0:00:07 > 0:00:121,200 years ago, a catastrophe struck.
0:00:17 > 0:00:23One of the most extraordinary civilisations the world has known disappeared.
0:00:26 > 0:00:29Millions of people died.
0:00:29 > 0:00:31Some were savagely murdered.
0:00:37 > 0:00:41Why it happened is a mystery.
0:01:01 > 0:01:05This is the story of one man's search for the truth.
0:01:09 > 0:01:15For years, Dick Gill has been on a personal quest to discover why the magnificent Maya society collapsed.
0:01:18 > 0:01:22Hidden deep in the tropical rainforest of Central America,
0:01:22 > 0:01:26are the ruins of the lost city of Tikal.
0:01:28 > 0:01:31It's now deserted,
0:01:31 > 0:01:36but, 1,200 years ago, Tikal stood at the heart of the Maya civilisation.
0:01:48 > 0:01:54Tikal was one of the greatest cities in the world, home to 100,000 Maya.
0:01:59 > 0:02:03They were deeply spiritual, worshipping dozens of gods -
0:02:03 > 0:02:08of the sun and the moon, the earth and wind, fire and rain.
0:02:12 > 0:02:16Their priests were superhuman rulers.
0:02:16 > 0:02:20They alone could communicate with the celestial world of the gods.
0:02:26 > 0:02:32The Maya lived in, what is today, Southern Mexico and Central America.
0:02:33 > 0:02:38From the jungles and plains rose cities and towns,
0:02:38 > 0:02:40great centres of worship,
0:02:40 > 0:02:43of art and learning.
0:02:49 > 0:02:53The Maya's achievements were staggering.
0:02:53 > 0:02:58They developed their own writing and mastered astronomy and mathematics.
0:02:59 > 0:03:06But they were also capable of brutality - sacrificing human victims to appease the gods.
0:03:11 > 0:03:13In the 9th century AD,
0:03:13 > 0:03:18it was a thriving culture. But then, at the very height of their glory,
0:03:18 > 0:03:22something terrible happened.
0:03:32 > 0:03:34In less than 100 years,
0:03:34 > 0:03:37the Maya were all but obliterated.
0:03:37 > 0:03:41Tikal and other cities were abandoned for ever.
0:03:45 > 0:03:48Archaeologists have always been mystified -
0:03:48 > 0:03:56why did a civilisation that had lasted for almost 2,000 years disappear in such a short time?
0:03:58 > 0:04:03Dick Gill's mission to solve this mystery started in 1968
0:04:03 > 0:04:07when a holiday in Mexico changed his life.
0:04:09 > 0:04:14I felt this magnetic attraction. I'm not really sure why,
0:04:14 > 0:04:16but I did feel it.
0:04:16 > 0:04:22I went home and told everyone that I was going to work with the Maya.
0:04:22 > 0:04:27Of course, my friends and family were quite amused by the idea.
0:04:30 > 0:04:38Back in Texas, they laughed, because Dick was the most unlikely person to tackle this puzzle.
0:04:38 > 0:04:43When I first turned my attention to the collapse of Maya civilisation,
0:04:43 > 0:04:46I was a banker.
0:04:46 > 0:04:51I was really an outsider with respect to the archaeological community.
0:04:53 > 0:05:00Archaeologists treated him with derision. What could a banker tell them that they didn't already know?
0:05:00 > 0:05:06Then fate stepped in. The family bank collapsed.
0:05:07 > 0:05:10I gave up banking
0:05:10 > 0:05:17and I set out on a quest to resolve the age-old mystery of what happened to the Maya.
0:05:56 > 0:06:02As he was now out of a job, Dick went back to college and studied archaeology,
0:06:02 > 0:06:07devoting his life to solving the riddle of the Maya.
0:06:07 > 0:06:15First, he needed to establish the scale of the disaster. How many people had actually disappeared?
0:06:17 > 0:06:20Dick knew just the man to ask.
0:06:28 > 0:06:33One of the first archaeologists to encourage Dick was Fred Valdez.
0:06:33 > 0:06:38Fred has turned his back on the glamorous Maya temples and palaces
0:06:38 > 0:06:43and, instead, works with his team deep in the mosquito-ridden jungle.
0:06:58 > 0:07:04They're looking for traces of the houses where the ordinary Maya lived.
0:07:04 > 0:07:10Fred calculates from the number of stone foundations, how many people once lived here.
0:07:10 > 0:07:13He was amazed.
