Zoology 445 Fall 20068 DecemberHuman Evolution: HandoutReading: This chapter covers more material than I expect for this course. The test will only cover the following:1. Pages 727 to 738 (stopping at Fossil Evidence.2. Skip the material on fossil evidence.3. Continue reading at the last paragraph on page 745 and end at 759.Start with...I. The PrimatesA. Evolutionary relationships within the Catarrhini.1. Classification - Figure 19.1B. The position of humans in the African Great Apes & Humans has been debated for nearly 20 years. Consensus now reached that true relationship has chimps and humans being the closest relatives. Figure 19.3Consensus:11 of 14 phylogenies based on different independent genes support this tree.Morphology:2 of 14 molecular phylogenies support this tree.AM Jarosz 1Zol 445 Jarosz1 molecular phylogeny supports this tree:Gene trees versus species trees. Example: Fig 19.5Therefore, the gene tree need not always mimicthe species tree.Last common ancestor between humans (genus Homo) and chimpanzees (genus Pan) was about 5 MYA. (See Fig 19.2 & 19.6)2Zol 445 JaroszII. The Human Lineage1. Bipedal gaita. Allows us freedom to use our hands for tool use.Note arm to leg ratios:Knuckle walking > 1.0Bipedal < 1.0Note point of attachment of head on spinal cord.2. Big brainsA. Phylogenetic relationships - Fig 19.16bTraits in the phylogeny.Group Arm to leg ratios:Chimps & Gorillas 1.10Ratios in A. afarensis >1.0All other Austrolrpithecus <1.0Humans 0.90Brain size:3Zol 445 JaroszIII. Origin of our species, Homo sapiens.Four hypotheses:African Replacement and Multiregional have received the most attention, because they predict very different patterns of phylogenetic relationships among the races.4Zol 445 Jarosz5Zol 445 JaroszNew species described in 2004 issue of Nature. Nature 431:1055 (2004) Paper posted on course web site.Homo floresiensis Nicknamed the “Hobbits”- Short (3ft tall), Small brains (380 cc; modern humans 1400cc), but upright gait - Lived as recently as 13,000 YA- On island between Java and AustraliaControversy on whether it is a new species or diseased H. sapiens. If it is a new species, its place in the phylogeny is unclear\Evolution Zol 445\2006\ Human Evolution