Final Project: Geographical Distribution of Hominid Species

Introduction

This document explores various evolutionary trends among hominid species using a dataset of fossil records. The analyses focus on the relationships between physical and environmental variables over geological time.

Cranial Capacity vs. Height

Investigation

This scatter plot investigates the relationship between the cranial capacity and the height of different hominid species to explore how brain size may have correlated with physical stature over time.

library(ggplot2)

# Data preparation and plot
data <- read_csv("C:/Users/ipasq/OneDrive/Desktop/Masters Work - Robert Morris University/Data Visualization/Week 2/Evolution_DataSets.csv")

## Rows: 12000 Columns: 28
## ── Column specification ────────────────────────────────────────────────────────
## Delimiter: ","
## chr (25): Genus_&_Specie, Location, Zone, Current_Country, Habitat, Incisor_...
## dbl  (3): Time, Cranial_Capacity, Height
## 
## ℹ Use `spec()` to retrieve the full column specification for this data.
## ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.

species <- unique(data$`Genus_&_Specie`)
colors <- rainbow(length(species))

par(mar=c(5, 4, 4, 2) + 0.3)  # Adjust plot margins
plot(data$Cranial_Capacity, data$Height, type='n', main="Cranial Capacity vs. Height", xlab="Cranial Capacity (cc)", ylab="Height (cm)")
for (i in seq_along(species)) {
  species_data <- data[data$`Genus_&_Specie` == species[i], ]
  points(species_data$Cranial_Capacity, species_data$Height, pch=19, col=colors[i])
}

Cranial Capacity vs. Height

Reference Plot for Species Colors

Analysis

This scatterplot shows the relationship between cranial capacity (cc) and height (cm) across various hominid species, differentiated by color. Data points span a range of cranial capacities from approximately 200 cc to 1500 cc and heights from about 80 cm to 180 cm, suggesting substantial variability in these traits.

A general trend indicates that larger brain sizes are associated with taller statures, particularly evident within specific species clusters. This pattern could reflect evolutionary adaptations where increases in body size and brain volume are linked, potentially due to environmental, dietary, or social influences.

The plot also highlights outliers and species-specific variability, emphasizing the need for detailed statistical analysis and further data collection to refine these observations and explore underlying evolutionary narratives.

Introduction

This analysis explores the geographical distribution of hominid species using a dataset of fossil records, focusing on cranial capacities to understand potential environmental influences on evolutionary development.

Plotly Graph: Species Distribution by Country with Cranial Capacity

Investigation Statement

This interactive bubble map will display each species’ location based on fossil findings, with bubbles sized according to cranial capacity. This visualization aims to explore the relationship between geographical diversity and cranial capacity among different hominid species.

Analysis

This map features a color-coded, concentric circle heat map overlaid on a world map, highlighting the distribution of cranial capacities among hominid species in a specific region. Concentric circles with varying colors indicate different ranges of cranial capacity, measured in cubic centimeters (cc), with colors transitioning from blue (lowest capacities) to red (highest capacities) as indicated by the adjacent color scale.

This visualization suggests a regional concentration where species with larger cranial capacities are centrally located within the depicted area, diminishing outward to species with smaller capacities.

The map effectively illustrates not just the variance in cranial capacity, but also hints at potential evolutionary or environmental factors influencing these traits in a geographically specific context.

Cranial Capacity Over Geological Time

This graph will use ggplot2 to visualize changes in cranial capacity across different geological periods, potentially illustrating evolutionary trends in brain size.

ggplot2 Time Series Code

library(ggplot2)

# Ensure the 'Time' and 'Cranial_Capacity' are numeric
data$Geological_Time <- as.numeric(data$Time)
data$Cranial_Capacity <- as.numeric(data$Cranial_Capacity)

# Generate colors for each species, ensuring consistency across plots
species <- unique(data$`Genus_&_Specie`)
colors <- setNames(rainbow(length(species)), species)

