no text exists for this slide

1911-fossilized skull discovered in a gravel pit in Piltdown, England
1911-fossilized skull discovered in a gravel pit in Piltdown, England
Large, modern brain case
Entirely ape-like jaw
Hailed as ‘missing link’
Example of ‘European supremacy’
Fit idealized notion of ‘Humanness’

no text exists for this slide

Why did hominids emerge?
Why did hominids emerge?
Terminology and timing:
The term ‘Hominid’ refers to bipedal primates who first emerged in Eastern Africa
Hominids diverged from their last common ancestor with the apes in the Miocene approx. 5-7 mya
The end of the Miocene is characterized by environmental change
Our first hominid fossils date to the Pliocene
Pliocene (5 mya to 1.8 mya)- transition from arboreal environment to mosaic-trees and savanna grasslands

There are many differences between modern humans and modern primates, but these do not define our earliest ancestors
What makes a Hominid?:
Bipedal anatomy:
Pelvis is shorter and more flared
Legs are longer than arms
Foot has double arch
No opposable big toe
Foramen magnum placement
Nonhoning chewing complex:
Refers to the way the mouth processes food
Lack of projecting canine, diastema
More pressure on front portion of chewing muscles

no text exists for this slide

no text exists for this slide

no text exists for this slide

no text exists for this slide

Why did hominids emerge?
Why did hominids emerge?
Darwin first proposed hypotheses about hominid origins
Hypothesized that hominids went from an arboreal to a terrestrial pattern
Argued that advantage of bipedalism was to carry weapons for hunting
This required intelligence
Canines decreased
Thought larger brains were due to language
Tool production and use essential for development of human intelligence; New evidence shows this not to be the case
Many of these hypotheses were wrong, but very helpful

Why did hominids emerge?
Why did hominids emerge?
Patchy Forest Hypothesis
Human origins and bipedalism related to the greater efficiency in some habitats of moving on two limbs rather than four
Bipedalism arose in areas where forests were fragmented and food resources also became scattered
As forests fragmented, bipedalism freed the hands to pick up food allowing for both tree and ground food resources to be exploited

Why did hominids emerge?
Why did hominids emerge?
Lovejoy’s Provisioning Hypothesis
Freeing the hands was important in allowing males to assist females more efficiently in procuring food; thus “provisioning” acted as a form of sexual competition among males for females
Birth spacing would also be reduced, since females would have to move around less and would have access to greater food resources.
Lovejoy’s hypothesis makes the argument for monogamous fathers
Lack of sexual dimorphism in Hominids may support this
Bipedalism conferred benefits, but it also has its costs…

East Africa- Ethiopia, Kenya, Tanzania
East Africa- Ethiopia, Kenya, Tanzania
Site of many hominid fossil loci
Active volcanoes, earthquakes and mountain building for millions of years
Sediments and fossils exposed- allows for very accurate dating

no text exists for this slide

no text exists for this slide

Who Were the First Hominids?
Who Were the First Hominids?
The Pre-Australopithecines
Sahelanthropus tchadensis
Found by Michel Brunet in 2001
Located in central Africa and dated to 7–6 mya
Brain size (cranial capacity) of 350 cc
Foramen magnum indicative of likely bipedality
Nonhoning chewing complex
Date is close to pongid/hominid divergence

Orrorin tugenensis
Lake Turkana, Kenya
6 mya
Thick molar enamel
Ape-like canine
Curved phalanges
Nonhoning complex
Biped femur
Lived in a forest

no text exists for this slide

Ardipithecus ramidus
Ardipithecus ramidus
Located at Aramis in Ethiopia Awash River Valley
Dated to 4.4 mya
Skeletal remains show mixed traits including:
Biped on the ground, quadruped in trees
350 cc cranial capacity
Reduced dentition
Flexible hands that would have facilitated moving on top of branches
Mixed foot morphology
Pelvis built for both bipedal and climbing locomotion
Lived in a forest

no text exists for this slide

no text exists for this slide

By 4.2 million we have definite evidence of bipedal hominids in East Africa
Genus Australopithecus (‘Southern Ape’)
Lived in eastern and southern Africa for at least 2 million years
Predominate the early hominid fossil record

no text exists for this slide

no text exists for this slide

Australopithecus afarensis:
3.6 mya-3.0 mya
6 sites in East Africa; over 70 individuals. Most well known.
Smaller canines than A. anamensis; no sectorial premolar; large thick molars with thick enamel
Small brain size (430 cc)
Modified pelvis, femur, tibia and feet (bipedal)
Long arms and curved phalanges
Lived in varied habiats

no text exists for this slide

no text exists for this slide

no text exists for this slide

no text exists for this slide

Diversification of the Hominidae: Emergence of Two Evolutionary Lineages from One (3–1 mya)
Diversification of the Hominidae: Emergence of Two Evolutionary Lineages from One (3–1 mya)
Robust group-
Stout mandibles
Massive teeth
Large chewing adaptations
Gracile group-
Teeth are large
Slightly built
Possibly the first representatives of the genus Homo

no text exists for this slide

Australopithecus garhi (2.5 mya): First maker and user of tools ?
Australopithecus garhi (2.5 mya): First maker and user of tools ?
Located in Ethiopia and dated to 2.5 mya
Bones, teeth, partial skeleton, and a skull
Larger teeth than earlier australopithecines
More humanlike humerus-to-femur ratio
Cranial capacity of 450 cc
Probable ancestor of Homo
Associated mammal bones with cut marks, leading to conclusion that A. garhi made Oldowan tools, the earliest stone tools
Stone tools long associated with meat consumption; some wear may indicate tools were also used for digging in ground

no text exists for this slide

no text exists for this slide

Australopithecus africanus
Australopithecus africanus
Found by Raymond Dart
At least 50 individuals at Taung, South Africa and other sites
Dated to 3–2 mya
Larger teeth than A. afarensis
Brain size of 450 cc
Arms longer than legs; Big toe slightly divergent
Pelvis similar to A. afarensis

no text exists for this slide

no text exists for this slide

Australopithecus aethiopicus and Australopithecus boisei
Australopithecus aethiopicus and Australopithecus boisei
Found in Lake Turkana (A. aethiopicus), Olduvai Gorge (A. boisei), and other locations in Africa
A. aethiopicus dates to 2.5 mya and had a cranial capacity of 410 cc
A. boisei dates to 2.3–1.2 mya and had a cranial capacity of 510 cc
Smaller front teeth, larger back teeth
Sagittal crest for attachment of chewing muscles
Dietary focus on harder foods
Evolutionary dead end

no text exists for this slide

no text exists for this slide

Australopithecus robustus
Australopithecus robustus
Found in South Africa and dated to 2 mya
Large premolars and molars, with a large face and sagittal crest
Similar to East African forms
Brain size of 530 cc

Evolution of earliest hominids resulted in a diverse group of species
Evolution of earliest hominids resulted in a diverse group of species
Differences in facial structure reflect dietary specialization
No large increases in brain size
A. garhi may have been ancestor of the genus Homo, but we don’t know for sure 

no text exists for this slide