0:07:13 > 0:07:16It was most surprising.
0:07:16 > 0:07:22The biggest surprise for us on the project was how large the population was, out away from the major centres.
0:07:22 > 0:07:26We're talking millions and millions of ancient inhabitants.
0:07:28 > 0:07:33But, suddenly, 1,200 years ago, the house building stopped.
0:07:35 > 0:07:37The Maya that were living here
0:07:37 > 0:07:42were very interested in continuing to occupy this location.
0:07:42 > 0:07:49They built one house over the other. That's what these floors represent. With this last floor,
0:07:49 > 0:07:53that was the end of construction. Then this place is abandoned.
0:08:04 > 0:08:08The mystery is, what happened?
0:08:08 > 0:08:11There's no sign of mass migration,
0:08:11 > 0:08:15no increase in population anywhere else.
0:08:15 > 0:08:20This led Fred to one horrible conclusion.
0:08:20 > 0:08:26I would estimate that 80% to, perhaps, as much as 90% of the population died off at this time.
0:08:32 > 0:08:37Most of the Maya probably died, here in the very place they were born.
0:08:46 > 0:08:50It's possible up to 11 million people perished.
0:08:50 > 0:08:55What could explain how so many died, so quickly?
0:08:59 > 0:09:05Dick's quest was given an even greater poignancy by a grim discovery.
0:09:22 > 0:09:29In 1980, archaeologist, Tom Hester and his team were digging near an ancient Maya palace.
0:09:31 > 0:09:34When we began to excavate,
0:09:34 > 0:09:38it was the most dramatic thing I've ever seen.
0:09:47 > 0:09:54On the top of the neck, the top of the back, is a single, killing blow.
0:09:57 > 0:10:01"Oh, my God! What is this?" Nobody had ever seen anything like this.
0:10:04 > 0:10:11They'd found evidence of savage murder at precisely the same time as the Maya collapse.
0:10:12 > 0:10:17The scar on the bone shows that the axe that was used,
0:10:17 > 0:10:21the weapon that was used, came up from the bottom of the body
0:10:21 > 0:10:29up towards the chin, up towards the back of the ears and the back of the head. Right like this.
0:10:32 > 0:10:39Finding the skulls and no bodies attached to them was...quite a shock.
0:10:41 > 0:10:44This is a six-year-old child
0:10:44 > 0:10:50and, over the corner of the eyes, there are cut marks.
0:10:50 > 0:10:54Part of the face, if not all of the face, was removed.
0:10:59 > 0:11:03We found thirty - ten men, ten women, ten children.
0:11:09 > 0:11:16What affected me was...just the sheer mass of the number of skulls.
0:11:18 > 0:11:24The most horrible killing is to a baby - a six-month old.
0:11:24 > 0:11:27On the baby,
0:11:27 > 0:11:32the killer didn't stop with one blow. It didn't sever the head.
0:11:33 > 0:11:36And there's a second chop
0:11:36 > 0:11:41comes in from the back of the neck that delivered
0:11:41 > 0:11:47a much deeper, a much stronger blow to the back of the head than to the front.
0:11:48 > 0:11:51Truly, a horrible, horrible thing.
0:11:56 > 0:12:01These killings did not bear the hallmarks of ritual human sacrifice.
0:12:07 > 0:12:14The unusual savagery suggested a society in the midst of some cataclysmic shock.
0:12:19 > 0:12:24I felt, whatever the explanation for the Maya disappearance was,
0:12:24 > 0:12:32it had to explain the disappearance of millions of people and it had to cover the whole Maya area.
0:12:32 > 0:12:38We're talking about hundreds of miles, north and south, east and west.
0:12:38 > 0:12:44I looked at some explanations that had been proposed -
0:12:44 > 0:12:49warfare, disease, declining agricultural productivity,
0:12:49 > 0:12:55plant disease, religious inflexibility and on and on.
0:12:55 > 0:12:58I've collected over a hundred now.
0:12:59 > 0:13:03Dick was unconvinced by any of the conventional theories,
0:13:03 > 0:13:09which failed to account for the speed and scale of the Maya collapse.
0:13:09 > 0:13:12There must be something else,
0:13:12 > 0:13:15something the academic world had neglected.
0:13:17 > 0:13:21It was then that I turned my attention to natural disasters,
0:13:21 > 0:13:25to see whether there might be a natural disaster,
0:13:25 > 0:13:31that explained how this great civilisation came to an end so quickly.
0:13:41 > 0:13:44Dick had one particular disaster in mind,
0:13:44 > 0:13:48a force of nature that he knows all too well.
0:13:50 > 0:13:53I'm a Texan. I know what drought can do.
0:13:53 > 0:13:57I have lived with drought all of my life.
0:14:06 > 0:14:12I was a child in the 1950s when Texas was devastated by a serious drought.
0:14:22 > 0:14:28I remember my father taking me into the hill country near San Antonio.
0:14:28 > 0:14:33I remember seeing the dead animals, the countryside burned to a crisp,
0:14:33 > 0:14:38the sunny days that went on and on and on without end.
0:14:38 > 0:14:41There was nothing that anyone could do.
0:14:41 > 0:14:47The drought started when it started and it finally ended when it ended.
0:14:57 > 0:15:02It was a very dramatic experience and it is one...
0:15:02 > 0:15:04that is burned into my memory.
0:15:04 > 0:15:07And...
0:15:07 > 0:15:13it has left me with a very clear understanding...
0:15:13 > 0:15:20of the awful, devastating, destructive power of drought.
0:15:38 > 0:15:45It would be difficult for Dick to persuade sceptical archaeologists that the Maya had run out of water.
0:15:45 > 0:15:51His theory had one very big and rather obvious problem.
0:15:52 > 0:15:55THUNDER CRASHES
0:15:56 > 0:16:01Tikal is in the middle of a rainforest.
0:16:06 > 0:16:12I can understand why many of my colleagues have difficulty accepting the possibility
0:16:12 > 0:16:17that drought would occur in many parts of the Maya lowlands.
0:16:17 > 0:16:22After all, we're sitting here in Tikal, surrounded by high forest.
0:16:22 > 0:16:30We've seen parrots flying in and out among the tree tops, toucans, vines hanging out of the branches,
0:16:30 > 0:16:33there are rainstorms all around us today.
0:16:33 > 0:16:38It's hard to convince someone that, yes, right here in this spot,
0:16:38 > 0:16:44they had a terrible drought and it wiped out a great civilisation.
0:16:45 > 0:16:48It's just...hard to accept.
0:16:48 > 0:16:51It's kind of intuitive.
0:16:58 > 0:17:05But a clue from the present day suggested that Dick's idea might not be quite so outlandish.
0:17:08 > 0:17:14Here, the descendants of the few Maya who survived the catastrophe
0:17:14 > 0:17:17are praying for rain.
0:17:20 > 0:17:28Secret ceremonies take place at the end of the dry season. While the women prepare a feast for the gods,
0:17:28 > 0:17:35the men perform rituals, combining Maya and Christian ceremonies.
0:17:38 > 0:17:42HE PRAYS IN OWN LANGUAGE
0:17:49 > 0:17:56Pleading with the gods, just like their ancestors did, not to allow the rains to fail.
0:18:13 > 0:18:20Dick went back to Tikal, searching for evidence that the ancient Maya were in fear of drought.
0:18:20 > 0:18:27Far from any rivers or lakes, the people of Tikal were completely reliant on the summer rains,
0:18:27 > 0:18:30which last for six months of the year.
0:18:40 > 0:18:48Dick was fascinated to find that the whole city was designed to conserve water.
0:18:48 > 0:18:53Plazas and streets sloped to channel the rain into dozens of reservoirs.
0:18:53 > 0:18:58The main problem the Mayas had in Tikal was solving the water problem
0:18:58 > 0:19:02since we have no rivers, no lake and no underground waters.
0:19:02 > 0:19:09Dick has enlisted the help of local guide, Rafeno Ortiz who knows every inch of the city.
0:19:09 > 0:19:16As you notice, there is a reservoir here. We're gonna go down the side of a retaining wall.
0:19:16 > 0:19:21- What is this we're coming down? - One of the largest reservoirs...
0:19:21 > 0:19:28Rafeno is taking Dick to hidden parts of Tikal - one of the huge reservoirs now smothered by jungle.
0:19:28 > 0:19:31Do you have any idea how deep it is?
0:19:31 > 0:19:38- From the top to the bottom of the reservoir, there's about 125ft of depth.- How much water will it hold?
0:19:38 > 0:19:44This has the capacity, it's estimated, about 100 million gallons of water.
0:19:44 > 0:19:49These are rain-fed reservoirs. This had to fill up from rainwater.
0:19:49 > 0:19:52Exactly. Everything is rain fed here
0:19:52 > 0:19:57because, at Tikal, we don't have lakes, rivers or underground water.