# Create the ggplot for cranial capacity over geological time with species color differentiation
ggplot(data, aes(x = Geological_Time, y = Cranial_Capacity, color = `Genus_&_Specie`)) +
  geom_point(size = 3, aes(color = `Genus_&_Specie`)) +  # Apply colors based on species
  scale_color_manual(values = colors) +  # Use the manually set colors
  geom_smooth(method = "loess", se = FALSE, color = "red") +  # Adding a LOESS smoothed line for overall trend
  labs(title = "Cranial Capacity Over Geological Time",
       x = "Geological Time (million years ago)",
       y = "Cranial Capacity (cc)") +
  theme_minimal() +
  theme(legend.position = "none")  # Hide the legend to keep the plot clean

## `geom_smooth()` using formula = 'y ~ x'

Cranial Capacity Over Geological Time

Analysis

This plot displays the progression of cranial capacity in cubic centimeters across various hominid species over geological time, measured in millions of years.

The graph uses a vibrant color palette to differentiate between species, depicting a general increase in cranial capacity over time as illustrated by the red trend line. This upward trajectory, especially notable from around 2 to 6 million years ago, suggests significant evolutionary changes possibly linked to factors like environmental adaptations and increased cognitive demands.

The dense clustering of points in later periods indicates a higher diversity of species with larger brain sizes, aligning with known patterns of hominid evolution towards modern humans.

Reference Guide for Species in the Cranial Capacity Over Geological Time Graph

For the second part of your request, to create a reference guide for the species in the “Cranial Capacity Over Geological Time” graph, here’s how you can do it:

# Generate a color reference plot for the species
par(mar=c(0, 0, 0, 0))  # Remove all margins

plot(1, type='n', xlim=c(1, 3), ylim=c(1, length(species)), xaxt='n', yaxt='n', xlab='', ylab='')

colors <- rainbow(length(species))  # Re-generate colors if not stored from previous plot

# Draw color points and labels for each species
for (i in seq_along(species)) {
  points(1, i, col=colors[i], pch=19, cex=2)  # Draw the color point
  text(1.5, i, species[i], cex=0.8, adj=0)  # Place text next to the color point
}

Reference Guide for Species

Plotly Graph: Cranial Capacity Distribution by Habitat

This visualization will enable us to see if certain habitats are associated with larger or smaller cranial capacities, which could suggest environmental adaptations.

library(plotly)
library(readr)
library(dplyr)  # Load dplyr for data manipulation

# Load the dataset
data <- read_csv("C:/Users/ipasq/OneDrive/Desktop/Masters Work - Robert Morris University/Data Visualization/Week 2/Evolution_DataSets.csv")

# Convert 'Habitat' to a factor and ensure 'Cranial_Capacity' is numeric
data$Habitat <- as.factor(data$Habitat)
data$Cranial_Capacity <- as.numeric(data$Cranial_Capacity)

# Generate colors for each species
species <- unique(data$`Genus_&_Specie`)
colors <- setNames(rainbow(length(species)), species)

# Calculate the average cranial capacity by habitat and species
habitat_capacity_species <- data %>%
  group_by(Habitat, `Genus_&_Specie`) %>%
  summarise(Average_Cranial_Capacity = mean(Cranial_Capacity, na.rm = TRUE), .groups = 'drop')

# Create the Plotly bar graph
fig <- plot_ly(habitat_capacity_species, x = ~Habitat, y = ~Average_Cranial_Capacity, 
               type = 'bar', color = ~`Genus_&_Specie`, colors = colors,
               marker = list(line = list(color = 'rgba(255, 255, 255, 1.0)', width = 1)))
fig <- fig %>% layout(title = 'Average Cranial Capacity by Habitat and Species',
                      xaxis = list(title = 'Habitat'),
                      yaxis = list(title = 'Average Cranial Capacity (cc)'),
                      barmode = 'stack')

fig

Analysis

This chart uses a stacked bar graph to depict the cranial capacities of various hominid species across different habitats. Each bar represents a specific habitat type, such as forests, savannahs, and jungles, with colors within the bars indicating individual species.

Notably, habitats like savannahs and mixed forests display higher and more diverse cranial capacities, suggesting these environments may have fostered or required more complex cognitive abilities. The color-coded breakdown allows for easy identification of species contributions to cranial capacity within each habitat, highlighting evolutionary trends such as larger brain sizes in open environments like savannahs, potentially linked to the demands of a more complex social structure or diverse survival strategies.