Presentation on theme: " Aristotle Living things are “Immutable” Observed anatomical features that seemed to serve no purpose and wondered why they existed. Theorized."— Presentation transcript:
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.
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.
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.
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.
- The father of geology. He studied rocks and fossils and came up with the opposite conclusion to Cuvier.
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.
22 years old, he set sail along the HMS Beagle for a five year voyage.
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.
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.
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 enough evidence for the theory to be seriously considered.
Epigenetics is the study of heritable changes in gene activity which are not caused by changes in the DNA sequence.heritablegeneDNA Changes can occur response to environmental influences http://www.youtube.com/watch?v=kp1bZEUgqVI 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.