NCHHSTP Social Determinants of Health. Definitions. The National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention uses the words below to describe health equity and social determinants of health. These words are also used by the World Health Organization and the Department of Health and Human Service's Healthy People 2020.
Scientists have narrowed down several of the most likely causes of mass extinction. Flood basalt events (volcano eruptions), asteroid collisions, and sea level falls are the most likely causes of mass extinctions, though several other known events may also contribute. These include global warming, global cooling, methane eruptions and anoxic eventsâwhen the earth's oceans lose their oxygen.
Extinctions can happen for many reasons but recently people have been a major cause. Over hunting can led to extinction as can diseases, climate change or habitat loss which is when animalâs homes are destroyed. In the past, there have been very large extinctions where many species have gone extinct together. This is called an extinction event. One of these events wiped out the dinosaurs. 65 million years ago, all dinosaurs (except birds) went extinct as did many other types of plants and animals.