The Fremont Frontier

class: title-slide, right, top
background-image: url("images/title-western_Utah.webp")
background-size: contain

# The Fremont Frontier  
### Living at the Margins of Maize Farming

.author-date[
Kenneth Blake Vernon, Jerry Spangler, Weston McCool, Peter Yaworsky, Simon Brewer, and Brian Codding  
March 31, 2022
]

---
class: middle center

???

In trying to understand the maize farming niche, people tend to focus on the places where it farming is most productive. This is important, but it doesn't give us the whole picture. We also need to understand how maize farmers adapted at the margins. The Fremont can help us answer this question.

---
name: north_america
class: full-slide-fig animated fadeIn

???

Current research suggests that maize evolved on the southwest coast of Mexico. It then expanded northward through settlement, trade, and adaptation. At around 500 CE, maize reached what would become its northern frontier in present day Utah, introduced to the region by a loose network of people collectively referred to as the Fremont.

---
background-image: url("images/fremont-provinces.png")
background-size: contain
class: animated fadeIn

???

At its greatest extent, the Fremont complex encompassed two major physiographic regions: the Great Basin to the west and the Colorado Plateau to the east. The former consists of dry desert and grassland basins bisected by north-south running mountain ranges. This is the area I am focusing on with this project.

---
background-image: url("images/fremont-west.png"),url("images/satellite_imagery.webp")
background-size: contain
class: animated fadeIn middle
name: total-area

.pull-right-39.fremont-area.f4[

**An area of extremes** 
.f5[
- <30 cm of rainfall a year  
- 1-3,000 meters of elevation  
- 25&#176;C swing in daily temperature 
]

**Elevation drives everything**  
.f5[
- -2.1&#176;C for every 300 m of elevation  
- 90% of precip is winter snow pack  
]

**Trade-off between temperature and precipitation**

]

---
background-image: url("images/fremont-farmstead.jpg")
class: center

## Despite these hardships, the Fremont flourished

.absolute.bottom-2.right-2.pr4.pb4.mr2.mb2.grey[_artist unknown_]

???

We use the word 'Fremont' to refer to a distinctive material culture characteristic of people who lived in the region of present day Utah from roughly 500 to 1400 CE, but they were not in the same way a homogenous "people." The Fremont were maize farmers (mostly), but they were also hunters and foragers, at least when they needed to be. Some times they would settle into villages, other times they would move with the seasons. They were, in a word, adaptable, as they needed to be to make a living in this place.

---
background-image: url("images/fremont-site_counts.png"),url("images/satellite_imagery.webp")
background-size: contain
class: middle

.pull-right-39.fremont-area.f4[

**Unit of analysis: HUC10** (N = 183)

**Total Site Count: 2,447**  
.f5[\* _weighted by the number of features_]

**Range: 0, 117** (min, max)

]

???

The bright areas to the southeast represent the Parowan Valley, where famous Fremont sites like Evans Mound are located. The area just east of the Great Salt Lake is the Willard Wetlands, where dozens of human remains were excavated in the early nineties by Steve Simms and others.

---
class: middle center

## Environmental Covariates

Median value for each watershed over the Fremont sequence (from 400 to 1400 CE)

???

Estimates for climate variables generated using Kyle Bocinsky's paleocar package in R. Streams cost-distance come from the hiker package in R.

Two things to note here:
- First, cost-distance to streams is a proxy for the cost of irrigation and/or the availability of summer run-off from winter snow pack. 
- Second, as a general rule, for GDD and precipitation, higher values represented by the lighter colors are better, but for streams, lower values represented by the darker values are better.

---
class: middle center

## The Maize Niche in Ecological Space

---
class: middle center

## The Maize Niche Through Time

???

Used the model to estimate the distribution of Fremont in a 2d ecological space for each decade from 950 to 1340. This is a bit difficult to interpret, so let me draw your attention to three important features.

- First, the high probability or high suitability areas tend to stay in the northwest quadrant, around 2 to 400 mm of precipitation and 13 to 1500 degrees Celsius. 
- Second, the range of variation along the x-axis is extremely narrow, suggesting greater sensitivity to change in precipitation.
- Finally, the range of variation along the y-axis is much wider, suggesting less sensitivity to change in GDD.

Obvious result that confirms a popular hypothesis for farming in the southwest. The mega drought that hit the area around 1300 probably pushed the Fremont well outside this niche, thus leading to collapse.

