1. A Look Into Our Past “It has often and confidently been asserted, that man's origin can never be known: but ignorance more frequently begets confidence than does knowledge: it is those who know little, and not those who know much, who so positively assert that this or that problem will never be solved by science.” - Charles Darwin

2.  A taxonomic group that includes humans and their sister taxa chimpanzees. - fossils date back between 6-7 million years  Genetic analysis shows that humans diverged from chimpanzees between 5-6 million years ago

3.  Two debated theories:  1. Multiregional Hypothesis  Locally adapted populations  interbreeding  2. “Out of Africa” Hypothesis  Single population leaves and replaces existing populations over time. Darwin predicted this when he wrote “The Descent of Man”

5. All mitochondria in human population are descended from the mitochondria of a single woman called “Mitochondrial Eve” about 200,000 years ago Mitochondrial DNA (mtDNA) only transferred via eggs (maternal)

6.  Sahelanthropus  Dates 6-7 mya  Western Africa  Small brain and most primitive hominin fossil  Was bipedal

7.  Kenyanthropus platyops  3.5 mya  Represented by skull fragments, jaws, teeth, and leg and arm bones

8.  Australopithecus afarensis  3.5 mya  Fossil remains are most extensive found (named “Lucy”)  Bipedal (fossilize footprints)  Primitive features: low face, long canines, long arms, small brain (400 cc), and curved fingers (tree climbing) Lucy Video - Biointeractive

9.  Paranthropus  “robust” australopithecines  Three named species  Large molars and premolars for chewing plant material  May have made stone tools (2.6 mya)  Went extinct and didn’t contribute to human lineage

10.  Homo halibis  Missing link between Australopithecus and Homo (1.9 - 1.5 mya)  Greater cranial capacity (610- 800 cc)  Flatter face and shorter tooth row  Stone tools (Olduwan technology)

11.  Homo erectus  1.6 mya – 200,000 years ago  Modern human skull features  Larger cranial capacity (avg. 1000 cc)  Spread out from Africa to Asia  Associated with stone tools (Acheulian culture), more diverse than the Olduwan tools of H. halibus  First to use fire (500,000 years ago)

12.  Homo neanderthalensis  Europe and SW Asia  Dense bones and projecting brow  Larger brains than us (1500 cc)  Mousterian culture (stone tools, burial rituals, brain surgeries?)  NOT a direct ancestor, but we may have interbreed with them

13.  Modern Homo sapiens  170 – 160 Kya  Modern cranial capacity (avg. 1400 cc)  Indistinguishable from us  Started in Africa and overlapped range with Neanderthals  Abrupt change 40,000 years ago allowed for “replacement” of Neanderthals  Crossed land bridge 12,000 years ago to Americas

14.  Selective pressures put a premium on two traits throughout our evolution: 1. Bipedalism - A. afarensis fossil footprints (3.6 mya in Tanzania) - great toe not splayed out 2. Cranial Capacity and Intelligence (high selection!) - learning and communication