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Human Evolution

Human Evolution. D.3 Chapter 15. D.3.1: Outline a method for dating rocks and fossils using radioisotopes, with reference to 14 C and 40 K. Fossils, or the rocks containing fossils can be dated using radioisotopes

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Human Evolution

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  1. Human Evolution D.3Chapter 15

  2. D.3.1: Outline a method for dating rocks and fossils using radioisotopes, with reference to 14C and 40K • Fossils, or the rocks containing fossils can be dated using radioisotopes • When an atom of a radioisotope decays, it changes into another isotope and gives off radiation • Isotopes: different number of neutrons in an element

  3. D.3.1: Outline a method for dating rocks and fossils using radioisotopes, with reference to 14C and 40K • Radiocarbon dating: the % of surviving 14C atoms in a sample is measured • Useful in dating samples that are between 1000-100,000 years old • C-14 and C-12 are present in living organisms • Once an organism dies it no longer takes in C-14 and the existing C-14 decays

  4. D.3.1: Outline a method for dating rocks and fossils using radioisotopes, with reference to 14C and 40K • Potassium-argon dating: the % of surviving 40K atoms and daughter 40Ar atoms are measured • Used to measure the age of rocks • Useful in dating samples older than100,000 years old.

  5. D.3.2: Define half-life • The number of years it takes 50% of the sample to decay • 14C half-life is 5730 years • 40K half-life is 1.3 billion years

  6. D.3.3: Deduce the approximate age of materials based on a sample decay curve for a radioisotope • To be done in radioactive decay lab

  7. D.3.4: Describe the major anatomical features that define humans as primates • Opposable thumbs: allows for grasping hands and feet • Long, thin, straight fingers: fine motor skills • Fingernails instead of claws • Shoulder flexibility (socket): for greater mobility (swinging in trees) • Forward-facing eyes: stereoscopic (3D) vision and depth perception • Extensive care of young

  8. D.3.5: Outline the trends illustrated by the fossils of . . .

  9. D.3.6: State that, at various stages in hominid evolution, several species may have coexisted • Examples: • Homo neanderthalensis and Homo sapiens • A. afarensis and A. africanus

  10. D.3.7: Discuss the incompleteness of the fossil record and the resulting uncertainties about human evolution • Incompleteness due to: • Bits and pieces of skulls & skeletons discovered • Discrepancy in the number of fossils found for each species • Estimations in characteristics (cranial capacity) are imprecise due to differences between males, females, and juveniles • Oldest fossils are most difficult to find because they degenerate over time

  11. D.3.7: Discuss the incompleteness of the fossil record and the resulting uncertainties about human evolution • Incompleteness results in slightly different timelines of human evolution with different dates and phylogenetic connections between species

  12. D.3.8: Discuss the correlation between the change in diet and increase in brain size during hominid evolution • The consequence of a larger brain is the need for more energy • Early hominids were foragers and ate fruit & nuts, and only on occasion meat • As tools became more sophisticated, hunting techniques improved & availability of meat increased Meat in diet + complex tools bigger brain sizes

  13. D.3.9: Distinguish between genetic evolution and cultural evolution • Genetic evolution: inherited characteristics • Body morphology (cranial capacity, skull shape, height, robustness) • Number of chromosomes • Biochemicals (blood proteins) • These (features of hominids) are passed on through chromosomes.

  14. D.3.9: Distinguish between genetic evolution and cultural evolution • Cultural evolution: acquired characteristics • Language (spoken and written) • Customs and rituals (ethnic or religious) • Art (sculpture, pottery, painting) • Technology (comfort, obtaining food, warfare) • These can be passed on within a social group or family.

  15. Note: The whole process of the increase in hominid cranial capacity was through natural selection.- over-production of offspring - variation in a population so some offspring had bigger brains - bigger brains could have meant better problem solving skills thus better fitness due to an ability to find food and shelter more successfully - better fitness would increase the chances of survival - those who survived passed on their genes to the next generation

  16. D.3.10: Discuss the relative importance of genetic and cultural evolution in the recent evolution of humans • As brain size increased, so did the quality of tool-making • Genetic evolution preceded cultural evolution • Genetic evolution was really important up until Homo sapiens • After that, cultural evolution increased in importance • For the last several thousand years, humans have altered the environment so much that we don’t need to genetically evolve • We evolve tools (cultural) to better solve problems

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