0:19:57 > 0:20:04So they had to use the surface areas to channel the water and store it in these low reservoirs.
0:20:04 > 0:20:08- So, if they didn't get rain, they were in trouble.- Exactly.
0:20:21 > 0:20:28So, Tikal's only source of drinking water during the dry months were the reservoirs.
0:20:31 > 0:20:37If the annual rains failed to fill them, the Maya would be in serious trouble.
0:20:59 > 0:21:04Dick still needed proof that there had ever been a drought at all,
0:21:04 > 0:21:07and that took him to Mexico City.
0:21:11 > 0:21:16Hola. Soy Dick Gill. Tengo una cita para revisar datos meteorologicas...
0:21:16 > 0:21:2120.25. ..19.87.
0:21:21 > 0:21:271. ..15. ..1.5. 18.75.
0:21:27 > 0:21:34To his delight, the city authority's meticulous weather records revealed just what he'd hoped to find.
0:21:34 > 0:21:37..14. ..6.25.
0:21:37 > 0:21:4089.62.
0:21:40 > 0:21:45'It turns out that, in the last century,'
0:21:45 > 0:21:50there was one severe drought. It was really a pretty bad drought.
0:21:50 > 0:21:54In fact, it happened in 1902, 1903 and 1904.
0:21:54 > 0:22:01Given the fact that really severe drought is so rare, we're pretty lucky that it showed up,
0:22:01 > 0:22:04in this 100-year record that we have here.
0:22:06 > 0:22:10A drought that lasted three years proved to Dick
0:22:10 > 0:22:15that severe droughts not only could happen, but had happened.
0:22:15 > 0:22:19This was, certainly, a very extraordinary moment.
0:22:19 > 0:22:25If a pretty bad drought happened at least once, maybe it happened twice.
0:22:25 > 0:22:30And maybe that other time was when the Maya disappeared.
0:22:33 > 0:22:40But one destructive drought in the last 100 years was not enough to hang a whole theory on.
0:22:40 > 0:22:43He had to search further back in time.
0:22:44 > 0:22:52To delve more deeply into Mexican history, Dick had to visit a most unlikely place -
0:22:52 > 0:22:55the city prison.
0:22:57 > 0:23:04Now the national archives, it houses a unique collection of handwritten books,
0:23:04 > 0:23:08some dating back to the 16th century.
0:23:08 > 0:23:12WHISPERING: "The land was everywhere dry and barren."
0:23:12 > 0:23:17"Those became the five years during which there was nothing to eat."
0:23:17 > 0:23:20"The deadly hunger continued."
0:23:20 > 0:23:23"There was no water in the wells."
0:23:23 > 0:23:28After months of searching, Dick found a number of haunting accounts
0:23:28 > 0:23:35of devastating droughts from the Yucatan province of Mexico - the heartland of the ancient Maya.
0:23:35 > 0:23:38"The entire forest was burned."
0:23:38 > 0:23:42"That which came was a drought
0:23:42 > 0:23:46"where the hooves of the animals were burnt."
0:23:46 > 0:23:50VOICES CONTINUE TO WHISPER
0:23:59 > 0:24:06These reports that are contained in these books here, are reports made by the Spanish colonial authorities
0:24:06 > 0:24:10to their superiors in Mexico City or in Madrid.
0:24:10 > 0:24:15This one, for example, that I've found, is a plea for help
0:24:15 > 0:24:18from the authorities in Yucatan.
0:24:18 > 0:24:21The crops had been very bad in the year 1795.
0:24:21 > 0:24:24They were running out of grain.
0:24:24 > 0:24:31They were very much afraid that the terrible death they had seen so much in the past would repeat itself.
0:24:33 > 0:24:35So they say, "Send help now."
0:24:37 > 0:24:42Dick was now certain that he was on the right track.
0:25:13 > 0:25:19He now had evidence of several severe droughts. But that wasn't enough.
0:25:19 > 0:25:25There were no records for as far back as the 9th century.
0:25:31 > 0:25:38Back at the ranch, Dick's research now took off in a completely new direction.
0:25:39 > 0:25:43He studied meteorology and read hundreds of scientific papers,
0:25:43 > 0:25:49looking for anything that might shed light on the collapse of the Maya.
0:25:50 > 0:25:54I don't think climate events happen in isolation.
0:25:54 > 0:25:58Weather is part of a global pattern.
