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Human Evolution. “I came from a monkey!”. Primate Phylogeny. Human evolution began 60 million years ago with the earliest primates. Gradually , they evolved three notable traits: More flattened molars – better suited to a plant diet.
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Human Evolution “I came from a monkey!”
Primate Phylogeny • Human evolution began 60 million years ago with the earliest primates. Gradually, they evolved three notable traits: • More flattened molars – better suited to a plant diet. • Grasping hands and feet with opposable first digits • Forward-directed eyes that – provide binocular vision and depth perception
Primate Phylogeny • During the next 20 to 30 million years, these mammals evolved into prosimian organisms (lemurs, lorises, pottos, tarsiers) and anthropoid organisms (monkeys, apes, humans). • 25-30 million years ago: The anthropoid lineage split numerous times to give rise to old world monkeys, new world monkeys and hominids (humans and recent human like ancestors).
Primate Phylogeny • Humans share physical and behavioural traits with other hominoids and exhibit dramatic genetic similarity to them. • The key distinguishing features of humans vs. the great apes include: • Bipedal motion (and related anatomical features - wide pelvis, curved spine) • A very large brain • Use of complex language • Construction and use of complex tools
Emergence of Humans • The current fossil records show that the hominid clade (group of species) has a rich history of many branching lineages and related species. • The hominid clade includes all descendants of the most recent common ancestor of humans and apes. Fossil records indicate that at least six different species of australopithecines lived in Africa between 4.2 and 1.0 million years ago. • Modern humans, Homo sapiens, originated in Africa about 200,000 years ago, had a brain size of 1400 cm3 and are the sole surviving representatives of a family that was formerly diverse.
The Fossil Record Homo neanderthalensis • Discovered in the mid 1800s in the Neander valley of Germany • Lived 200,000 to 30,000 years ago. • Had shorter more powerfully built skeletons than modern human and a brain size of 1300 cm3 • Lived a combined scavenger and hunter-gatherer life style. • For the last 10,000 years of their existence, Neanderthals shared Europe with modern humans and it is possible that the two species may have interbreed. • Neanderthals were skilled at making tools, they performed burial ceremonies and may have been capable of complex speech.
The Fossil Record Homo neanderthalensis
The Fossil Record Australopithecus africanus • Discovered in 1924, in Taungs South Africa • Known as the Taungs child • Had a relatively large jaw and brain size of 450cm3 - midway between that of the chimpanzee and gorilla. • The fossils were later described as A. africanus – the South African apeman • Was probably omnivorous, feeding on plant materials, insects and other small animals. • Lived in Africa from 3.2 to 2.3 million years ago
The Fossil Record Australopithecus africanus
The Fossil Record Homo erectus • 1927-1937: remains of 30-40 individuals were discovered along with evidence for the use of fire and tools. • fossils were named, Sinanthropuspekensis- Chinese Man from Peking • In 1891, the remains of an early human were discovered near the Solo River in Java. • Given the name Pithecanthropus erectus - Java Man. • Java man and Peking Man were reclassified as Homo erectus. • H. erectus was about 5 feet tall and 175 pounds • Had a brain size of 1000 cm3 • Verified to be an earlier form of human • Lived from 1.8 million to 300,000 years ago
The Fossil Record Homo erectus
The Fossil Record Paranthropusrobustus(aka Australopithecus robusts) • Discovered in South Africa in 1938 • Larger than A. africanus • Had a brain size of 500 cm3 • Molars were larger than A. africanus, suggests that the A. robustus form was a more efficient herbavore. • Lived 2 to 1.2 million years ago • The robust australopithecines are a specialized offshoots in the australopithecine line
The Fossil Record Paranthropusrobustus
The Fossil Record Paranthropusboisei(aka Australopithecus boisei) • Discovered in 1959 in Tanzania • Had a brain size of 530 cm3 – slightly larger than other known australopithecines • P. boisei skulls show an increased size in jaws and cheek teeth. This hominid probably fed on tough vegetable matter. • Lived about 2.6 to 1.2 million years ago
The Fossil Record Paranthropusboisei
The Fossil Record Homo habilis • Skull was discovered in Kenya in 1972 • Had a brain size of 775 cm3 • Lived 2.4 to 1.6 million years ago • H. habiliswas the first hominid to be given the same genus designation as modern man; could be regarded as the first true human. • This skull was a very significant find for 2 reasons. • Gave confirmation that early homo lived along side australopithecines, rather than being linearly descended from Australopithecus. • Indicated that human ancestry can be traced back to much earlier than had previously been believed.
The Fossil Record Homo habilis
The Fossil Record Australopithecus afarensis • A 40% complete skeleton named Lucy was discovered in northern Africa in November 1974. • Measured at 3.5-4 feet tall and was well adapted for bipedal locomotion. • Fossil hand bones strongly resemble the modern human hand. • Lived 3.8 to 2.6 million years ago • Lucy was given the name Australopithecus afarensis – Afar apeman. • A later discovery of a set of 69 footprints made 3.7 million years ago show that human ancestors evolved the ability to walk upright before they had large brains.
The Fossil Record • Australopithecus afarensis
G. Homo heidelbergensis, 300 kya H. Homo neanderthalensis, 70 kya I. Homo neanderthalensis, 60 kya J. Homo neanderthalensis, 45 kya K. Homo sapiens, Cro-magnon, 30kya L. Homo sapiens, modern • Chimpanzee, modern • Australopithecus africanus, 2.6 mya • Australopithecus africanus, 2.5 mya • Homo habilis, 1.9 mya • Homo habilis, 1.8 mya • Homo erectus, 1.75 mya
Rise of the Humans • Palaeontologists have been able to propose a hypothetical phylogenetictree for humans. • The oldest fossils of Homo were Homo habilis. • 1.6 million years ago to H. Habilis gave rise to H. erectus. H. erectusspread out from Africa into Europe and Asia. • Within the last 600,000 years, H. erectus may have evolved into H. neanderthalensis and H. sapiens. • 200,000 years ago, H. sapiensfirst appeared in Africa when H. neanderthalensis was already living in parts of Europe and Asia.
Rise of the Humans • Homo sapiens evolved in Africa and then migrated to other continents, displacing the Neanderthal and other descendants of the earlier H. erectus populations. According to this theory, regional genetic differences in humans evolved within the past 80,000 to 100,000 years, since H. sapiens left Africa. • This has been verified using recent findings from the Human Genome Project.
Rise of the Humans • One would expect less genetic diversity among descendants of small founder populations that had migrated around the globe relatively recently, compared with that of long-established populations • A study of 1600 individuals from 42 populations showed that greater genetic diversity exists within African populations than in other parts of the world • This suggests that humans have existed in Africa far longer than in other parts of the world.
