Origins

  

Lewis Dartnell’s book, Origins: How Earth’s History Shaped Human History (Basic Books: 2019) contains surprising gems, like this one: 

“We are a species of apes born of the climate change and tectonics within East Africa” (p. 25).

 

Or this one:

“There’s more genetic diversity between two groups of chimpanzees living on opposite sides of a river in Central Africa than there is between humans on opposite sides of the world” (46).

 

Which is to say that we humans are all one species, more alike than the surface characteristics that divide us suggest, and all derived from “a single exodus event out of Africa, rather than multiple waves of migration, and probably from no more than a few thousand original migrants” (46). Furthermore, what seems to have driven our one primate ancestor to develop our most distinguishing characteristic—a huge brain—was the adversity of extreme climate variability in the tectonic rift valley of East Africa. That’s because, as Dartnell informs us, 

“Intelligence…is the evolutionary solution to the problem of an environment that shifts faster than natural selection can adapt the body” (19). 

 

And so, in three of these rapidly shifting climatic events in East Africa’s Great Rift Valley (occurring roughly 2.7, 1.9 and 1 million years ago), new hominin species, marked by greater brain size—including Homo Erectus, the direct ancestor to our species—emerged. This latter is important, since some Homo Erectus left Africa in the variable climate phase around 1.8 million years ago, to eventually become Neanderthals in Europe; while those who stayed in Africa gave rise around 300,000 years ago, to anatomically modern humans, Homo sapiens. They, in turn, migrated out of Africa about 60,000 years ago. So both Homo sapiens and Neanderthals are our ancestors, both deriving from that big-brained Homo Erectus. 

            The other important takeaway from this book is the somewhat startling and humbling fact that the alleged ‘superiority’ of western or European culture is really an accident of geography, and a product of plate tectonics as well. As Dartnell explains it, the continent of Eurasia has benefited from its massive grasslands or steppes, where grains such as wheat, barley and oats (all variants of grasses) grew wild. This led to their cultivation, and then to more or less permanent settlements whose agriculturalists, thriving on grains, could set aside surpluses. This in turn led to priest classes who did not have to toil or spend time hunting and gathering, and eventually to kingly classes who could afford to go to war. But Eurasia was blessed with one other critical element: ruminants such as cows and horses, both of which fed on those expansive grasslands, and which could be used not only for protein foods, but for work such as pulling plows and wagons, and carrying individual humans. Indeed, Eurasia was home to the most important of the domesticated mammals:

The five most important animals through human history--sheep, goats, pigs, cows, horses—as well as the donkey and the camel that provided transport in particular regions, were present only in Eurasia (88).

 

By contrast, the Americas, where the horse and the camel had actually evolved (both migrated out to develop in Eurasia), had only one domesticated ruminant, the llama, and very few other large mammals. So with these natural endowments, the civilizations of Eurasia were able to develop major technologies long before the equally sophisticated civilizations of the Americas—which also had grains such as corn that could be stored, but lacked those large mammals to boost their energy capacity. 

            It was not only the natural flora and fauna that provided for advanced civilizations, however. Again, plate tectonics provided the soil and water that seeded most civilizations—the Mesopotamians, the Harappans in India, the Minoans and Greeks and Tuscans, the Mayans and Aztecs. All of them developed, Dartnell informs us, “near plate boundaries.” Why? Because they are located where rich arable land formed in “depressed basins at the feet of mountains ranges caused by continental collisions” (27-8)—that is, huge tectonic plates smashing into each other and raising mountains such as the Himalayas and the Alps. The other element that contributes to such fertile land, of course, is volcanoes. And they too “arise in a broad line 100 Kilometers or so away from the subduction line, as the swallowed plate sinks deeper into the hot interior and melts to release rising bubbles of magma to feed eruptions on the surface above” (ibid). And further, such faults create springs “which become a water source for settlement in arid regions” (29). The Eurasian continent, according to Dartnell, had one other lucky advantage over the Americas: its orientation. Eurasia, that is, runs roughly east to west, whereas the Americas are oriented roughly north to south. That means that animals and crops that adapted to the grasslands of the Steppes could be utilized far to the west in Europe, and vice versa; their latitudes and hence their climates are roughly the same. Not so with the Americas: what works in Mexico’s climate and terrain will not necessarily work far to the north in Canada, and animals that thrive in The Great Plains do not adapt well far to the south in Peru (87-88).