---
layout: true
class: center middle short-headers

## The Mega-Drought of 1276
### Decoupled Maize GDD and Precipitation (PPT) Optima (*)

---

???

Here is an east-west profile of elevation in the northern part of the project area. According to our model, optimal values of precipitation and temperature co-occur only with a narrow band of elevation, right around the elevation of the Pinion-Juniper Zone and just below that.

---
count: false

???

As the Medieval Climate Anomaly (MCA) starts to slowly ease off in the late 13th century, a transition from a warm and dry climate to a cool and dry climate begins. The consequence of this cooling trend is that maize farmers in Utah must look at lower elevations for temperatures conducive to maize.

---
count: false

???

However, because of the severe drought that started in 1276, water-resources necessary for maize only occur at increasingly higher elevations.

---
count: false

???

Thus, the optimal elevation band for maize farming shrinks, eventually reaching the point where it could no longer sustain a maize farming strategy.

---
count: false

---
layout: false
class: middle

.center[
## Conclusions
]

.f3.w-70.ml-auto.mr-auto.tl[
1. Niche models require full range of ecological variation 📊

2. The Western Fremont struck a balance between water 💦 and  temperature 🌡️

3. Climate change can quickly degrade niches comprised of partially overlapping ecological gradients, like the boundaries between mountains ⛰️ and deserts 🏜️️
]

---
background-image: url("images/desert_parchment.webp")
background-size: contain

.acknowledgment[.inner[

## 🤝 Acknowledgments

.pull-left[
- James F. O'Connell
- Joan Coltrain
- Kristen Hawkes
- Shane Macfarlan
- Paul Algaier
- Kate Magargal
]

.pull-right[
- Ishmael Medina
- Danica Vasic  
- Maren Moffat  
- Percy Schryver  
- Jason Fisher  
- Alex Shumate  
- Deb Miller
]
<br>

Slides at [github.com/kbvernon](https://github.com/kbvernon/saa_2022-western_fremont) [![License: CC BY 4.0](https://img.shields.io/badge/License-CC_BY_4.0-lightgrey.svg)](https://creativecommons.org/licenses/by/4.0/)

]]

.logos[.inner[

## <svg viewBox="0 0 576 512" style="height:1em;position:relative;display:inline-block;top:.1em;fill:#F2B007;" xmlns="http://www.w3.org/2000/svg">  <path d="M568.2 336.3c-13.12-17.81-38.14-21.66-55.93-8.469l-119.7 88.17h-120.6c-8.748 0-15.1-7.25-15.1-15.99c0-8.75 7.25-16 15.1-16h78.25c15.1 0 30.75-10.88 33.37-26.62c3.25-20-12.12-37.38-31.62-37.38H191.1c-26.1 0-53.12 9.25-74.12 26.25l-46.5 37.74L15.1 383.1C7.251 383.1 0 391.3 0 400v95.98C0 504.8 7.251 512 15.1 512h346.1c22.03 0 43.92-7.188 61.7-20.27l135.1-99.52C577.5 379.1 581.3 354.1 568.2 336.3zM279.3 175C271.7 173.9 261.7 170.3 252.9 167.1L248 165.4C235.5 160.1 221.8 167.5 217.4 179.1s2.121 26.2 14.59 30.64l4.655 1.656c8.486 3.061 17.88 6.095 27.39 8.312V232c0 13.25 10.73 24 23.98 24s24-10.75 24-24V221.6c25.27-5.723 42.88-21.85 46.1-45.72c8.688-50.05-38.89-63.66-64.42-70.95L288.4 103.1C262.1 95.64 263.6 92.42 264.3 88.31c1.156-6.766 15.3-10.06 32.21-7.391c4.938 .7813 11.37 2.547 19.65 5.422c12.53 4.281 26.21-2.312 30.52-14.84s-2.309-26.19-14.84-30.53c-7.602-2.627-13.92-4.358-19.82-5.721V24c0-13.25-10.75-24-24-24s-23.98 10.75-23.98 24v10.52C238.8 40.23 221.1 56.25 216.1 80.13C208.4 129.6 256.7 143.8 274.9 149.2l6.498 1.875c31.66 9.062 31.15 11.89 30.34 16.64C310.6 174.5 296.5 177.8 279.3 175z"></path></svg> Funding

.logo-align[
<img src="images/logo-gcsc.png" width="219" class='fl w-60 pt4' style="display: block; margin: auto;" />

<img src="images/nsf.png" width="765" class='fl w-30 pl4' style="display: block; margin: auto;" />
]

]]