Origin of life through chemical evolution Steps of chemical evolution Chapter 22 Human Evolution o Gases of the primitive atmosphere formed small organic molecules o Molecules combined to form macromolecules o Only RNA might have been needed to form the first cells this is supported by the fact that RNA can act as enzymes called ribozymes RNA first hypothesis o Protocells made of proteins and lipids could metabolize by using oceanic organic molecules but could not reproduce o The true cell can reproduce and has DNA as its genetic material Biological evoution Biological evolution change in population or species over time 2 important points o Living things descended from a common ancestor and thus have common chemistry o Livings things adapt to their environment Adaptation a characteristic that enables an organism to survive and reproduce in its environment Natural selection is a theory by Charles Darwin that describes a mechanism by which a species becomes adapted to its environment Charles Darwin Father of evolution 3 vital elements o Variation there must be physical variations that can be passed from generation to generation o Competition there must be competition for limited resources food mates shelter and those better adapted will survive and reproduce o Adaptation subsequent generations will see an increase in individuals with the same adaptations as long as the environment remains unchanged Evidence to support the theory of evolution by common descent 1 Fossil record 2 Biogeographical evidence 3 Anatomical evidence 4 Biochemical evidence Primates Characteristics o Opposable thumb o Stereoscopic vision depth perception o Well developed brain o Reduced number of offspring usually a single birth with an increased period of parental care o Emphasis on learned behavior and social interactions 2 major groups suborders o Prosimians includes lemurs tarsiers and lorises Comparing the human skeleton to the chimpanzee o Anthropoids includes monkeys apes and humans Evolution of primates Evolution of hominins Hominins All species of the genus Homo and their close relatives Characteristics o Bipedal o Flatter face with more pronounced chin o Brain size is 600 cm3 or greater o Evidence of tool use o Jaw and teeth resemble humans o Early Homo representatives Homo habilis Homo erectus o Later Homo representatives Neanderthals Cro Magnons Modern humans Homo Sapiens Replacement model or out of Africa hypothesis is the most widely accepted hypothesis o It proposes that modern humans evolved from archaic humans only in Africa o Then modern humans migrated to Asia and Europe where they replaced the archaic species Human Variations Human variations between populations are called ethnicities Variations evolved as adaptation to local environments o Skin color ranges from dark to light o Body shape Bergmann s rule colder regions mean bulkier build more muscle mass for more heat High in a mountain low oxygen Content higher levels of hemoglobin Allen s rule colder regions mean shorter limbs digits and ears Chapter 23 Global Ecology Human Interferences The nature of ecosystems Biosphere the regions of the Earth s waters crust and atmosphere inhabited by living organisms Ecosystem a place where organisms interact with each other and their environment o Terrestrial several distinct types based on temperature and waterfall o Aquatic freshwater and marine Hypothesis for modern human evolution
View Full Document
Unlocking...