Chapter 11

March 30, 2012

Humans

• Kingdom: Animalia

• Phylum: Chordata

• Class: Mammalia

• Order: Primates

• Family: Homonidea

• Genus: Homo

• Species: Sapiens

• Subspecies: Homo sapiens sapiens

Other Primates

• Suborder: Haplorhini

– Humans, tarsiers (left), monkeys, apes

– Infraorder: Catarrhinni

• Humans, old world monkeys, apes

– Infraorder: Platyrrhinii

• New world monkeys

• Suborder: Strepsirhini

– Lemurs (above right), lorises (above left)

Primates

• Hominoidea – superfamily including humans, the small apes (gibbons - above), and the great apes (chimps, orangutans, gorillas)

• Similarities in blood and protein chemistry• Humans share 98% of DNA with chimps• Pentadactyl – having 5 fingers and toes• Prehensile – ability of hands and feet to grasp objects

Primates

• Clavicle and scapula (shoulder blade) allow for great range of movement and strength

• Reduced sense of smell compared to other mammals• Stereoscopic, color vision• More mobility in head movement versus other

mammals• Molars, canines, and incisors – adaptation to

generalist diet• Large brains

Adaptations to Arboreal Existence?

• Prehensile hands and feet, shoulder and arm design

• color stereoscopic vision – for judging distance, identifying food and predators

• Low numbers of offspring• Molecular clock – when did humans diverge

from chimp ancestors?– mtDNA from mother– 5 to 10 mya

Early Primates• Arose 70 mya during late Cretaceous• Related by common ancestor to insectivores and bats• Extinct suborder Plesiadapiformes – appeared in North America 65

mya

Early Primates

• Early primate-like mammals were not immediately important following dinosaur extinction 65 mya

• The most dramatic changes were brought about by the emergence of large grazing and browsing mammals with tough hoofs, grinding teeth, and digestive tracts specialized for the processing of grass, leaves, and other fibrous plant materials.

Early Primates

• The beginning of the Eocene Epoch - appearance of early forms of most of the placental mammal orders that are present today

• Among them were primate species that somewhat resemble modern prosimians such as lemurs, lorises, and possibly tarsiers.

• This was the epoch of maximum prosimian adaptive radiation.

• Eocene prosimians lived in North America, Europe, Africa, and Asia. It was during this epoch that they reached the island of Madagascar.

Early Primates

• Monkeys evolved from prosimians during the Oligocene or slightly earlier.

– They were the first species of our suborder

• Several genera of these early monkeys have been identified—

– Apidium - fat squirrel (2-3 pounds),

– Aegyptopithecus - size of a large domestic cat (13-20 pounds)

• Both were probably fruit and seed eating forest tree-dwellers.

• Compared to the prosimians, these early monkeys had fewer teeth, less fox-like snouts, larger brains, and increasingly more forward-looking eyes.

Early Primates

Early Primates• 23 to 14 mya – great increase in ape

diversity and range• Beginning of Miocene, extensive

forests covered Africa and Eurasia• 20 different genera of Caterrhinii apes

from Africa, to western Europe, to southeast Asia– Pliopithecus – western Europe –

similar to modern gibbons– Gigantopithecus – China and India

– larger than modern gorillas• Ramapithecines – jaws and teeth like

humans and apes; skull like orangutans– 14 mya – climate changes

requiring adaptation to savanna climate

– Lived at forest edge– Bipedal – uses less energy– Reduced canines

Gigantopithecus

Pliopithecus sp. (1); Dryopithecus sp. (2); Australopithecus afarensis (3)Homo habilis (4) (Mammiferi, Primati).

Pliopithecus sp.

Hominids and Climate Change

• Models of how animal and plant distributions are affected by climate change may also explain aspects of human evolution.

• The research also leads to interesting conclusions as to how and why Neanderthals evolved in the first place.

• Adoption of a new refugium (an area of refuge from the harsh climatic conditions of the Ice Age) by a subgroup of a species may lead to important evolutionary changes, ultimately leading to the origins of a new species.