Lucy%20in%20Texas

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Lucy in Texas
Fig. RT Bakker
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What is so special about Lucy?

• Oldest nearly complete skeleton of a homonid that
  shows human characteristics.

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Ancestors from Africa

• Hadar

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Famous Early ManLocations
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Volcanoes in the Afar Triangle

• 3 moving plates split the crust.
• Volcanos produce ash that causes mineralization
  of bones
• Low elevations cause lakes and swamps during wet
  periods
• Food for animals

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Hadar, Ethiopia
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Other A. afarensis site - Sterkfontein

• Sinkhole collecting bones.
• No volcanic ash layer for age dating.

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• Probably has a more complete skeleton than Lucy.
• Bones are imbedded in flow stone and are very
  well preserved.

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Leopards like to eat primates!

• Many skulls have 4 bite marks.
• Leopards drag their prey into trees to keep them
  away from hyenas.

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Putting it in perspective

• How are modern monkeys and great apes related
  using DNA?
• Extrapolate that backwards to the extinct great
  apes.

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DNA based similarity
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Family Tree

• Australopithicus afarensis Southern Ape from
  Afar Lucy

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Lucy In Context

• From apes to humans

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Gorilla

• No fossil record!
• Ape features no chin, big fangs, brow ridge

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Chimp

• No fossil record !
• Ape features no chin, big fangs, brow ridge.

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Sahelanthropus tchadensis

• 6,500,000 ybp
• Chad, Africa
• Brain 350 cc
• Ape

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Kenyanthropus platyops

• 3,500,000 ybp
• Brain ?
• Kenya, Africa
• Ape

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Australopithicus afarensis

• 3,600,000 ybp
• Olduvai, Kenya
• Ape but with an arched foot and a non separated
  big toe.

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Australopithicus afarensis

• 3,100,000 ybp
• Hadar, Ethiopia
• Lucy!
• Brain 430 cc
• Though it has small fangs, the small brain makes
  it an ape.

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Australopithicus africanus

• 2,600,000 ybp
• From a cave in South Africa
• Brain 500 cc
• The small brain makes it an ape.

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Australopithicus boisei

• 1,800,000 ybp
• Olduvai, Kenya
• Brain 480 cc
• The small brain makes it an ape.
• The huge teeth indicate a plant diet.
• Evolutionary dead end

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Homo habilis (handy man)

• 1,800,000 ybp
• Olduvai, Kenya
• Brain 650 cc
• First use of simple stone tools makes this a man
  (Homo).
• Small teeth, and small brow ridge.

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Stone tools made by H. habilis

• 1,800,000 ybp
• Olduvai, Kenya
• A man because
• Hammer stones to break bones for marrow
• Sharp edges to butcher meat.

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Homo erectus (Peking man)

• 1,600,000 ybp
• Peking, China
• Brain 900 cc
• A man because of the brain size and small teeth.
• No stone tools ??

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Homo ergaster (working man)

• 1,500,000 ybp
• Kenya
• Brain 880 cc
• First flaked stone tools.
• A man because of the tools.

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Stone tools - Homo ergaster

• 1,500,000 ybp
• Kenya, Africa
• Mass manufacturing of 1000s of stone tools

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Homo heidelbergensis

• 120,000 ybp
• South Africa
• Brain 1300 cc
• Nearly modern brain size.

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Homo neanderthalensis

• 45,000 ybp
• Israel
• Brain 1600 cc
• Used fire and throwing sticks without flint
  points.
• Modern brain size.
• Massive teeth

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Cro-magnon Homo sapiens

• 195,000 ybp
• Ethiopia
• Brain 1600 cc
• Earliest modern man found.
• Overlap with H. neanderthalensis

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Lucy is an Ape

• Ape characteristics
• small brain, brow ridge,moderate canine teeth,
  small head crest, no tools, arms can be vertical,
  strong wrist, curved fingers, semi-divergent big
  toe
• Human Characteristics
• Broad pelvis, biped (lock knees), skull centered
  on spine, jaw is a U, foot is arched, femur puts
  feet directly below pelvis.

