Human Evolution

1. Human Evolution

2. Did Man evolve from Apes? • No!! • Similar ancestor • Both: Animalia Chordata Mammalia Primates Hominoids Hominins

3. We are(Humans) mammals • Mammals are warm blooded vertebrates that bear live young. • All mammals have hair or fur over their body surface, milk producing mammary glands, teeth comprising incisors, canines, pre-molars and molars, the lower jaw made of a single bone and three bones in the middle ear.

4. Primates

5. Prosimians are the oldest living primates. • They are mostly small and nocturnal. • Primates evolved into prosimians and anthropoids.

6. Humans are Primates( lemurs, lorises,galagos,tarsiers,monkeys,apes,humans) At this level of classification primates are separated from other mammals by the following characters: • Hands and feet with five digits that can grasp or curl around objects. Thumb or big toe is opposable. • Flattened nails on digits that are sensitive to touch. • Stereoscopic (3D) colour vision. • Small number of offspring with relatively long gestation period. • Skeletons have flexibility. • Relatively large brains compared to other mammals

10. Evolution of Primates • Ida was a lemur-like primate that lived 47Mya in and area that is now Messel, Germany. • “Ida” was announced to the world in 2009 as “the ancestor of us all” • It is a small mammal with some primate characteristics. • What characteristics would you expect Ida to have?

11. Family-Hominoidae(chimpanzees, gorillas, orangutansand humans) • Hominoidea, the members of which are called hominoids.

12. Chimpanzee Hominoids Gorilla Humans Orangutan

13. Humans are Hominoids At this level of classification hominoids are separated from other primates by the following characters: • no tail • The molars have five cusps (monkeys have four) • The rib cage is flattened. • Locomotion is by brachiation, knuckle walking or bipedalism.

14. Sub Family-HomininaeHumans are Hominins • Locomotion is bipedal • Position of foramen magnum is centered under the skull. • Larger brain compared to apes. • Smaller jaws and teeth. • Very fine hair • Longer curved lower spine • Shorter broader pelvis

15. Chimps and Humans • Pelvis is tall and narrow • Femur and tibia joined in a straight line • foot bones were straight resulting in flat feet • toe bones were long and curved for grasping tree branches when climbing • big toe is opposable (could touch the other toes) • foramen magnum (hole through which the spinal cord passes) is located at the back of the skull base. • Backbone is attached at the back of the skull base so that the head was positioned in front of the body. • lower backbone is not strongly curved . • Jaw is box shaped • pelvis is short and wide • femur and tibia (shin bone) join at an angle • foot bones are curved, resulting in arched feet • toe bones are short and straight • big toe is aligned with the other toes and not opposable (cannot touch the other toes) • foramen magnum (hole through which the spinal cord passes) is located at the centre of the skull base. • backbone attaches to the middle of the skull base • lower backbone is strongly curved so that the upper body sits above the pelvis and the backbone is aligned for an upright posture • Jaw is parabolic

16. At this level of classification humans are separated from great apes by the following characters: Hominoid and Hominin Hominoid

17. foramen magnum (hole through which the spinal cord passes) is located at the back of the skull base. foramen magnum (hole through which the spinal cord passes) is located at the back of the skull base.

18. Distinguishing features between Hominids and hominins • In humans the femur is at an angle so that the two bones come close together at the knees. This contributes to better bipedal walking than what is possible by a chimpanzee. • In chips the femur is in straight line with the tibia.

19. Distinguishing features between Hominids and hominins • In chimps, -big toe is not parallel with the other toes. The big toe is used in a manner similar to the thumb. -foot bones are straight resulting in flat feet • In humans -the big toe is parallel with the other toes and is important for walking bipedally. -foot bones are curved, resulting in arched feet

20. - prominent brow ridge -large lower jaw bone -back of skull pointed -Jaw is box shaped -incisors are large -diastema present -canines are large -molars have large cusps -Jaw is parabolic -incisors are small -diastema absent -canines are small -molars have small cusps -less prominent brow ridge -small lower jaw bone -back of skull rounded

21. lower backbone strongly curved. S shaped. lower backbone not strongly curved. C shaped. pelvis is short and wide Pelvis tall and narrow foramen magnum located at the back of the skull base. foramen magnum is centrally located under the skull

22. There are many fossils of extinct hominins. • Most homininsare either the genus Australopithecus or Homo. • Australopithecines were a successful genus. • The Homo genus first evolved 2.4 million years ago.

