Another explanation of different in levels of illness and life expectancy is natural or social explanation. This explanation believes that people are in low class because they have poor health and have lack motivation and energy needed to get a job or promotion. It suggests that ill health causes people to fall into poverty, rather than poverty causing ill health. On the other hand, weaknesses of this explanation is poor health is result of poverty and deprived circumstances and not a cause of it. Trends and patterns suggest that people in lower social groups according to this theory will suffer more ill health and premature deaths because they are naturally less health and fit.