36
Hominin Evolution Chapter 15 – Part 2

Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Embed Size (px)

Citation preview

Page 1: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Hominin EvolutionChapter 15 – Part 2

Page 2: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Hominin Species: When Did They Live?

The oldest hominin fossil that has been found would have lived between 6-7 million years ago.

Early hominins shared some of the derived characteristics of humans.

E.g.: they had reduced canine teeth, and some fossils suggest that they had relatively flat faces. They also show signs of having been more upright and bipedal than other apes.

One clue to their upright stance can be found in the foramen magnum, the hole at the base of the skull through which the spinal cord exits.

In chimpanzees, the foramen magnum is relatively far back on the skull, in early hominins (and in humans), it is located underneath the skull.

This position allows us to hold our head directly over our body.

Page 3: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7
Page 4: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

The AustralopithecinesThe fossil record indicates that hominin diversity

increased dramatically between 4 million and 2 million years ago.

Many of the hominins from this period are collectively called Australopiths.

Page 5: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

The AustralopithecinesThere appear to have been several species of

Australopithecus.

Some of these are likely to have been in the human line.

There are two general types of Australopithecines:Robusts Graciles

Page 6: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Australopithecus afarensis

Australopithecus africanus

Robust Australopithicusextinct

Homo habilis

4 mya

2 mya

1.5 mya

Page 7: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

The Robust AustralopithecinesThe robust Australopithecines 3 – 1.5 mya

Australopithecus aethiopicusAustralopithecus boiseiAustralopithecus robustus

Main features of the robust Australopithecines:Brain size around 500 mLVery large molarsBony crest on top of the skulls of males.Males range from 1.3-1.4 m tall and females

range from 1.0-1.3 m

Page 8: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Robust Australopithecines

Page 9: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

The Gracile Australopithecines

The gacile Australopithecines were ancestral to the first Homo species

Some examples of gracile Australopiths: Australopithecus anamensis Australopithecus afarensis (Lucy) Australopithecus africanus (Taung Child)

Some of the main features of the gracile Australopithecines include: Brain size around 400 mL Large molars Rounded top skull Males range from 1.4-1.5 m in height and the females range

from 1.0-1.2 m in height

Page 10: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Lucy Lucy is the most complete skeleton of an early hominid.

Found in Hadar, Ethiopia (1974). Dated at 3.2 million years old 40% of her skeleton was found. Bipedal

Australopithecus afarensis Found in many areas of East Africa. 4.0 – 3.0 mya.

Lucy was a small-brained biped. Small brain 380 – 500 mL Lucy was 3’6” tall 50 lb Dates to 3.2 mya

Page 11: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Sexual dimorphism in Australopiths

Australopithecus individuals displayed sexual dimorphism.

This is when the male and female of the species look different to each other.

E.g.: in the case of the Australopithecines, the males are much larger than the females.

Page 12: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Social OrganisationSocial organisation amongst species determines

the degree to which sexual dimorphism is displayed.

Species who form monogamous pairs show little dimorphism, whereas polygamous spices show significant differences between males and females.

Page 13: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Diets

Studying fossilised skulls can provide us with evidence of the diet of a particular species.

For example studying the zygomatic arches , the muscles that run through them and the jaw (including teeth).

The size of the zygomatic arches indicates the size of the muscles associated with the movement of the jaw.

Zygomatic Arches

Page 14: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

DietsThe robust Australopithecines had diets which

included mainly tough and fibrous vegetable matter.

This is evidenced by large jaws and jaw muscles Flat, large molars provide

The gracile Australopithecines also had a diet mainly consisting of vegetable matter, however, their smaller jaws and jaw muscles suggest that the food they ate was of a less fibrous nature.

Page 15: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

DietsAs the species of

Australopithecines were herbivorous, they had relatively large digestive tracts.

In order to accommodate this, they had wider rib cages and waists.

Page 16: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

HabitatsThe Australopithecines had various habitats, but

these habitats were usually in or near forests.

A few species of Australopithecines also lived in grassland savannahs.

Page 17: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

LocomotionThe Australopithecines had skeletons which

were capable of bipedal locomotion.

However, they were also capable of life in trees (arboreal) as they had long digits on their hands and feet, as well as long arms for swinging in between branches.

It is thought that these hominins hunted out in open landscapes during the day and then retreated into the forest at night for shelter and protection.

Page 18: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

The genus HomoThe first members of the genus Homo were

found in Africa, dating back to 2.4 million years ago.

