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.
The fifth one was 65 million years ago, when the dinosaurs vanished. Today we're losing biodiversity at a similar rate. And this is, of course, an anthropogenic mass extinction. The primary cause is human communities. But what we're trying to do in extinction studies is to think about scale in different ways.