuel can be extracted from seawater, and the operation of such reactors produces no carbon dioxide or long-lived radioactive waste. So fusion offers not only abundant energy, but this time also cleanly. In this sense we will have come full circle: from the earliest agrarian societies capturing the energy of sunlight with their fields of crops and felled woodland, to installing a miniature sun within our fusion reactors, and so cutting out the middleman.fn9

  Coda

  The human world is now clearly visible from space, highlighted by the electric brilliance of our towns and cities – a sparkling galaxy of artificial stars. This composite image was created by satellite, photographing the vista below on clear nights and then stitched together into a single omniscient view of the Earth from the heavens. In this way it’s almost an abstraction, depicting the whole world simultaneously at night time and without any veiling of clouds. And it isn’t a complete map of human habitation – much of the world’s population in developing nations is still rural – but of industrialised urbanisation. Still, I think it beautifully illustrates the global civilisation we have built over the millennia, and how we’ve been moulded by the planet we live on.

  The densest concentrations of humanity are immediately apparent: northern India and Pakistan, the Chinese plain and coastline – two of the earliest cradles of civilisation – as well as the lattice of cities and highways in the eastern US, grading gently into the central prairies. The crowded North European Plain, stretching across parts of France, Germany, Belgium and the Netherlands, shines a brilliant white. This is the end result of the gradual but decisive shift in population distribution from the Mediterranean rim to Northern Europe through the first millennium AD, driven by the use of iron-edged axe and plough that transformed the forests and damp clay soil into highly productive farmland. The intricate outline of the Mediterranean – the puddle remnant of the once-vast ancient Tethys sea – can be clearly made out, especially the bright coastal strip in the east showing up the crowded urbanisation of Israel, Lebanon and Syria.

  Just as revealing are the dark areas on land. These are the landscapes and climate zones unsuited for dense human habitation. Mountain ranges are conspicuous by their invisibility: the shining furrow of the Po Valley at the top of Italy is capped by the gloomy Alps, the intense gleam of northern India abruptly cut by the curve of the Himalayas. Deserts appear as patches of broad darkness in the heart of Australia, southern Arabia and northern Africa. The ribbon oasis of the Nile Valley and its delta burns like a river of fire through this otherwise inhospitable region. The radiant triangle of the Indian subcontinent also stands out within the band of deserts reaching around the planet, dampened by the monsoons that seasonally suck in moisture from the enveloping ocean.

  And it’s not just the hyper-arid regions of the world that have hindered inhabitation, but also the equatorial zone of our planet with its high precipitation and therefore dense rainforest: Central Africa, the Amazon and the heart of Indonesia. These absences of electric light reveal both the rainy rising arm and the dry descending zone of the Hadley cell, the circulation current in the Earth’s atmosphere.

  Within Asia, the glittering froth of human activity is broken by the dark cavities of the freezing heights of the Tibetan plateau and the deserts of the continental interior. And running east–west through the heart of the continent are two roughly parallel stripes of diffuse glow. The more southern streak is the old course of the Silk Road, threaded between the mountains and deserts. It once carried commerce and knowledge across the breadth of Eurasia, connecting cultures on the continent’s extremities, and today its imprint is still visible from space by the electric lustre of the cities that grew from the ancient oasis towns and entrepôts. The northern band follows the ecological zone of the grassy steppes, once an unknown wilderness from where nomadic pastoralists threatened the agrarian civilisations around the continental rim. The western half of this zone has now been put to the plough and transformed into great swaying fields of wheat, feeding the new cities all along this climate band, strung like pearls along the Trans-Siberian Railway.

  You might think that other features of the planet that played such a pivotal role in our history ought not to be perceptible in this map of human light – such as the global pattern of contrary wind bands and the great swirling currents of the ocean gyres. We exploited them to build vast intercontinental trade networks and maritime empires, which in turn provided the raw materials and economic drivers for the Industrial Revolution. But although currents in the air and sea are invisible, their effects are still revealed in this image. The lights of fishing boats can be discerned from space, swarming like
fireflies in the coastal regions where ocean upwelling brings nutrient-rich waters to the surface and where plankton – and the fish that feed on them – can thrive, such as along the continental shelf of Peru. And the glow of Norway, Sweden and Finland reveals habitation far further north than in the corresponding latitudes in Canada and Siberia. This is due to their milder climate granted by westerly winds blowing over the ocean and by the Gulf Stream – they are warmed by transported Caribbean sunshine. Even the deep subterranean reservoirs of fossil energy are rendered visible by flare stacks burning the natural gas released in the oilfields of the North Sea, the Persian Gulf and northern Siberia.

