"How could something as simple as salt... connect to all of life?" "To humans." "To Earth." "And to civilization itself." "The answer lies in big history." "We think of history as a timeline... a series of events stretching a few thousand years into the past." "It's time to think bigger." "Instead of a line, imagine a Web of infinite connections... interacting over billions of years... linked together to create everything we 've ever known- our universe, our planet and us." "When We consider our most epic moments through the lens of science..." "We unleash a revolutionary new idea." "The movement of atoms steer the movements of men... civilizations, galaxies." "History as We know it is about to get big." "Thousands of laborers are making 25 cents a day... digging a ditch 350 miles long." "The Erie Canal." "Traditional history tells us it's the most ambitious engineering project... ever attempted in America." "Big history tells us it's the key to a secret map of the World- designed mainly to transport one precious item: salt." "America has a shortage." "But upstate New York has a natural supply." "By connecting that salt-rich region... to the country's Water highway system... the shortage Will be solved." "The Erie Canal lets you bring salt by water to the Hudson River." "From the Hudson River, you can get down to New York... and from New York, by water, you can move anywhere." "The Erie Canal Will be called "the ditch that salt built. "" "But it leaves another mark on America." "Trade explodes between the Great Lakes and the Hudson River." "And since all that trade... has to pass through the port at the mouth of the Hudson... that port explodes as Well." "So, in a big history sense, New York City... would not be the city that it is without salt." "Big history is about taking simple things... and making epic connections." "It links events on a global scale... to a craving in the animal kingdom." "All animals need salt... and carve out trails to Where it exists naturally... called "salt licks. "" "In prehistoric New York..." "Where there are far more buffalo than people... vast herds carve a trail to one salt lick" "in the spot Where the Erie Canal Will one day empty into Lake Erie." "The site Will be called Buffalo, New York." "Early hunters follow these paths..." "Which become trails... and then our earliest roads." "If you looked at a road map of North America before the 1960s... before they created the national highway grid... you would see a very odd formation of roads." "And that's because most of these roads... were just paved-over animal paths to salt licks." "Around the World, salt leaves its mark on the map." "In ancient Rome, the very first paved road... is built to carry salt." "It is called the Via Salaria" ""the Salt Road. "" "Centuries later, salt roads and shipping routes... built Venice into a powerhouse of trade." "Salt is so important..." "We mark the places Where it's found by name." "Like Salzburg in Austria..." "Which means "Salt Town. "" "And any town in England that ends in "Wich. "" "Greenwich and Sandwich and Norwich... and any place with a "wich"... is a salt-making town in England." "So much of our map, from the Erie Canal... to the salt-making towns of England... can be traced back to the quest for salt." "So much seems to rest on Why salt ended up Where it did." "But how did salt end up in these places and not others?" "Three billion years ago... salt is dissolved by rain... and flows into early seas." "These oceans evaporate, leaving huge deposits behind." "Earth's shifting crust... folds these massive salt flats deep underground." "Deposits of salt are basically just prehistoric oceans dried up." "Later, the remnants of these ancient seas... break to the surface, but only in some places" "rare sites that Will have a massive impact on civilization." "Just five percent of the Earth... is Within 10 miles of a natural salt supply." "All of man's earliest cities..." "Will be built not only next to sources of Water... but also next to these sources of salt." "And even in the places Without a natural supply... salt connects the World... by linking salt outposts like Timbuktu... to other cities through trade." "Salt was so rare, it would actually trade ounce for ounce with gold." "And then the beautiful thing is, from a big history standpoint... once you had this trade network built... you could transport anything." "Salt has silently engineered our global map." "But before that, it Was the key ingredient- in one of the most revolutionary moments... in big history." "Big history is a new Way to see the World." "It reveals how our cities... our roads... our map... are all built on salt." "But Why is a simple molecule so important... that man will move mountains to get it?" "Three billion years ago." "The world is covered by one giant ocean." "The Water is teeming With elements and minerals... including 35parts per thousand of salt." "In this chemical bath... life mysteriously appears." "For billions of years in the history of the Earth... there were only single-celled organisms... and they lived predominantly in the oceans." "Life evolves over billions of years." "But even as continents emerge... life stays in the ocean, clinging to Water and salt." "Some animals experiment." "They take their first steps on land... but return to the salt Water to reproduce." "The key to surviving on land?" "Bring the salty ocean Water With them." "The solution?" "The egg." "When we started crawling onto the land... certain creatures figured out- birds, reptiles- that they could lay eggs... that have a nice, hard shell... that kind of keeps the salt water contained in a small space for them." "And even mammals today- you can think about the womb with the amniotic sac... as sort of a little ocean that the fetus can live in." "So all life