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 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. Primate Grades ProsimiansNew World Monkeys ApesHominidsOld 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 monkey Ruffed 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: FemaleMale Very small sagittal crest Small nuchal crest Female skull smaller than male Large sagittal crest Large nuchal crest

Gorilla Skull Features Sagittal crest (attachment site 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 for grinding vegetation Massive jaw with no chin Foramen magnum positioned at rear Massive zygomatic arch through which jaw muscles pass Nuchal crest (for the attachment of neck muscles) Protruding muzzle

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 Chimpanzee Hand Foot Gibbon Hand Foot Gorilla Hand Foot Loris Hand Foot Orangutan Hand Foot Tarsier Hand Foot Baboon Hand

Primate Feet and Hands Human handHuman footTarsier footGorilla foot Opposable thumb Non-opposable big toe Claws on some fingers Nails 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

OrderSuborderInfraorderSuperfamilyFamily SubfamilyTribe Examples PRIMATESPRIMATES Prosimii (prosimians) Plesiadapiformes (archaic primates) extinct plesiadapiformes (Purgatorius) Lemuriformes Lemuroidea Lemuridae Indriidae lemur indri AdapoideaAdapidaeextinct adapiformes LorisiformesLorisoideaLorisdaeloris, galago (bush baby) TarsiiformesTarsioidea Tarsiidaetarsier Omomyid ae extinct omomyiformes Anthro- poidea (simians or anthro poids) Platyrrhini (New World simians) Ceboidea (New World Monkeys) Callitrichid ae marmoset, tamarin Cebidae (true mon keys) cebus monkey, spider monkey, howler monkey, capuchins, owl monkey, sakis Catarrhini (Old World Simians) Cercopithecoide a (Old World Monkeys) Cercopith ecid ae colobus, langurs, macaque, baboon Hominoidea (apes and humans) Oreopitheci dae extinct Oreopithecus Hylobatid ae gibbon, siamang Hominida e Pongidaeorangutan, Homininae Gorillini gorillas Panini chimpanzees Hominini humans Human classificationExtinct 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 GibbonsOrangutansGorillasChimpanzeesHumans Present PLEISTOCENE PLIOCENE UPPER MIOCENE MIDDLE MIOCENE LOWER MIOCENE Millions of years ago OLIGOCENE 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 Prohylobates Micropithecus? Aegyptopithecus Propliopithecus Oligopithecus Catopithecus Afropithecus Proconsul Dryomorphs Kenyapithecus Dryopithecus After Colin Groves Ouranopithecus Sivapithecus Krishnapithecus Gigantopithecus Haplorhines Split between hominids and chimpanzees about 8-6 mya Oldest known anthropoids about million years ago O. tugenensis S. 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 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: