Dolphins are capable of “highly developed spoken language” which closely resembles human communication, scientists have suggested.
While it has long been acknowledged dolphins are of high intelligence and can communicate within a larger pack, their ability to converse with each other individually has been less understood.
But researchers at the Karadag Nature Reserve, Feodosia, Crimea, believe the pulses, clicks and whistles – of up to five “words” – made by dolphins are listened to fully by another before a response is made.
“Essentially, this exchange resembles a conversation between two people,” wrote lead researcher Dr Vyacheslav Ryabov in the study, published in the journal Mathematics and Physics.
Dr Ryabov said each pulse produced by a dolphin “is different from another” in its time span and the frequencies it emits.
“In this regard, we can assume that each pulse represents a phoneme or a word of the dolphin’s spoken language,” Dr Ryabov wrote.
However: “The dolphin’s speech unfortunately lies beyond the time and frequency characteristics of the human hearing, and is thus unavailable to humans.”
Annual dolphin hunt in Taiji, Japan
Annual dolphin hunt in Taiji, Japan
1/15 The annual dolphin hunt in Taiji, Japan
A bottlenose dolphin was seen floating on back before slaughter
2/15 The annual dolphin hunt in Taiji, Japan
Fishermen hiding their culture and tradition
3/15 The annual dolphin hunt in Taiji, Japan
Remaining pod swims just a few feet from the slaughter of their family
4/15 The annual dolphin hunt in Taiji, Japan
Dolphin drive out to sea
5/15 The annual dolphin hunt in Taiji, Japan
Lathered in blood, fishermen receive more transfers of dolphin carcasses
6/15 The annual dolphin hunt in Taiji, Japan
Fishermen enter the cove just after sunrise
7/15 The annual dolphin hunt in Taiji, Japan
A juvenile Bottlenose barely surfaces during drive out. The chances of survival are slim after 5 tormenting days in the cove
8/15 The annual dolphin hunt in Taiji, Japan
Cove Guardians Jac and Ian document the slaughter
9/15 The annual dolphin hunt in Taiji, Japan
SSCS Cove Guardian Leader Melissa Sehgal interviews for CNN
10/15 The annual dolphin hunt in Taiji, Japan
Fishermen in wetsuits hunt dolphins at a cove in Taiji, western Japan; U.S. ambassador to Japan Caroline Kennedy has expressed deep concern over the traditional dolphin hunt. Local fisherman corral dolphins in a secluded bay before killing many for meat
11/15 The annual dolphin hunt in Taiji, Japan
The selection process of dolphins, during the annual dolphin hunt in Taiji. With 250 dolphins, this was the largest round-up in years
12/15 The annual dolphin hunt in Taiji, Japan
The agitated dolphins in the cove during the selection process. According to Sea Shepherd, Japanese fisherman rounded up more than 250 dolphins, including babies and juveniles
13/15 The annual dolphin hunt in Taiji, Japan
Japanese fisherman are shown in the cove. Taiji town claims the hunt is an important ritual dating back centuries
14/15 The annual dolphin hunt in Taiji, Japan
A rare albino calf swims close to his/her mother as the pod was herded into the cove. Dolphins captured in the cove are either sold into captivity, or slaughtered and sold for consumption, despite pleas from animal conservationists around the world against the event
15/15 The annual dolphin hunt in Taiji, Japan
The process of selecting dolphins during the annual cull, which the mayor of the town defends 'on scientific grounds'
The study was conducted on two adult Black Sea bottlenose captive dolphins, a male named Yasha and a female called Yana.
The pair have lived for 20 years in a swimming pool, which measure just 27 metres by 9.5 metres and is four metres in depth. Without food rewards, a special audio system recorded the exchanges between the dolphins.
The noises emitted were of a different pattern to those produced in a pod.
Dr Ryabov continued: “The analysis of numerous pulses registered in our experiments showed that the dolphins took turns in producing pulse packs and did not interrupt each other, which gives reason to believe that each of the dolphins listened to the other’s pulses before producing its own.
“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.”
It has long been accepted that dolphins exhibit behaviours not found in other animals. For instance, they are known to have a self-identifying whistle and to communicate phrases to other dolphins in a pod.
The findings should provide incentive for humans to further develop relationships and improve communication with the creatures, Dr Ryabov said.