The Natural World of Lewis and Clark
A Scientific Journey into the American West
How two military captains became America's first pioneering naturalists
Introduction: Jefferson's Scientific Vision
When Meriwether Lewis and William Clark embarked on their legendary expedition across the American West from 1804 to 1806, they were undertaking more than a mere journey of geographic discovery. Commissioned by President Thomas Jefferson—a renowned Enlightenment thinker and avid naturalist—the Corps of Discovery was effectively one of young America's first major scientific expeditions 2 4 .
While their primary mission was to find a practical water route to the Pacific Ocean and establish American sovereignty, Jefferson provided them with detailed scientific instructions: to observe, collect, and document the landscape, climate, and countless "objects worthy of notice" they would encounter 4 . What resulted was an unprecedented documentation of North America's natural wealth that would forever change science's understanding of the continent and cement Lewis and Clark's legacy as America's pioneering naturalists 4 .
The Expedition's Scientific Mission
Thomas Jefferson was exceptionally qualified to plan a scientific expedition. He had spent years studying geography and was knowledgeable about scientific practices and instruments 2 . His instructions to Lewis were remarkably detailed and comprehensive, reflecting the scientific spirit of the Enlightenment era 4 .
Jefferson directed Lewis to document everything from "the animals of the country generally, & especially those not known in the U.S." to the seasonal appearances of birds, reptiles, and insects 4 . He was particularly interested in understanding the continent's climate and instructed the captains to record weather observations throughout their journey 4 . The president also emphasized the importance of documenting Native American tribes, their cultures, and their relationships with the natural world 4 .
Discovering New Species: Lewis as Naturalist
As the Corps of Discovery traveled through lands virtually unknown to European Americans, Lewis proved remarkably adept at identifying and documenting new species. His careful observations and collections would introduce hundreds of previously unknown plants and animals to science.
Botanical Discoveries
Lewis served as the expedition's principal botanist, while Clark focused more on cartography and zoology 1 . Together, they documented and collected specimens of 178 plants new to science 1 .
Bitterroot
Lewisia redivivaDouglas Fir
Pseudotsuga menziesiiPrairie Sagebrush
Artemisia tridentataPonderosa Pine
Pinus ponderosaZoological Discoveries
The expedition documented 122 animals previously unknown to science, providing the first scientific descriptions of many iconic western species 1 .
Grizzly Bear
Ursus arctos horribilisPronghorn Antelope
Antilocapra americanaPrairie Dog
Cynomys ludovicianusCoyote
First detailed descriptionSelected Species First Documented by Lewis and Clark
| Species | Common Name | Date First Documented | Significance |
|---|---|---|---|
| Arctostaphylos uva-ursi | Bearberry | April 8, 1805 | Documented medicinal use by Native Americans 5 |
| Gaultheria shallon | Salal | February 6, 1806 | Evergreen shrub with edible berries 5 |
| Ursus arctos horribilis | Grizzly Bear | May 5, 1805 | First scientific description of this formidable predator 1 |
| Antilocapra americana | Pronghorn Antelope | September 6, 1804 | Noted as "wild goat" with remarkable speed 1 |
| Cynomys ludovicianus | Black-tailed Prairie Dog | September 7, 1804 | Sent live specimen to President Jefferson 1 |
Grizzly Bear
Lewis provided the first detailed description of this massive predator, noting its strength and ferocity 1
Pronghorn Antelope
Often called "prongbuck" by Lewis, who marveled at its speed 1
Prairie Dog
Lewis called them "barking squirrels" and sent live specimens back to Jefferson 1
Bitterroot
A beautiful pink flowering plant whose roots were a food source for Native Americans 1
The Science of Survival: Living Off the Land
The Corps of Discovery's scientific observations were not merely academic—they were often essential to their survival. The expedition demonstrated remarkable adaptability in learning to utilize the resources they encountered, effectively practicing what we would now call In-Situ Resource Utilization (ISRU) 6 .
Hunting and Foraging
The expedition consumed approximately one buffalo, two elk, or four deer per day, supplemented with roots, berries, and fish 1 .
When they reached the Columbia River region, they adopted new food sources, including wapato root (an aquatic plant resembling a small potato) and eulachon (candlefish), which were staples for local Native American tribes . At the Pacific coast, they learned to preserve salmon and make salt from seawater 3 .
Environmental Adaptation
As they traveled through dramatically different ecosystems—from the grasslands of the Great Plains to the rainforests of the Pacific Northwest—the Corps had to continuously adapt their methods and equipment.
They built dugout canoes when their keelboat became impractical, crafted leather clothing and moccasins when their uniforms wore out, and learned to use local materials for shelter and medicine 3 9 .
The Scientist's Toolkit: Instruments of Discovery
The Lewis and Clark Expedition represented one of the young republic's first significant applications of scientific instrumentation 2 . The captains were equipped with an array of tools and instruments essential for documenting their journey and making scientific observations.
Scientific Instruments Used by Lewis and Clark
| Instrument | Primary Function | Specific Use | Training Received |
|---|---|---|---|
| Sextant | Measuring lunar distances and altitudes | Determining longitude through lunar observations 2 | Trained by Andrew Ellicott and Robert Patterson 2 |
| Octant | Measuring altitudes of sun and stars | Determining latitude 2 | Practiced under Major Ellicott's supervision 2 |
| Artificial Horizon | Creating a reference line for celestial measurements | Used when natural horizon was unavailable due to weather or terrain 2 | Learned to use both mercury and water-based versions 2 |
| Chronometer | Keeping precise time | Essential for calculating longitude 2 | Limited training; instrument ultimately insufficient for precise longitude 2 |
| Thermometers | Recording temperature | Documenting climate conditions as instructed by Jefferson 3 | Part of Jefferson's climate observation directive 4 |
| Portable Inkwell | Preserving written records | Maintaining journals in all weather conditions 3 | Recognized as perhaps their most important tool 3 |
Legacy and Influence on Science
For nearly a century after the expedition, the full scope of Lewis and Clark's contributions to natural science remained underpublished and something of a disappointment to scientists expecting more comprehensive documentation 4 . However, when their journals were finally published in their entirety, they were recognized as classics of American scientific exploration 5 .
Biological Documentation
Their specimens and descriptions formed the foundation for understanding western North American flora and fauna 5
Ethnographic Record
Their detailed accounts of Native American tribes provide an invaluable snapshot of cultures that would soon be dramatically transformed 4
Geographic Knowledge
Their maps, while imperfect, opened the West to further exploration and settlement 4
Ecological Baseline
Their observations created a record of pre-settlement conditions that modern ecologists use to measure environmental change 7
Conclusion: An Enduring Scientific Legacy
The Lewis and Clark Expedition represents far more than a dramatic adventure story—it stands as a landmark achievement in the history of American science. Through careful observation, meticulous documentation, and remarkable adaptability, Meriwether Lewis and William Clark created an unprecedented record of the American West's natural wealth at the threshold of Euro-American settlement.
Their work embodied the Enlightenment ideal of systematic observation and classification, while also demonstrating the practical application of scientific knowledge in challenging environments. As we continue to study environmental change and seek to understand North America's ecological history, the detailed journals of these "pioneering naturalists" remain an invaluable resource, preserving a lost world for future generations of scientists and nature enthusiasts alike 4 .