Transcript Anthropology and Human Evolution

What Makes Us Human?
 The answer to this question may seem simple.
 Humans walk upright, communicate through oral and
written forms, can think and problem solve.
 But how did humanity become the most dominant
species on the earth?
 Anthropological studies provides a part of the answer
to the question of humanness.
 Physical Anthropologists investigate human biological
evolution through the study of fossil evidence
(palaeontology) and the study of cultural remains
(archaeology).
 Recent advancements have added the study of DNA to
this investigation.
 It is hypothesized that, like all life, humans evolved
over time from earlier species and share genetic
relationships to all other forms of life on the Earth.
 The study of human evolution involves understanding
the similarities and differences between humans and
other species in their genes, physical structure, and
behaviour.
 Modern humans belong to the group of mammals
known as primates.
 Anthropology has examined evidence from millions of
years to develop a theory of the evolution of humanity.
 This investigation has been ongoing for centuries and
is built on the findings of various scientists.
 Was one of the earliest topics investigated by
Anthropologists.
 As Europeans began to explore the world in the 1500’s
and 1600’s, new species of plants and animals were
discovered.
 One of the earliest naturalists to develop a theory of
species classification was Carolus Linnaeus of Sweden.
 As a Christian, he believed in the Devine origin of
creation and organized his system to reflect God’s
perfection.
 His first idea was to classify plants and animals by
their anatomical structure – if they looked similar,
they could be classified together.
 He also believed that plants and animals could not
change.
 In the late 1700’s and early 1800’s discoveries began to
be made that indicated that humans had existed on
Earth for a long period of time.
 Fossil discoveries even began to indicate that an
evolutionary process occurred.
 Significant evidence was discovered by Jacques
Boucher de Crevecoeur de Perthes, a French
Anthropologist.
 de Crevecoeur’s Findings
 He discovered stones along the Somme river in France that
were not naturally shaped, they appeared to have been
moulded or shaped into tools and weapons.
 The stones were evidence of an earlier, more primitive tool
making stage.
 Since his generation was capable of making much more
elaborate tools, it seemed reasonable that some
evolutionary process had taken place.
 Many religious leaders at the time opposed de
Crevecoeur’s theory.
 Many held that the Bible’s version of creation, that
God created the world in 7 days, was the only possible
explanation to the question of humanness.
 Others argued that a species always kept its
characteristics, and while changes in appearance are
possible, the “uniqueness” of a species was unalterable.
 Evidence of evolution was proposed by Charles Darwin in
1831.
 He spent 5 years aboard the HMS Beagle travelling around
the world.
 He visited South America, Australia and many of the
islands in the Pacific Ocean.
 He discovered several forms of evidence to support an
evolutionary theory.
 Seashells in the Andes Mountains of South America
indicated that they had once been underwater.
 He used evidence of fault lines to explain earthquakes
and proved the theory of altered coastlines.
 In biological terms, his greatest discoveries were found
on the Galapagos islands off the west coast of Ecuador.
 Darwin used observations and developed a collection of
specimens to research.
 He began to document variation within species, primarily
size and colour.
 He also was able to compare species found on the
Galapagos with those found in South America and he
speculated that the differences were a result of long term
isolation requiring adaptation to the environment.
 Darwin observed 4 main groups of finches with different
physical characteristics.
 These differences led to differences in diet.
 One group had large powerful beaks that were able to break open
large seeds.
 Smaller finches had short thick beaks that allowed them to eat
leaves and blossoms.
 A third group had long straight beaks and ate nectar from local
cacti.
 Darwin’s theory on evolution published in his 1858 On the
Origin of Species.
 Basic premise was that species were forced to evolve by
their environment or face extinction.
 Those species whose changes best suited survival in the
environment survived.
 These adaptations were then passed down to successive
generations.
 Phrase attributed to Darwin, but not really the central
focus of his work.
 He proposed a “natural balance” theory that stated
when changes in population or food supply occurred,
adaptations within a species re-established a balance
between food supply and species growth.