  This single image encapsulates the culmination of our human story thus far – and we have come a long way since our origins. The Earth is a restlessly dynamic place, and its facial features and planetary processes have played a decisive role throughout the human story. Our species emerged within the unique tectonic and climatic conditions of the East African Rift, where the versatility and intelligence that allowed us to progress from apeman to spaceman were bestowed by environmental fluctuations driven by cosmic cycles. And before that, the intense temperature spike of the PETM 55.5 million years ago saw the emergence and rapid dispersal of our lineage, the primates, as well as the orders of ungulate mammals whose descendants we came to domesticate. Other global changes have been more gradual, such as the overall cooling and drying trend over the past few tens of millions of years that drove the spread of the grass species we came to cultivate as cereal crops. This planetary chilling culminated in the current period of flickering ice ages which moulded much of the landscape and allowed our species to populate the world.

  The entire history of civilisation is just a flash in the current interglacial period – a transient spell of climatic stability. During these past few millennia we’ve dug up Earth’s stony subterranean layers and piled them above ground to construct our buildings and monuments. We’ve excavated rich ores where metals have been concentrated by particular geological processes. And in the last few centuries we’ve mined the coal formed during a quirky period of the planet’s past when ancient forests refused to rot, and we’ve sucked up the oil created by plankton settling to the asphyxiated seafloor of a drowned world.

  We’ve now turned over a third of the Earth’s total land area to agriculture. Our mining and quarrying moves more material than all the world’s rivers combined.1 And our industrial exhalations release more carbon dioxide than volcanoes, warming the climate of the entire planet. We have profoundly altered the world, but we only recently acquired such overwhelming dominion over Nature. The Earth set the stage for the human story and its landscapes and resources continue to direct human civilisation.

  The Earth made us.

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  NOTES

  INTRODUCTION

  1. For a much more complete description of how the elements in the human body came from the Earth see Stager (2014) and Schrijver (2015).

  2. Crutzen (2000); Ruddiman (2015); Lewis (2015).

  3. Dartnell (2015).

  1 THE MAKING OF US

  1. Arnason (1998); Patterson (2006); Moorjani (2016).

  2. Rothery (2010), p. 53.

  3. Cane (2001).

  4. King (2006).

  5. Stow (2010), Kindle location 740.

  6. Maslin (2014).

  7. Ibid.

  8. Jung (2016).

  9. Maslin (2013); Shubin (2014), p. 179; Fer (2017).

  10. Cane (2001).

  11. Lieberman (2014), p. 68.

  12. Chorowicz (2005).

  13. King (1994).

  14. King (2006); Bailey (2011).

  15. Maslin (2014).

  16. Ibid.

  17. Berna (2012).

  18. Gibbons (1998).

  19. Ermini (2015).

  20. Bramble (2004).

  21. Bradley (2008).

  22. Maslin (2014).

  23. White (2003).

  24. Potts (2013).

  25. Maslin (2007).

  26. Maslin (2007); Trauth (2010).

  27. Maslin (2007).

  28. Maslin (2007); Trauth (2010).

  29. Trauth (2010).

  30. Maslin (2014); Potts (2015).

  31. Trauth (2007); Maslin (2007).

  32. Maslin (2007).

  33. Potts (2015).

  34. Maslin (2014).

  35. Ibid.

  36. Neimark (2012).

  37. Ibid.; McKie (2013).

  38. Jung (2016).

  39. Giosan (2012).

  40. Reilinger (2011).

  41. Garzanti (2016).

  42. US Geological Survey publications, ‘Plate tectonics and people’, https://pubs.usgs.gov/gip/dynamic/tectonics.html.

  43. Shuckburgh (2008), p. 133.

  44. This section on the link between ancient civilisations and plate boundaries: Force (2008); Force (2010); Force (2012); Force (2015), Ch. 15.

  45. Jackson (2006).

  46. http://worldpopulationreview.com/world-cities/tehran-population.