The defining features of the Homo genus were:Reduction in size of teethAn increase in brain size Increase in size of the cranium (to accommodate

the brain)

Page 19: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

The genus HomoThere are many features associated with the genus

Homo, including:Enlargement of brainReduction of tooth sizeShortening of faceMaking and using fireCaring for aged and ill membersBurying the deadDevelopment of artLanguageMusicThe use and development of technology.

Page 20: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Homo habilis: The First Toolmaker

Homo habilis had the following features:Face is much

flatterReduced brow

ridgeLarger cranial

capacity (680 mL)

Homo habilis also used tools in order to strike things, such as nuts.

Page 21: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Homo erectus

Homo erectus evolved from Homo habilis about 2 million years ago.

It is widely believed that Homo erectus was the first species to venture out of Africa.

This is evidenced fossils of Homo erectus being found in continents out side of Africa.

Page 22: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Larger brained and smarter

The brain size of Homo erectus was between 900 and 1,000 mL.

As a result of the increased brain size (and intelligence), Homo erectus displayed some new skills:Use of fireCrafting of better toolsCooperative hunting

Page 23: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

The Hobbit: Homo floresiensis

In 2004, a number of fossilised remains were found in Indonesia of a new hominin species.

It has been estimated that this species existed around 18,000 years ago.

Until the discovery of these fossils it was believed that Homo sapiens were the only hominin species after the Neanderthals became extinct.

The discoveries of these fossils suggest that Homo floresiensis and Homo sapiens would have existed alongside each other.

Page 24: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Homo heidelbergensisHomo heidelbergensis was an intermediate species

between Homo erectus and Homo sapiens.

Their brain capacity is between 1,100 and 1,200 mL

The fossils that have been found have been dated between 400,000 and 40,000 years ago.

These fossils have been found on a number of continents including:AsiaEuropeAfrica

Page 25: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Homo neanderthalensisFossils of Neanderthals have been found all over the

world.

These individuals had large brains (1,400 mL).

They were built strongly, with larger bones.

It is thought that the Neanderthals may have buried dead individuals.

They existed between 150,000 and 35,000 years ago.

This species existed at the same time as Homo sapiens and therefore they are NOT our ancestors.

Page 26: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Modern Humans: Homo sapiens

Evolved in eastern Africa.

Appeared 100,000 years ago.

Highly complex weapons and tools.

Brain capacity around 1,400 mL

Page 27: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Agriculture and the first villages

Evidence has indicated that Homo sapiens had set up agricultural farms and tended to domestic animals around 10,000 to 12,000 years ago.

This was mainly in the Middle East in what is known as the “fertile crescent”

The first plants to be cultivated were wheat, barley and pea plants.

Page 28: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Changes in human population

Changes in human populations have been driven by a number of factors, including:Biological evolutionCultural evolutionTechnological evolution

Page 29: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Human biological evolution

Biological evolution refers to the changes in human populations that has resulted from natural selection.

This allows the population to adapt to their particular geographic area.

Some of the traits that have been selected for in different human populations include:Physical traits: such as variation in skin colour and hair

texture.Biochemical traits: such as ABO and Rhesus blood types.Physiological traits: such as tolerances to non-human

milk, extreme temperatures, etc.

Page 30: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Climate and body shapeThe climate of regions have major effects on body shape.

For example, people living in hotter areas are generally thinner and taller, those living in colder environments are shorter and wider.

This difference can be explained by comparing the surface area to volume ratio of individuals from hot and cold climates. Individuals from hotter climates have a high surface area to

volume ratio, allowing them to lose heat more rapidly when they sweat.

Individuals from colder climates have a low surface area to volume ratio, allowing them to retain heat more efficiently.

Page 31: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Human Cultural EvolutionCultural evolution refers to any type of learned

behaviour (either learned or imitated).

This can include:Making toolsLearning to writeLearning rules in social groupingsNew ideas and knowledgeCustomsSymbolsSkillsLearning to play musical instruments

Page 32: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Technological EvolutionTechnological evolution refers to changes over

time in technology that give humans increased control over their environment.

Page 33: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Technology extends capabilities

Humans have developed and used technology to allow us to achieve things beyond our physical capabilities.

For example:Using glasses to seeUsing various vehicles to travelBionic Ear

Page 34: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7

Biology, culture and technology interact

It is important to remember that biology, culture and technology are interrelated.

Biological evolution created larger brains in the Homo sapiens, this allowed them to develop the technology of tool use, and developed their culture so they hunted in cooperative groups.

Page 35: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7
Page 36: Hominin Evolution Chapter 15 – Part 2. Hominin Species: When Did They Live? The oldest hominin fossil that has been found would have lived between 6-7