Human Evolution PDF

Skeletal changes 1. Scapula and clavicle - the scapula moved back and lay flat against the ribcage while the clavicle lay back and became elongated. This allowed for the arm to sit on the side of the body and improved throwing power and accuracy which is an adaptive advantage...

Skeletal changes 1. Scapula and clavicle - the scapula moved back and lay flat against the ribcage while the clavicle lay back and became elongated. This allowed for the arm to sit on the side of the body and improved throwing power and accuracy which is an adaptive advantage for hunters 2. Spine - c shaped to s shaped. This allowed for the center of gravity to be directed downwards towards the lower back and pelvis to support bipedal movement 3. Pelvis - went from box shape to bowl shape. Allowed center of gravity to be evenly dispersed throughout the legs to help improve balance to stop swaying when walking bipedaly Cranial changes 1. Saggital crest - reduced from significant size to virtually no crest. This is due to the diet change as they went from eating hard plant material to softer meat for food. This meant the jaw reduced in size as didnt need as big of a jaw. So energy was able to be used somewhere else for expansion e.g brain expansion 2. Brow ridges - reduced in size. As jaw muscles reduced the less support of the face was needed so as a result the brow ridges were reduced in size and allowed the expansion of cranial cavity which allowed the brain to expand 3. Mandible - the mandible reduced in size due to the change in diet from hard plant to soft meat. This meant large jaw muscles werent required so reduced in size. Energy saved from this was used elsewhere e.g rounding cranium for brain expansion The selection pressure for bipedalism is environmental change. This is because around 6 MYA in Africa the weather became much warmer and drier, as well as this the forests went from being very dense to scattered wooden savannahs. This created a more open habitat where you had to walk long distances to find food and water as it was more dispersed Survival advantage of bipedalism - Energy efficient way of moving around as favours slower pace and long distances. Means bipedal homins could walk further to get food and water so therefore are more likely to be able to survive and reproduce successfully so they can pass on their pibedal alleles so it becomes more frequent in population - Can see above tall trees/grass better meaning they can spot prey or food in the distance so therefore …. - Freeing of hands - Use of objects like weapons and tools more accurately so more likely to kill prey and so have more food and therefore … Multiregional hypothesis - This hypothesis is the older one and was used until dna evidence was dissovered - The multiregional hypothesis suggest homo erectus moved out of africa around 1.5-2 mya years ago and evolved into archiac humans and then anatomically modern humans i n multiple different countries throughout the world in different regions. These populations interbreed as gene flow the general modern features were adapted by all Evidence of multiregional - Intermediate fossils between homo erectus and homo sapiens were found out of africa which suggests homo sapiens did in fact evolve from homo erectus out of africa in different regions across the world - Dna evidecne found similarities between homo sapiens and homo neanderthaness dna sequence so suggests interbreeding did occur between multiple regions Out of Africa hypothesis - Preffered hypothesis - The OOA hypothesis suggests that homo erectus evolved into homo sapiens in Africa around 200 MYA and then they ventured out to other countries in the world in asia and europe etc. and became dispersed. States that there was no interbreeding (gene flow) between different populations after dispersal. Evidence of OOA - Homo sapiens fossils appeared in africa around 200,000 years ago and apperead at the same time as homo erectus and homo neanderthalensis. Because they were found at the same time then shows they cannot be ancestral so they existed as different populations. - mtDNA is passed down so can track ancestry through maternal (mothers) line over time like a biological clock and y chromosome in DNA can be used to track ancestry through paternal (fathers) line through checking genetic markers. Scientists can trace everyones ancestry through 1 female who lived in africa around 140,000 years ago using mtDNA. Also Y chromosome mutation is found in all non africans and appeared around 44,000 years ago so suggests that successful migration occurred. Overall suggests homo sapiens did evolve in african then left to europe and asia. - There is high genetic variation in african populations compared to Asian and European populations with low variation. This is because homo sapiens evolved in africa then left for asia and europe as founder populations so may have experiecned bottlenecks. Biological evolution - is the changes in genetic information that is passed from one generation to the next Cultural evolution - is the development of learned behaviours that is passed from one generation to the next Gene flow - is the movement of alles between different populations Trends in tool culture - Number of blows from 6-10 to 250+ - Changes from stone pebbles to various types of stone to stone, wood tools - All purpose tools to range of highly specilised tools Significance of tool culture innovation - Allowed change in diet from vegetation to meat based diet which is high in proten and fat. Did this via effective hunting and being able to fully butcher a carcass. Gave  them more energy so fuelled development of brain (size and complexity) which further improved tool culture and communication - Also upper palaeolithic tools such as bone needles helped manufacture tailored clothing and build shelters to survive in colder climates Tools - Oldowan: homo habilis, simple pebble tools, 6-10 blows, used to fully butcher carcass - Acheulean: homo erectus, quartz and flint tool, 50+ blows, tear drop shape used from chopping and scraping (butchering) food - Mousterian: homo neanderthalensis, flint tools, 150 blows, more specilised and advanced techniques for creatin