0:25:58 > 0:26:04So I began looking at ancient climate records from all over the world,
0:26:04 > 0:26:10trying to understand what was going on around the world at the time that the Maya disappeared.
0:26:10 > 0:26:15I looked at records from North America, South America,
0:26:15 > 0:26:20from Australia, from Asia, from Europe.
0:26:21 > 0:26:26And it was from Europe that he got his breakthrough.
0:26:26 > 0:26:28A paper with the catchy title...
0:26:28 > 0:26:35"Dendorochronology, mass balance and glacier front fluctuations in Northern Sweden."
0:26:35 > 0:26:38The dates just leapt out at him.
0:26:38 > 0:26:431,200 years ago, at precisely the time when the Maya collapsed,
0:26:43 > 0:26:48tree rings in Sweden revealed an exceptionally cold period.
0:26:48 > 0:26:53Could freezing weather in Europe be linked to drought in Central America?
0:26:53 > 0:26:57The experts were extremely sceptical.
0:26:58 > 0:27:06The first thing that I did was to get in contact with distinguished and respectable meteorologists
0:27:06 > 0:27:13to ask them what kind of a tie can there be here? No-one had really looked at this before.
0:27:16 > 0:27:21I seem to have been the first to have stumbled across this.
0:27:21 > 0:27:25In fact, I got one letter that said
0:27:25 > 0:27:30that most meteorologists would probably find the idea far-fetched.
0:27:32 > 0:27:35It was nothing more than a hunch.
0:27:36 > 0:27:40People get hunches and they follow up on their hunches.
0:27:40 > 0:27:44My hunch was that there was a connection.
0:27:48 > 0:27:54Dick threw himself back into the record books, looking for the connection.
0:27:54 > 0:28:02The best place to start, he thought, was one of the weather systems that links Europe and Central America -
0:28:02 > 0:28:06the North Atlantic high-pressure system.
0:28:06 > 0:28:09It was a daunting task.
0:28:09 > 0:28:13As you can see, I've got over 1,000 pages of just numbers.
0:28:13 > 0:28:20I almost went blind trying to find which was the highest pressure out of all of these numbers here.
0:28:20 > 0:28:25It was just thousands of pages that I had to go through.
0:28:28 > 0:28:32He scoured the records for the 20th century.
0:28:32 > 0:28:35It took him over two years.
0:28:38 > 0:28:40But what he found was a revelation.
0:28:42 > 0:28:48Areas of high pressure are associated with calm, settled weather.
0:28:48 > 0:28:52There are high-pressure systems in the North Atlantic.
0:28:52 > 0:28:58One in particular normally stays near Europe, and that's where it was for most of the time.
0:28:58 > 0:29:06But Dick discovered that, just once during the 20th century, this system moved towards Central America.
0:29:08 > 0:29:12That was a time of severe drought in the Maya lowlands,
0:29:12 > 0:29:19AND it was a period where the coldest Arctic temperatures were recorded for the 20th century.
0:29:31 > 0:29:36Dick had found that weather systems half a world apart could be linked.
0:29:36 > 0:29:39Was he at last onto something?
0:29:41 > 0:29:45There was only one man who could tell -
0:29:45 > 0:29:48climate modeller Tony Broccoli.
0:29:49 > 0:29:53With the computer, I can change the world's climate.
0:29:56 > 0:30:01I don't have to go to the polar regions or sweat in the Tropics.
0:30:01 > 0:30:08I can just sit in my office, comfortable and dry, and perform my experiments.
0:30:08 > 0:30:12At the touch of a button on my keyboard, I can, say...
0:30:12 > 0:30:15make the sun stronger or brighter
0:30:15 > 0:30:21and see what happens to the rains in tropical Africa or the US.
0:30:27 > 0:30:33In his virtual world, Tony has a unique overview of the Earth's climate.
0:30:34 > 0:30:41This map shows us the distribution of rain throughout the whole world for a particular time of year.
0:30:41 > 0:30:48This is January, and one of the interesting features is this rain belt throughout the tropical regions.
0:30:50 > 0:30:53As we go through the seasons -
0:30:53 > 0:30:56January, February, March -
0:30:56 > 0:31:02we see that that tropical rain belt slowly shifts northward.
0:31:02 > 0:31:06We see the rains come to Central America
0:31:06 > 0:31:10during June, July, August, September.
0:31:14 > 0:31:19Tony looked at what might shift these tropical rains
0:31:19 > 0:31:22away from Central America, creating drought.
