The First Bipeds - PowerPoint PPT Presentation


PPT – The First Bipeds PowerPoint presentation | free to view - id: 41b0c-M2Q4N


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation

The First Bipeds


Who were the Australopithecines and what were they like? ... brain suggest a intelligence similar to a modern bonobo, chimpanzee, or gorilla. ... – PowerPoint PPT presentation

Number of Views:98
Avg rating:3.0/5.0
Slides: 15
Provided by: sta45
Tags: bipeds | first | gorilla


Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: The First Bipeds

Chapter 6
  • The First Bipeds

Chapter Outline
  • What Is the anatomy of bipedalism and how is it
    preserved in the fossil record?
  • Who were the Australopithecines and what were
    they like?
  • What is the role of bipedalism in human
    evolutionary history?

Anatomy of Bipedalism
  • Forward position of the large opening in the base
    of the skull
  • Series of curves in the spinal column
  • Basin-shaped structure of the pelvis
  • Angle of the lower limbs from the hip joint to
    the knees
  • Shape of the foot bones

Australopithecus The Earliest Hominine
  • Appeared in Africa 4 million years ago.
  • From the waist down, fully adapted for
  • From the waist up, still apelike, with
    intellectual abilities comparable to those of a
    modern-day African ape.

Forms of Australopithecus
  • Earliest forms preserve a number of features
    that indicate an apelike ancestor.
  • By 2.5 m.y.a. new form with larger chewing
    apparatus and more massive head, while brain
    size remained stable.

Gracile Australopithecus
  • The size of a modern human pygmy.
  • Chewed food like humans.
  • General appearance resembled an apelike human.
  • Size and outward appearance of brain suggest a
    intelligence similar to a modern bonobo,
    chimpanzee, or gorilla.

Robust Australopithecus
  • Shared most of the traits of the Gracile
  • Bones were thick with prominent markings where
    muscles attached.
  • Skull was thicker and larger with a slightly
    larger cranial capacity.
  • Skull possessed a simianlike sagittal crest.

Species of Australopithecus
  • Gracile Species - Location
  • A. afarensis - Ethiopia and Tanzania
  • A. africanus - South Africa
  • A. anamensis - Kenya

Species of Australopithecus
  • Robust Species - Location
  • A. aethiopicus - Kenya
  • A. boisei - Kenya
  • A. gahri - Ethiopia
  • A. robustus - South Africa

Bipedalism Drawbacks
  • Makes an animal more visible to predators.
  • Exposes the soft underbelly.
  • Interferes with the ability to change direction
    instantly while running.

Bipedalism Drawbacks
  • Quadrupedal chimpanzees and baboons are 30 to 34
    faster than bipeds.
  • Frequent lower back problems, hernias,
    hemorrhoids, and other circulatory problems.
  • Consequences of a serious leg or foot injury
    seriously hinders a biped and they are an easy
    meal for some carnivore.

Fossil Sites in South Africa
  • Dirt, bones, and other matter fell down the shaft
    becoming fossilized.
  • In the Pliocene, the earth next to the shafts
    opening provided a shelter for trees that may
    have been used by predators for eating without
    being bothered by scavengers.

Reasons for Bipedalism
  • A way to cope with heat stress.
  • Allowed them to gather food and transport it to a
    place of safety for consumption.
  • Mothers were able to carry their infants safely.
  • They could reach food on trees too flimsy to
  • Allowed them to travel far without tiring.

Reasons for Bipedalism
  • Food and water were easier to spot.
  • More likely to spot predators before they got too
    close for safety.
  • Hands freed from locomotion provided protection
    by allowing them to brandish and throw objects at