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Human Evolution Darwins shocking idea... It is...probable that Africa was formerly inhabited by extinct apes closely allied to the gorilla and chimpanzee, and as these two species are now mans nearest allies, it is somewhat more probable that our early progenitors lived on the African continent than elsewhere. (from The Descent of Man)

Dryopithicus found in 1856

Java man Homo erectus found 1896

Primates = Apes + Humans Catarrhini

Old World Monkeys baboons macaques

Great Apes gibbon, orangutan,

gorilla, chimpanzee, human

human & ape synapomorphies:

new world monkeys old world monkeys

24 source trees inferred from mitochondrial DNA, nuclear DNA, and retroposon characters

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Hominid the group consisting of all modern and extinct Great Apes (that is, modern humans, chimpanzees, gorillas and orangutans plus all their immediate ancestors).

Hominin the group consisting of modern humans, extinct human species and all our immediate ancestors (including members of the genera Homo, Australopithecus, Paranthropus)

Human evolution:

Among all hominoids, evolutionary changes in humans allowed them to take bipedal terrestrial locomotion the furthest!

several anatomical adaptations underlie human bipedalism: curved lower spine, shorter, broader pelvis; angled femur; lengthened lower limbs, enlarged joint surface areas; extensible knee joint, platform foot, enlarged great toe; movement of foramen magnum toward center of basicranuim

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origin of bipedalism? the family tree - based on fossils

http://humanorigins.si.edu/evidence/human-fossils/species/human-family-tree

The Fossil Record:

Sahelanthropus tchadensis aka Toumai found in 2001 in Chad, dating ~7 mya, mostly complete cranium with a small brain (between 320 and 380 cc) comparable in size to that of chimpanzees.

oldest member of the family so far:

skull was crushed...

Ardipithecus Group: 7 to 4.4. mya

human-like features: flattened face reduced canine teeth enlarged cheek teeth More upright posture

Ororrin tugenensis 5.72-5.59 mya, found in Kenya,

fossils include fragmentary arm and thigh bones, lower jaws, and teeth

lived near the time DNA data suggest our oldest hominin ancestor split from the oldest ancestor of the great apes

Key hominin features: Teeth have thick enamel Muscle & ligament attachment sites

indicate erect gait

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Ardipithecus ramidus - 4.4 mya

partial skeleton and indirect evidence from skeletal fragments indicate that this species may have walked upright

Structures marking the articulation of the spine with the skull are more forwardly located in humans rather than in apes, while the base is shorter front to back.

Hominid-like A. ramidus cranial base

A. kadabba subspecies of A. ramidus? Mandibular fragments date back 5.5 mya and appear to be distinct.

Australopithecus Group: A. anamensis - 3.9-4.2mya (knee joint

suggest stress from walking upright) A. afarensis (clearly bipedal) -

3.0-3.9mya; Lucy A. bahrelghazali - 3.4 mya A. garhi - 2.5 mya, larger teeth A. africanus - 2.4-2.8mya (curve of lower

spine similar to modern humans, thus walked similarly; larger molars)

A. africanus skull Lucy

Paranthropus aethiopicus 2.7-2.3 mya (known from 1 specimen; baffling mixture of primitive and advanced traits)

P. robustus - 1.5-2 mya P. boisei - 1.4-2.3 mya;

largest teeth & jaws

Nutcracker man

P. robustus

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Homo Group larger brain size, flatter face, no skull crest,

reduced brow ridges, smaller cheek teeth, reduced canine teeth

H. rudolfensis - 1.8-2.4 mya H. habilis - 1.6 - 1.9 mya (680 cc brain;

handy-man - precision grip) H. erectus - 1.5 - 1.8 mya (1,000 cc brain size; pelvis and thigh bones allow for long strides)

hand axe 1.5 mya

GAME OF THRONES!!! A Complete Skull from Dmanisi, Georgia, and the Evolutionary Biology of Early Homo

first completely preserved adult hominid skull from the early Pleistocenecombines a small braincase (546 cubic centimeters) with a large prognathic face and exhibits close morphological affinities with the earliest known Homo fossils from Africa

This implies the existence of a single evolving lineage of early Homo, with phylogeographic continuity across continents

NATURE PAPER (Oct. 2013), Lordkipanidze et al.

1.77 - 1.85 mya

Specimens commonly deemed H. erectus (Schwartz et al., 2014)

H. heidelbergensis - 200 - 700 Ka The first truly cosmopolitan species of Homo, is

first known from Africa at ca. 600 Ka , before appearing at sites in Europe and eastern Asia from ca. 500 Ka onward. (stone tools similar to H. erectus)

H. neanderthalensis - 28,000 - 200 Ka H. sapiens - 200 Ka to present uniquely derived among hominids in the

structure of its skull and postcranial skeleton

La Chapelle-aux-Saints

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H. floresiensis? Remains of the most recently discovered

early human species, (nicknamed Hobbit), have been found between 95,000 and 17,000 years ago on the Island of Flores, Indonesia

individuals stood approximately 3 feet 6 inches tall, had tiny brains, large teeth for their small size, shrugged-forward shoulders, no chins, receding foreheads, and relatively large feet due to their short legs.

Downs syndrome? Strong words over Hobbit

out of Africa hypothesis supported by genetic data the earliest fossils that resembled members of our species came from southern and eastern Africa. 650,000 genetic markers in nearly 1,000 individuals from 51 populations around the globe

mtDNA tree

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Y chromosome tree relationships among humans and extant apes

genomic phylogeny aligns Gorilla as nearest relative

phylogeny of COX I (mtDNA) aligns Pan as sister taxa to Homo

Gene trees dont always line up with species trees-If the ancestral species was genetically variable for the region under study, then the gene tree estimated from sequence data may differ from the true species tree

MRCA = most recent common ancestor T1 and T2 denote the speciation events of humans and chimpanzees, and of

gorillas, respectively. 23,210 alignments of human, chimpanzee, gorilla, orangutan, and rhesus DNA

sequences from randomly chosen regions of the human genome using maximum likelihood. We infer that for about 23% of our data set chimpanzees are not the closest genetic relatives to humans... (Ebersberger et al. 2007)

If the ancestral species was genetically variable for the region under study, then the gene tree estimated from sequence data may differ from the true species tree

selective sweeps in the humanchimp ancestral species would remove any ancestral polymorphisms and, thus, result in islands in our genome, where incongruent sequence trees are depleted