Evolution Lesson 2 – Evolution of an Idea

EvolutionLesson 2 – Evolution of an Idea

Aristotle

Living things are “Immutable”

Buffon (1707-1788) Observed anatomical

features that seemed to serve no purpose and wondered why they existed.

Theorized that this was evidence that species have changed over time.

Carl Linnaeus (1707-1778) – Developed classification system that highlighted similarities between organisms.

Erasmus Darwin (1731-1802) – Believed organisms change over time and the earth was millions of years old. All life originated

from a single source. Did not propose a mechanism for this.

Chevalier de Lamarck (1744-1829) One of the first scientists to propose a mechanism for evolution.

Lamrack’s First Principle: Use and disuse

He believed that structures an individual used became larger and stronger, while structures that were not used became smaller and weaker.

Lamrack’s Second Principle: The Inheritance of Acquired Characteristics

He believed that individuals could pass on to their offspring characteristics they had acquired during their lives.

Lamarck’s Contributions

All species evolve over time A species evolves in response to its

environment and becomes better adapted to that environment

Changes are passed on from generation to generation

Georges Cuvier (1769-1832): a famous paleontologist who conducted the first

detailed studies of fossils. He noted the following: Fossils of very simple organisms are found in all

depths of fossil deposits Fossils of more complex organisms are found

only at shallower depths, in younger rock Fossils in the shallower depths are more likely to

resemble living species Rock layers contain fossils of many species that do not occur in layers above or below them.

Theory of Catatrophism (Cuvier) the theory of catastrophism which states that the patterns of fossils could be

accounted for by a series of global catastrophes (such as floods) that wiped out most species on Earth. These wiped out species were then replaced with a newly created set of species.

Charles Lyell (1797-1875): - The father of geology. He studied

rocks and fossils and came up with the opposite conclusion to Cuvier.

Charles Lyell

He proposed the theory of uniformitarianism. Earth has been changed by the same processes in

the past that are occurring in the present Geological change is slow and gradual rather than

fast and catastrophic Natural laws that influence these changes are

constant and eternal, and they operated in the past with the same intensity as they do today.

Lyell’s theories directly challenged the belief in a very young Earth. If he was right, Earth was extremely old and life had had a very long time to undergo evolutionary change.

Charles Darwin (1809-1882): 22 years old, he set sail along the

HMS Beagle for a five year voyage.

Darwin

During his travels, he visited the Galapagos Islands where he made a valuable observation. He noted that the flora and fauna on the Galapagos Islands resembled to the ones on continental South America even though they had complete different habitats.

Darwin

He also noted that there were no amphibians or large mammals on the island, indicating that only species that could arrive by air or water lived in the Galapagos.

It seemed that the islands had been populated by species that arrived from elsewhere; however, most of these species only resembled species in the mainland. This was the beginning of the theory of evolution.

Darwin’s Finches

Why’s Darwin a Big Deal? Although Darwin was not the first to

propose the theory of evolution he (along with Alfred Wallace) proposed natural selection as the mechanism of evolution. His years of study, observations and

writing gave enoughevidence for the theory to be seriously considered.

http://www.youtube.com/watch?v=vfmOaAz371M

Current Interest in Lamarckism Epigenetics is the study of heritable changes in 

gene activity which are not caused by changes in the DNA sequence.

Changes can occur response to environmental

influences

http://www.youtube.com/watch?v=kp1bZEUgqVI

ARTICLE: http://discovermagazine.com/2013/may/13-grandmas-experiences-leave-epigenetic-mark-on-your-genes

Examples - Diet in Humans Pregnant Woman who experience

starvation have abnormally small babies.

Their children (even if dietary needs are meet) have small Babies.

May be some epigenetic factors in obesity.