Charles Darwin
Charles Darwin
1. Who Was Charles Darwin?
Charles Darwin (1809–1882) was an English naturalist and biologist best known for developing the theory of evolution by natural selection. His work transformed modern biology and explained how species change over long periods of time.
2. Darwin’s Journey: How It All Started
The HMS Beagle Voyage (1831–1836)
Darwin traveled around the world on a scientific expedition aboard the ship HMS Beagle.This journey provided him with the observations that led to his theory of evolution.
Key stops included:
South America
Galápagos Islands
Australia
Africa
3. How Darwin Noticed Differences in Species
Darwin saw that finches on different islands had different beaks:
Long, thin beaks → for picking insects
Large, strong beaks → for cracking seeds
Sharp beaks → for eating cactus
Even though they looked related, each group had changed to fit the environment and available food.
This observation helped Darwin see that:
Species are not fixed — they change over time.
4. Artificial Selection
Before understanding natural selection, Darwin studied how humans breed plants and animals.
Examples he studied:
Pigeons — different breeds created by choosing specific traits
Dogs — selected for hunting, herding, size
Farm animals — chosen for milk, strength, wool
Darwin realized:
If humans can create new breeds by selecting traits, then nature can do the same over long time periods.
This was one of the keys that helped him understand evolution.
5. Natural Selection
Darwin proposed that evolution happens because of natural selection, meaning:
1. Variation
Individuals in a species vary (different size, color, speed, beak shape, etc.).
2. Overproduction
More offspring are born than can survive.
3. Competition
Organisms compete for food, shelter, mates, etc.
4. Survival of the Fittest
Those with helpful traits survive better.
5. Reproduction
They pass those helpful traits to their offspring.
6. Over many generations
The species changes — this is evolution.
6. Darwin’s Book
In 1859, Darwin published:
“On the Origin of Species”
This book introduced:
Evolution
Natural selection
Common ancestry
Evidence from fossils, animals, geology
It changed biology forever.
7. Evidence Darwin Used
1. Fossils
Showed organisms changed over time.
2. Geographic distribution
Similar animals on nearby islands with small differences.
3. Comparative anatomy
Similar bone structures in humans, whales, birds → common ancestor.
4. Embryology
Similar embryos in early development.
8. Why Darwin’s Theory Matters
Darwin’s ideas explain:
Why species look different around the world
How new species form
How humans, plants, and animals share common ancestry
The foundation of modern genetics and evolution
His work is the foundation of all modern biology.