For the first time Russian researchers have recorded a conversation between two dolphins -- Yasha and Yana -- who were talking to each other in a pool. An anonymous Slashdot reader quotes The Telegraph: Scientists developed an underwater microphone which could distinguish the animals' different "voices" [and] have now shown that dolphins alter the volume and frequency of pulsed clicks to form individual "words" which they string together into sentences in much the same way that humans speak.
"This language exhibits all the design features present in the human spoken language, this indicates a high level of intelligence and consciousness in dolphins, and their language can be ostensibly considered a highly developed spoken language, akin to the human language... Humans must take the first step to establish relationships with the first intelligent inhabitants of the planet Earth by creating devices capable of overcoming the barriers that stand in the way of using languages and in the way of communications between dolphins and people."
The dolphins listened to an entire "sentence" before replying, according to the article, which points out that dolphin brains are larger and more complex than the brains of humans.