            Beyond even this, Dartnell shows us how metals, too, are products of the massive movements of the earth, leading to the development of some civilizations due to the luck of their location. Consider the Great pyramids of Egypt, or the astonishingly advanced civilization of the Minoans on Crete. It is easy to think of them as the result of some superior endowment of their people, or of “genius” individuals. But more likely, it is the result of ancient processes deep in the earth. In the Egyptian case, the pyramids were built of limestone. And what forms limestone? foraminifera shells deposited on the sea floor of the ancient Tethys Ocean that once covered most of what are now the lands around the Mediterranean Sea—all that is left of the Tethys Ocean. These shells were, over eons, adhered together to become Nummulites (the word means ‘little coins’ in Latin), the foundation of the nummulitic limestone Egyptians used to build the pyramids (128). Similarly, the copper that made Minoans on Cyprus rich (around the second millennium BC, Cyprus was the major copper supplier for Mesopotamia, Egypt and the entire Mediterranean) was the product of an ocean vent pushed up onto Cyprus by plate tectonics. So too, iron and the process of smelting that transformed civilizations (in Europe from the 1300s on) and the weapons and tools they used, likewise comes from processes deep in the earth, and billions of years before that, in the furnace of the stars. Dartnell, in fact, calls iron “the star-killer element” (167) because 

once iron is created in nuclear fusion, the star can no longer produce enough energy to hold up its outer layers, and collapses on its own core, before exploding in a supernova.

 

And from that supernova comes all the iron deposited on our planet and in us, via many foods we eat. And iron, of course, is what makes our blood red, something else Dartnell startles us with:

…the iron in your blood not only links you to the ancient stars that created it in their nuclear forge, but also to the magnetic shield around our world that protects life on earth (169).

 

That is, the magnetic field acts like a “deflector shield” to prevent the solar wind particles from blowing our atmosphere off into space. All because of the lucky happenstance of iron. 

            There are many more amazing facts that Dartnell gives us—including how coal is produced due to the trees of the Carboniferous Era not rotting as normal trees do, but being preserved almost whole as peat, and then diving deep into the earth’s hot interior to rise again in the mountain rocks from tectonic events—but one had particular resonance for me personally. He describes the crucial role of the winds that we now know circle the earth in belts, and how critical they were when boats had to rely on winds to fill their sails. The so-called Age of Discovery depended on some of these wind discoveries, one of which the Portuguese discovered called the volta do mar: on their return trips from Africa, sailors would go north out into the ocean so as to exploit westerly winds (winds blowing east)—to get back to Portugal. This knowledge affected Columbus and his epic journey, but Dartnell calls his success “a sheer historical fluke.” Columbus, that is, had tried initially to convince King Joao of Portugal to sponsor his journey. The King declined, and so the great mariner had to turn to Queen Isabella of Spain. This meant that “Columbus attempted his crossing from an archipelago [the Canary Islands, the only Atlantic islands controlled by Spain] that happens to be upwind of the Americas. If his expedition had set sail from the Azores, it would likely have perished deep in the ocean” (230). That is, if Columbus had been sponsored by Portugal, he would likely have tried to sail from the Portuguese-controlled Azores against prevailing westerly winds (very difficult if not impossible in those days). Since he was sponsored by Spain, however, he headed west from the more southerly Canaries, caught the easterly trade winds, and driven by these favorable winds, made it to the Caribbean just in time to survive. On the return, he was clever enough to use the Portuguese-discovered volta do mar and the westerly trade winds, made it back first to the Azores, and then to Spain. 

            In sum, this is a book full of gems that are not commonly considered, and certainly not collected in one volume. And it’s written so that a layman like myself can understand most, if not all, of those ancient geological processes—which, as Dartnell tells us, have so fundamentally shaped our history and culture. 

 

Lawrence DiStasi