Biological and Sociocultural Evolution

• Biological and cultural evolution are key concepts in understanding the origins of modern humans.

Biological Evolution

• Biological evolution involves changes, modifications, and variations in the genetics and inherited traits of biological populations.
• Evolution is diverse, occurring at the level of species, organisms, and even at the molecular level.
• Scientists study changes in the physical body of humans in biological evolution.
• Biological evolution includes changes in posture and movement.
• Biological evolution includes the development of bipedalism or walking in two feet in an upright position.

Sociocultural Evolution

• Sociocultural evolution is also called cultural evolution.
• Sociocultural evolution consists of changes in the development of cultures from simple to more complex forms.
• This type of evolution results from human adaptation to factors such as climatic changes and population increase.
• Cultural evolution is studied by analyzing changes in lifestyle reflected in tools and human-made objects.

Theory of Evolution

• Biological evolution is based on the theory of evolution.
• The theory was introduced by Charles Darwin, an English naturalist and geologist.
• Darwin concluded that each species was not created in a fixed form.

Natural Selection

• Darwin hypothesized that evolution happens through natural selection.
• Natural selection is the outcome of processes affecting the frequencies of traits in a particular environment.
• Traits that enhance survival and reproductive success increase in frequency over time through natural selection.

Three Principles of Natural Selection

• Variation

• Heritability

• Differential reproductive success

• Every species contains a variety of individuals with differing adaptations to their environment.

• Organisms produce progeny with different sets of inheritable traits.

• Organisms with traits most suitable to their environment will survive.

• Organisms will transfer these variations to their offspring in subsequent generations.

Fossils and Artifacts

• Fossils and artifacts are used by archaeologists and social scientists to understand the development of humans.
• Fossils and artifacts can be found through excavation.
• They provide information about the origins of humans.
• They are important sources of information in the reconstruction of human evolution.

Fossils

• Fossils are human, plant, or animal remains preserved over time.

Artifacts

• Artifacts are objects that were made and used by humans.

Hominids

• Hominids are a general group of early humans and other humanlike creatures that can walk erect during prehistoric times.

• Four categories of hominids:

  • Sahelanthropus
  • Australopithecus
  • Ardipithecus
  • Homo

• Australopithecus and Homo had the greatest number of species based on excavated fossils and artifacts.

• Many scholars consider Australopithecus as the first stage of human evolution.

• Homo is considered the last stage of human evolution

Hominid Classification

• Australopithecus, Sahelanthropus, and Ardipithecus represent the prehuman stage of evolution with apelike and human-like characteristics.
• Their fossils were excavated in the African continent.
• Homo represents part of the human stage of evolution, possessing biological and cultural characteristics of modern humans.
  • Fossil evidences show they first lived in Africa.

Sahelanthropus Tchadensis

• The first hominid came from sahelanthropus tchadensis species.
  • The species is approximately 6-7 million years old.
• This hominids had both apelike and humanlike characteristics.
• There skulls were similar to both Australopithecus and modern humans.
• Orrorin tugunensis lived 5.7 million years ago
• Ardipithecus means “ape on the ground", while ramidus means "root"
• Ardipithecus kadabba lived 5.6 million years ago
• Ardipithecus ramidus lived 4.4 million years ago
• Sahelanthropus Tchadensis had a similar height to chimpanzees
• Sahelanthropus Tchadensis had a brain size of 320-380 cm
• Sahelanthropus Tchadensis had similar small teeth with other hominids
• Sahelanthropus Tchadensis had the ability to walk upright

Characteristics of Ardipithecus

• Approximately 4ft in height
• Weighed approximately 120 lbs
• Had as similar skull size to an ape
• Had a small brain
• Walked on two legs or feet (biped)
• Lived in jungles and forests like chimpanzees

Australopithecus

• Australopithecus is the name of the "southern ape."
• Australopithecus considered the "next group of hominids."
• They lived in the African jungle from 5 to 1 million years ago.
• Brain size of 500 cubic centimeters or 1/3 size of the modern human brain
• Were upright
• Bipedal
• Tool users
• Sticks and stones were used for digging
• Lived in small social groups
• Traveled ~15km or more to search for stones
• Were food scavengers
• Consumed insects, eggs, plants, fruits, and sometimes meat

Australopithecines

• Gracile species has small teeth and jaw

• Robust species has large teeth and jaw and muscular build (for the australopithecus boisei)

• Gracile australopithecines include:

  • Australopithecus Anamensis
  • Australopithecus Afarensis
  • Australopithecus Africanus

• Robust australopithecines include:

  • Australopithecus Aethiopicus
  • Australopithecus Robusts
  • Australopithecus Boisei

• Australopithecus Afarensis considered to be the common ancestor of the Australopithecus species.

