Human Evolution. The Evolutionary Path to Humans Begins with Early Primates The story of human evolution begins around 65 M.Y.A. This time marks the explosive

Human Evolution

The Evolutionary Path to Humans Begins with Early Primates

• The story of human evolution begins around 65 M.Y.A.

• This time marks the explosive radiation of a group of small, arboreal mammals called the Archonta

they were likely nocturnal and were arboreal and insectivorous

their radiation gave rise to different types of mammals, including

• bats, tree shrews, and primates

• primates are the order of mammals that includes humans


• Primates are mammals with two distinctive features that allowed them to succeed in the arboreal, insect-eating environment

grasping fingers and toes• the first digit in many primates is opposable and at

least some of the digits have nails

binocular vision• this permits the brain to judge distance precisely

Origin of Anthropoids

• Anthropoids are higher primates and include monkeys, apes and humans.

• Almost all diurnal (active during the day).• Evolution:

Eye changes; Larger brains; Social interactions; Long-term tending of their young to improve learning

and brain development.

Early Primates - Traits

• Common physical primate traits: Dense hair or fur covering Warm-blooded Live young Suckle Infant dependence

• Common social primate traits: Social life Play Observation and imitation Pecking order

Common Primate Traits


• About 40 M.Y.A. the earliest primates split into two groups

prosimians• surviving representatives today include the tarsiers, lemurs,

and lorises• most are nocturnal

anthropoids• these higher primates included monkeys, apes, and humans• the early anthropoids, now extinct, likely evolved in Africa

Figure 27.1 A primate evolutionary tree

8

Hominin Diversity: Fossil Sites in the Old World


• The monkeys are a very successful group of primates

New World monkeys• South American descendants of African ancestors• all are arboreal, have flat spreading noses, and prehensile

tails

Old World monkeys• descendants of the ancestral anthropoids that remained in

Africa• none have prehensile tails• include both ground-dwelling and arboreal species

How the Apes Evolved

• Hominoids evolved from anthropoid ancestors

hominoids are comprised of the apes and the hominids (humans and their direct ancestors)

27.2 How the Apes Evolved

• Studies of ape DNA have revealed much about how living apes evolved

Asian apes evolved first• gibbons diverged from other apes about 15 M.Y.A.• orangutans split off about 10 M.Y.A.• neither are closely related to humans

African apes evolved more recently (between 6 to 10 M.Y.A.)

• these apes are the closest living relatives to humans

27.2 How the Apes Evolved

• Chimpanzees are more closely related to humans than gorillas are

chimpanzees diverged from the ape line less than 6 M.Y.A.

the genes of humans and chimpanzees have not had time to evolve many differences

• humans and chimpanzees share 98.6% of their nuclear DNA

gorilla DNA differs from human DNA by about 2.3%• gorillas split off from the ape line around 8 M.Y.A.

How the Apes Evolved

• The common ancestor of apes and hominids is thought to have been an arboreal climber

• Much of the subsequent evolution of the hominoids differs with respect to locomotion hominids evolved bipedal walking

• anatomical features include S-shaped spine, bowl-shaped pelvis, lower limbs larger than upper limbs

apes evolved knuckle-walking• anatomical features include slightly curved spine, long pelvis,

upper limbs larger than lower limbs

Evolution of Bipedalism• Anatomical changes

Neck (1), chest (2), lower back (3), hips and

pelvis (4), thighs (5), knees (6), feet (7)

• Theories

Tool use and bipedalism (Darwin/Washburn)

Energy efficiency and bipedalism

(Isbell/Young)

Radiator theory (Falk)

Body temperature and bipedalism (Wheeler)

Habitat variability and bipedalism (Potts)

Reproduction and bipedalism (Lovejoy)

Canine reduction and bipedalism (Jolly) (Click for interactive skeleton)

Figure 27.3 Walking upright has evolved many times among vertebrates

A comparison of ape and hominid skeletons

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The first of our genus: Early Homo

Hominin Evolution

• Major Homo advances: Brain size Better bipedalism Hunting Fire (H. erectus) Tools

• Oldowon (H. habilis)• Acheulean (H. erectus)• Mousterian (H. heidelbergensis)• Solutrean (H. sapiens)

Built shelters (H. heidelbergensis) Clothing (H. neandertalensis) Language (Neandertals?)

