In a stunning revelation, researchers have unlocked the genetic secrets of ancient Mayan children sacrificed at Chichén Itzá, uncovering a deep-rooted connection to present-day descendants and shedding new light on the mysterious rituals of one of Mesoamerica’s most iconic civilizations.
Twins in Mayan Mythology and Rituals
Scientists examined the remains of 64 children, dating from AD 500 to 900, found in a subterranean mass burial. The burial site was near the Sacred Cenote, a central ceremonial site in the Mayan city of Chichén Itzá. Genetic analysis revealed that all the individuals were male, with some being closely related, including two pairs of identical twins.
This is particularly notable as twins hold a special place in Mayan mythology, often symbolizing duality among deities and heroes. The Popol Vuh, a sacred K’iche’ Mayan text, details the story of twin heroes who undergo cycles of sacrifice and resurrection, indicating that such sacrifices may have been believed to hold powerful spiritual meaning.
These familial ties suggest that the children might have been chosen for sacrifice based on their biological relationships. Also, most of the boys found were around the same age. The Maya employed child sacrifices to appease the gods and enhance the fertility of their crops.
“The main motivation behind this study was to answer some questions that classical archaeology and anthropology couldn’t answer back when the burial was found. Given the context, we aimed to answer many things at once, from population genetics to selection and adaptation. For the first time, we could use this “molecular time machine” that ancient DNA is, to assess the people that once lived in Chichén Itzá. This allowed us to complement the previous knowledge with novel results that gave a full story, one that we were not expecting. Our main findings are: the burial contained only males, around one-quarter of them were found to be related to each other, we found two sets of twins, and there are signatures of natural selection in the Maya region carried out by pathogens,” study author Rodrigo Barquera of the Max-Planck Institute for Evolutionary Anthropology told ZME Science.
The study doesn’t simply highlight ancient practices that are ghastly by today’s standards. It traces the genetic lineage of these ancient Maya to present-day populations. By comparing the ancient DNA of the sacrificed children with that of contemporary Maya from the nearby town of Tixcacaltuyub, the researchers found significant genetic continuity. However, they also noted changes in specific genetic loci related to immunity. This was likely influenced by diseases introduced during the colonial period.
Impact of European Diseases on Maya Genetic Adaptation
The arrival of Europeans in the Americas had a devastating impact on the indigenous populations, including the Maya, primarily due to the introduction of diseases to which they had no immunity. Diseases such as smallpox, influenza, measles, and typhus decimated the native populations. This led to catastrophic mortality rates, sometimes wiping out entire communities.
However, the few survivors went on to form new generations that were more resistant to these diseases, including Salmonella enterica. Specifically, there was an increase in the frequency of the HLA-DR4 allele among present-day Maya populations. This allele provides greater resistance to Salmonella enterica, the causative agent of enteric fever. This adaptation is likely a result of selection pressure from epidemics during the colonial period, such as the 1545 Cocoliztli pandemic.
“Many years ago, in my Immunology course, we had to present a project as an end-of-course task. It had to be an educated guess on an actual research question, and I decided to present the idea that this particular variant was implicated in the resistance to infection by Salmonella enterica. This came from the observation of the variant being very prevalent in Latin Americans, particularly in Mexicans, and the empirical and widespread knowledge of Mexicans being naturally resistant to enteric fever. Many years later, we could prove that this is actually the case, and that the introduction of Salmonella to Mexico during the colonial period drove major changes in the immunogenetic makeup of present-day Mexicans,” said Barquera.
“We as a species keep adapting and evolving. How present-day Latin Americans are better adapted to withstand enteric fever comes from centuries of the pathogen and the human host competing in a molecular battle. What we learn from the past can be applied to the future. How we observe adaptation in the past may bring new ideas to the table when it comes to discussing health policies or intervention during pandemic or epidemic events.”
Chichén Itzá in Maya History
Chichén Itzá, located in the northern part of the Yucatán Peninsula, stands as one of the most significant and extensively studied archaeological sites of the ancient Maya civilization. Founded around the 6th century AD, it rose to prominence during the Late Classic period (600-900 AD) and continued to flourish into the Terminal Classic period (900-1000 AD). The city is renowned for its architectural marvels, including the iconic El Castillo pyramid, also known as the Temple of Kukulkán. This temple stands as a testament to the Maya’s advanced knowledge of astronomy and engineering.
However, as these new findings show, the significance of Chichén Itzá in Maya culture extends beyond its architectural achievements. It was a hub of ritual activity, with many offerings centered around the Sacred Cenote, a large natural sinkhole used for human sacrifices. The recent genomic studies of individuals found near the Sacred Cenote reveal the deep cultural and spiritual importance of such rituals, showcasing the Maya’s intricate belief systems and their connection to the natural world.
“Chichén Itzá became one of the main political and religious centers in Mesoamerica after the fall of the Classic Period Maya sites, and incorporated not only Maya architecture but also some styles from the central part of what today is Mexico. This makes it an interesting place to look for surprises. We were also interested in aiding in solving long-standing questions about the site and the chultún in particular, which we could do with the use of modern techniques. The fact that there were many individuals to be analyzed also made it a good candidate for performing population genetics and immunogenetics analyses,” said Barquera.
“It is important to incorporate as many lines of evidence in telling such a complex story as possible, and this is only possible when all available techniques are used, together with inter- and trans-disciplinary analyses, enriched by the perspectives coming from inviting indigenous communities into the discussion of the results.”
