Whenever I wander through ruins I imagine people centuries hence picking through the ruins of my world and wondering about the people who lived there. We can learn from ruins, and as I walked through those of the Mayan city of Chichen Itza last week I learnt not only about the Mayan world but also our world and its likely fate.

Chichen Itza, which is situated in the jungle of the North of the Yucatan peninsula, flourished between 600 AD and 1200 AD. Mayan culture was dominated by priests and warriors. The biggest of the ruins is El Castillo, a pyramid (actually a zigerat) that stands 100 feet high and at the top has a box like temple. A staircase runs all the way up the pyramid to the temple. It was the site of human sacrifice, something that ran through all the Mesoamerican cultures. The priests would remove the heart of those who were sacrificed and offer it to the gods. Human sacrifice was necessary to appease the gods, which were angry gods.

The city was built on the site because it includes two cenote, large holes filled with water. There are thousands of cenote across the peninsula, and some believe that they were caused by a meteorite that hit the peninsula and caused the dark winter that led to the extinction of the dinosaurs. One of the cenotes is the Cenote Sagrado, and it too had to be sustained by human sacrifice.

The Spanish Conquistadors made propaganda from the Mesoamerican custom of human sacrifice, showing how they were bringing “civilisation” to “barbarians.” The Inquisition, of course, was delighted to burn heretics alive, but, as James, my son, pointed out, the Mesoamerican and Catholic religions collided in that the Mayan gods demanded that people’s sons be sacrificed whereas the Christian god gave his own son to be crucified/sacrificed for mankind to be saved. This was a great selling point for the Catholic religion.

High Mayan culture faded away in the 13th century, and nobody knows exactly why. But what does seem crucial is that the Mayans devoted themselves to worship and war. They built temples not universities, and, although they created a remarkable calendar through observation of the stars, their developments were mostly in theology and war not science. The whole civilisation was built on a narrow base of small farmers. The Mayans never invented the plough and had no large mammals to help till the land.

As I walked through the impressive and beautiful ruins I thought of Easter Island and how there seems to be an overlap between the decline of the Mayans and the Easter Islanders. I’ve blogged before how the Easter Islanders devoted themselves to building huge heads for their gods and destroyed their environment.

Both the Mayan and Easter Island empires died because they “fouled their own nest” and ignored the ecological base of their empires. Ronald Wright in his masterful A Short History of Progress argues that this has happened to all empires and leaves open whether it will happen to our now global empire—but he does make clear that our global empire is gambling with the whole planet whereas the Easter Islands risked only a small island and the Mayans the Yucatan peninsula.

The gods we worship are as monstrous as those of the Mayans. Our gods are money, growth, and like the Mayans “things”—cars, second homes, yachts, hifi systems, aeroplanes, iPads, mobile phones, and alcohol. We are willing to neglect our environment to have ever more of these things. Are we any wiser than the Mayans?

But at least we don’t have human sacrifice, or do we? We are content to let a billion people live in extreme poverty so that we who have lots can continue to have lots. And many people work at jobs devoid of meaning to keep our world, our economy, alive.

And when I reflected on the ruins of our world that will be left I concluded that hospitals may dominate. In many cities now the biggest building is the hospital. I imagine people walking through the sparse remains of Cambridge colleges as I walked through the lower ruins of Chichen Itza and coming to the enormity of Addenbrooke’s Hospital as I came to El Castillo. Perhaps as they walk through deserted operating theatres, empty wards, the ruined laboratories, and the cold mortuary past MRI scanners, and X- ray and radiotherapy machines, the interplanetary tourists will wonder if there were places of human sacrifice.

They may be. As today’s doctors undertake heroic operations and fill patients full of poisonous chemicals in the hope of keeping them alive for a few more weeks might we be practising a form of human sacrifice? Worshipping the god immortality, who has never yet been satisfied, we condemn people to a state that might be described as worse than death.

I grow fanciful, but surely the great benefit of ruins is to help us imagine our own ruins. That is, I’m sure, what the more than a million people who visit Chichen Itza each year are busy doing.

Richard Smith was the editor of The BMJ until 2004.