Humans are very loud animals. He babbles and sings and he invents technical devices that constantly click, beep or make other strange noises. People build roads into the most remote corners, on which traffic is noisy day in day out and even at night.
It is obvious that this constant noise pollution harms many living beings – including people themselves – and has already been proven in several studies. Researchers led by Alizée Meillère from Deakin University in Australia have now shown that human noise causes damage even in embryos, i.e. before birth, which continues into adulthood.
For their study, which is currently in the science journal Science published, the researchers exposed zebra finch eggs to traffic noise and the chirping of other zebra finches – both at a volume of 65 decibels, which, according to the researchers, corresponds to the natural background noise. A third group was subjected to absolute silence.
The study is also notable because the harmful effects of noise on unborn life have long been suspected, but it is very difficult to clearly prove them. Finally, negative consequences such as developmental delays or slower growth after birth can also be due to the fact that it is not the embryo itself that has been damaged, but rather that the parents are stressed by the noise and are therefore less able to care for their offspring.
Road noise had a drastic effect on the chicks in the egg
In order to rule out such indirect effects, the researchers took the eggs of zebra finches that were breeding in an aviary from the nest in the evening five days before the chicks hatched and exposed them to different noises in an incubator, or not at all. In the morning they put the eggs back in the nests, where they were further incubated by the parents.
The effects of exposure to street noise were drastic: the embryos died significantly more often before hatching than when exposed to sound with chirping. “The hatching success in the silent group was somewhere in between,” the researchers write in their study. According to the results, chicks that hatched despite being exposed to traffic noise suffered disadvantages throughout their lives: They grew more slowly as young birds and had fewer offspring as adults, which the scientists examined once at the age of two and once at the age of four .
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The zebra finches exposed to street noise also differed from the birds in the other two groups in terms of cell biology. Among other things, their telomeres – genetic structures at the ends of chromosomes – were shorter. The researchers interpret this as an indication of severe cellular damage. “Our results suggest that the effects of noise pollution are more profound than expected,” the authors write in Science.
According to Hans Slabbekorn of Leiden University in the Netherlands, the study results could mean that noise could also have worse effects on human babies than previously thought. “In humans, acoustic life also begins before birth and noise can have an impact on the unborn child in utero,” writes Slabbekorn in an accompanying commentary Science . Especially in hospitals, i.e. where particular attention should be paid to the well-being of mother and child, noise pollution is often very high.
Newborns are also often exposed to high levels of noise in the hospital – for example from constantly beeping devices, conversations from hospital staff or frequent telephone calls. “This can lead to deterioration in health,” writes Slabbekorn.
If the noisy human animal were to become a little quieter, for example through technical innovations, it would not only benefit nature, but also humans themselves.