title: Enzymes provide demographers with food for thought.
abstract: Life expectancy has increased by 20 years since the middle of the last century, but children under five have fared better than adult males.
authors.affiliation: is in the  Modelling and Economics Unit ,  Health Protection Agency ,  London ,  UK , and  the Department of Infectious Disease Epidemiology ,  London School of Hygiene and Tropical Medicine ,  London ,  United Kingdom mark.jit@hpa.org.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Jit
authors.forename: Patrick
authors.initials: P
authors.lastname: Gerland
mesh_terms: D005260:Female; D015658:HIV Infections / Q000191:economics*; D006801:Humans; D007182:Income / Q000706:statistics & numerical data*; D008017:Life Expectancy / Q000639:trends*; D008297:Male; D015233:Models, Statistical; D012907:Smoking / Q000191:economics*