Charles Darwin’s scientific career began humbly. In 1831, and in the teeth of a gale, the HMS Beagle, a British warship, left Devonport, England, for an expedition to map the South American coastline and to carry out chronometer surveys all over the globe. Darwin embarked as a naturalist, although he had no formal training and had recently left Cambridge University because he grew disinterested in his studies. But he was a very sharp observer of the natural world, and he lived at a time when a revolution in thinking was going on. Scientists were feverishly re-examining age-old questions, such as how old was the Earth? How did various features of the planet form? How old and diverse was Earth’s animal life?
Darwin was also fortunate that the Beagle took him to the Galapagos Islands, where he observed various animals and birds that had evolved in an isolated environment. His observations led him to his famous theory of natural selection. According to Darwin’s theory, variations within species occur randomly and the survival or extinction of an organism is determined by its ability to adapt to its environment. (Another young naturalist of the time, Alfred Russell Wallace, had independently come to similar conclusions about evolution and natural selection.)
Darwin also made important observations about the geology of the islands and coastlines he visited. He proposed a theory about the formation of atolls. Atolls are coral reefs that form small islands that enclose a lagoon. They are found mostly in the Pacific. An example is Bikini Atoll located northwest of Hawaii. Darwin proposed that the foundation for the atoll was a volcano that was sinking because of its weight. As the volcano sinks, coral reefs that rim the volcano grow upwards. As long as the rate at which corals grow kept up with how fast the island was sinking, then small coral islands would remain in a ring around the now sunken volcano.
Perhaps our first association with the word "Galapagos" is the name "Darwin." Darwin's visit to the Galapagos Islands had a resounding impact on the formation of his Theory of Natural Selection.
A rather unmotivated and failing medical scholar, Charles Darwin accompanied Captain Robert Fitzroy as a travel companion and naturalist on the HMS Beagle. His book the Voyage of the Beagle is an account of his worldwide journey.
When setting off from England in 1831 for a five-year voyage, Darwin had little ambitions for groundbreaking scientific research. After surveying the coasts of South America, the ship stopped over in the Galapagos Islands.
During his visit to the islands, Darwin noted that the unique creatures were similar from island to island, but perfectly adapted to their environments which led him to ponder the origin of the islands' inhabitants.
Among those that struck Darwin so greatly were the finches that are now named in his honor. Darwin would later base some of his thought from the supposing that these finches were all descendents of the same lineage.
Years later in 1859, Darwin finally consolidated all of his observations into his famous book On The Origin of Species, drastically and controversially altering the scientific view on the biological origins of life.
Follow in Darwin’s Footsteps
What's that big red pouch?
The Frigate bird of the Galápagos Islands. This bird can be found throughout the tropical Atlantic down to the Galápagos Islands and Ecuador, but not in Europe or South America, so Darwin may never have come across one until he landed on the Galápagos. Such a unique creature was bound to make a naturalist such as Darwin wonder why. Why do they look the way they do? What's that big red pouch? What are the advantages?
The Englishman Charles Darwin is one of the most famous scientists who ever lived. His place in the history of science is well deserved. Darwin’s theory of evolution represents a giant leap in human understanding. It explains and unifies all of biology.
An overview of evolution can be seen at //www.youtube.com/watch?v=GcjgWov7mTM(17:39).
As you view Introduction to Evolution and Natural Selection,focus on the following concepts:
- the meaning of "evolution,"
- the relationship between evolution and natural selection,
- the relationship between natural selection and variation,
- the evolution of the peppered moth.
Darwin’s theory of evolution actually contains two major ideas:
- One idea is that evolution occurs. In other words, organisms change over time. Life on Earth has changed as descendants diverged from common ancestors in the past.
- The other idea is that evolution occurs by natural selection. Natural selection is the process that results in living things with beneficial traits producing more offspring than others. This results in changes in the traits of living things over time.
In Darwin’s day, most people believed that all species were created at the same time and remained unchanged thereafter. They also believed that Earth was only about 6,000 years old. Therefore, Darwin’s ideas revolutionized biology. How did Darwin come up with these important ideas? It all started when he went on a voyage.
In 1831, when Darwin was just 22 years old, he set sail on a scientific expedition on a ship called the HMS Beagle. He was the naturalist on the voyage. As a naturalist, it was his job to observe and collect specimens of plants, animals, rocks, and fossils wherever the expedition went ashore. The route the ship took and the stops they made are shown in the Figure below. You can learn more about Darwin’s voyage at this link:www.aboutdarwin.com/voyage/voyage03.html.
Voyage of the Beagle. This map shows the route of Darwin’s 5-year voyage on the HMS Beagle. Each stop along the way is labeled. Darwin and the others on board eventually circled the globe.
Darwin was fascinated by nature, so he loved his job on the Beagle. He spent more than 3 years of the 5-year trip exploring nature on distant continents and islands. While he was away, a former teacher published Darwin’s accounts of his observations. By the time Darwin finally returned to England, he had become famous as a naturalist.
One of the most productive marine food webs on the planet is located on the Farallon Islands, just 28 miles off the San Francisco, California coast. These islands also host the largest seabird breeding colony in the continental United States, with over 300,000 breeding seabirds. The islands are known as the Galapagos of California. Why? Find out at //science.kqed.org/quest/video/...ias-galapagos/ .
- Darwin’s theory of evolution by natural selection states that living things with beneficial traits produce more offspring than others do. This produces changes in the traits of living things over time.
- During his voyage on the Beagle, Darwin made many observations that helped him develop his theory of evolution.
- Darwin's most important observations were made on the Galápagos Islands.
Use this resource to answer the questions that follow.
- Beagle Voyage at //www.nhm.ac.uk/nature-online/s...beagle-voyage/.
- Describe Darwin's role on the Beagle.
- Describe what Darwin encountered in the following places:
- Salvador, Brazil,
- Punta Alta, Argentina,
- Chiloe Island, Chile,
- Galapagos Islands,
- Sydney, Australia.
- State the two main ideas in Darwin's theory.
- What was Darwin's role on the Beagle?
- Describe two observations Darwin made on his voyage on the Beagle that helped him develop his theory of evolution.
- Why did Darwin’s observations of Galápagos tortoises cause him to wonder how species originate?
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