Humans are not the only animals to get drunk, and the symptoms can be remarkably similar in other species. The latest example is that zebra finches, after hitting the bottle too hard, can't stick to their melody any more than the karaoke enthusiast who had a few too many waiting their turn for the mike.
“Speech impairment is one of the most intriguing and least understood effects of alcohol on cognitive function, largely due to the lack of data on alcohol effects on vocalizations in the context of an appropriate experimental model organism,” write a team led by Dr Claudio Mello of Oregon Health and Science University in PloS ONE. The authors decided to see if zebra finches could fill the gap. While not capable human sounds lile parrots, or lyrebird level mimicry, male zebra finches are enthusiastic singers
Finches keep the same song from adulthood, often with similarities to those they heard growing up. This, along with their easiness to breed, have made them a popular animal for studying speech acquisition.
Being native to the central Australian deserts, zebra finches like a drink and the researchers found that this applies to alcohol as much as water. Once drunk, their song takes on an “altered acoustic structure.” The authors note, “The most pronounced effects were decreased amplitude and increased entropy, the latter likely reflecting a disruption in the birds’ ability to maintain the spectral structure of song under alcohol.” So while the notes became more random, they also became softer – something many of us might have wished for when the neighbors got into Bohemian Rhapsody towards the end of a well lubricated party.
Mello and colleagues add, ”Furthermore, specific syllables, which have distinct acoustic structures, were differentially influenced by alcohol, likely reflecting a diversity in the neural mechanisms required for their production.” Yep shlurring those esshes ish not jusht for humansh.
One bird, because there is always one, became so much more likely to sing when drunk that he skewed the whole sample, but when his data was removed the effect lost significance for the remaining birds.
In order to achieve these effects the birds didn't have to get all that drunk – their blood alcohol concentration was enough to get a human booked for DUI but not paralytic, and other behavior was unaffected. The researchers didn't ask the birds to walk a chalk line, but note, “We did not detect visible effects on the birds’ general behaviors or health, as indicated by the normal appearance of feathers and the ability to perch, feed, maintain normal posture and fly inside the cage.”
The researchers hope to study the impact on finch brain circuits to gain insight into the effects on humans, as well as seeing how alcohol affects the ability of adolescent finches to learn to sing.
December has been something of a red letter month for Mello, who was part of team to publish a set of 23 papers mapping the family trees of bird species back to the dinosaurs.