Eat junk, look good, die young

A study published today by Glasgow University scientists shows that finches given a poor diet briefly in early life become adults that can’t cope with ageing. Birds that had a low quality diet for just two weeks grew into adults with much lower levels of antioxidants in their blood, and such birds have shorter lives.

Antioxidants are a key part of the body’s defences against ageing; they reduce the damage caused by free radicals that are produced during normal metabolism. Animals cannot make these antioxidants (which include Vitamins A and E, and also carotenoids), so must get them from their food. The birds given the poor diet were not short of food, but the food they had was low in protein and vitamins. It is interesting that all the zebra finches were given the same normal diet after the early chick stage, so had been eating the same amount of these valuable substances for most of their lives. The birds all grew into apparently normal adults. However, it seems that the birds given the low quality diet early in their development were then less able to use the antioxidants that they ate when they grew up.

Professor Pat Monaghan, who led the study, said, ‘This work demonstrates a mechanism that links diet during early life to what happens much later. The reason for this has so far been poorly understood”

A further finding of the study is that birds, faced with a shortage of life-extending materials, choose to spend them on looking good to attract a mate rather than saving them for old age. Some antioxidants (such as carotenoids) are also used as pigments, often involved in red and yellow coloration. So there is potentially a conflict between the amount an animal invests in preventing ageing and the amount it puts into its body colouration. In the case of the zebra finches, the early diet of the birds did not alter the redness of their beaks, so there was no change in the amount of carotenoids used as pigments. Females prefer males with bright red beaks.

Pat Monaghan added, “Perhaps it’s not surprising that animals go for attracting mates rather than ‘saving’ for old age. Better red than, well, not dead in this case.”

The study was funded by the Natural Environment Research Council, and involved collaboration between biologists at Glasgow University and at the Scottish Agricultural College at Auchencruive near Ayr.