0:31:26 > 0:31:31Here, he starts with a tropical rain belt on top of the equator.
0:31:31 > 0:31:36But when he makes the far north colder, the effect is dramatic.
0:31:37 > 0:31:42The rain belt is forced south and doesn't reach Central America.
0:31:42 > 0:31:45The result is drought.
0:31:46 > 0:31:53It would only take a relatively small shift in the average position of that tropical rain belt
0:31:53 > 0:32:01to make the difference between abundant summer rains in Central America and drought conditions.
0:32:10 > 0:32:16Dick was now more convinced than ever that it was drought that had destroyed the Maya.
0:32:21 > 0:32:25Support for his theory came from a most surprising place.
0:32:27 > 0:32:30The frozen north.
0:32:36 > 0:32:41Paul Mayewski, an expert in ancient climates,
0:32:41 > 0:32:46was intrigued by Dick's idea about exceptional weather conditions.
0:32:46 > 0:32:52Not for him the warm comfort of an office. He prefers the freezing landscape of Greenland
0:32:52 > 0:32:57where he analyses chemicals in the ice.
0:32:57 > 0:33:02The beauty of the ice cores is they've built up over the years,
0:33:02 > 0:33:07each layer preserving precise evidence of past climates.
0:33:09 > 0:33:15If we walked outside right now, we could tell that it was cloudy, cool
0:33:15 > 0:33:18and that there wasn't a great deal of wind.
0:33:18 > 0:33:24But we wouldn't know about the greenhouse gas content, if the oceans were stormy.
0:33:24 > 0:33:31We wouldn't be able to tell as richly what we can tell from the ice-core record going back through time.
0:33:31 > 0:33:36That's a pretty odd thought when you think about it.
0:33:36 > 0:33:42It's almost better at telling us about the past than we're able to tell by going outside.
0:33:44 > 0:33:51Paul has constructed a uniquely accurate history of global weather from his ice cores.
0:33:51 > 0:33:58When he heard about Dick's drought theory, he decided to check his cores for the 9th century.
0:33:58 > 0:34:06Would HE be able to find evidence of any dramatic climate change in the northern hemisphere?
0:34:06 > 0:34:10First thing that we looked at was our record of ammonium.
0:34:10 > 0:34:16Ammonium is a chemical that gets into the atmosphere which tells us whether or not there was...
0:34:16 > 0:34:21a lot of vegetation in the northern hemisphere.
0:34:21 > 0:34:26If there's a lot of vegetation, one assumes it was probably warm and wet.
0:34:26 > 0:34:31Low amounts - it was probably drought conditions. The soil had dried up.
0:34:33 > 0:34:38When he looked at the ice that was 1,200 years old, he was astonished.
0:34:38 > 0:34:44We found that there was a tremendous drop in ammonium.
0:34:44 > 0:34:51They'd probably not experienced a drought like this going back two, maybe three, thousand years.
0:34:52 > 0:34:56So the ice cores confirmed Dick's hunch.
0:34:56 > 0:35:02At the time of the Maya collapse, it was dry and cold across the northern hemisphere -
0:35:02 > 0:35:06conditions that would indicate drought in the Maya areas.
0:35:27 > 0:35:31But archaeologists remained unconvinced.
0:35:31 > 0:35:38If there HAD been such a severe drought, why was there no record of it in the Maya's own chronicles?
0:35:40 > 0:35:47The Maya carvings tell of great battles, of ruling dynasties and all-powerful gods.
0:35:47 > 0:35:49But on drought, they are silent.
0:36:13 > 0:36:15I decided to see
0:36:15 > 0:36:21whether the Maya had written anything about drought.
0:36:21 > 0:36:25We don't find anything on their monuments and buildings,
0:36:25 > 0:36:32but, IF drought were a regular part of Maya life, they must have written about it somewhere.
0:36:32 > 0:36:35Then he had a stroke of luck.
0:36:35 > 0:36:42He came across this rare manuscript written by the Maya, one of the few not destroyed by the Spaniards.
0:36:45 > 0:36:51I came to this Maya book to see whether there was any discussion of drought
0:36:51 > 0:36:55and, right here on the last page, there it is.
0:36:55 > 0:36:58There's a hieroglyphic symbol for drought.
0:36:58 > 0:37:06They did write about drought, it was an ongoing part of their life, and there it is right there.
0:37:10 > 0:37:15It was just what he'd hoped to find - a voice from the past.