  47. Jackson (2006); Shuckburgh (2008), p. 133.

  2 CONTINENTAL DRIFTERS

  1. Kukula (2016), Kindle location 4136; Ruddiman (2016), Ch. 4.

  2. Woodward (2014), p. 28.

  3. Ibid., p. 111.

  4. Stager (2012), Kindle location 305.

  5. Ibid.

  6. Summerhayes (2015), p. 264.

  7. Ibid.

  8. Ruddiman (2016), p. 45.

  9. Feurdean (2013); Liddy (2016).

  10. Summerhayes (2015), p. 255.

  11. Franks (1960).

  12. Woodward (2014), p. 102.

  13. Ibid., p. 112.

  14. Ibid.

  15. Ibid., p. 116.

  16. Maslin (2014).

  17. Ruddiman (2016), p. 42.

  18. Lenton (2013), p.353; Woodward (2014), p. 111.

  19. Nield (2014), p.213; Woodward (2014), p. 35.

  20. Ibid.

  21. Stow (2010), p. 131.

  22. Summerhayes (2015), p. 368; Stager (2012), Kindle location 1178.

  23. Woodward (2014), p. 121; Lieberman (2014), p.68; Ruddiman (2016), p. 42.

  24. Woodward (2014), p. 121.

  25. Woodward (2014), p. 121; Maslin (2007).

  26. Mendez (2011).

  27. Woodward (2014), p. 121; O’Dea (2016).

  28. Maslin (2007); Woodward (2014), p.121; Ruddiman (2016), p. 19.

  29. Summerhayes (2015), p. 369.

  30. Oppenheimer (2011), p. 176.

  31. Bowden (2012).

  32. Ermini (2015); Lopez (2015); Tucci (2016).

  33. Eriksson (2012); Lenton (2013), p. 367.

  34. Oppenheimer (2011), p. 178; King (2006).

  35. Morris (2011), Kindle location 1274; Lieberman (2014), p. 130.

  36. Ermini (2015).

  37. Abi-Rached (2011).

  38. Ermini (2015).

  39. Carotenuto (2016).

  40. Eriksson (2012).

  41. Lenton (2013), p. 367.

  42. Oppenheimer (2011), p. 179.

  43. Eriksson (2012).

  44. Ibid.

  45. Paine (2013), p. 14.

  46. McNeill (2012).

  47. Woodward (2014), p. 29.

  48. Ibid.

  49. Morris (2011), Kindle location 1444.

  50. Holen (2017).

  51. Rose (2011).

  52. Bradley (2008).

  53. McNeill (2012).

  54. Ermini (2015).

  55. McNeill (2012).

  56. US Geological Survey publications, ‘Past Glaciations and ‘“Little Ice Ages”’, https://pubs.usgs.gov/pp/p1386i/chile-arg/wet/past.html.

  57. Novacek (2008), p.267.

  58. Discussion on the consequences for American history of a less icy Ice Age appeared in Dutch (200
6); Alvarez (2018), p. 68.

  59. Stager (2012), Kindle location 305; Summerhayes (2015), p. 264.

  60. Woodward (2014), p. 29.

  61. Ruddiman (2016), p. 44.

  62. Gibbard (2007).

  63. Gibbard (2007); Gupta (2007); Gupta (2017). Discussion on the consequences for European history of the last Ice Age appeared in Dutch (2006).

  64. Frankopan (2016), p. 387.

  65. Kaplan (2017), Kindle location 643.

  66. Marshall (2016), p. 91; Kaplan (2017), Kindle location 650.

  67. Frankopan (2016), p. 386.

  3 OUR BIOLOGICAL BOUNTY

  1. Shakun (2012).

  2. Murton (2010).

  3. Törnqvist (2012); Summerhayes (2015), p. 255.

  4. McNeill (2012).

  5. Belfer-Cohen (1991); Bar-Yosef (1998); Grosman (2008).

  6. Teller (2002); Tarasov (2005); Woodward (2014), p. 130.

  7. Belfer-Cohen (1991); Bar-Yosef (1998); J. R. McNeill (2004), p. 23; Grosman (2008); Balter (2010); Shubin (2014), p. 177.

  8. McBrearty (2000); Sterelny (2011).

  9. Ruddiman (2016), p. 63.

  10. McNeill (2012); Lenton (2013), p. 369.

  11. White (2012); Balter (2010).

  12. Morton (2016), p. 226.

  13. Richerson (2001).

  14. Hodell (1995); Mayewski (2004). And see, for general discussion, Diamond (2011); Cowie (2012); Brooke (2014).

  15. McNeill (2012)

  16. Petit (1999); Wright (2006), p. 50.

  17. Sage (1995); Richerson (2001); Morton (2016), p. 229.

  18. Kilian (2010).

  19. Lenton (2013), p. 369.