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Fossil Evidence Fossils- any traces of dead organisms dinosaur bones insects trapped in tree sap leaf impressions footprints Fossil Evidence Transitional species- species that have been found in the fossil record that are intermediates between two other species in the evolutionary process. Radiometric dating- a dating technique that measures amount of radioactive material in a rock or fossil. Relative dating- a dating technique that estimates the date of a fossil by relating it to the age of the layers of rock around it. Fossil Evidence To fossilize an organism must be buried by sediment. In swamps, mud, tar pits, or the ocean bottom. Hard stuff fossilizes (bones, nails). Radiometric and relative dating are used to find out how old the fossil is. Relative Dating Radiometric Dating Fossil Evidence Fossils show: Life has been around for millions of years Transitional species link older to newer species Darwin proposed the idea of transitional species, though he had no evidence Today we have evidence: • Archaeopteryx • Whales Fossil Evidence-Archaeopteryx WINGS BEAK Fossil Evidence Whales--60 million years of evolution Descended from 4-legged wolf-like animals that were also ancestors to cows and horses Fossil evidence shows slow loss of legs Pelvis still remains with no rear legs Fossil Evidence-Whales Whale Video Earth is estimated to be about 4.6 billion years old. Atmosphere was harsh. Very Hot. Lots of water vapor Volcanoes NO BREATHABLE OXYGEN GAS! CO2, ammonia, methane present Origin of Life Stromatolites Scientists had hard time finding evidence of early life. 45 years ago we found out why…. Most ancient life was microscopic=microfossils in stromatolites. 1st organisms to evolve were prokaryotes Oldest microfossil3.5 billion years old Cyanobacteria fossil about 1,000,000,000 (1 billion) years old found in stromatolites Origin of Life’s Chemicals Miller-Urey Hypothesis: Can organic compounds form in early Earth conditions? Experiment recreated atmosphere of early Earth Results: building blocks of life were formed. Amino acids (proteins) Nucleotides (DNA, RNA) Lipids Carbohydrates Self Assembly Some molecules can spontaneously form into droplets Solution with lipids and proteins will self assemble into a lipid bilayer like a cell membrane First cell membrane and beginning of prokaryotic life took 1 billion years. What else is needed for life? 1st genetic material- RNA Earth’s early surface was inhospitable due to immense UV radiation Deep sea vents may have provided sheltered location for life. Oldest living prokaryotes found there today… RNA can form under conditions similar to deep sea vents Road to Modern Organisms 1st life was bacteria unicellular prokaryotes Cyanobacteria- photosynthetic blue-green prokaryotes later changed Earth’s atmospherereleased O2! 2nd was unicellular eukaryotes Endosymbiotic Theory 3rd was multicellular organisms Classification/Evolution 6 Kingdoms Classifying Living Things Carl Linnaeus was a scientist who developed a classification system for living things. Wrote book Systema Naturae in 1735 to reveal his classification system. How biologists classify 1. Comparing morphology (physical traits) 2. Looking at genetic similarities & differences 3. Biochemical make-ups 4. Behavioral similarities Origin of Life Video Cladograms Cladogram- a branching diagram that shows evolutionary relationships. We use taxonomy – the science of classifying living things, to help us determine the cladogram. Scientific Naming Binomial nomenclature- unique 2-word naming system used by scientists. 1st word is the genus, 2nd is the species. Genus- group of organisms that share similar characteristics. Panthera leo-lion Panthera pardus-leopard Species- group of organisms that can successfully breed within their group, but not others. How to write a scientific name Genus is always capitalized Species is always lower case The whole name is underlined if written or italicized if typed. Example: Homo sapiens Examples Homo sapiens: Homo = genus sapiens = species Common name = humans Quercus rubra– Quercus = genus rubra = species Common name = red oak Scientific names are in Latin b/c scholars in the Middle Ages communicated using it! 6 Kingdoms There are six kingdoms all living things are classified into: Animals Plants Fungi Protists Eubacteria Archeabacteria Classification Scientists have determined seven levels of classification: Kingdom = Kings Phylum = Pass Class = Classes Order = to Order Family = Families Genus = and their Good Species = Sons around Classification of Modern Humans Kingdom = Animalia Phylum = Chordata Class = Mammalia Order = Primates Family = Hominidae Genus = Homo Species = sapiens Evolution of Primates Primate- mammal with 5 flexible fingers Earliest dwelled in trees-arboreal Needed special adaptations for this: – Opposable thumb….Why? – Binocular vision- eyes in front of head in which field of vision of eyes overlap—depth perception….Why? – Rotating Shoulders Evolution of Humans Vocab: – Bipedal- walk upright on two legs – Hominid- bipedal primates such as humans and their closest fossil relatives Hominids Hominids are the ONLY bipedal primates: – Locking knee joints – Spine enters skull at bottom of head – Femurs (thigh bone) tapers in – Big toe in line with others Laetoli Footprints Hominid vs. chimpanzee Chimps most closely related primate to humans—95% similarity in the sequence of our genes! Human’s jaw arc shaped with smaller canines; chimps’ are U shaped with larger canines and larger gaps. Hominid vs. chimpanzee Hominid spine S– chimps’ is C shaped Hominid pelvis is bowl-shaped, chimps’ long Hominid thigh bones taper in—chimps’ out Human Evolution Video Clip Early Hominids Genus Australopithecus – LucyAustralopithecus afarensis – Fossil found in Africa – They were hominids Shape of pelvis and femurs showed they were bipedal. Locking knee joints – – – – Short—3’6’’ Brain size of chimps Jaws more rounded than apes Teeth like humans LUCY 3.5 million years old 40% complete Female Showed us: – Walked upright first – Brain size grew LATER. SKULLS A. afarensis (Lucy) Homo sapien SKULLS Lucy had a small skull like an ape, but she wasn’t one. LUCY APE LUCY VS. APE Homo habilis Means: Handy man Small structure like Lucy Skull 2X’s the size of Lucy 2- 1.8 mya in Africa Tools made of bone and stone. Homo erectus Peking man Africa / Asia / Europe Larger than H. habilis Larger brain Excellent tools, used fire 1.5 mya – “immediate” ancestor Where Did H. sapiens evolve? Out of Africa hypthothesis- idea like Darwin’s which states H. sapiens evolved IN Africa H..sapiens and spread to rest of H. erectus world Out of Africa hypothesis supported by fossils of modern-like humans found in Africa Early H. sapiens Homo neanderthalensis discovered in Neander Valley in Belgium Massive skulls and protruding brows 400,000-100,000 years ago Early H. sapiens Great controversy: did they die off (genes no longer) or did they interbreed with us so their genes are still in our gene pool? Modern H. sapiens probably evolved in Africa and replaced Neanderthals. APES Mated???? Homo neanderthalensis Homo sapiens transitional species Homo erectus Homo habilis Australopithecus afarensis common ancestor to ape and H. sapiens