Chapter 34 Humans

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Chapter 34Humans

• Charles Page High School
• Stephen L. Cotton

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Section 34-1 Primates and Human Origins

• OBJECTIVES
• Describe the characteristics and primates.

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Section 34-1 Primates and Human Origins

• OBJECTIVES
• Compare New World monkeys with Old World monkeys.

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Section 34-1 Primates and Human Origins

• The study of human origins is an exciting, and
  often controversial, search for our past
• has often been spiced with competition among
  scientists who have different interpretations of
  the data gathered about our past

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Section 34-1 Primates and Human Origins

• But, all researchers agree on certain basic facts
• humans evolved from common ancestors we share
  with other living primates, such as apes and
  chimpanzees
• our species almost certainly evolved in Africa,
  then spread

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Section 34-1 Primates and Human Origins

• The first Homo sapiens appeared around 500,000
  years ago
• practically the day before yesterday on an
  evolutionary scale
• dinosaurs had been extinct for more than 60
  million years

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Section 34-1 Primates and Human Origins

• What are Primates? Animals that share several
  important adaptations, many of which are very
  suitable for a life spent mainly in trees
• faces are flatter than most other animals- eyes
  point forward, snout is reduced

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Section 34-1 Primates and Human Origins

• This allows both eyes to inspect the same area at
  the same time- called binocular vision, or
  stereoscopic vision
• equips primates with a three-dimensional view of
  the world
• handy when judging distances and location of tree
  branches

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Section 34-1 Primates and Human Origins

• Primates have flexible fingers (and some flexible
  toes) that can curl around objects- grasping
• arms are also well-adapted to swinging and
  climbing, because they rotate in broad circles
  around the shoulder

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Section 34-1 Primates and Human Origins

• Primates have a large and complicated cerebrum
• display complex behavior
• mothers take care of their young for a much
  longer time
• complicated social behavior- friendship, adopt
  orphans, unfortunately-war among rivals

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Section 34-1 Primates and Human Origins

• How Did Primates Evolve?
• In their early history, primates split into
  several lines
• those that evolved from 2 of the branches look
  like typical monkeys and are called prosimians
  (simian means flat-nosed)

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Section 34-1 Primates and Human Origins

• Living prosimians include lemurs, lorises, and
  aye-ayes (bottom of page 758)
• almost entirely nocturnal, have large eyes for
  seeing in dark
• More familiar primates include monkeys, apes, and
  humans- called anthropoids (or human-like
  primates)

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Section 34-1 Primates and Human Origins

• The anthropoids have over time given rise to
  several major primate branches
• 2 anthropoid branches- the two major groups of
  monkeys and apes- separated about 45 million
  years ago-result of the moving continents, no
  longer connected by land bridges

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Section 34-1 Primates and Human Origins

• One branch- the New World monkeys- evolved into
  the monkeys found today in Central and South
  America
• the term New World comes from the days of
  Columbus when the Americas were called the New
  World

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Section 34-1 Primates and Human Origins

• New World monkeys are virtually tree dwellers,
  and many have prehensile (grasping) tails that
  aid in balance and movement through tree branches
• Figure 34-3, page 759

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Section 34-1 Primates and Human Origins

• The other anthropoid group evolved into the Old
  World monkeys and the great apes
• do not have prehensile tails
• includes baboons and macaques - page 759
• may live in trees or on ground

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Section 34-1 Primates and Human Origins

• The great apes, also called hominoids, include
  gorillas, gibbons, orangutans, chimpanzees, and
  Homo sapiens

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Section 34-2 Hominid Evolution Human Ancestors

• OBJECTIVES
• Describe the importance of various hominid
  adaptations.

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Section 34-2 Hominid Evolution Human Ancestors

• OBJECTIVES
• Discuss the evolutionary trends in hominids that
  led to Homo sapiens.

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Section 34-2 Hominid Evolution Human Ancestors

• Some time between 4 and 9 million years ago, the
  hominoid line in Africa gave rise to a small
  group of species called hominids-
• not yet human, but had several evolutionary
  trends that distinguish them from other hominoids

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Section 34-2 Hominid Evolution Human Ancestors

• What are Hominids?
• Were omnivores that ate both meat and vegetable
  foods as modern humans do
• the spinal column, hip bones, and leg bones
  changed to make it easier to walk upright on two
  legs

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Section 34-2 Hominid Evolution Human Ancestors

• This bipedal locomotion ( two-foot) was
  important- it allowed free hands to use tools
• the thumb became more independent from the
  fingers
• an opposable thumb enabled ancient hominids to
  grasp objects to use as tools

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Section 34-2 Hominid Evolution Human Ancestors

• There was also a significant increase in brain
  size, exceptionally large even for primates
• chimpanzee brain size of about 280 to 450 cubic
  centimeters (cm3)
• Homo sapiens 1200 to 1600 cm3

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Section 34-2 Hominid Evolution Human Ancestors

• Most of this difference in brain size results
  from the enormously expanded human cerebrum
• the thinking area of the brain
• How Did Hominids Evolve?
• To follow this story, we need fossils of human
  ancestors

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Section 34-2 Hominid Evolution Human Ancestors

• Much of our recent evidence comes from a small
  area in eastern Africa between Tanzania and
  Ethiopia
• here, several researchers have found fossils of
  several species of hominids dating from about 4
  million to 1.5 million years ago

