History of Evolutionary Thought 1707-1788 - Buffon: Frenchman, said that living things do change over time due to influences from the environment; disputed age of the Earth as older than 6,000 years; hid his views to avoid public criticism. 1731-1802 - Erasmus Darwin: Charles Darwin's grandfather; closet evolutionist; not sure what caused evolution, but thought it was happening (even to humans); suggested the Earth was millions of years old.

History of Evolutionary Thought 1785-James Hutton: proposed the idea of uniformitarianism - Earth is shaped by the same geological forces that have taken place over very long periods of time; estimated Earth to be millions of years old. 1798-Thomas Malthus: noticed that babies were being born faster than people were dying. He predicted that if the human population continued to grow at this rate, there would be insufficient living space and food for everyone.

History of Evolutionary Thought :1809-Jean-Baptiste Lamarck made a hypothesis of the inheritance of acquired traits (which we now know is incorrect). He was the first to propose a mechanism that explains how organisms change over time (others before were scared). Main ideas: if organisms use particular organs/parts often, they would become better or more complex, and these traits could be passed down to their offspring. example: Mrs. Ellis, the bodybuilder NOT Genetic -trait must be in DNA

History of Evolutionary Thought cont'd. 1815 - George Cuvier: discredited Larmarck's theory of inheritance of acquired characteristics; documented extinctions; theory of catastrophism - violent, sudden natural catastrophies the kill life and be replaced by remaining life 1820s-1830s - Charles Lyell: agreed with Hutton about uniformitarianism due to gradual changes in species seen in the fossil record; discredited Cuvier (but what about mass extinctions?)

History of Evolutionary Thought cont'd. 1831 - Charles Darwin: went on a 5-year trip around the world (Voyage of the Beagle), where he developed his theory of evolution by natural selection. Darwin used scientific evidence to propose this theory about how life changes over time. He used Malthus' idea of limited resources for all populations = Survival of the Fittest. 1858 - Alfred Wallace: worked with Darwin; also found that evolution occurred by natural selection based on his studies of the distribution of plants and animals. 1859 - Darwin published his work on natural selection in the book On the Origin of Species after reading essay from Wallace (oh, the DRAMA!). 1859 (1838) - Boucher de Perthes: found tools made by Neanderthals, but his idea that human-like organisms existed long ago was rejected in 1838 until Darwin's publication gave it evidence

Darwin’s Theory of Evolution Evolution- is the process by which modern organisms have descended from ancient organisms due to gradual changes over time Natural Selection or Survival of the Fittest Darwin proposed that fitness (ability of an individual to survive and reproduce) is a result of adaptations (characteristics that increase a chance of survival in their specific environment) Generation after generation, individuals compete to survive and produce offspring chance mutations (changes in DNA) produce modifications (changes) in organisms Individuals with low levels of fitness die or leave few offspring Individuals with high levels of fitness survive and reproduce successfully and leave many offspring, increasing the number of “fit” individuals

Darwin’s Theory of Natural Selection 5 Components of NATURAL SELECTION Individual organisms differ, and some of this variation is inheritable. Organisms produce more offspring than can survive They compete for limited resources Individuals best suited to their environment survive and reproduce most successfully passing their heritable traits to their offspring (Other individuals die or leave fewer offspring). Species alive today are descended with modification from ancestral species that lived in the distant past.

Natural Selection results in change Over time natural selection results in change in the inherited characteristics of a population. These changes increase a species’ fitness in its environment. It can not be seen directly; it can be observed as changes in a population over many successive generations

More “fit” genes The frequency of genes that improve the chance for survival and reproduction will increase in a population’s gene pool (become more common) Webbed feet on aquatic mammals Sharp tearing beak on a hawk Coloring or markings that camouflages an animal Resistance of weeds to herbicides

Less“fit” genes The frequency of genes that reduce the chance for survival and reproduction will decrease in a population’s gene pool (become less common) Short legs on an animal that needs to run Health problems in animals Plant susceptibility to chemicals Poor eye sight

Examples of Evolution due to Natural Selection Peppered Moths During the 19th century in England, sooty smoke killed the lichen on trees and darkened the bark The dark colored ones were harder to spot by birds that ate them. So, they lived long enough to reproduce Over generations the darker moths became more common 1950’s air pollution was reduced, the lichen grew back, making the trees lighter in color Now, natural selection favors the lighter moths and over generations the lighter moths are more common

Examples of Evolution due to Natural Selection MRSA (methicillin-resistant Staphylococcus aureus) A population of bacteria exists with variations due to random mutation When the population of bacteria is treated with an antibiotic, the bacteria that contain the beneficial mutation, that allows them to be resistant to the antibiotic, survive while the others die. The resistant bacteria reproduce quickly and produce many more bacteria that are not killed by the antibiotic

To help with Natural Selection Remember “ VIST” if you are stuck… Variation: All life forms vary genetically within a population. It is this genetic variation upon which selection works. I Inheritance: Genetic traits are inherited from parents and are passed on to offspring. S Selection: Organisms with traits that are favorable to their survival get to live and pass on their genes to the next generation. T Time: Evolution takes time. Evolution can happen in a few generations, but major change, such as speciation, often takes long periods of time.