Castaway is a classic movie starring Tom Hanks about a man who survives five years on a desert island. This is by no means the first time this story has been told. There were castaways in the Aeneid or the Odyssey, although their islands were inhabited.
Robinson Crusoe, published in 1719, tells the story of a shipwrecked man who must survive on his own. It is inspired by the true story of Alexander Selkirk, a Scottish buccaneer who survived four years on an island in the South Pacific. There are also modern examples, such as the Chinese sailor Poom Lim who survived 133 days on an island in World War II, or the Salvadoran fisherman José Salvador Alvarenga, who spent 14 months adrift in a boat in the Pacific and was rescued in 2014.
The question is: could you survive? You’re not going to like the answer, because there’s little chance. The survival of a person in the wild is determined by the rule of threes. This rule says that we can survive 3 minutes without breathing, 3 hours without shelter from extreme heat or cold, 3 days without water, and 3 weeks without food.
If you haven’t drowned in the shipwreck, and the weather is harsh, your priority should be finding shelter. We all think of making a cabin out of coconut leaves, but if the island is a bare rock, or you are in the Arctic Ocean, it may not be that simple. The next thing is to get fresh water to drink. You can use a plastic to collect rainwater or distill salt water, but if it doesn’t rain, or you don’t have anything to store water with, you probably won’t make it past the third day.
When we think of surviving on an island, the first thing that comes to mind is food, when in reality it is the least urgent thing. We can fast for weeks using the body’s reserves. But if you already have shelter and water, it’s time to search for food. Have you ever fished with a harpoon made from a sharp branch? It is more difficult than it looks. If you don’t know how to hunt or fish, or there is no food available, in a few weeks things will get very ugly.
Finally, if at any time you get into an accident and are injured or incapacitated, it’s game over, as you won’t be able to get water or food, or repair your shelter. This is where one of the most important factors for survival comes in: having other people.
Groups of people who collaborate with each other and help each other are much more stable, because that is how our species managed to survive and adapt. But this we will tell in the next episode.