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Section 34-2 Hominid Evolution Human Ancestors

• Australopithecus the First Hominids
• the first hominid fossil to be found, a nearly
  complete skull of a young child, was discovered
  in South Africa in 1924- placed in a new genus
  called Austropithecus

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Section 34-2 Hominid Evolution Human Ancestors

• Since it was from a child, it could not be used
  to determine how adults looked
• but, 12 years later, fossils from an adult
  australopithecene were found- a hip bone,
  indicating Australopithecus walked upright

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Section 34-2 Hominid Evolution Human Ancestors

• Walking erect was an essential step in the
  evolution of our species from an apelike ancestor
• many more complete homonid fossils have since
  been found
• 1974- Donald Johanson and Tim White found a
  nearly complete skeleton

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Section 34-2 Hominid Evolution Human Ancestors

• It was clear that this was the skeleton of a
  female, and the fossil has since been called Lucy
• Figure 34-5, page 761
• named from the Beatles song Lucy in the Sky with
  Diamonds which they listened to in the camp that
  night

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Section 34-2 Hominid Evolution Human Ancestors

• In 1977, anthropologist Mary Leakey made an
  equally exciting discovery a set of fossil
  hominid footprints- dated at 4 million years old
• probably from a parent and child gave clear
  evidence that the animals walked erect

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Section 34-2 Hominid Evolution Human Ancestors

• In recent years, other hominid fossils have been
  placed in the genus Australopithecus
• current studies suggest there were at least 4
  species
• A. boisei, A. robustus, A. afarensis, and A.
  africanus
• (letter A. represents genus)

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Section 34-2 Hominid Evolution Human Ancestors

• These lived between 4 and 1.5 million years ago
  walked upright and had much smaller brains than
  present-day humans
• Many questions as to how these species were
  related to each other, as well as to human
  evolution, still remain to be answered

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Section 34-2 Hominid Evolution Human Ancestors

• For a while, australopithecines were the only
  known links in the chain of human evolution
• Then, anthropologist Richard Leakey found another
  fossil with a smaller face, and a significantly
  larger brain- he placed it in our genus, Homo

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Section 34-2 Hominid Evolution Human Ancestors

• Fossils of this hominid were found with tools
  made of stone and bone
• to emphasize this fact, scientists have called
  these hominids Homo habilis, which appropriately
  means handy man

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Section 34-2 Hominid Evolution Human Ancestors

• Near one of these fossil finds of Homo habilis,
  in a valley in Kenya called Olduvai Gorge, is the
  oldest human settlement yet discovered
• inside, the floor is littered with animal bones
  and stone tools dont know how they were used

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Section 34-2 Hominid Evolution Human Ancestors

• Evidence suggests that Homo habilis disappeared
  within a few thousand years, and was replaced by
  a larger-brained species called Homo erectus
• man who walked upright
• by 1 million years ago, had spread over most of
  the world

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Section 34-2 Hominid Evolution Human Ancestors

• The cranial capacity was over 800 cm3 was an
  excellent toolmaker
• carefully made hand axes
• charred animal bones around fire sites
• indicates using fire for cooking

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Section 34-2 Hominid Evolution Human Ancestors

• From a site in France dated at about 400,000
  years old, the remains of primitive huts have
  been discovered
• not too different from some still in use in parts
  of the world today
• Figure 34-7, page 762

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Section 34-2 Hominid Evolution Human Ancestors

• About 500,000 years ago, the first hominids
  assigned to our own species (Homo sapiens) first
  appeared
• would not be easily recognizable as modern humans

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Section 34-2 Hominid Evolution Human Ancestors

• Around 150,000 years ago, a new hominid walked on
  Earth
• first discovered in the Neander valley in
  Germany, this species was called Neanderthal man,
  or Homo neanderthalensis
• not like seen in movies probably much like us

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Section 34-2 Hominid Evolution Human Ancestors

• The first hominids truly identical to modern
  humans appeared in locations scattered throughout
  the Old World roughly 100,000 years ago
• these large-brained people, called Cro-Magnon,
  were more slender than Neanderthals

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Section 34-2 Hominid Evolution Human Ancestors

• Had a more complex culture made a variety of
  stone and bone tools, including spear points,
  knives, chisels, and needles
• more talented artists cave work
• now classified as modern humans Homo sapiens
  sapiens

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Section 34-2 Hominid Evolution Human Ancestors

• Most paleontologists interpret the dates of
  Cro-Magnon fossils found throughout the world as
  indicating that modern humans originated in
  Africa, and from there spread out over the rest
  of the world

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Section 34-2 Hominid Evolution Human Ancestors

• Other scientists say that modern humans evolved
  from Neanderthals in several regions, including
  Europe, the Middle East, and Asia
• There is no clear resolution to this complex
  debate at this time

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Section 34-2 Hominid Evolution Human Ancestors

• However and wherever the Cro-Magnon originated
  there is ample fossil evidence that they lived
  side by side with Neanderthals for some time
• around 30,000 years ago, the Neanderthals
  disappeared

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Section 34-2 Hominid Evolution Human Ancestors

• Some scientists believe that the Cro-Magnon
  interbred with Neanderthals, blending their
  characteristics
• Others believe that the more intelligent
  Cro-Magnon slaughtered their older relatives, but
  there is no evidence of this