As in wealthy countries, most people in poor countries die from curable illnesses, such as lung infections and diarrheal diseases [source: WHO]. That fact suggests that low-income nations need more than cures. They need preventions, like sanitation and health education. They also require the money to pay for treatments, and the experts and clinics to distribute them.
In our imaginary world, we'll pretend cures come for free and with the necessary infrastructure. If so, children would benefit first. Children die at much higher rates in poor countries than in rich ones. If you live in Chad, you're about 50 times more likely to die before age 5 than if you live in Denmark [source: WHO]. The youngest ones pass on as babies because they're premature, weigh too little, or the mother or baby suffers stress during birth [source: WHO]. The rest expire mostly from pneumonia and diarrheal diseases [source: WHO].If these killers never existed, women would need fewer pregnancies to have families of the same size, which could allow them to spend less time pregnant or grieving.
If these sicknesses suddenly disappeared, there'd be more babies and children running around the developing world, at least at first. To explore what a lower death rate would do for low-income countries in the long term, see our article on a world without illness.
Put away your malaria pills and suit up for a futuristic voyage of the HMS Beagle. We'll now predict what cures could mean for human evolution.