No silver lining for malnourished babes
Hard times Contrary to a popular theory, people born during hard times have no advantage when it comes to coping with future famines, suggests a new study.
Researchers from two UK universities looked at more than 3000 people -- virtually the whole populations of two isolated parishes -- who faced a severe famine in Finland between 1866 and 1868.
People who had been born in times of scarcity were more likely to die in this famine and were also less likely to have children in the famine years, says Dr Ian Rickard of Durham University, one of the authors of the study, published this week in the Proceedings of the National Academy of Sciences.
Genealogists waded through two Finnish parish registers - "huge leather tomes" - collecting information about all the people born in the parish during the 50 years prior to the severe famine who lived long enough to face it.
This was combined with detailed information on rye and barley yields from a large estate fairly nearby, which enabled the researchers to estimate how well each individual had been nourished in the womb.
"The crop data, I think, is really quite rare," says lead author Dr Adam Hayward of Sheffield University, "It provides an insight into the conditions they were facing."
Although crop yields were at their worst during the severe famine, they varied considerably over the 50 years before, with some people born in times of abundance and others at times of shortage.
Switching on thrifty genes?
The study tests an idea, known as the 'Predictive Adaptive Response' hypothesis (PAR), which suggests that people experiencing adverse conditions in the womb, permanently activate genes which put their metabolism into a 'thrifty' state, which is better at coping with hardship.
The notion is that the PAR gives people a life-time advantage in hard times, which has been selected for by evolution.
This comes at a cost though, because if these people encounter times of plenty in later life, it is postulated their programmed metabolic thrift makes them more susceptible to 'lifestyle' diseases such as diabetes, heart disease and cancer.
There is good evidence that poor nutrition in the womb makes people more prone to lifestyle diseases in later life, the authors say.
Contrary to the PAR hypothesis, this study found people born in harsh times did worse at weathering the Finnish famine (with survival rates 7 to 9 per cent lower than people well-nourished in the womb).
And women born in times of poor grain harvest were less likely to go on to have children during the 1866-68 famine, suggesting that natural selection was not acting in their favour.
"As an ecologist - which is where I'm coming from - in birds and mammals, having a bad start in life is universally bad for you, and it demonstrates to me that humans are similar to that." says Hayward.
The PAR is an interesting idea, he says, "but from an ecologist's point of view, it doesn't quite add up."
Hypotheses - there to be proven
Professor Caroline McMillen, an animal physiologist from the University of Newcastle, and an expert on the effects of poor nutrition in the womb on later metabolic health, thinks the study is important.
She says the PAR hypothesis is frequently invoked to explain why restricted growth in the womb leads to poor health later in times of plenty, but just because such findings seem to be consistent with the hypothesis it doesn't follow that it is correct.
"The PAR hypothesis has been championed actively by its proponents ... but I think the direct evidence for [it] is difficult," she adds.
She says the study shows "having a period of hardship in utero is actually associated with poorer survival and reproductive success [in later famine], which is inconsistent with the premise of the PAR."