Darwin and Lamark

1. Evolution and
Adaptation
Early Theories, Darwin & Natural Selection

2. Jean-Baptiste Lamarck
(France - 1744-1829)
 Based theories on observations of
similarities between ancient fossils
and modern animals, vestigial
structures and passing on of desired
traits by selective breeding
 Proposed than an individual gains
or loses traits during its lifetime
which are then passed on to its
offspring.
 Believed evolution is a constant
process striving toward greater
complexity and perfection.

3. Jean-Baptiste Lamarck
Mechanisms of Change:
 Law of Use and Disuse
 Body parts most frequently used become stronger and more
developed and parts used less are reduced.
 Ex. Penguins wings – Small due to disuse.
 Transmission of Acquired Characteristics
 Qualities acquired during an organisms life time are passed down to
offspring
 Ex. Parents who develop strong muscles will pass strong muscles down
to offspring

4. Jean-Baptiste Lamarck
Important contributions to evolutionary theory:
Organisms change over time
Organisms adapt to their environment
Traits found in parents are passed to offspring
What Lamarck got wrong:
Evolution tends towards perfection & complexity
Organisms are constantly evolving
Acquired characteristics are passed on

5. Pre-Darwinian Ideas About Evolution:
Life has existed on Earth for a long time
Organisms have changed since the dawn of life
Many extinctions have happened since life began
Fossil evidence, embryology and comparative anatomy
show similarities between related species and suggest a
common ancestor.
Mendel’s work with genetics showed how genetic
elements are passed through generations

6. Charles Darwin
(England 1809-1882)
 Naturalist
 1831: Embarked on 5 year
around the world voyage
aboard the HMS Beagle.
 Studied the diversity of life
with a particular focus on the
Galapagos Islands
 Returned home to continue
his research
 1859: Published On the
Origin of Species

7. Voyage of the Beagle

8. Galapagos Islands
Group of Volcanic Islands off the coast of South America
Darwin observed variation between the animals species
on each of the islands and the mainland
Famously, he observed, collected and measured the
many different species of finches found on the islands

9. Darwin’s Finches

10. Darwin’s Finches
Noticed huge variation in beak type and size
Beak type correlated with the type of food source on
each island
Hypothesized the beak type had adapted to the type of
food available in the finch habitat
Led to theory of Natural Selection

12. Alfred Russell Wallace
Darwin wasn’t the only one putting all the pieces
together…
https://www.hhmi.org/biointeractive/origin-species-making-
theory
(30 min)