Hominid Evolution

Monkeys• Hominins are organisms

that is more closely related to a human than a chimpanzee– Chimps are our closest

relative of the primates

• There is a large amount of confusion about their origin

• To understand where we came from we have to understand where they came from

Monkeys

• Humans are a member of the order primates

• This means we have opposable thumbs, flexible hips and shoulders, forward facing eyes and increased sensory processing abilities

• Primates are generally found in the tropical or sub tropical regions of Asia, Africa or South America

Monkeys

• A common misconception is that humans evolved from monkeys

• Monkeys are their own branch in the order of primates

• Old World monkeys (Asia and Africa) were the first to evolve

• They do not have a prehensile tail and their nostrils open downward

Monkeys

• New World monkeys are found in the Americas and probably traveled to those locations on logs and debris

• NWM have prehensile tails, wide set nostrils and are all tree dwelling

Apes

• The remaining primates are “Apes”

• Lesser Apes are gibbons and Siamangs

• These are classified as hylobatidae

• These are smaller, have more slender limbs and have less sexual dimorphism than their other ape counterparts

Apes

• Great Apes are classified as the sub order homininea

• These include orangutans, gorillas, chimps and humans

• These all lack tails, large brain size compared to body size, have broad flat faces and a socialized culture

Apes

• http://www.animalplanet.com/tv-shows/jane-goodall/videos/almost-human-chimps-human-tools/

Hominins

• There have been 20 species of hominins that have been discovered through evolutionary history

• Each and every one has been more related to humans than chimps

Hominins

• Since hominins only appeared 7 million years ago, there were several periods where several hominin organisms appeared at once on the earth

• However many of those species died out

• Around one million years ago there was only the homo genus left

The Starting Lineup

• There were many discoveries along the line to understanding human evolution

• There are several different genus and species that are well researched or particularly important

The Starting Lineup

• The Australopithecus genus is a genus of extinct bipedal organisms with a smaller brain

• Evidence that they were bipedal comes from their hip joints, their spinal chord position and limb position

The Starting Lineup

• The genus homo is a collection of great apes that are characterized by the evolution of larger brains

• Brain size relative to body size can be an indicator of intelligence

• However it does matter how the brain is developed and shaped

The Major Players

• Australopithecus afarensis appeared roughly 4 million years ago

• They had small brains, a protruding face and walked upright

• Probably lived in small social groups like modern apes

• Most famous fossil is “Lucy”

The Major Players

• Homo erectus means “upright man”

• Appeared around 1.9 million years ago

• Much larger brain size than habilis (940cc avg)

• Thought to be a hunter that used tools to help

• Evidence of the use of fire, however no evidence of cooking

• First evidence of leaving Africa

The Major Players

• Homo habilis stands for “handy man”

• Appeared around 2.2 million years ago

• Smallish brain size (510cc – 690cc)

• Well known for mastering a set of stone tools that allowed them to be more successful in their environment

• Thought to be a scavenger instead of a hunter

The Major Players• Homo neanderthalensis had

a massive brain size (1600cc avg)

• However it was structured differently than ours

• .3% difference in DNA (that is two times larger than the largest human gap)

• Ranged from Europe to Central Asia

• Possible cause of many or modern traits

• Probably driven extinct by modern humans

Major Players

• Homo sapiens means “thinking man”

• Brain size averages 1350cc

• Characterized by a large brain and a complex social environment

• Amazing ability to alter their ability to alter the environment

Frontal Lobe

• The large and complex frontal lobe is theorized to be on of the major reasons for the survival of homo sapiens

• It is the center that allows us to have complex thought, metacognition and complex planning

• This allows Homo sapiens to have the ability to live in many different environments

Frontal Lobe• Many studies have been

done on people with damaged frontal lobes

• The most famous is Phineas Gage

• He damaged his frontal lobe while working on a train track

• Later his doctors reported he had difficulty keeping plans, use very profane language, and had little ability to balance his “intellectual faculties and animal propensities”