The scent of age.

Area of Science:

• Animal Behavior
• Chemical Ecology
• Olfactory Communication

Background:

• Mate selection often favors older males due to perceived genetic quality.
• The mechanisms by which females assess male age, particularly through scent, remain unclear.
• Chemical communication is crucial for many species, suggesting scent may indicate age.

Purpose of the Study:

• To investigate age-related changes in mouse body odor.
• To identify specific chemical compounds responsible for age-related scent differences.
• To determine if mice can discriminate age based on urine odor composition.

Main Methods:

• Mice were trained in a Y-maze to differentiate urine odors from adult and aged mice.
• Gas chromatography-mass spectrometry (GC-MS) analyzed the chemical composition of urine volatiles.
• Specific volatile compounds were manipulated to test their role in age discrimination.

Main Results:

• Mice successfully discriminated between adult and aged male urine odors based solely on scent.
• GC-MS revealed significant differences in urinary volatile ratios between age groups.
• Aged mice had higher levels of 2-phenylacetamide and lower levels of methylbutyric acids compared to adult mice.

Conclusions:

• Mouse urine odor composition changes with age.
• Specific volatile compounds, including 2-phenylacetamide and methylbutyric acids, are key indicators of male age.
• Mice utilize these age-specific scent cues for olfactory discrimination.