Hominin Evolution - Classification

•Aims:

•Must be able to outline the characteristics used

for classification of Hominins.

•Should be able to outline the main differences

between species for the main characteristics.

•Could be able to apply knowledge of

characteristics to group organisms.

Hominin Evolution - Classification

Human evolution is the

physical and cultural

development and change

of our hominin ancestors

to modern humans.

Humans are Mammals:

Humans are Primates:

Homo sapiens = One of approximately 200 living primate species, which together constitute the order Primates.

Homo sapiens have inherited a set ofanatomical and behavioral features thatreflect our evolutionary history.

By studying the characteristicsof present-day primates,we are able to look backat stages in our ownevolutionary development.

Primate Grades

Prosimians New World Monkeys

Apes HominidsOld World Monkeys

Primate Characteristics

• Combination of features that are unique to their group.

• Anatomy is well adapted to an arboreal (tree-dwelling) lifestyle.

• They possess:

• Superior intelligence

• Often complex social behavior

• A highly developed problem solving ability

• Features that distinguish primate species from each other include:

• Tail anatomy

• Skull anatomy, including: Brow ridges

Vision

Nostrils

Snout and lips

• Limb length

• Hand and foot anatomy

Primate Physical Features

Primate Skulls•The skulls of various primate groups:

Borneo Orangutan

Chacma Baboon

Tarsier

Chimpanzee

Spider monkeyRuffed Lemur

• Some primates have a heavy brow ridge while others have little or no apparent brow ridge.

Gorilla Skulls• Gorillas exhibit sexual dimorphism in skull features.

• Female gorilla skulls differ from those of males by having:

Female Male

Very small sagittal crest

Small nuchal crest

Female skull smaller than male

Large sagittal crest

Large nuchal crest

Gorilla Skull FeaturesSagittal crest (attachmentsite for jaw muscles)

Low, small cranial vault

Brow ridge

Heavy malar(cheek bone)

Diastema (gap)

Large incisors

Large canines used as defensive weapons

Large molars forgrinding vegetation

Massive jawwith no chin

Foramen magnumpositioned at rear

Massive zygomatic arch through which jaw muscles pass

Nuchal crest (for the attachment of neck muscles)

Protrudingmuzzle

Primate Tails

•Features that distinguish primate tails:

•Tails present or absent

•A prehensile tail can be used to grip things

•Furred or not furred

•Long or short

Primate Feet and Hands• Hands and feet of various primate groups:

Hand

Foot

Squirrel Monkey

Foot

ChimpanzeeHand

Foot

GibbonHand

FootGorillaHand

FootLorisHand

FootOrangutan

Hand

FootTarsierHand

FootBaboonHand

Primate Feet and Hands

Human hand Human foot Tarsier foot Gorilla footOpposable

thumb

Non-opposable

big toe

Claws on

some fingersNails

Opposable

big toe

•Hands and feet of various primate groups can be distinguished by the following features:

•The presence of claws or nails

•Thumbs or big toes opposable or non-opposable

Primate Limbs

• An important feature that distinguishes certain primates is limb length - the ratio of the length of arms to legs

Arms longer than the legs Legs longer than the arms

Order

Suborder

InfraorderSuperfamil

yFamily

Subfamily

TribeExamples

PRIMATES

Prosimii(prosimian

s)

Plesiadapiformes

(archaic primates)

   extinct plesiadapiformes

(Purgatorius)

LemuriformesLemuroidea

Lemuridae

Indriidae

lemurindri

Adapoidea Adapidae extinct adapiformes

Lorisiformes Lorisoidea Lorisdae loris, galago (bush baby)

Tarsiiformes Tarsioidea

Tarsiidae tarsier

Omomyidae

extinct omomyiformes

Anthro-poide

a(simians or

anthropoid

s)

Platyrrhini(New World

simians)

Ceboidea(New World

Monkeys)

Callitrichidae

marmoset, tamarin

Cebidae(true

monkeys)

cebus monkey, spider monkey, howler

monkey, capuchins, owl monkey, sakis

Catarrhini(Old World

Simians)

Cercopithecoidea

(Old World Monkeys)

Cercopithecidae

colobus, langurs, macaque, baboon

Hominoidea(apes and

humans)

Oreopithecidae

extinct Oreopithecus

Hylobatidae

gibbon, siamang

Hominidae

Pongidae orangutan,

Homininae

Gorillini gorillas

Panini chimpanzees

Hominini

humans

Human classification Extinct lineage

Primate Classification – Based on Physical Characteristics

Hominid or Hominin?

Hominid – Group consisting of all modern

and extinct Great Apes (Modern human beings,

chimpanzees, gorillas and orang-utans and all

immediate ancestors).

Hominin – Group consisting of modern

humans, extinct human species and all of our

immediate ancestors.

Classifications Can Change…

•Pre 1980 hominid had the same meaning that

hominin now has…

•Hominid has now been designated a broader

meaning (including Great Apes and their

ancestors).

•Many texts and websites still use the old

naming system – beware!

Modern humans, extinct human species and all immediate

ancestors.

Why Change?

•Over time biological classification

changed due to improved techniques

and better knowledge about the biology

and the evolutionary relationships of

different living things:

•E.g. DNA analysis

Genetic Similarity of Primates• The genetic relationships among the primates have been investigated

using DNA hybridization as well as comparing DNA sequences.

DNA Similarity (%) to Humans

Genetic Similarity of Primates• Human DNA was compared with that of the other primates and

largely confirmed what was suspected from anatomical evidence.

Patterns of relationship among the apes and Old World monkeys based on information from DNA-DNA hybridization:

Human

Pygmy chimpanzee

Common chimpanzee

Gorilla

Orangutan

Gibbons

Old World monkeys

Primate Evolution

Lemurs & lorises Tarsiers

New World monkeys

Old World monkeys Gibbons Orangutans Gorillas Chimpanzees Humans

Present1.8

5

PLEISTOCENE

PLIOCENE

UPPER MIOCENE

MIDDLE MIOCENE

LOWER MIOCENE

10

15

Mill

ions

of y

ears

ago

20

25

30

35

40

45

505560

OL

IGO

CE

NE

EOCENE

PALEOCENE

Adapiformes

Purgatorius

Strepsirhines

May have given rise to the primates, in Africa 60 million years ago (probably tree-dwelling and adapted to gliding between trees)

Omomyiformes

Afrotarsius

Branisella

ProhylobatesMicropithecus?

AegyptopithecusPropliopithecusOligopithecusCatopithecus

AfropithecusProconsul

Dryomorphs

KenyapithecusDryopithecus

After Colin Groves

OuranopithecusSivapithecus

Krishnapithecus

Gigantopithecus

Haplorhines

Split between hominids and chimpanzees

about 8-6 mya

Oldest known anthropoids about 40-30 million years ago

O. tugenensisS. tchadensis

Hominoid Evolution•Classification of the great apes

and humans is difficult.

• In the light of DNA comparisons, one solution is to place orangutans in the subfamily Ponginae and to combine African apes and humans in the subfamily Homininae.

• In addition, a new level ofclassification is created, called tribes:

• Hominini for humans andpre-humans

• Gorillinae for the gorillas

• Panini for the chimpanzees.

Modern Classification - Hominoids

• This modern classification of the hominoids addresses the genetic similarity of gorillas, chimpanzees, and humans.

• Note that under this scheme, the term ‘hominid’ (i.e. a species from the Hominidae) would refer to a ‘great ape’ or human species.

• This scheme is still not widely adopted.

Activity

•Complete the questions on page 371

to 373 In the Biozone book: