The ancient remains of three people thousands of years old have been unearthed at the Puyil Cave in southern Mexico. Archaeologists say two sets of the remains are early ancestors of the Mayan civilization dating back around 4,000 years, but the third set is believed to be much older. 

Around 7,000 years old, the third set of human remains represents a time when people transitioned from hunting and gathering to a more sedentary lifestyle. Because of the 5,000-year gap between the three humans, archaeologists believe the skeletons are from two different groups who used the caves for similar reasons. The cave wasn't one where humans lived but instead appeared to serve a more ritualistic purpose. Experts speculate the Mayans who buried their dead there probably found the earlier remains and left them in a respectful manner.  

Diego Prieto, general director of the National Institute of Anthropology and History (INAH), tweeted the discovery in early August, saying a combination of multidisciplinary and inter-institutional work led researchers to believe the Puyil cave not only housed Maya burials of the Late Classic period, but also "the remains of [an] older individual considered [to be an] ancestor of contemporary Tabasco” – the region of Mexico where the remains were found

The collapse of the Mayan civilization has long mystified archaeologists and historians. Why would an empire responsible for elaborate structures and cities – whose civilization spanned present-day Mexico, Honduras, Guatemala, and El Salvador – suddenly collapse? Dominating Mesoamerica for nearly 2,000 years, they were responsible for early scientific advances in agriculture, mathematics, and calendar-making before mysteriously disappearing in 900 AD, at which point their elaborate stone cities were mostly abandoned.

Theories have ranged from wars with nearby tribes to overpopulation, and, most recently, extreme weather events. Earlier this month, new research suggested a drought responsible for dropping annual precipitation to as much as half of its normal amount could have caused the collapse.

In January, scientists in Mexico discovered the world's largest flooded underwater cave on the Yucatan Peninsula. Two months later, they revealed discoveries of archaeological significance, including ancient remains, ceramics, and cave wall etchings. 

The Puyil Cave remains are currently on display in an exhibition called Puyil: The Cave of Ancestry, along with other artifacts discovered like ceramics and jade. 

[H/T: CBC News]