23. The earliest human species is now generally accepted as Homo habilis. • The first tool makers: Homo habilis The first human emigrants: Homo erectus

24. Homo habilis Homo erectus Homo ergaster

25. A SNAPSHOT OF HUMAN EVOLUTION

27. Trends in Hominin Evolution • All are bipedal • Increase in size of brain • Decrease in size of teeth • Decrease in size of zygomatic arch ( cheek bone) • Forehead changes from low and flat to vertical • Reduce in size of lower jaw • Back of skull changes from pointed to rounded • Increase in tool making • Change from vocalization to true speech • Increase in use of symbols & ritual • Increase in problem solving capacity.

28. Australopithecus afarensis Homo habilis Homo neanderthalensis Homo sapiens

30. Favourite exam Question • Differences between Chimps,Austrelopithecus &Humans • -brow ridge • -size of the teeth • -shape of • -size of lower jaw • -

33. How did early hominins live? Inferences can be made about • Diet • Social organisation • Habitat • Locomotion

34. Inferring diets Prominent cheek bone means jaw muscles were very large : fibrous diet -pot belly means long intestine to digest fibrous food -large rib cage to fit the long intestine

35. Inferring habitat by examining the fossils of plants and animals found in association with the fossils or by analyses of fossil pollen.

36. Bipedalism • Walking upright has important adaptive advantages like: • -increasing the eye level above the ground so that potential predators are more easily seen • -is more efficient in keeping the body and the head cool during activity in the hot dry daylight hours in open habitats in the tropics. • -relieve hands for other purposes like • carrying infants and food • using tools • Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs, or legs.

37. At last Homo sapiens !Humans are Homo sapiens • Humans, as Homo sapiens, are a species that: • walks fully upright • lacks heavy brow ridges • has a large cranial capacity, • makes tools • uses languages and art • self-aware

39. Changes in human population • biological evolution • • cultural evolution, also termed cultural change • • technological evolution. • Changes in these three areas over time resulted in the transformation of our homininancestors to modern human beings.

40. Cultural Evolution • -the transfer of non-genetic information from one individual to another through learning and teaching. • Eg. new ideas,knowledge, customs, symbols, making a tool, learning • a social rule and learning to play a musical instrument.

41. Biological evolution Biological evolution refers to changes in inherited phenotype of human populations from natural selection under a particular set of environmental conditions. • physical traits, such as variation in skin colour and hair texture • physiological traits, such as variation in tolerance to milk.

42. Technological Change Technological evolution refers to changes over time in technology that give humans increased control over their environment. Eg. the change from stone tools to metal tools, from steam power to electric power etc

43. Biology, culture and technologyinteract • The development of a tool-making culture by early human species dependedonboth technological evolution and biological evolution. • Eg. • Tool making was possible only because, much earlier, biological evolution in homininshad resulted in two important developments: • 1. bipedal (two-footed) locomotion that freed the hands for other purposes • 2. increased brain size that gave the capacity for greater problem-solving skills. • So, biological evolution provided the physical and cognitive framework in • which cultural change based on technology could take place in human species.

44. Changing lifestyles of Homo sapiens • from the hunter-gatherer lifestyle to the sedentary. • Developed cooperative skills and division of labour. • Domestication of animals and plants as a ready food source resulted in larger sedentary groups to develop other skills. • Increasing use of technology producing tools. • The last two hundred years: rapid technological change impacts on culture and biology.

45. Is Hominin evolution straight line or is multi-branched? -more than 15 different hominin species appeared in the fossil record. At many periods, several hominin species coexisted and each is believed to have been adapted to a particular habitat.

46. out-of-Africa or multi-regional Hypothesis to support