27.5 African Origin: Early Homo

• The first humans evolved from australopithecine ancestors about 2 million years ago

• Homo habilis it had a larger brain volume than Australopithecus but

was similarly short in stature called “handy man” because of its association with

tools.

Figure 27.6 Homo habilis

Homo habilis

612 cc brain

2.3 - 1.6 mya

first toolmaker

prognathic face, brow ridge

probable meat-eater

possibly arboreal

discovered in 1960 by LeakeysER-1813 – Homo habilis

Artist rendition of H. habilis.

Oldowan Tool Industry• Chopper with simple edge

• Chopping tool

• Unretouched biface

The Oldowan is the first known industrial complex in prehistory. It takes its name from Olduvai Gorge, Tanzania

Oldowan tool use is estimated to have begun about 2.5 million years ago (mya), lasting to as late as 0.5 mya.

It is thought that Oldowan tools were produced by several species of hominids ranging from Australopithecus to early Homo.

H. habilis vs. H. erectus• Finds in east Africa indicate that Homo habilis was not very

different from the australopithecines in terms of body size and shape.

• The earliest Homo erectus remains indicate rapid biological change. H. erectus was considerably taller and had a larger brain

than H. habilis.

Figure 27.7 Homo ergaster

27.5 African Origin: Early Homo

• Too few fossils have been found of early Homo to explain with certainty the evolution of Homo

if two species are accepted, then it would appear Homo underwent an adaptive radiation

because of its modern skeleton, Homo ergaster is thought to be the most likely ancestor to later species of Homo and is often lumped with Homo erectus

27.6 Out of Africa: Homo erectus

• Homo erectus is definitely a true human and has been supported by many specimen finds, including those of Java Man and Peking Man

• Homo erectus was taller and had a larger brain than H. habilis the shape of the skull interior suggests that it was

able to talk it was a social species

Homo (ergaster) erectus1891 - Eugene Dubois discovers H. erectus in JavaDubois calls it Pithecanthropus erectus initially, also dubbed “Java Man”Dates from 1.9 mya to 27,000 years B.P.994 cc brain size (compare to 612 for H. habilis)Acheulean tool industryAll finds in E. Asia are H. erectus, everywhere else is called H. ergaster. Photograph of Nariokotome boy,

an early Homo erectus found near Lake Turkana, Kenya.

Turkana Boy Homo ergaster

Turkana Boy: a nearly complete skeleton of an 11 or 12 year old boy who died approximately 1.5 million years ago near Lake Turkana in Kenya by Kamoya Kimeu and Richard Leakey in 1984.

Homo ergaster – 1.9mya to 27k yBP

• Why was H. erectus so successful? Less hair on body = wearing of furs, other clothing. Wearing of furs = ability to live further north.

Quick adaptation to environment without physical changes.

Culture is main reason H. erectus was so successful

• organization for hunting• ability to protect against

predators• control of fire?• possible campsites• tools (Acheulean industry)

Distribution of H. erectus

Acheulean Tools

• Acheulean tools are typically found with Homo erectus remains.

• It was the dominant technology for the vast majority of human history and more than one million years ago it was Acheulean tool users who left Africa to first successfully colonize Eurasia.

Homo neanderthalensis

• discovered in the Neander Valley (Tal) near Dusseldorf, 1856

• massive brain--about 1,400cc on average

• large torso, short limbs, broad nasal passages

• later remains show decrease in robustness of the front teeth and face, suggesting use of tools replaced teeth

• retained occipital torus, some mid-facial prognathism

The skull of the classic Neandertal found in 1908 at La Chapelle-aux-Saints.

Range of Homo neanderthalensis

First reconstruction of Neanderthal man.

http://www.youtube.com/watch?v=CgEFoY-hoT4&feature=SeriesPlayList&p=39B8670A9074CF60&index=2

http://www.youtube.com/watch?v=5OJcS3y3mlI&feature=SeriesPlayList&p=39B8670A9074CF60&index=0

http://www.youtube.com/watch?v=pKs1Q7f1Uzg&feature=SeriesPlayList&p=39B8670A9074CF60&index=3

http://www.youtube.com/watch?v=o589CAu73UM&feature=SeriesPlayList&p=39B8670A9074CF60&index=5

Neandertal Culture

• Homesites – In caves, also in the

open (near rivers, framed with

wood and covered with skins)

• Burial – Is there evidence of

purposeful burial and ritual?

• Language – Could Neandertals

talk or not?