• Lucy is a 3.2 million year old Australopithecus afarensis fossil.

  • Lucy, one of the earliest ancestors of the modern human

• Lucy is the most famous homonid discovered.

  • Discovered by Dr. Donald Johanson, a paleoanthropologist in Hadar, Ethiopia in November 1974.

• After almost one million years Australopithecus disappeared and was replaced by the Homo

• The homo were a much more intelligent group of homonids

• The homo considered classified as humans because of they had big brains and were bipedal

• Homo first lived in Africa 2.4 million years ago

Homo Classification

• Homo habilis translated to handy man
• Homo Erectus means upright man
• Homo sapiens means wise man
• Homo habilis is believed as the direct ancestors of modern humans because they could produce tools.

Homo Habilis Characteristics

• 3-4ft height
• Brain size is half the size of the modern human, approximately 700 cubic centimeters
• Made tools called Oldowan
• Used tools for hunting and food gathering

Oldowan Tools

• The name Oldowan comes from the place where it was found, Olduvai Gorge, Tarzania
• Used as cutting tools
• Made from volcanic stones

Homo Ergaster

• Homo Ergaster lived as early as 1.8 million years ago
• Homo Ergaster where Homo erectus came from
• Homo Erectus lived 1.8 million years ago to 300,000 years ago
• Homo Erectus Brain size 1000 cubic centimeter or 2/3 of the modern human brain
• Homo Erectus was 5 ft height
• Homo Erectus Walks upright
• Homo Erectus was more intelligent and adaptable compared to Homo habilis
• Homo Erectus manifested cultural evolution
• Homo Erectus Made complex tools for digging, cutting, and scraping
• Homo Erectus Made and used hand axe tools
• Homo Erectus was skillful hunters

Homo Erectus Achievements

• Used fire

• Lived in caves and small houses made of tree branches

• Used spoken language

• Left Africa

• Lived and survived in Asia

• Fire allowed the Homo Erectus to live in cold and dark places.

• Fire allowed the Homo Erectus to cook food and meat.

• Fire allowed the Homo Erectus to protect themselves from wild animal.

• Spoken language allowed the homo erectus to exchange ideas with one another.

• Spoken language allowed the homo erectus to plan hunting.

• Spoken language allowed the homo erectus to help others.

• Spoken language allowed the homo erectus to give names to people, objects, etc.

• Spoken language allowed the homo erectus to develop religious rituals (burial practices).

Homo Erectus Fossils

• The first homo erectus fossil was found in the Longgupo Cave in China
  • The fossils lived around 1.9 million years ago
• Another homo erectus fossil was found in Trinil, Java, Indonesia by Eugene Dubois in 1811
  • The fossil is known as the Java man
  • The Java man is dated to be 1.8 million years of age
• Eugene Dubois was an 1848-1940 Dutch anatomist and geologist.
• In 1920, another homo erectus fossil was found in Zhoukoudian Cave in China
  • The fossil is known as the "Peking Man"
  • The Peking man lived 1.1 – 1 million years ago

Homo Sapiens

• Homo sapiens are the last genus in the evolution ladder.
• Homo sapiens are thinking man.
• Homo sapiens are considered modern humans.
• Homo sapiens are physically similar to modern humans.
• Archaic Homo sapiens of Africa
• Homo heidelbergensis
• Homo neanderthalensis
• Homo sapiens sapiens
• It is believed Homo Sapiens developed and used oral language
• Through language they could communicate effectively when working in groups

Homo Sapien Characteristics

• Large brain size, 1400 cubic centimeters
• Lived in shelters
• Were food gatherers
• Ate plants and fruits
• Hunted animals
• Learned to gather and cook shellfish approximately 164,000 years ago
• Used fire
• Crafted metals
• Made sophisticated and smoothened tools
• Developed shelters
• Advanced technology
• Homo sapiens created different stone tools, fishing tools, harpoons, bows & arrows, spear throwers, and sewing needles
• The first fossil skeleton to be considered as a species of the homo sapiens called as the Homo sapiens sapiens (wise man)
  • The first fossil skeleton to be taken from a rock shelter in France in 1868
• The skeletons were considered the oldest population of Homo sapiens in Europe
• Homo sapiens appeared 40,000 years ago
• Cro-Magnon characteristics:
• 5 1/2 ft tall
• strong body
• brain size of 40,000 cubic centimeters
• Cro-Magnon fossils and artifacts were first found in Europe.
• It is believed that the first Cro-Magnon lived in North Africa and later travelled in Europe and Asia.