I. Transformation of Humans A. Primate Relationships Overview 1. Earliest primates appear 2. - Previously Prosimians vs. Anthropoids - 3. Platyrrhines vs. Catarrhines a. Early Anthropoids show up 4. 5. a. Members of the Family Hominidae comprise - includes Orangutan, Gorilla, Common Chimpanzee, Bonobo, Human b. Historically, c. Now d. Fossils suggest recent relationship with apes - earliest Great Ape fossils around - human, chimp, bonobo, gorilla divergence much more recent 6. The a. For years there was controversy regarding the closest relatives of humans b. disagreement among researchers using morphological characters c. Initial molecular results disputed d. Accumulated evidence from analysis of - suggest strongly that - sister taxon to humans is - outside of chimp/bonobo/human are gorillas - all are i. Considerable homoplasy
B. Recent Human Ancestry 0. Historically referred to as 1. Common ancestor with chimps had likely characteristics a. knuckle walker b. fruit eater - omnivore - some hunting c. complex social structure d. perhaps rudimentary tool use 2. Australopithecines and Ardipithicus a. earliest species on distinct lineage to humans -earliest bipedal hominids b. - dated to about - very ape-like - may be bipedal - almost complete skeleton still being assembled c. - earliest Australopithicus form - teeth less ape-like 3. a. key transformation leading to hominids b. evolved as ancestors - response to climate changes in Africa - reasons for evolution of bipedalism remain controversial i ii * allow wider range of gathering and cooperation * increased bonding iv. c. Keys to identifying a bipedal homonid from a knuckle walking ape - b = bipedal, k = knuckle walking b. Oriented under skull to sit on vertebral column k. oriented at back of skull, extends out from vertebrae b. s - shaped, more curved k. slight convex curve b. arms shorter than legs k. arms longer than legs b. broader, bowl shaped, centered over legs k. long narrow, illia extend anteriorly b. angled inward to support weight
4. Many Australopithicines known - likely common ancestor to known hominid lineages - fossils found from - clearly bipedal - erect posture mya b. Multiple species existing together - lack exact understanding of relationships 5. Early Homo a. Human lineage grew out of Australopithicines i. Some recognize three species oldest form ~2.4-1.8 mya intermediate form ~1.9-1.6 mya most likely ancestor ~1.8-1.6 mya b. Eventually lead to i. More modern version ii. Some consider to be separate species * not leading to humans iii. Some consider to be direct ancestor * difficult to determine with morphology 6. Common trends in evolution of hominids - Brain size measured as b. is brain size simply due to body size increases? - dramatic increase in cranial capacity in Homo c. Large increases
7. Modern hominid species had three forms - often considered ancestral to more recent humans - oldest fossil dated to - contemporary with i. Some consider H. erectus as * H. ergaster ancestor to both ii. Some consider b. - Some consider to be part of human species, some consider to be separate species i. intensive controversy for many years - some superficial differences in form ii. Skulls with iii. - Use of stone tools, some simple clan based sociality - disappear from fossil record about - Recent evidence from DNA i. Examined ii. Compared to 1000s of humans * as many populations as possible iii. Originally only one Neanderthal sample - many years of effort iv.
8. a. appears about - some fossils in Israel dated to around - non-african H. sapiens forms not found earlier than b. two competing theories for expansion of humans ii. Replaced existing species in Europe and Asia with little or no hybridization ii. Originally touted to explain morphological differences among races iii. Would have earliest human divergence c. Molecular Evidence for i. African humans have ii. Estimated time of earliest divergence * based on single locus - control region sequence iii. Recent divergence estimates on most data * using subset of representative samples *based on i. 30 dinucleotide tandem repeat regions ii. Found African to be oldest populations iii. Estimated time to divergence i. African populations show greatest diversity ii. Other human populations appear to be iii. Loss of allelic diversity associated with