• Tools – Mousterian tradition

Top: Reconstruction of Neandertal burial from Shanidar caveBottom: Mousterian tools

What happened to Neandertals?• H. neanderthalensis coexisted

with H. sapiens for at least

20,000 years, perhaps as long as

60,000 years

• What happened?

Neandertals interbred with H.

sapiens

Neandertals were killed off by

H. sapiens

H. sapiens drove Neandertals

into extinction by competitionhttp://www.youtube.com/watch?v=IsSOcwY79ig&feature=related

Homo sapiens• Archaic – 150,000 to 35,000 years BP

Earliest members of the species Homo sapiens with different subspecies such as H.s. neanderthalensis or H. s. idaltu

• Modern – 50,000 years BP to present Fully modern behavior& anatomy

becomes prominent.

Ritual burying; reproduced tools of bone & antlers; fishing (costal sites show evidence of fishing after 50k ya).

First hominids to reach Australia (language?).

Cultural universals emerge: art, music, religion.

Sometimes called Homo sapiens sapiens

Modern Homo SapiensRegional-Continuity Model (Milford Wolpoff, UMich)

Humans evolved more or less simultaneously across the entire Old World from several ancestral populations.

Rapid-Replacement Model (Chris Stringer, NHM London)Humans evolved only once--in Africa from H. heidelbergensis ancestors--and then migrated throughout the Old World,

replacing their archaic predecessors. Also called the “Out of Africa” and “Killer Ape” hypothesis.

http://www.youtube.com/watch?v=doF4sNrQtmg&feature=related

http://www.youtube.com/watch?v=MIQNzbd4-RY

Upper Palaeolithic – Hotbed of Culture

• 40 – 10k yBP• Shelters

15,000 yBP Ukraine Some made with mammoth

bones Wood, leather working;

carpentry

• Tools From cores to blades Specialization Composite tools Bow and arrow

• Domestication of dogs • Gathering rather than hunting

became the mainstay of human economies.

Top: Straw Hut

Left: Mammoth bone hut

Bottom: Tool progression

Early H. sapiens Culture Art

Traces of art found in beads, carvings, and paintings

Cave paintings in Spain and southern France showed a marked degree of skill

Female figurines

27,000 to 22,000 years B.P. (Western Europe to Siberia)

Called “venuses,” these figurines depicted women with large breasts and broad hips

• Perhaps it was an example of an ideal type, or perhaps an expression of a desire for fertility or abundance.

Venus of Willendorf. Discovered in 1908 in Austria and dated to approximately 23,000 years ago.

Archaic H. sapiens Culture

• Cave paintings Mostly animals on bare walls Subjects were animals favored for their

meat and skins Human figures were rarely drawn due to

taboos and fears that it would somehow harm others

Cave paintings from 20,000 years ago at Vallon-Pont-d’Arc in southern France (left) and from Lascaux, in southwest France

http://www.youtube.com/watch?v=oSHKqX8_pqU&feature=related

The Hominid Family Tree

• In 1995, hominid fossils dating 4.2 million years old were found in the Rift Valley of Kenya they were assigned to the species

Australopithecus anamensis they represent an intermediate form between

apes and A. afarensis this species represents a base of the family

tree for human evolution

The Hominid Family Tree

• Scientists have taken two different approaches in classifying the species of Homo “Lumpers” recognize three species of Homo,

focusing on common elements among fossils and attributing the differences to diversity within the group

“Splitters” recognize at least seven species of Homo

Figure 27.5 A hominid evolutionary tree

African Origin: Early Homo

• Homo rudolfensis described from a specimen discovered in 1972 with a

larger brain capacity than H. habilis

• Homo ergaster a species used to describe specimens that have a

larger brain capacity than H. rudolfensis and a skeleton more like modern humans and less like australopithecines

Brain size increased as Homo evolved

Out of Africa: Homo erectus

• The oldest specimen of H. erectus is from Africa, indicating that H. erectus arose in Africa

• Homo erectus survived for over a million years, longer than any other species of human

• Homo erectus disappeared about 500,000 years ago in Africa, but the species survived even longer in Asia

Homo erectus

1891 - Eugene Dubois discovers H. erectus in JavaDubois calls it Pithecanthropus erectus initially, also dubbed “Java Man”finds in China called Sinanthropusdates from 1.9 mya to 27,000 years B.P.994 cc brain size (compare to 612 for H. habilis)Acheulean tool industry

Photograph of Nariokotome boy, an early Homo erectus found near Lake Turkana, Kenya.

