Study indicates ancient use of corn in animal feed

Ancient communities in southern Belize incorporated protein from animals fed with maize into their diet around 6.100 years before present. This conclusion comes from isotopic analysis of amino acids in directly dated human remains. The study indicates a dietary strategy to compensate for the nutritional limitations of maize, especially its low lysine concentration (DOI 10.1126/sciadv.aec3522).

Scientists analyzed 39 human individuals from archaeological sites in southern Belize. The samples cover the period between 6.100 and 1.100 years before present. The study also evaluated modern plants and modern turkeys fed on corn.

Corn has a high energy value. However, it has a low protein content and is deficient in lysine. Lysine is one of the essential amino acids. Humans need to obtain it through their diet. To give an idea of ​​the nutritional challenge, scientists calculate that a 68 kg adult would need to devour more than 6 kg of dried corn daily to meet their lysine needs, a humanly impossible goal that forced our ancestors to seek a creative solution: meat.

C4 sources in protein

The models indicated an increase in the share of C4 sources in human protein over time. Between 6.100 and 3.000 years before present, individuals obtained an average of 22,8% of their protein from C4 sources. After 3.000 years before present, this percentage reached 79,6%.

The results point to regular animal consumption linked to corn. Researchers used modern turkeys as a reference for omnivorous or herbivorous animals fed with corn. The study suggests trophic transfer of lysine derived from corn. In this process, animals consumed corn. Then, humans assimilated the lysine by consuming these animals.

The hypothesis does not depend on formal domestication. The work mentions the handling, direct provision, or use of animals near cultivated areas. The evidence predates the first direct records of domesticated animals in regional zooarchaeological assemblages by approximately 4.000 years.

Scientists argue that maize likely did not replace diverse food systems based on C3 resources. It entered into combination with plants, wildlife, and management practices. This combination may have supported the expansion of maize cultivation in Mesoamerica.