• Hominin Evolution - Classification

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:
Primate Grades
 Homo sapiens = One of approximately 200 living
primate species, which together constitute the order
Primates.

Homo sapiens have inherited a set of
anatomical and behavioral features that
reflect our evolutionary history.

By studying the characteristics
of present-day primates,
we are able to look back
at stages in our own
evolutionary development.
Prosimians
New World
Monkeys
Old World
Monkeys
Apes
Hominids
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
Primate Physical
Features
• 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 Skulls
• The skulls of various primate groups:
•
Ruffed Lemur
Tarsier
Spider monkey
Chacma Baboon
Borneo Orangutan
Chimpanzee
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:
Very small
sagittal crest
Small
nuchal
crest
Large
sagittal
crest
Female skull smaller than male
Large
nuchal
crest
Female
Male
Gorilla Skull Features
Sagittal crest (attachment
site for jaw muscles)
Low, small
cranial vault
Brow ridge
Nuchal crest (for
the attachment of
neck muscles)
Heavy malar
(cheek bone)
Massive zygomatic
arch through which
jaw muscles pass
Diastema (gap)
Protruding
muzzle
Foramen magnum
positioned at rear
Large
incisors
Massive jaw
with no chin
Large molars for
grinding vegetation
Large canines used as
defensive weapons
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
Hand
Tarsier
Loris
Foot
Hand
Foot
Foot
Squirrel Monkey
Hand
Baboon
Hand
Orangutan
Foot
Hand
Foot
Gibbon
Foot
Foot
Hand
Gorilla
Hand
Chimpanzee
Foot
Primate Feet and Hands
• 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
Human hand
Human foot
Opposable
thumb
Non-opposable
big toe
Tarsier foot
Claws on
some fingers
Gorilla foot
Nails
Opposable
big toe
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
Primate Classification – Based on Physical Characteristics
Order
Suborder
Infraorder
Superfamily
Family
Subfamily
Tribe
Plesiadapiformes
(archaic primates)
Lemuriformes
Prosimii
(prosimians)
Lorisiformes
P
R
I
M
A
T
E
S
Tarsiiformes
Platyrrhini
(New World
simians)
Anthropoidea
(simians or
anthro
poids)
extinct plesiadapiformes
(Purgatorius)
Lemuroidea
Lemuridae
Indriidae
lemur
indri
Adapoidea
Adapidae
extinct adapiformes
Lorisoidea
Lorisdae
loris, galago (bush baby)
Tarsiidae
tarsier
Omomyid
ae
extinct omomyiformes
Callitrichid
ae
marmoset, tamarin
Cebidae
(true
mon
keys)
cebus monkey, spider monkey,
howler monkey,
capuchins, owl monkey,
sakis
Cercopith
ecid
ae
colobus, langurs, macaque,
baboon
Tarsioidea
Ceboidea
(New World
Monkeys)
Cercopithecoide
a
(Old World
Monkeys)
Catarrhini
(Old World
Simians)
Examples
Oreopitheci
dae
Hominoidea
(apes and
humans)
Human classification
extinct Oreopithecus
Hylobatid
ae
gibbon, siamang
Pongidae
Hominida
e
Homininae
Extinct lineage
orangutan,
Gorillini
gorillas
Panini
chimpanzees
Hominini
humans
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…
Modern humans, extinct human species
and all immediate ancestors.
•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!
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
Present
Tarsiers
New World
monkeys
Old World
monkeys
Gibbons
Orangutans
Gorillas
Chimpanzees
Humans
PLEISTOCENE
1.8
PLIOCENE
Gigantopithecus
5
O. tugenensis
S. tchadensis
Ouranopithecus
10
Sivapithecus
Krishnapithecus
Kenyapithecus
Dryopithecus
Dryomorphs
Micropithecus?
Afropithecus
Prohylobates
Proconsul
MIDDLE
MIOCENE
15
LOWER
MIOCENE
20
25
30
35
OLIGOCENE
Millions of years ago
UPPER
MIOCENE
Omomyiformes
Afrotarsius
Branisella
Aegyptopithecus
Propliopithecus
Oligopithecus
Catopithecus
40
EOCENE
45
Adapiformes
50
PALEOCENE
55
60
Purgatorius
Strepsirhines
May have given rise to the primates, in Africa
60 million years ago (probably tree-dwelling
and adapted to gliding between trees)
Haplorhines
Oldest known
anthropoids about 4030 million years ago
Split between hominids
and chimpanzees
about 8-6 mya
After Colin Groves
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 of
classification is created, called tribes:
• Hominini for humans and
pre-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: