David Sadava H. Craig Heller Gordon H. Orians William K. Purves David M. Hillis Biologia.blu B – Le basi molecolari della vita e dell’evoluzione The Evolution of the Human Species

Who were the first humans? When and where did they live? The Evolution of the Human Species Who were the first humans? When and where did they live? What makes us human?

The Evolution of the Human Species - Who were the first humans? Human appearance on Earth

Domain Eukaryota Kingdom Animalia Phylum Chordata Subphylum Vertebrata The Evolution of the Human Species - Who were the first humans? Human taxonomy Domain Eukaryota Kingdom Animalia Phylum Chordata Subphylum Vertebrata Class Mammalia Order Primates Superfamily Hominoidea Family Hominidae Genus Homo Species Homo sapiens Subspecies Homo sapiens sapiens 4

Digit mobility (grasping and opposability) Optical shift Bipedalims The Evolution of the Human Species - Who were the first humans? Primate evolutionary trends Digit mobility (grasping and opposability) Optical shift Bipedalims Relative size of the cerebral cortex Parental care 5

The Evolution of the Human Species - Who were the first humans? Close relatives Human species and anthropomorphic apes (gorilla, gibbon, orangutan, chimpanzee) belong to the superfamily of the Hominoidea, primates without tails. 6

The Evolution of the Human Species - What makes us humans? Hominidae characteristics The spine meets the skull, balancing the head in a vertical position The face is straight The spine meets the skull in the back The face shows a relative degree of prognation Quadrupedal gait (knuckle-walking) Bipedal gait (man is truly vertical) Opposability of big toe Non-opposability of big toe Plantar arch missing Plantar arch and a more robust calcaneus Short pelvis allows bipedalism Femoral shaft angle,(feet directly below the center of gravity) Femur almost vertical within a horizontal plane 7

The Evolution of the Human Species - Where did the first humans live? A common ancestor Different climates in the two areas of the Eastern African Rift Valley are thought to have caused the evolutionary divergence between Hominidae and anthropomorphic apes.pes Atlantic ocean Indian ocean 8

Brain size grew larger (genus Homo) The Evolution of the Human Species - Who were the first humans? Early hominid characteristics Bipedalism Brain size grew larger (genus Homo) Reduction of sexual dimorphism (Homo erectus) 9

Mean cranial capacity (cm3) The Evolution of the Human Species - When did the first humans live? Species Date (thousand years) Body weight (kg) Mean cranial capacity (cm3) Cephalic index* Homo s. sapiens To present 58 1349 5.3 Homo sapiens 35-10 65 1492 5.4 Homo neandertaliensis 75-35 76 1498 4.8 Late Homo erectus 600-400 68 1090 3.8 Early Homo erectus 1800-600 60 885 3.4 Homo habilis 2400-1600 42 631 3.3 Australopithecus africanus 3000-2300 36 470 2.7 Australopithecus afarensis 4000-2800 37 420 2.4 Chimpanzee 45 395 2.0 Gorilla 105 505 1.7 *ratio of the maximum width of the head multiplied by 100 divided by its maximum length The first members of the genus Homo appeared around 2.5 million years in Africa. 10

The Evolution of the Human Species - Who were the first humans? Turkana Boy (Homo erectus) Homo erectus is generally considered to have been the first species to have expanded beyond Africa, and related fossils are spread over two continents. A nearly complete 1.6-million-year-old skeleton, found near Lake Turkana, Kenya, belonged to an eight-year-old boy. 11

The Evolution of the Human Species - Who were the first humans? Professor Svante Pääbo holding the skull of a Homo neandertaliensis An international consortium of researchers has sequenced the genome of our closest relative, the Neandertal. Results indicate that Neandertals are slightly more closely related to modern humans outside Africa. The team also identified several genomic regions that appear to have played an important role during human evolution. (Science on May 7, 2010) 12

The Evolution of the Human Species - What makes us humans? Two possible models Out-of-Africa model Multiregional model Europe Africa Asia Europe Africa Asia (present) Interbreeding between people living in Europe, Asia, and Africa (gene flow) Homo sapiens evolved from Homo erectus in Africa 0.5 million years ago Modern humans evolved more or less simultaneously in all major regions of the Old World from local archaic humans. Humans with modern traits left Africa from 50,000 to 60,000 years ago to settle the world (1.8 million years ago) 13 13

Worked stone tools Evolution of language Cave art, burials The Evolution of the Human Species - What makes us humans? Cultural evolution Worked stone tools Evolution of language Cave art, burials Domestic animals and agriculture 14 14