emerged from salt Water." "All creatures need it, crave it- and quickly die Without it." "If you think about that in big history context... we would not even maybe have life at all were it not for salt." "That's one reason for salt's oversized impact on history." "It's a key to life itself." "Cells need salt to function." "Bacteria need it, we need it." "All organisms need salt." "It's a link We carry in our own bodies." "Our tears and sweat reflect the same salt content... as in the ancient ocean." "And salt rules our minds." "Sodium helps transmit signals between our brain cells." "Our actual thoughts are made of salt." "The actual cerebral activity inside of your brain... is just a bunch of sodium and potassium ions... going in and out, in and out of cells." "Our consciousness itself is made out of salt." "But if salt is so vital... that We build structures as small as the egg... and as large as a canal to get it... another mystery remains." "Our bodies tell us We need food... through hunger." "We know We need Water through thirst." "How do We know When We need salt?" "What our body did is sort of give us cravings for salt... and we sort of got addicted to it." "You may not specifically think to yourself..." ""I crave salt," but you crave... that taste sensation that salt gives food." "You could call this craving our "salt sense. "" "There's an evolutionary component to this as well." "Some call salt "the primal addiction."" "These are the sort of connections that big history shows us very well, I think." "According to recent research, our addiction to salt... might be the root of all addictions." "So, it could be that a craving for tobacco or alcohol or something... is just an unfortunate side effect... of these biologically necessary addictions." "Big history reveals that our salt addiction... is the key to some unexpected connections." "200 B. C." "More than one million laborers... are building the longest defensive fortification in the World" "the Great Wall." "When complete, it Will stretch more than 3, 000 miles... across China's northern border." "It is a massive undertaking... and the emperor has an enormous problem" "how to pay for it." "His advisers propose a clever solution." "Tax salt." "The economists are saying to the government..." ""We need to monopolize salt." "You need to take control of salt because this is incredibly valuable."" "Taxes make salt expensive... and salt addicts angry." "But the people need salt." "And the emperor gets his Wall." "But a salt tax can backfire." "In India in 1930..." "Where Mahatma Gandhi's march against the British salt tax... ultimately leads to independence." "In France in 1789..." "Where a crushing tax on salt pushes the people to their breaking point." "And this discontent feeds into other discontents... and is at least partly responsible for the outbreak of the French Revolution." "The simple stuff of salt... sets in motion the complex forces of history." "But how does it affect everything from the death of pharaohs... to the birth of civilization?" "The secret is in the superpower of salt." "We've seen that salt led to the rise of cities... and the fall of kings." "And it is the key to life itself." "A tiny crystal With a giant impact." "Because salt has a superpower." "Egypt, 1213 B. C." "Pharaoh Ramses has died." "If priests can't preserve his body before rot sets in... his soul Won't make it to the afterlife." "And salt is how they do it." "The Egyptians used a type of salt called natron... to preserve the human body." "It's probably the most effective preservative ever made in human history." "It's a funny thing to think about... but if you look at- there are recipes- how they made mummies, and it's... very much the same recipe as how you preserve a fish." "You remove the entrails and you pack them with salt." "It's a human codfish." "Why does salt preserve things?" "Because salt has a superpower over Water." "Big history zooms in to the microscopic World of salt." "We 're looking at a clump of salt molecules... in tissue that's filled With Water." "As the Water molecules float by, they lock onto the salt... and pull it apart." "The salt molecules separate and draw the Water out of the tissue." "Without Water, the microbes that cause decay die... and the dry tissue lasts for months or years." "The disco very of salt's power to preserve meat... fish, vegetables and even mummies..." "Was a great step forward for civilization." "In a World before electricity, salt Was mankind's refrigerator... the key Way to preserve food from one harvest to the next." "One of the great problems for agricultural societies... is how to preserve things, and salt is the answer." "The Word "salami"... an ancient form of salted meat... comes from the Latin Word sal or salt." "So do the Words "sausage, " "sauce"and "salsa. "" "Since salt saved both food and people... so does the Word "salvation. "" "And since salt Was so valuable that the Romans paid their soldiers With it... so does the Word "salary. "" "We've seen that salt is so essential to life... that humans became salt addicts." "That this tiny crystal built our roads... our canals, our cities." "That it preserved our food, saved us from starvation... and allowed civilization itself to arise." "History transformed by the simple chemistry of salt... and the invisible Way that salt draws moisture out of things." "Salt is a really cool example of big history because... through the crystal of one grain of salt... you can see all of history." "But the story of salt is just the beginning." "There's a much bigger puzzle hidden in big history." "Each episode unlocks a clue." "Everyday things like flight... gold... and mountains hold the key." "Watch them all, and you'll see this grand mystery revealed- the big history of time, of space... the big history of us."