Can we explain why Brazilian babies are becoming lighter?

Can we explain why Brazilian babies are becoming lighter?

BACKGROUND We tried to explain why a marked decrease in birthweight of 122 g occurred over a 15-year period in Ribeirão Preto, Brazil. METHODS Factors reflecting biological, social, and health care characteristics (infant gender, parity, maternal age, marital status, type of hospital, maternal smoking, preterm birth, small for gestational age [SGA], and prenatal care) were assessed on 6711 ne...

Evolutionary theories of aging can explain why we age.

Evolutionary theories of aging explain why we age. These theories take into account the fact that, in the wild, mean lifespan of many species is usually shorter than it could be in protected environments. In such conditions, because most of animals die before reaching old age, there is no selection in favor or against alleles with effects at old age. Alleles with negative effects at this age ca...

We can prevent mothers from dying and babies from becoming infected with HIV

Are we becoming less disposable?

Time and again we see not only does our mean life expectancy keep increasing (Fig 1), but also that this linear increase means that all predictions of our maximum life expectancy so far have turned out to be gross underestimates (Oeppen & Vaupel, 2002). Today, citizens in developed countries can easily expect to live beyond the age of 75 years—81 for women—but if we take Fig 1 as an indication,...

Possible reason why leptons are lighter than quarks.

The minimal model of spontaneously broken leptonic colour and discrete quarklepton symmetry predicts that charged leptons have the same masses as their partner charge +2/3 quarks up to small radiative corrections. By invoking a different pattern of symmetry breaking, a similar model can be constructed with the structural feature that charged leptons have to be lighter than their partner quarks ...