 An imbalance in this relationship motivated the
evolutionary adaptation.
 Darwin provided the groundwork for the general
theory of evolution, but he could not explain how
evolution occurred through heredity.
 He believed that survival traits were passed through
blood to the reproductive cells, but did not have the
ability to observe or test the theory.
 Was discovered by Gregor Mendel.
 A priest and a biology teacher who carried out a series of
breeding tests with plants.
 He crossbred flowers with different colours and observed
that the offspring were always one of the two colours.
 He developed the theory of dominant traits and applied it
to humans.
 It is the scientific category describing a diverse range of species
including lemurs, monkeys and apes.
 As primates, we share many characteristics such as:
 Overlapping fields of vision caused by forward looking eyes.
 The ability to grasp and handle objects with our hands.
 Enlarged brains relative to body size.
 The evolution of primates started nearly 55 million years ago.
 By comparing humans to other living species, we have
learned that humans are most similar to the large apes
of Africa and Asia.
 Humans and apes are the most alike in terms of brain
& body form, and both have complex social lives.
 The split between old world monkeys (baboons) and
the apes (chimpanzees, gorillas and humans)
happened at least 20 million years ago.
 DNA Comparisons show that our closest living relations
are the Ape species of Africa.
 Most studies indicate the humans and chimpanzees are
more closely related than either species is to gorillas.
 Recent studies indicate that humans and chimpanzees
share 96% of the same DNA.
 It is believed that the 4% difference is responsible for all of
the differences between the two species.
 96% seems like a large number, but this has to be placed into
context.
 The human genome contains 3 billion DNA molecules called
nucleotides.
 The 4% genetic difference represents nearly 40 million identified
different DNA molecules.
 When viewed in this context, it is clear that a 4% genetic
difference is quite significant and can only be explained by
millions of years of cumulative mutations within the DNA of
both species.
 Based on DNA comparisons, it is estimated that
humans and chimpanzees split from a common
ancestor that lived some 6 million years ago.
 Within this time, researchers hypothesize that several
significant mutations occurred which are responsible
for the majority of modern differences.
 With an estimated date of between 5 and 8 million years ago for
the existence of a common ancestor to modern chimps and
humans, the study of fossils is needed to reconstruct the
evolution from this common ancestor.
 Aside from DNA estimates, there does not yet exist any physical
evidence of the existence of a common ancestor.
 Fossil evidence does indicate that a pattern of human evolution
does exist.
 This pattern indicates that the further back in the past you go,
the more ape-like are the features of human ancestors.
 Distinctly human traits: bipedal, large brains, or certain cranial
features; did not appear recently or all at once.
 The evolution of modern human traits took place piecemeal over a
period of roughly 5 million years.
 By 4 million years ago, humans were bipedal and their brains were the
size of modern ape brains.
 By 2.5 million years ago we began to manufacture stone tools.
 More complex changes, like the adaptation to living in a wider range of
environments and cultural diversity occurred within the last 10,000
years.
 The species of possible human ancestors are grouped together under
the category of Hominids.
 Hominids are the species that evolved after the split between humans
and chimps over 5 million years ago.
 Hominids are classified by the differences of their fossil remains, the
primary area for these differences is in the skull or cranial bones.
 Not every hominid species is believed to be a human ancestor.
 Some are believed to form an evolutionary chain leading back to the
theorized common ancestor while others are believed to have become
extinct.
 First discovered in 1992 by Dr. Gen Suwa of the
University of Tokyo in Ethiopia.
 It is the oldest Hominid fossil ever discovered dating
back to between 4.2 and 4.7 million years ago.
 It is also the most apelike human ancestor
 First discovered in 1974 by Donald Johanson in Ethiopia.
 He found one intact skeleton of a female and named it “Lucy”
 At the site where Lucy was found, nearly 60 individuals, or parts of, were found.
 This indicates that there was a large local population.
