Dolphins Keep Tabs on Each Other by Tasting Pee, Especially if It's Pee From a Friend

Think about people you know, and how you could tell if they were around even if you couldn't see them.

The taste of urine and signature whistles allow bottlenose dolphins to recognize their friends at a distance, according to a study published Wednesday.

The first author of the book said that dolphins keep their mouths open and sample urine longer from familiar people.

This is important because dolphins are the first animal to have social recognition through taste alone.

The team, which included Sam Walmsley andVincent Janik from the University of St Andrews, wrote that the use of taste could be beneficial in the open ocean because urine can linger for a while after an animal has left.

Even if the individual had not signaled its presence, this will alert the dolphins.

It has been difficult to answer the question of whether animals can attach labels to their friends.

An interesting test case was the bottlenose dolphins, who use signature whistles to address specific individuals, and can remember these for over 20 years.

The dolphins were presented with urine samples from familiar and unfamiliar people, and they spent three times as long sampling urine from those they knew.

In social interactions, dolphins use their jaws to touch the genitals of others, giving them a chance to learn the taste of urine.

The dolphins were trained to give urine samples on demand in exchange for food.

The team is certain that it was taste and not smell, because they don't have olfactory bulbs.

For the second part of the experiment, the team played recordings of signature whistles from the same dolphin that provided the urine sample, or a different dolphin that provided a different sample.

The two congruent lines of evidence together evoked more interest when the vocalizations matched the urine samples.

It is not every day that scientists find evidence of a non-human vocal system using signals. That is pretty exciting.

It may be beneficial for a dolphin to recognize alliance members as it is for them to recognize potential antagonists, he said.

The team suggested that the individual chemical signatures were likely caused by lipids.

The recognition skills revealed in the study suggest that dolphins can use other information from urine, such as reproductive state, to influence each other's behavior.

In a surprising twist, the research could have implications for human weight gain, as the same genes that allow dolphins to identify lipids in urine are present in humans.

Understanding how the genes work in people could be improved by studying the genes in dolphins.

The work could have other implications, such as pollution caused by oil spills or other chemicals that may impede the dolphins ability to signal one another, thus doing even more harm than previously thought.

Agence France-Presse