About the Project


The primary objective of this website is to create an online repository for information about accurately dated maize samples in order to help trace its geographic spread from its original homeland in western Mexico to the northern and southern extremes of its range at the time of European contact ca. 1500 CE.

The primary goals of this website are:

  1. Dating: to gather together, in a publicly accessible database, all the radiocarbon dates available on ancient directly dated maize macrobotanical and microbotanical remains as well as the indirectly dated maize microbotanical remains from archaeological and environmental sites across the Americas;
  2. Interactive Mapping: to map the temporal distributions of these four classes of ancient maize data across North and South America.

The secondary goal is to facilitate future research in the following areas:

  1. Morphology: to gather and make available morphological data from directly dated ancient maize macrobotanical remains—consisting of precise measurements of cob (rachis) lengths and diameters, number of rows, cupule widths and depths, and kernel sizes and shapes;
  2. Ancient DNA: to compile a database of selected genetic characteristics of archaeological maize by geographic region and by time period using ancient DNA;
  3. Stable Isotopes: to build a database of stable isotope measurements (δ13C and δ15N) on directly dated human bone (and other remains) indicating the direct consumption of maize (or more generally, C4 plants) in ancient diets; and

We hope that the Ancient Maize Map database and mapping feature will be a useful research tool for formulating and testing hypotheses about the origins and spread of maize agriculture during the past nine millennia.

So far, only goals (1) and (2) have been reached in the present version of Ancient Maize Map. Future versions (see below) will eventually, we hope, allow us to map maize morphological data, genetic variations, and stable isotope measurements.

How to Cite this Website

Please use the following citation when referring to this website in other publications:

Blake, M., B. Benz, D. Moreiras, L. Masur, N. Jakobsen and R. Wallace
2017 Ancient Maize Map, Version 2.1: An Online Database and Mapping Program for Studying the Archaeology of Maize in the Americas. http://en.ancientmaize.com/. Laboratory of Archaeology, University of B.C., Vancouver.

Previous version that used Google Earth Overlays (until early 2016):

Blake, M., B. Benz, N. Jakobsen, R. Wallace, S. Formosa, K. Supernant, D. Moreiras and A. Wong
2012 Ancient Maize Map, Version 1.1: An Online Database and Mapping Program for Studying the Archaeology of Maize in the Americas. http://en.ancientmaize.com/. Laboratory of Archaeology, University of B.C., Vancouver.

Database of Radiocarbon Dates

The maize database is organized by country of origin, regions (states or provinces) within countries, and finally individual archaeological or environmental sites where the maize data were recovered. All samples are linked to the sites where they were collected, and where possible, the individual deposits, features, or artifacts within the sites where they were found. Each individual maize sample is identified by a unique radiocarbon lab sample number—whether directly or indirectly dated. Different maize samples will occasionally have the same radiocarbon lab sample number, for example, when both maize starch grains and maize phytoliths were extracted from the same AMS-dated sample of residue adhering to a piece of pottery.

We provide the uncalibrated radiocarbon age (uncal BP) in radiocarbon years BP (before present, i.e., 1950) with a plus or minus value in years indicating one standard deviation (1σ). We also provide the median calibrated age of the sample, in years BP (cal BP). These calibrations have been calculated using the latest version of OxCal http://c14.arch.ox.ac.uk. Along with the median cal BP age of the sample, we include the lower (oldest) and upper (youngest) calibrated age estimate bracketing the median with a 95.4% probability—in other words a two sigma (2σ) range. This means that there is an approximately 95% chance that the true age of the sample lies somewhere between the upper and lower range, and the median estimate therefore tells us the central tendency of this estimate. All radiocarbon samples have been corrected for isotopic fractionation. We include the measured δ13C ‰ values for each sample where available—missing values in the database indicate that it was either unmeasured or unreported. For all samples north of the equator, calibrations are made using IntCal13, the northern hemisphere calibration curve, and for all samples coming from south of the equator, ShCal13, the southern hemisphere calibration curve is used.

For each archaeological site and dated radiocarbon sample, we provide, where possible, the primary references to the publications in which the information was originally presented. Most of the samples have been previously published, but in some cases they have not—instead being cited by others, as secondary publications or personal communications, and we occasionally rely on these sources for information about such samples. References are downloadable in text format, by cutting and pasting, or in Endnote format [coming soon we hope].

Feedback and Comments

Ancient Maize Map, Version 2.1, is designed to show the spatial distribution of maize dates (and eventually the other types of data) using a visual format similar to a heat map.

However, the maps are only as good as the data that are available at the moment. So, in order to make the database more flexible, we have built this website to be "reciprocal." Ancient Maize Map’s pages have click-on buttons for comments and we invite fellow researchers to contact us with clarifications or corrections in cases where there may be errors or omissions. We also encourage colleagues to contact us with updated publication information, links to relevant websites, and links to pdfs of original publications and manuscripts. Likewise, we are pleased to upload examples of illustrations and photos of samples, excavations, and the archaeological sites where the samples originate (to the extent that copyright regulations allow and, of course, with appropriate credits and citations). In this way we hope that new information can be quickly added to the database allowing visitors to create new, updated distribution maps.

Future Plans

The current version of Ancient Maize Map, Version 2.1 (updated February 20, 2017) is a work in progress. At present we have implemented goals (1, dating) and (2, interactive mapping). In future versions we hope to add the other categories of information about ancient maize, each of which will also be able to be mapped on Google Maps (Goals 3, 4, and 5 above): stable isotope, maize morphology, and ancient DNA.

Funding and Support

Ancient Maize Map was funded (2007-2012) as part of a research grant from the Social Sciences and Humanities Research Council of Canada (SSHRC Standard Research Grant: 410-2007-1111) "The Evolution and Dispersal of Maize in Latin America: AMS Radiocarbon Dating, DNA and Morphological Analyses," to Michael Blake (University of British Columbia), Bruce Benz (Texas Wesleyan University).

We are grateful to Safe Software, Inc. (Surrey, B.C., Canada), the creators of the FME Server program that was used to power the mapping function on an earlier this website, and who generously provided us with access to and support for their program from 2010 to 2016.

We also thank the University of British Columbia's IT Services department which provided the server support for our mapping programs from 2010 through 2016.

Ancient Maize Map Team

Regional Contributors

The following individuals have generously contributed either maize samples for direct dating, unpublished information concerning previously dated samples, and/or information about site locations:

Institutional Contributors

We acknowledge the kind assistance of several institutions, and their specialists, who have made it possible to access, analyze, and/or date maize collections: