An analysis of 20 urine samples from chimpanzees in Uganda found byproducts of ethanol in at least 17 samples, indicating that apes ingest significant alcohol from the fermented fruit in their diet.
Aleksey Maro knows far more than he cares to know about the urination habits of chimpanzees. But if you want to measure the alcohol intake of chimps in a Ugandan rain forest, where a breathalyzer is impractical, collecting urine for analysis is your only choice.
Last year, Maro and adviser Robert Dudley, UC Berkeley professor of integrative biology, documented that the fruits chimps eat in the wild contain enough alcohol from fermentation to provide around 14 grams per day — the equivalent of two standard drinks. But the proof is in the urine.
To perfect his urine sampling techniques, Maro, a UC Berkeley graduate student, worked alongside Sharifah Namaganda, a Ugandan graduate student at the University of Michigan who has experience collecting urine samples for previous projects at Ngogo. Under her guidance, he gathered forked branches and covered the ends with plastic bags, creating shallow plastic bowls suitable for stealthy sampling. Longer handles proved best to stay clear of the spray zone.
Maro then hung out under trees with feeding chimps, looking for signs of movement — they tend to urinate before leaving their feeding spot. The improvised collector worked well, though he discovered that a more reliable and less icky method was gathering the urine from leaves under the trees. He thought about staking out trees where chimps sleep, since, like humans, they urinate upon waking. Perhaps next time.
He also got samples from puddles of urine on the forest floor. When the urge hits while chimps are out and about, they like to straddle small logs, defecating on one side and peeing on the other. Who knew?