Homo erectus – 1.9mya to 27k yBP

• Why was H. erectus so successful? Less sexual dimorphism = possible pair bonds, marriage Less hair on body = wearing of furs, other clothing Wearing of furs = ability to live further north Quick adaptation to

environment without physical changes

Culture is main reason H. erectus was so successful

• organization for hunting• ability to protect against

predators• control of fire?• possible campsites• tools (Acheulean industry)

Distribution of H. erectus

Neandertal Culture

• Homesites – In caves, also in the

open (near rivers, framed with

wood and covered with skins)

• Burial – Is there evidence of

purposeful burial and ritual?

• Language – Could Neandertals

talk or not?

• Tools – Mousterian tradition

Top: Reconstruction of Neandertal burial from Shanidar caveBottom: Mousterian tools

What happened to Neandertals?

• H. neanderthalensis coexisted with H. sapiens for at

least 20,000 years, perhaps as long as 60,000 years

• What happened?

Neandertals interbred with H. sapiens

Neandertals were killed off by H. sapiens

H. sapiens drove Neandertals into extinction by

competition

Our Own Species also Evolved in Africa

• Modern humans first appeared in Africa about 600,000 years ago

• According to some scientists, there have been three species of modern humans Homo heidelbergensis Homo neanderthalensis Homo sapiens


• Homo heidelbergensis is the oldest known modern human an Ethiopian fossil dates back to 600,000 years ago it co-existed with H. erectus in Africa but had more

advanced features it had a bony keel running along the midline of the

skull, a thick ridge over the eye sockets, and a large brain

its range included parts of Africa, Europe, and western Asia


• About 130,000 years ago, Homo neanderthalensis appeared in Europe compared to modern humans, Neanderthals

were short, stocky, and powerfully built their skulls were massive


• The oldest known fossil of Homo sapiens is 130,000 years old and occurred in Africa

• Outside of Africa and the Middle East, the earliest known fossils of H. sapiens are no older than 40,000 years old

• This implies that Homo sapiens first evolved in Africa and then migrated to the rest of the world


• Recently-Out-of-Africa model this view of Homo evolution states that Homo

sapiens evolved in Africa and then migrated to Europe and Asia

• Multiregional hypothesis this view of Homo evolution states that the

human races evolved independently from Homo erectus in different parts of the world


• Studies of human mitochondrial DNA (mtDNA) and chromosomal nuclear DNA have helped to clarify the controversy over the origin of Homo sapiens

because DNA accumulates mutations over time, the oldest populations should show the greatest genetic diversity

all modern humans of different ethnic backgrounds share common ancestor dating back 170,000 years ago

only 52,000 years ago do Africans separate from non-Africans

essentially the migration of Homo sapiens out of Africa followed the same paths taken by Homo erectus half a million years before

Out of Africa---many times

The Only Surviving Hominid

• Neanderthals this species of modern human were common in Europe in Asia

around 70,000 years ago they made diverse tools and lived in huts or caves they did not interbreed with members of Homo sapiens

• Cro-Magnons fossils of these early members of Homo sapiens date back as

late as 100,000 years ago in Europe they appear to have completely replaced the Neanderthals

around 34,000 years ago they used sophisticated tools and likely had full language

capabilities

Homo sapiens• Archaic – 100,000 to

35,000 years BP (before present) Sometimes called Homo

sapiens and Homo sapiens neanderthalensis

• Modern – 35,000 years BP to present Anatomically modern

Sometimes called Homo sapiens sapiens

Cro-Magnon Man

Cro-Magnon humans

35,000 years B.P. in western Europe to 17,000 years B.P.

1,600 cc cranial capacity

Name comes from a hotel in France

Not a different species, just old Homo sapiens from Europe

Artist’s reconstruction of a Cro-Magnon man

The Only Surviving Hominid

• Modern Homo sapiens humans eventually spread across Siberia to

North America about 13,000 years ago• a recent genomic survey provides clear evidence

human evolution has been characterized by an increase in brain size and the ability for conceptual thought

Figure 27.10 Homo sapiens is still evolving

Documents

Human Evolution. The Evolutionary Path to Humans Begins with Early Primates The story of human evolution begins around 65 M.Y.A. This time marks the explosive