Changing Climate and the Maya

Archaeologists have puzzled over the "collapse" of the ancient Mayan civilization. What led to the massive depopulation of major Mayan cities in the 900's C.E.? Scientists have considered war and political factors but this segment deals with another new emerging explanation. New data suggests climate, specifically, severe drought, played a key role. In the segment, we see how scientists can use snail shells and sediment layers from the bottom of a lake to create a picture of climate at various periods in the ancient past.

Maya civilization thrived thousands of years ago in present-day Central America. Anthropologists and archaeologists thought Maya culture originated in the northern reaches of what is now Guatemala about 600 BCE, and migrated north to the Yucatan Peninsula beginning around 700 CE.

Throughout the film Quest for the Lost Maya, a team of anthropologists led by Dr. George Bey discovers the Maya may have been in the Yucatan as far back as 500 BCE. This new evidence indicates the Maya of the Yucatan had a very complex social structure, distinctive religious practices, and unique technological innovations that made civilization possible in the harsh jungle.

Archaeologists have long puzzled over the collapse of Mayan civilization. What led to the massive depopulation of major Mayan cities in the 900s? Scientists have considered war and political factors, but this segment of Quest for the Lost Maya suggests another explanation.

In a University of Florida lab, Dr. Mark Brenner evaluates sediment cores which have produced new data that suggests climate—specifically, severe drought—played a key role in the decline of Maya civilization. This segment of Quest for the Lost Maya outlines how scientists use snail shells and sediment layers from the bottom of a lake to create a picture of climate conditions at various periods in the ancient past.

Although climate was likely a major factor of the Mayan collapse, it's not the only one. Civilizations carefully balance a host of factors—political, environmental, military, and cultural. Troubles in one area often lead to problems in other areas.
1. What do different bands of color in the core sediment samples represent?
  
  Show Answer
  
  Brown bands represent organic material, whereas white bands represent gypsum (a type of salt).
2. How does the gypsum found in the core sediment samples form? What does this formation indicate?
  
  Show Answer
  
  The gypsum sediment layer formed as water evaporated. Salt in the water did not evaporate, and settled in layers at the bottom of the lake. This evaporation process indicates a period of drought.
3. How did scientists determine the age of the gypsum? With what did these dates coincide?
  
  Show Answer
  
  Scientists performed radio-carbon dating to find that the gypsum layers dated from the same time period as the collapse of Mayan civilization.
4. How have snail shells helped climatologists determine aspects of the ancient environment of the Stairway site?
  
  Show Answer
  
  Snail shells contain two distinct oxygen isotopes, one of which occurs much more strongly in a drought environment. Analysis of shells obtained from sediment cores at the Mayan archaeological site indicates droughts of the highest magnitude during the last 7,000 years.
5. How many serious droughts were recorded in the sediment core, and how long did they last? What were their impacts?
  
  Show Answer
  
  Climatologists determined there were a series of eight droughts lasting three to twenty years. These droughts likely forced the people living at the Stairway site to evacuate the area.
Articles & Profiles
- PBS: Quest for the Lost Maya
- National Geographic Magazine: Maya Special Issue

Term	Part of Speech	Definition	Encyclopedic Entry
anthropology	Noun	science of the origin, development, and culture of human beings.	Encyclopedic Entry: anthropology
archaeologist	Noun	person who studies artifacts and lifestyles of ancient cultures.
chemist	Noun	person who studies the theory and application of atoms and molecules, and their relationships and interactions.
civilization	Noun	complex way of life that developed as humans began to develop urban settlements.	Encyclopedic Entry: civilization
climate	Noun	all weather conditions for a given location over a period of time.	Encyclopedic Entry: climate
climatologist	Noun	person who studies long-term patterns in weather.
data	Plural Noun	(singular: datum) information collected during a scientific study.
deforestation	Noun	destruction or removal of forests and their undergrowth.
dendrochronology	Noun	study of tree rings and how they can identify and date weather events and changes in the atmosphere.
drought	Noun	period of greatly reduced precipitation.	Encyclopedic Entry: drought
erosion	Noun	act in which earth is worn away, often by water, wind, or ice.	Encyclopedic Entry: erosion
evidence	Noun	data that can be measured, observed, examined, and analyzed to support a conclusion.
geologist	Noun	person who studies the physical formations of the Earth.
ice core	Noun	sample of ice taken to demonstrate changes in climate over many years.
isotope	Noun	atom with an unbalanced number of neutrons in its nucleus, giving it a different atomic weight than other atoms of the same element.
jungle	Noun	tropical ecosystem filled with trees and underbrush.
lake	Noun	body of water surrounded by land.	Encyclopedic Entry: lake
landscape	Noun	the geographic features of a region.	Encyclopedic Entry: landscape
Maya	Noun	people and culture native to southeastern Mexico and Central America.
migration route	Noun	path followed by birds or other animals that migrate regularly.
pollen	Noun	powdery material produced by plants, each grain of which contains a male gamete capable of fertilizing a female ovule.
sea level	Noun	base level for measuring elevations. Sea level is determined by measurements taken over a 19-year cycle.	Encyclopedic Entry: sea level
sediment	Noun	solid material transported and deposited by water, ice, and wind.	Encyclopedic Entry: sediment
speleothem	Noun	rock or mineral formations, such as stalactites and stalagmites, created in a cave environment. Also called a cave formation.
stalactite	Noun	rock formed by mineral-rich water dripping from the roof of a cave. The water drips, but the mineral remains like an icicle.
stalagmite	Noun	mineral deposit formed on a cave floor, usually by water dripping from above.
urban area	Noun	developed, densely populated area where most inhabitants have nonagricultural jobs.	Encyclopedic Entry: urban area
volcanic eruption	Noun	activity that includes a discharge of gas, ash, or lava from a volcano.

Credits

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Writer

Hannah Herrero

Editors

Caryl-Sue, National Geographic Society
Anne Haywood, National Geographic Society

Last Updated

April 12, 2012

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