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• Comparisons

Fig. RT Bakker
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Fig. RT Bakker
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• Lucy vs H. sapiens

Fig. RT Bakker
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What things make us Human?

• Well, Ive got your final grades ready, though
  Im afraid not everyone here will be moving up.
• Intelligence is hard to measure in a fossil.
• We can measure brain size, observe tools and
  cultural practices.

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Tools

• Stone tools have NOT been found with Lucy.
• These are by H. habilis and are way too
  advanced!!
• Chimps can be trained to make better tools than
  Lucy.

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Getting out of the Trees

• Going biped frees up the hands for tools, infant
  care, and permits the growth of intelligence.
• Being bipedal does NOT intelligence.

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Walking Upright

• Dinosaurs, birds, and humans are bipeds.
• Not related to tool use or carrying infants.
• Not as energy efficient as running on 4 feet but
  better than knuckle walking.

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Lucy doing the Knuckle Walk

• Hypothesis During an Ice Age, so much water was
  trapped in the ice sheets that the Mediterranean
  dried up and Africa also.
• Forests declined.

Fig. RT Bakker
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• Apes moved out of the forest into the savanna.
  Knuckle walking is inefficient for long distance
  walking.

Fig. RT Bakker
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• Femur
• Bent to put the feet under the pelvis.
• Huge end to allow the knee to lock.
• Pelvis
• Wide to support the back.

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Big Toe as a Thumb

• The big toe on an Orang utan is a functional
  thumb.
• Lucy has a big toe for walking

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Shoulders and Wrists

• For Apes and Lucy, the shoulder allows the arm to
  be vertical.
• H. sapiens has to strain to hold arm vertical.
• Bones have enlarged muscle attachments for
  strength at the expense of quickness.

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Brain Connection
Ape
Man
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Language A. afarensis has a hyoid bone.

• But that does not mean they could speak.
• It is the position of the bone relative to the
  larynx that is key.

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Bipeds strange back design

• This is why your back hurts.

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Lower Jaws hominids broad U
Chimp
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Biped broad pelvis to support the back

• Homo sapiens has a really broad pelvis for the
  babies skull.

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Costs for being Intelligent

• Modern brain uses 20 of energy
• Human infant is born with ¼ of ultimate brain
  size forcing long infancy.
• Hard birth process.

Human Pelvis female male
Chimp
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Skull Crests chewing power
Gorilla
A. boisei
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Firsts in Human Evolution
Mybp Firsts Who?
4.4 Biped A. afarensis
3.0 Simple Tools H. habilis
1.7 Hand Axes H. ergaster
1.0 Moved Asia H. erectus
0.5 Moved Europe H. heidelberensis
0.4 Fire H. neaderthalensis
0.2 Art, Burial Cro-magnon H. sapiens
0.01 Agriculture Modern man
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How old are the fossils? Radioactive Dating

• Mass Spectrometry accelerates ions in a
  magnetic field.
• Different masses follow different paths.

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Radioactive parent element gt normal daughter
element
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K40/Ar40 and Ar39/Ar40 looks for argon trapped in
the crystal
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Drawing by Dr. Bakker

• Elapsed time since the crystal cooled.

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Drawing by Dr. Bakker
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Ar39/Ar40 Correct for weathering by progressive
heating
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What do you date?

• Date every ash layer and lava you can find.
• Hopefully they will bracket the fossils you want
  to date This is Olduvai Gorge.

Basalt
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Drawing by Dr. Bakker
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Drawing by Dr. Bakker
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Drawing by Dr. Bakker
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Biostratigraphic Dating

• Pigs and Elephants evolve through time and are
  much more abundant and durable.
• Match the homonid fossil to another dated fossil
  and you can predict the age.

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The more things change, the more they stay the
same.
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Houston Museum of Natural Science will host Lucy
from September 1 to April 20dont wait until
the last minute to see this show
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