If you've ever been unfortunate enough to be stuck on public transportation with poor ventilation while a bunch of high school students boarded the bus after a long day at work, you'll know that teenagers smell bad. This is an objective fact. They stink.
We know that along with a series of developmental changes during puberty, the unique odor of teenagers comes from the hormonal activation of sweat glands. The combination of sweat and a unique microbiome produces an odor that is arguably unique.
But until now, the actual chemical makeup of this distinctive body odor has remained relatively unknown. A new study led by a German research team has for the first time compared the chemical composition of adolescent and infant body odor, finding the exact compounds that make babies smell like flowers and teenagers like lamb.
The study brought together two groups - 18 infants aged 0 to 3 years old and 18 adolescents aged 14 to 18 years old. Each subject slept overnight wearing a pre-treated cotton T-shirt with pads under their armpits. In the 48 hours before the study night, each subject adhered to strict dietary and hygiene protocols and did not use fragrance-containing cleaning products or eat spicy foods.
The researchers then analyzed the cotton pads using various methods including gas chromatography-mass spectrometry and gas chromatography-olfactometry. Based on this data, the researchers broke down body odor into 42 different odor-active compounds.
Overall, the study found that the chemical composition of body odor was relatively similar between the infant and adolescent groups. However, the researchers also found some key quantitative differences that are thought to account for the disparity in body odor between the two groups.
In infants, a compound called alpha-isomethylionone was detected in large amounts. This compound produces a violet-like smell. Another unknown "perfume scent" differentiates babies from teenagers. The researchers speculate that the pleasant smell may be the residue of perfumed detergents or cleaning products, which may remain on the baby despite rinsing for 48 hours.
Teenagers, on the other hand, have a much stronger odor. In addition to some new compounds that have only been discovered in teenage body odor, a number of compounds such as 4-ethyloctanoic acid (described as smelling like "goat") and dodecanoic acid (described as "waxy") were also detected.
Two steroid compounds—5α-androsten-16-en-3-one and 5α-androsten-16-en-3α-ol—were found only in adolescent samples. These compounds have been described as having an odor similar to sweat, urine, musky, and sandalwood.
One of the important takeaways from this study is that it is hypothesized that the main reason why babies smell better than teenagers is due to a lack of these specific steroid compounds. It's not so much a matter of babies naturally smelling good, but rather that they simply don't emit certain unpleasant-smelling steroid compounds.
So, the weird smells on teenagers are real, and they do smell a little like goats and urine.
The new research is published in the journal Communications Chemistry.