Beginning of Human Culture Chapter 3 Cultural Anthropology

Human culture came into existence 2. 5 million years ago This is when humans began to rely more on learned behaviour for survival

Humans and the other Primates Humans belong to the primate order Also includes lemurs, lorises, tarsiers, monkeys and apes

The first primates originated at a time when a new, mild climate favours the spread of dense tropical and subtropical forests over much of the earth Forestation set the development of evolution from the ground to tree living

Evolution through adaptation Adaptation refers to both a process organisms undergo to achieve a beneficial adjustment to an environment and the results of that process Natural selection favours the survival of welladapted individuals and the propagation of their genes Well-adapted individuals produce greater percentage of offspring for next generation Less suited individuals may survive but often do not reproduce because they may be incapable of attracting a mate, be sterile or produce offspring that die

What types of adaptations do you think would enhance survival in the trees?

Ancestral primates possessed characteristics that allowed them to survive in the forest Small size allowed them to use branches of trees that larger and heavier competitors could not and gave them access to an abundance supply of new food These primates could gather this food without having to wait for them to fall to the ground This adaptation to the trees required physical adjustments

Anatomical adaptation There exists characteristics common to all primates Primate dentition Diets of shoots, leaves, insects and soft fruit didn’t require specialized teeth Primate ancestors had 44 teeth Three incisors used for gripping and cutting, 1 canine used for tearing and shredding and four molars and three premolars used for grinding and chewing Evolutionary trend for primate teeth is toward smaller and fewer teeth Canines grew longer and first and second premolars became smaller and eventually disappeared and third and fourth premolars became bicuspids

Sense organs For mammals on the ground the sense of smell is extremely important in that it helps them operate at night and sense what is out of sight This allows ground animals to smell out food and predators In the trees, primates are away from predators and good vision is more important than smell in guiding through branches Thus the sense of smell declined and the sense of vision developed

Stereoscopic colour vision in primates creates the ability to see the world in three dimension of height, width and depth This is accomplished with two eyes set next to each other on the same plane so the visual field of two eyes overlap This has led to increased brain size in the visual areas in primates and a greater complexity at nerve connections

A more accurate sense of touch also characterized arboreal primates A good feeling and mechanism for grasping allowed them from falling from the branches as they sped through the trees Early mammals from which primates evolved had little hairs that gave them tactile sensitivity with were replaced by sensitive pads backed by nails in the tips of the fingers and toes

The primate brain The most outstanding characteristic of primate evolution is the increased brain size The cerebral hemispheres have grown dramatically In monkeys, apes and humans they completely cover the cerebellum which is the part of the brain that coordinates the muscles and maintains body equilibrium This is likely the result of their arboreal existence Living in the trees means an animal is constantly reacting to its environment in complex ways Signals from all parts of the body about various environmental factors have to simultaneously be relayed to the cortex, processed and then an appropriate response has to be sent down the motor nerves to the appropriate receptors This enlarged cortex not only allowed for survival in the trees but also paved the way for the capacity for heightened thought

The primate skeleton The trend in primates is for the foramen magnum, the hole at the base of the skull that the spinal cord attaches to, to move toward the base of skull In quadrupeds this hole in higher in the skull This shift allows for an animal to move in a more upright position

In most primates the snout or muzzle portion of the skull is reduced as the sense of smell has become less important This smaller snout offers less interference with stereoscopic vision and enables the eyes to place in a more frontal position

A developed orbital bone provides more protection for the eyes The clavicle or collarbone moves the arms to the side and allows for more movement with allowed primates to swing through the trees At the end of the hands and feet there exists five extremely flexible digits At the end of the digits are sensitive pads backed by nails which acts as an effective grasping mechanism The opposable thumb and great toe allow for greater manipulation of food, branches and other objects

Adaptation through Behaviour Jane Goodall’s work in studying chimps in Tanzania has provided an insight into the behaviour of our ancient ancestors

Chimpanzee behaviour Like all primates, chimps are social creatures A community of chimps can be up to 50 or more individuals These rarely gather at once and are usually found in subgroups consisting of adult males together, females with their young, or males and females with their young Subgroups may join forces to forage together but eventually break up again into subgroups When this happens members are often exchanged and new subgroups are composed that are different than the ones that initially came together

Dominance hierarchies can exist, despite the fact that most relationships between individuals in the community are stable Generally males outrank females, although high ranking females may outrank low ranking males Physical size and strength determine an animal’s rank but what really counts is mother’s rank and how that rank creates alliances

Grooming Besides is a common chimp pastime being hygienic, it’s a gesture of friendliness, submission, appeasement and closeness This closeness through embrace and touching is an expression of social stability

The sexes intermingle continually and like humans there is no fixed mating season Sexual activity occurs only during the month that the female is fertile and can be initiated by either the male or the female Once impregnated a females are not sexually receptive until their offspring are weaned, at around four Chimps are relatively promiscuous and so it is not guaranteed that a dominant male will impregnate a particular female Nonetheless a dominate male may try to monopolize a female But the female may exercise choice in that cooperation from the female is necessary and she may make herself scarce by going to a neighbouring group Alpha males have been known to monopolize many females at the same time

In primates, females and their offspring constitute the core of the social system Among chimps the mother-infant bond is especially strong in the first five years and a close association continues after this Commonly sons and daughters remain with their mothers for life, even if the mother leaves the group

Chimps appear to rely much on learned cultural behaviour This behaviour can be different from one chimp group to another E. g. : tool use, social interaction

Human Ancestors Studies in genetics, biochemistry and anatomy confirm that chimpanzees and gorillas are our closest living relatives Both are more closely related to us than orangutans 98% identical at genetic level Estimated that we split up 5. 5 to 8 million years ago on evolutionary tree

Ape like human ancestors were forced from the trees onto the ground as a result of climate changes that shifted the environment from a forest to grass Moving from one stand of trees to another Food was also getting scarce in the trees They likely walked on their hind legs as they didn’t have large upper bodies or long arms and thus their hands were free to gather food and transport it An erect posture also aided them in transporting their offspring more effectively and reduced the amount of body area exposed to the sun which helped avoid overheating

Activity In groups you will create mini poster presentations based on the following pages of your textbook. Groups First Hominines pg. 70 -73 Homo habilis pg. 73 -76 Homo erectus pg. 76 -79 Homo sapiens pg. 79 -81