Lecture 15
Lecture 15 Human Evolution Objectives • discuss primate evolution and the origin of modern humans Important Points • extant primates and their characteristics • trends in primate and human evolution Mammals: Living Groups Boreoeutheria: Primates • grouped with extant Scandentia (tree shrews) and Dermoptera (flying lemurs) to form Archonta • plesiadapiformes thought to be closest relatives (extinct)
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Plesiadapis (extinct) o early Eocene o squirrel-like tree climber that possessed grasping hands
Primate Characters • agile in trees o grasping hands/feet, sometimes opposable thumbs/toes o sensitive finger pads, flat nails • large brain-body size ratio, good binocular vision • enhanced parental care o one baby at a time (usually) o long period of development and parental care o delayed sexual maturity o long lifespan
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Prosimians: lemurs, lorises, galgos, tarsiers (radiation in Palaeocene and Eocene Monkeys: New World (prehensile tail, flat nose) and Old World (non-prehensile tail, narrow snout)
Apes (homiNOIDS) • no tails, large braincase, mobile shoulder joint allowing arm rotation in complete circle • origins in Africa (early Miocene/Oligocene) HomiNIDS • transition from tree climbing (Pongo) to terrestrial locomotion in Homininae • human split dated 5-8 mya, poor fossil record for gorillas and chimps but not humans Human Evolution • bipedalism: straight knee joint, longer leg bones, shortened pelvic and pectoral girdle, smaller arms • increased brain size, loss of tooth gaps, tools, gracile skeleton, prominent chin
o
First Humans: Sahelanthropus (~6mya) Orrorin (~6mya) Ardipithecus (~4.4-5.6 mya) Praeanthropus anamensis (3.9-4.1 mya) Praeanthropus afarensis (2.9-3.6 mya)
(red = Australopiths, blue = many species show 2-1.5mya overlap)
First Humans? • Sahelanthropus (~6mya): similar to chimps in brain size • Orrorin (~6mya): incomplete fossils • Ardipithecus (~5.6 - 4.4mya): forwards foramen magnum (biped) Preanthropus (extinct) • Preanthropus anamensis (4.1 - 3.9 mya) • Preanthropus afarensis (3.6 - 2.9 mya); Lucy: brain size bigger, ape-like characters but could stand upright (hipjoint) Australopithecus and Paranathropus (extincts) • later australopiths of Africa (3 - 1.4mya) are divided into lightly built Australopithecus and robust Paranthropus • robust forms were adapted to feed on a diet of tough plant material o broad face with skull crest for jaw muscle attachment o huge cheek teeth Homo habilis and rudolfensis (extincts) • 2.4 - 1.5mya found in association with australopith remains and primitive tools in Africa o Homohabilis: hands indicate ability to make tools, from stone age (habilis = skillfull o Homorudolfensis: proposed as contemporary of H. habilis but its designation as a species is controversial Homo Ergaster and Erectus (extincts) • H. Ergaster (1.3-1.9 mya) found in Africa, possible ancestor to H. erectus, or just its African variety • large eyebrow ridge, heavy jaw, no chin BUT fully bipedal • H. erectus (0.2 - 1.6 mya), the upright man found in Africa, Asia and Europe • EITHER migrated from Africa, or evolved in Asia and came back to Africa • Acheulean tools attributed to H. ergaster/erectus show advanced characteristics
Homo Neanderthalis (extinct) • 30 000 - 400 000 ya (Europe, Asia, Middle East) • similar to modern man but more compact and robust, presumably adaptation to cold climate (Ice Age) • advanced culture: clothes, fire, tools of wood bone and stone • may have interbred with Homosapiens and disappeared through hybridization over time Homo sapiens • 160 000 to present • single origin in Africa, spread worldwide in last 100 thousand years • more gracile skeleton, reduced bow ridge, prominent chin • early European forms produced advanced tools, paintings and carved objects • Homo sapiens displaced other early humans by competition or hybridization an issue that is debated
•
Plesiadapis (extinct) o early Eocene o squirrel-like tree climber that possessed grasping hands
Primate Characters • agile in trees o grasping hands/feet, sometimes opposable thumbs/toes o sensitive finger pads, flat nails • large brain-body size ratio, good binocular vision • enhanced parental care o one baby at a time (usually) o long period of development and parental care o delayed sexual maturity o long lifespan
• •
Prosimians: lemurs, lorises, galgos, tarsiers (radiation in Palaeocene and Eocene Monkeys: New World (prehensile tail, flat nose) and Old World (non-prehensile tail, narrow snout)
Apes (homiNOIDS) • no tails, large braincase, mobile shoulder joint allowing arm rotation in complete circle • origins in Africa (early Miocene/Oligocene) HomiNIDS • transition from tree climbing (Pongo) to terrestrial locomotion in Homininae • human split dated 5-8 mya, poor fossil record for gorillas and chimps but not humans Human Evolution • bipedalism: straight knee joint, longer leg bones, shortened pelvic and pectoral girdle, smaller arms • increased brain size, loss of tooth gaps, tools, gracile skeleton, prominent chin
o
First Humans: Sahelanthropus (~6mya) Orrorin (~6mya) Ardipithecus (~4.4-5.6 mya) Praeanthropus anamensis (3.9-4.1 mya) Praeanthropus afarensis (2.9-3.6 mya)
(red = Australopiths, blue = many species show 2-1.5mya overlap)
First Humans? • Sahelanthropus (~6mya): similar to chimps in brain size • Orrorin (~6mya): incomplete fossils • Ardipithecus (~5.6 - 4.4mya): forwards foramen magnum (biped) Preanthropus (extinct) • Preanthropus anamensis (4.1 - 3.9 mya) • Preanthropus afarensis (3.6 - 2.9 mya); Lucy: brain size bigger, ape-like characters but could stand upright (hipjoint) Australopithecus and Paranathropus (extincts) • later australopiths of Africa (3 - 1.4mya) are divided into lightly built Australopithecus and robust Paranthropus • robust forms were adapted to feed on a diet of tough plant material o broad face with skull crest for jaw muscle attachment o huge cheek teeth Homo habilis and rudolfensis (extincts) • 2.4 - 1.5mya found in association with australopith remains and primitive tools in Africa o Homohabilis: hands indicate ability to make tools, from stone age (habilis = skillfull o Homorudolfensis: proposed as contemporary of H. habilis but its designation as a species is controversial Homo Ergaster and Erectus (extincts) • H. Ergaster (1.3-1.9 mya) found in Africa, possible ancestor to H. erectus, or just its African variety • large eyebrow ridge, heavy jaw, no chin BUT fully bipedal • H. erectus (0.2 - 1.6 mya), the upright man found in Africa, Asia and Europe • EITHER migrated from Africa, or evolved in Asia and came back to Africa • Acheulean tools attributed to H. ergaster/erectus show advanced characteristics
Homo Neanderthalis (extinct) • 30 000 - 400 000 ya (Europe, Asia, Middle East) • similar to modern man but more compact and robust, presumably adaptation to cold climate (Ice Age) • advanced culture: clothes, fire, tools of wood bone and stone • may have interbred with Homosapiens and disappeared through hybridization over time Homo sapiens • 160 000 to present • single origin in Africa, spread worldwide in last 100 thousand years • more gracile skeleton, reduced bow ridge, prominent chin • early European forms produced advanced tools, paintings and carved objects • Homo sapiens displaced other early humans by competition or hybridization an issue that is debated