0:37:18 > 0:37:25But despite all the evidence he was accumulating, Dick's theory was still questioned by archaeologists.
0:37:27 > 0:37:32Drought as a solution to the Maya collapse
0:37:32 > 0:37:39has been very difficult for most of my colleagues in archaeology to accept.
0:37:39 > 0:37:43The current theories about the collapse of advanced civilisations,
0:37:43 > 0:37:49are that you have to have a very complex explanation
0:37:49 > 0:37:54and that an idea as simple as the idea of drought is too simple,
0:37:54 > 0:37:58and is probably proposed by a simpleton!
0:38:07 > 0:38:13But the final proof Dick was so desperately seeking was just around the corner.
0:38:17 > 0:38:22Out of the blue came a discovery made by three geologists,
0:38:22 > 0:38:27who had no particular interest in the history of the Maya.
0:38:27 > 0:38:30A University of Florida team
0:38:30 > 0:38:37happened to be researching climate history at their favourite location - the Yucatan in Mexico.
0:38:37 > 0:38:40Our basic research is to try to understand
0:38:40 > 0:38:46how the climate of the Yucatan has changed through the last several thousand years.
0:38:46 > 0:38:48In particular,
0:38:48 > 0:38:54we're interested in how rainfall may have varied over that time period.
0:38:58 > 0:39:05The focus of their attention is the bottom of the lake where the mud holds the secrets of past climates.
0:39:14 > 0:39:19They take a core down through the mud, layers and layers of sediment
0:39:19 > 0:39:23which have built up over thousands of years.
0:39:23 > 0:39:29We're taking it up from the bottom using these screw-together rods.
0:39:29 > 0:39:34At the bottom of this, we hope, we'll have a tube full of sediment.
0:39:34 > 0:39:39Sediments are a great trap of environmental information.
0:39:39 > 0:39:46Sediments will collect things like pollen and snail shells and bits of leaves and twigs.
0:39:48 > 0:39:52As they brought one core out of the water, they were amazed.
0:39:52 > 0:39:57Straightaway, they could see evidence of a severe drought.
0:39:57 > 0:40:02We have some very nice gypsum bands toward the base of this core.
0:40:02 > 0:40:06They indicate very dry periods, extreme drought in the area,
0:40:06 > 0:40:11when the lake level fell very low at some time in the past.
0:40:11 > 0:40:14Back in the lab, there was another surprise.
0:40:14 > 0:40:19This time, it came from the tiny snail shells found in the mud.
0:40:20 > 0:40:27In the shells are two sorts of oxygen from the lake water - a heavy one and a light one.
0:40:27 > 0:40:31Plenty of rain, and the light oxygen dominates.
0:40:31 > 0:40:38More of the heavy oxygen means it was dry. When they analysed the snails, they were astonished.
0:40:38 > 0:40:42They found a surge of heavy oxygen.
0:40:45 > 0:40:49It was the worst drought in the last 7,000 years.
0:40:49 > 0:40:52Do it very gently.
0:40:56 > 0:40:58But they had no way of knowing
0:40:58 > 0:41:03exactly when this apocalyptic drought had happened.
0:41:04 > 0:41:06Then they had a stroke of luck.
0:41:06 > 0:41:13Right in the middle of the driest part of the mud core, they found what they needed.
0:41:15 > 0:41:17A single seed.
0:41:22 > 0:41:26They sent it to be dated.
0:41:28 > 0:41:34When I looked at the result for the first time, it really was a eureka experience!
0:41:34 > 0:41:37I knew at that moment
0:41:37 > 0:41:44that this drought coincided with the collapse of Maya civilisation in the 9th century AD.
0:41:53 > 0:41:56When I heard the news,
0:41:56 > 0:41:59there was a tremendous sense of relief.
0:41:59 > 0:42:04Here was the evidence that finally supported my theory.
0:42:04 > 0:42:07When I first proposed my theory,
0:42:07 > 0:42:11there was no physical evidence from the Maya lowlands itself.
0:42:11 > 0:42:16There was nothing in the dirt or in the lake cores that I could point to
0:42:16 > 0:42:21that said, "This demonstrates that they had a terrible drought here."
0:42:21 > 0:42:23But, finally, here it was!
0:42:23 > 0:42:28It was a sense of relief mixed with excitement, too.
0:42:35 > 0:42:38As long as my theory was just a theory,
0:42:38 > 0:42:46I think that some of my colleagues in archaeology were sceptical, which I understand.
