Sun key to Mayan misery?

The drought cycle continues to this day

By BBC News Online's Ivan Noble

The ancient Mayans may have had good reason for their fascination with the heavens, new research by climate historians suggests.

It's hard for me to believe that's just a coincidence

David Hodell
University of Florida

It seems that the Mayan homeland in central America was plagued by droughts which appear to have followed a cycle determined by the Sun.

Researchers at the University of Florida, US, analysed sediments from a lake on the Yucatan Peninsula in Mexico and found a pattern of drought repeating every 208 years.

The pattern matches a cycle of brightening and dimming in the Sun.

Sediment sample

"It looks like changes in the Sun's energy output are having a direct effect on the climate of the Yucatan and causing the recurrence of drought, which is in turn influencing the Maya evolution," said David Hodell, lead author of the study.

In 1993, Professor Hodell and his colleagues extracted a sediment sample from Lake Chichancanab in northern Yucatan documenting 9,000 years of climate history.

They found that the driest period of the current era was from AD 800 to 1000, coinciding with the collapse of the classic Mayan civilisation in the 9th Century.

This time they went back to the lake and found data that backed up their findings and pointed to other periods of drought coinciding with other declines in Mayan building activity.

They found evidence for major dry periods between 475 and 250 BC, and AD 125 and 210, which, they believe, coincides with the abandonment of pre-classic Mayan sites in the Mayan Lowlands.

Tree rings

The evidence is by no means conclusive, but, as Professor Hodell explained to the journal Science: "It's hard for me to believe that's just a coincidence.

Archaeologists and climatologists are both examining what led to the decline of the Mayans

"I think drought did play an important role, but I'm sure there were other factors, such as increasing population, degradation of the land, and socio-political change, that interacted.

"Civilisation collapse has got to be complex," he said.

Archaeologists specialising in Mayan history have described the climate evidence as compelling, but agree with Professor Hodell that it is not sufficient by itself to explain the Mayan collapse.

But other climate researchers using tree ring dating (dendrochronology) have also found evidence of a bicentennial drought cycle in step with the variation of the Sun.

The research appears in the journal Science.