sharper more efficient tools - Upper paleolithic, homo sapiens, multiple materials like bone and fliny, 250+ blow, specilised and diverse tools with fine blades and points e.g spear thrower, bone needle and fishing hooks - Neolithic: homo sapiens, greenstone, bladed tools for agriculture Fire - Homo erecutus was first hominin associated with use of fire Survival advantages of fire - Provides light so can have light at night so can spend more time making more tools and improving them - Provides warmth so allowed expansion into colder climates and survival during the ice ages - Fire scares away predators so increases survival from predators - Cooking food with fire makes it easier to chew and digest meat which is high in protein and fat for growth and energy supply Significance of fire - Cooking with fire made meat much more enjoyable and digestible (more nutrients). Fire improved nutrition as meat is high in protein and fat. This fuelled development of brain (size and complexity) which further improved tool culture and communication. Also led to reduction in jaw size as no longer needed large jaw muscles to chew food. - Fire allowed migration out of africa into colder climates and survival during ice ages. Homo erectus lived in northern africa during ice ages - More hours of light meant more hours for tool making, communication and teaching of skills - Communal fire increases social interactions which can improved communication, hunting prepartion, tool making etc. Communication - Homo neanderthalensis first hominin associated with use of language wernickes area of brain is in control of comprehension of spoken language Brocas area of brain is in control of speech production Significance of communication - Use of language helped cultural evolution expand at a much faster rate. Language allowed highly specialized tool cultures to be learnt and complex group hunting plans to be created so better hunting and more food etc. Spirituality - First deomstrated by homo neanderthalensis as they practised ritualised burial with body placed in east-west position with the legs curled up in a sleeping position and a head placed on a stone and facing south - Also surrounded body with flowers as evidence of pollen grains found at burial sites. This shows concept of after life as gift for the departed - Significance of spiritual beliefs suggests brain devlopment of complex abstract thought in order to imagine life after death and rituals Clothing - Homo neanderthalensis demonstrate introduction of clothing as bone punches found however is thought that these clothes were not very good - Homo erectus had more specilised tools so had more tailored clothing so could outcompete other species in cold climates as they had better protection from their warm clothes - Clothing gives survival advantage as provides warmth especially for species travelling to europe as they have icea ages - Clothing such as shoes also gives survival advantages when migrating by walking as their feet are protected so can walk further distances Hunter Gatherer: food gathering involving a nomadic lifestyle with division of labour to gather plant based food and hunt animal based food - Likely that women gathered the plants and men hunted the meat - Hunter gatherers are smaller mobile groups that had basic temporary shelters due to moving around a lot - They moved from place to place as their resources availability changed due to migration of animals they hunted and seasonal growth of plants farming/agriculture: more settled and much larger groups that had permanent settlements and buildings as they didnt move around much - Farming involved developing the land and physically change the environment, domestication of animals and plants - Farming allows continuous and reliable supply of food in one area so dont have to move around Domestication: is bringing in of an animal or plant under human control - It is believed that domestication of animals came before domestication of plants as nomadic lifestyle was common during this time Reason for domestication  - Climate change occurred as the world came out of their last glacial period so warmer and moisterer conditions which is suitable for agriculture e.g growing plants - Lack of food supply and increase in population numbers so grew more plants to procide more food - Lots of cultural evolution had occurred Advantages of domestication - People could use crops and animals from local environment which helped create a reliable and stable supply of food which enabled stable development of settlements - Domestication of plants and animals led to more availability of food sources that came with more nutritional benefits so increases survival in large populations - Warmer climate allowed crops to be grown at settlements so meant people didnt have to travel around to get food so could conserve energy and support larger populations - Provided possibility of trade with other groups which helps improve cultural evolution. Also trading milk as an example allows you to keep animal alive and also making a steady income Disadvantages of domestication - Many years of selective breeding has changed the characteristics of domesticated animals and plants to the extent that they can not survive without human intervention - Suceptible to damage of natural disasters like floods or droughts as could damage/wipe out their supply of crops - If use monoculture farming a disease could wipe out their whole supply as seen in ireland with their potatoes. A disease in ireland wiped out their nations suppy of potatoes and at the time this was their staple food supply so thousands of people starved to death - Many human diseases have evolved from animal diseases e.g cow pox - small pox - Permanent settlements caused pollution to be a probelm Shelter - Started with caves where homo neanderthalensis used this form of shelter during ice age to protect from snow and rain etc. - Then moved to temporary settlements like building tents etc. as they moved around a lot so allowed their shelter to be flexible and move with them - Permanent settlements like small homes and dwellings for agriculture where they didnt move around and stayed at these settlements permanently -