Causes of Population Increase Medical Advances One of the biggest reasons because they directly effect death rate New medicines and inoculations have added over 60+ years to the average life expectancy Disease diffusion – the spread of disease – does not occur as widely as it used to

Causes of Population Increase Quantity and quality of food Advances in agriculture help feed billions Technology has allowed most crops to triple in production in the last 100 years alone Rice, corn and potatoes are the three most significant crops

Causes of Population Increase Ethnic and religious issues Many cultures forbid the use of any form of birth control Many cultures focus on male children – women many have many children attempting to produce sons

Causes of Population Increase Economic issues If the economy if based on agriculture, the country likely has a high growth rate If the economy is based on industry or services, the country likely has a minimal or zero growth rate

Causes of Population Decline Natural Hazards and Disasters Millions of people live in areas that are subject to natural hazards Earthquakes, tornados, hurricanes, floods, tsunamis, volcanoes, blizzards, etc Can kill thousands of people at a time Famines and plagues lead to mass starvation and disease Famines are usually caused by natural disasters – like drought – or political upheaval Poverty and lack of health care leads to plagues

Causes of Population Decline War or political turmoil War causes death and refugees Cambodia – 1970s – the Khmer Rouge killed millions – “The Killing Fields” Refugees flee for fear of persecution or death if they remain – Rwanda and Uganda Global wars impact global populations – WWII was one of the highest losses of life globally

Causes of Population Decline Economic issues The number one reason people move is for economic concerns – better employment opportunities – “out-migration” Much of the Great Plains of the US is experiencing out-migration Migration does not affect global population levels – just where the people are living