 In total, researchers have collected nearly 300 specimens of Australopithecus
Afarensis.
 Afarensis lived between 3 and 4 million years ago and is the first bipedal
Hominid.
 At the time, his theory that hominids originated in Africa
was very unpopular and the hostile response to his theories
by his peers led Dart to abandon plans for follow-up
excavations.
 Subsequent excavations in the area have failed to produce
any other specimens of this species.
 It was not until the 1940’s that evidence from other sites
would be discovered that supported Dart’s original idea.
 It is theorized that Africanus is descended from Afarensis,
but is not a direct human ancestor.
 For many years researchers believed that Africanus was the
link between Afarensis and the early Homo species.
 Africanus lived between 2.2 and 2.8 million years ago.
 Africanus is perhaps the greatest paleoanthropological
question as there is yet no definitive link to any species
before or after its time.
 The transition from Hominid to Homo Sapiens (from
the Australopithecus to the Homo group) is marked by
increasing brain size and the production and use of
tools.
 First discovered in the 1960’s by Louis and Mary Leakey in
Tanzania.
 Lived between 1.7 and 2.3 million years ago.
 Homo Habilis means “man with tool making ability”
because the Leakeys found primitive tools near the Habilis
fossils.
 Habilis had a larger brain and smaller teeth than
Australopithecus.
 First discovered in 1891 by Dr. Eugene Dubois in Java.
 Erectus lived between 500,000 and 1.8 million years ago.
 Erectus was a hunter who knew how to use fire (charred
remains were found near the fossils.
 Erectus split from its African relative, the newly named
Home Ergaster, and began to move out of Africa into
Europe & Asia 1.6 million years ago.
 Erectus produced more sophisticated tools than
Habilis, like stone axes.
 It wsa believed that Erectus disappeared roughly
400,000 years ago but new evidence indicates the
possibility of a community surviving as late as 50,000
years ago in Java.
 Originally believed to be Homo Erectus, scientists
grouped the African species with similarly developed
species in Asia and Europe.
 Homo Ergaster is essentailly the new name for African
Homo Erectus while Homo Ergaster is now primarily
used for later Asian populations.
 Ergaster, like Erecuts, produced complex stone tools.
 Is the name given to specimens of a species which lived
from 80,000 years ago to the appearance of
anatomically modern humans, Homo Sapiens.
 Originally discovered in Germany, Heidelbergensis
was once referred to as “Archaic Homo Sapiens” or
Homo Sapiens that didn’t look modern.
 Were discovered in 1865 in the Neander valley of Germany.
 Appeared as recently as 120,000 years ago.
 Neanderthals are the first modern humans.
 They lived throughout Europe and the Near East.
 They made complex tools.
 Brain size was large enough for the development of
primitive speech.
 Neanderthals buried their dead.
 This is evidence of the formation of a society with
religious beliefs.
 They began to disappear 60,000 years ago.
 Physically comparable to modern humans with smaller brain
size.
 Discovered in 1868 in France.
 One theory is that roughly 100,000 years ago they evolved in
Africa and began to migrate into Europe and Asia, replacing or
absorbing previous migrations of Homo Erectus.
 The second theory is that modern Homo Sapiens evolved
independently throughout the world in Asia, Africa, and Europe
from existing Homo populations.
 Regardless, remains of Homo Sapiens have been found in the Middle
East, China, Indonesia, Australia, Europe and Africa.
 It is by far the most widespread human ancestor.
 It is the last stage of the physical development of humans.
 Since then, technological & social change have affected our evolution
faster and more significantly than any physical development.
 Human evolution is a topic that has been studied for over 160
years.
 The most fascinating aspect of the study of human origins is that
every new discovery, either genetic or fossil, seems to generate
more questions than it answers.
 Despite a greater variety and greater volume of evidence to
support the theory of evolution, it still remains a theory.
 Human origins is an interesting, yet controversial, field within
the study of history, but this course is primarily concerned with
the study of early civilizations.