Humans Have a Relatively Short History

Fossil Records

Indicate that modern humans have a relatively recent history

Began in AfricaIn a short time, humans have become the most numerous and widespread large animal on Earth

A Closer Look at Primates

Primates (Order: Primates)Include Lemurs, monkeys, apes, and humansThere are approximately 300 primate species living today

Primates

Fossil evidence support the hypothesis that primates evolved from a small tree-dwelling, insect-eating ancestor 85 to 65 million years ago.

Primates

Primates retain adaptations from living in treesFlexible shoulder jointsHands that were used in hanging from branchesSensitive fingers and nails instead of clawsBinocular Vision

2 eyes close together on the front of the face

Justin Verlander

Wes Welker

Mike Lowell

Primates

Binocular VisionIn field of vision the two eyes overlapThis enhances depth perceptionsEye hand coordination

Primates

Mammals devote more time and energy to care for young, than most other vertebratesMost primates have single births and nurture their offspring

Two Primate Groups

1. Includes Lorises, Galagos, and LemursLemurs are found on Madagascar and the Comoro Island, off the coast of Africa.

Loris

Galagos

Two Primate Groups

Madagascar and the Comoro

Madagascar

Two Primate Groups

2. Includes: Tarsiers, New World Monkeys, Old World Monkeys

Tarsiers:Flat Faces with large eyesLimited to South East AsiaNocturnal

Two Primate GroupsNew World Monkeys

Found in the America’sTree DwellingPrehensile Tails – (grasping tails) function as an extra appendage for swinging on trees

So, if they swing on their tails = New World Monkey

Some Old World Monkeys have tails but their tails are not prehensile.

Two Primate Groups

Old World MonkeysInclude Baboons, Macaques, and Mandrills are mainly ground dwellers

Macaques

Baboons

Mandrills

The Apes

GibbonsOrangutansGorillasChimpanzees

Modern Apes live only in tropical areas of the Old World

• except for some gibbons; apes are generally

larger than other primates

• They have long arms, short legs, no tail

The Apes / Hominoids

All apes can move through trees but only the orangutans and gibbons are mainly tree dwellers Gorillas and chimps are very socialChimpanzees are biologically closest relatives of humans

DNA only 5% difference

Hominines – the hominoids in the lineage that led to humansHomo Sapien (modern human) – only species in existence today

• Many hominines lived in the past• Earliest hominines may have lived 6 to 7 million

years ago

Two important developments in the evolution of hominids:

1. Upright Posture (leading to 2 – legged walking)2. Brain enlargement

Sahelanthropus • 7million year old – Found in Central Africa• A million years older than any other known hominine • Brain about the size of a modern chimp• Short broad face was more human• Still debate whether this fossil represents a hominine

Walking UprightBipedalism – walking on two feet• Australopithecus Afarensis – oldest evidence of

upright posture and walking on two feet.• Walked upright 4 million years ago• Lucy – a female Australopithecus Afarensis

• 3 ½ feet tall, head about the size of a softball• Australopithecus Afarensis species were extinct by

about 1.2 million years ago

Lucy

Dikika Baby

Later species overlapped in time with early species of the genus homo.

Walking upright evolved before enlarged brain

Enlarged Brain• First enlarged brain relative to body size

appeared 2.5 million years ago• Many skulls have been found between the size of

Australopithecus and H. Sapiens• Simple stone tools were found with these species• Species name Homo habilis (Handy Man)

• Used skilled hands and big brains to invent tools

• Enhanced the ability to hunt, gather food, and scavenge for food

Homo habilis - Handy Man

Paranthropus• 3 recent species grouped

together which grew into the size of well-fed NFL Linebackers placed in their own genus

• Diets include course and fibrous plant foods like modern gorillas

Homo erectus – first hominine fossil observed in a continent other than Africa• H. Erectus was taller and had a larger brain tha

H. habilis• During their 1.5 million years of existence they

grew to about the size of modern humans• Oldest H. erectus fossils found outside of Africa

are 1.8 million years ago in the country of Georgia, near Russia

Early Homo Sapiens coexisted with another hominid species; Homo Neanderthalensis• Neanderthals

• Lived in area of Europe • Made tools from stone and wood

• Fossil records indicate that Neanderthals

• Did NOT give rise to modern Homo Sapien

• Became extinct 30,000 years ago

There are many hypothesis for the origin of fully modern humans

Fossil records now suggest that ancestors originated in Africa

Homo Sapien fossils that look like today’s modern Homo Sapien are about 195,000 years old and it was discovered in Ethiopia

Also discovered in EthiopiaAlso supported by DNA

Molecular biologist analyzed mitochondrial DNA from living humans around the world

determined when they last shared a common ancestor.

The estimated date for that African common ancestor is between 200,000 and 150,000 years ago.More recent DNA data suggest that a small subset of those African ancestors left northeastern Africa between 65,000 and 50,000 years ago to colonize the world.Data supports Theory

New Findings• In 2003 scientist discovered a fossilized skeleton

of a previously unknown hominine species• Found on the island of Flores, Indonesia

• Called Flores Man (Homo Floresiensis)• Only 18000 years old• Smaller skull and shorter than modern Homo Sapiens

• Previously thought no other hominine existed while Homo Sapiens had spread over most of the Earth