0:42:46 > 0:42:51But when we had hard evidence from the ground in the Maya lowlands,
0:42:51 > 0:42:59I felt that, maybe, at last, people would start to take my theory seriously.
0:43:03 > 0:43:09Dick had gathered clues from around the world. From the frozen north to tropical Central America,
0:43:09 > 0:43:13from rare Spanish documents, to an ancient Maya book.
0:43:13 > 0:43:20But it was the Mexican lake core that gave him the clinching scientific evidence -
0:43:20 > 0:43:26final proof that the glorious Maya civilisation had been destroyed by the awful forces of nature.
0:43:29 > 0:43:32It's a chilling scenario.
0:43:32 > 0:43:40As the drought tightened its grip, the Maya people would have turned to their ruling priests.
0:43:40 > 0:43:47With their superhuman powers and their direct access to the gods, they should have saved the Maya.
0:43:48 > 0:43:51But the priests proved to be powerless.
0:43:55 > 0:43:59It's this that may explain why 30 men, women and children
0:43:59 > 0:44:02were so savagely massacred.
0:44:08 > 0:44:13You've got ten adult males, ten adult females and ten children.
0:44:16 > 0:44:20It just screams that it's... an extended family.
0:44:20 > 0:44:26Small inherited details in the teeth confirmed Diane's suspicion.
0:44:26 > 0:44:32The men were related. Not only that, the teeth showed that this was no ordinary family.
0:44:32 > 0:44:37Some teeth had been carefully filed to make them pointed.
0:44:37 > 0:44:40One even had an inlay of a precious stone.
0:44:40 > 0:44:43Among the Maya,
0:44:43 > 0:44:51this is a status symbol. It's something that the upper classes did to show who they were.
0:44:52 > 0:44:58The common folk, the rural populations, didn't practise this.
0:45:07 > 0:45:13The massacred family may well have come from the elite priests whose powers had failed,
0:45:13 > 0:45:18sacrificed, perhaps, to appease the gods.
0:45:21 > 0:45:26Even after the murders, the frenzy and brutality continued.
0:45:30 > 0:45:36This is the skull of a young adult female. This skull has been burned.
0:45:37 > 0:45:42You can see the charring. The shiny black indicates that...
0:45:42 > 0:45:49the bone was burned at a low temperature while the bone was fresh, while it was green.
0:45:49 > 0:45:54That's what we call green, when it's very close to the time of death.
0:46:08 > 0:46:13Nothing could save the Maya from the horror that enveloped them.
0:46:13 > 0:46:21The gods had betrayed them, their reservoirs were empty. There was no drinking water, their crops failed.
0:46:21 > 0:46:23There was nothing to eat.
0:46:23 > 0:46:27The Maya civilisation was destroyed.
0:46:37 > 0:46:41When drought afflicts an area, it's really all-powerful
0:46:41 > 0:46:49and human beings are very helpless, powerless, in their ability to do anything about it.
0:46:53 > 0:46:58You can't govern better in order to avoid drought.
0:46:58 > 0:47:03You can't carry on religious ceremonies better.
0:47:03 > 0:47:09You can't have better agricultural practices in your fields to avoid drought.
0:47:09 > 0:47:16When drought hits, it's not the people themselves that are at fault and there's nothing they can do.
0:47:16 > 0:47:21They are the victims, they are not the perpetrators of the problem.
0:47:26 > 0:47:32Today, the Maya who survived this ancient apocalypse
0:47:32 > 0:47:36still perform some of their ancestral ceremonies.
0:47:42 > 0:47:46But they never returned to their once-glorious cities,
0:47:46 > 0:47:49which were abandoned forever.
0:47:51 > 0:47:53There's a certain satisfaction
0:47:53 > 0:48:00that I have finally understood what happened to the Maya, but, as a human being,
0:48:00 > 0:48:06it's awful to think about what happened to those people and how this civilisation came to an end.
0:48:23 > 0:48:29In the final Ancient Apocalypse, the story of Sodom and Gomorrah.
0:48:29 > 0:48:36In a storm of fire and brimstone, God destroyed whole cities to punish man's wickedness.
0:48:36 > 0:48:43Can science now show that this terrible legend is based on a real apocalypse?
0:48:43 > 0:48:46That's next Thursday at 9.00.
0:48:46 > 0:48:50Subtitles by Mary Easton BBC Scotland - 2001
0:48:50 > 0:48:54E-mail us at subtitling@bbc.co.uk