BIOL 112 1st Edition Lecture 4 Outline of Last Lecture I The Scientific Method II Evolution A Observations Significant to Evolution III Fossils IV Macroevolution of Horses V How Old are Fossils A Relative Dating B Absolute Dating VI Dating Math A Calculating Age VII Carbon Dating VIII Geological Dating IX Dating Observations Outline of Current Lecture X What Do We See in Fossils XI Anatomical Evidence XII Interpretation of Homology XIII Vestigial Organs XIV Embryology A What does it mean XV Molecular Homologies These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute XVI Interpretations A Theories of Evolution XVII St Augustine of Hippo A Problems with Augustine Model XVIII The Enlightenment XIX Jean Baptiste Lamarck A Examples of Lamarck s Model B Tests of Lamarck s Model XX Charles Darwin 1809 1882 Current Lecture I What Do We See in Fossils Few living organisms also seen in fossil record If they are most such fossils are quite recent not ancient The older the rocks fossils the less they resemble modern life forms Many extinct species in the fossil record most fossils represent species not seen today Fossils provide a record of evolution appearances disappearances and changes of organisms over long periods of time on the planet II Anatomical Evidence Homology fundamental identity of structure organization of structures in living creatures similar in spite of possible differences in function Example vertebrate forelimb Details highly modified but same fundamental pattern of arrangement of bones muscles nerves blood vessels etc among all vertebrate animals Distinguish from analogy similar function of structures on two different creatures but different organizations Example wing of bird and wing of insect Both flight organs but different structures organization Concept of homology developed in 18th Century before concept of evolution III Interpretation of Homology Theory is that all vertebrates descended from an original ancestor with fundamental forelimb bone arrangement Differences in details proportions sizes functions developed over time but all vertebrate forelimbs retain same common fundamental underlying pattern of organization Concept supported by detailed fossil evidence from early vertebrate evolution Concept further reinforced by molecular evidence sets of homologous genes used to develop homologous structures in different organisms IV Vestigial Organs Features in an organism that exist but to what purpose Related to homology Snakes have what looks like rudimentary pelvis and legs near anus Whales retain rudimentary pelvis and legs Fold of skin in inner corner of human eye vestigial nictating membrane haws of cats or dog Ear wiggling muscles in some humans homologous to muscles in animal ears cat or horse Appear to be remains of organs that were more developed in past history of species or its ancestors but no longer developed or used V Embryology Primitive ancestral structures seen in embryos that are not present in later developmental stages Phylotype Stage Fish embryos pharyngeal pouches become components of the gills Mammal bird reptile embryos pouches develop into jaw bones ear bones etc Human embryos with tails lost at later stages Embryos retain primitive developmental features regardless of later fates uses of features This is not the same phenomenon as vestigial organs those apply to adult form only A What does it mean Developmental homologies common animal embryonic developmental sequences for a diverse collection of species and adult organs Retention of basic developmental events developmental pathways regardless of later modifications von Baer s Law 18th century Suggests that embryos with common developmental patterns have a common ancestry similarities in time VI Molecular Homologies Organisms have homologies among their gene sequences and organization as well as in their anatomy and development All organisms use essentially the same genetic code Similar closely related organisms use extremely similar homologous genes expressed in similar patters of time and space to produce homologous structures More distantly related organisms have fewer molecular sequence similarities than closely related groups Diverse organisms had a common ancestor with particular set of genes sequences VII Interpretations All studies fossils anatomical homologies embryology molecular sequences indicate that evolution has occurred Evolution is a fact living things have changed and do change over time Critical question for interpretation how does evolution occur What is mechanism Theories of Evolution Attempts to explain observed facts Evaluate these models by scientific standard techniques A Theories of Evolution Must meet same evolution criteria as any other theory explain and predict Many have been proposed and considered some discarded some still being evaluated Homeobox Homology of arrangement of patterning genes VIII St Augustine of Hippo Philosopher and theologian Bishop of Hippo Carthage N Africa 4th Century CE Church father write Confessions and City of God Application of pagan philosophy logic to Christian theology Rationalization of Christian theology Proposed that God created universe at some remote time in a form unlike today but with the potential to develop eventually to present day conditions Required a very long time unspecified Programmed universe evolution of humans and other present species inevitable A Problems with Augustine Model God is central component of theory supernatural entity Science unable to analyze supernatural metaphysical phenomena Theory thus becomes unfalsifiable Basic trouble with all such creationist models IX The Enlightenment Formalization of scientific method in 16th and 17th Centuries Expansion of scientific knowledge through 18th and 19th Centuries Fossil record analyzed and understood embryology and anatomy exciting new discoveries Mass of data waiting for interpretation X Jean Baptiste Lamarck Naturalist geologist biologist anthropologist in late 18th Century First rigorously stated testable theory of evolution Recognized that evolution had occurred and that new species of plants and animals arose from older ancestral species Theory published in 1809 Mechanism depended upon two components Variations in organisms arise from use or disuse of organs Later postulated that a need for an organ could produce the beginnings of that organ in progeny