Sperm whales may have their own ‘alphabet’
MIT scientists used machine learning to analyze their complex communications system.
Sperm whales have their own unique cultures, accents, and potentially a phonetic alphabet. A team from MIT’s Computer Science & Artificial Intelligence Laboratory (CSAIL) and Project CETI (Cetacean Translation Initiative) may have decoded this phonetic alphabet that reveals sophisticated structures within sperm whale communication that could be similar to human phonetics and other animal linguistic systems.
“Sperm whale calls are, in principle, capable of expressing a wider space of meanings than we previously thought!” MIT computer science graduate student Pratyusha Sharma tells PopSci. Sharma is a co-author of a new study published May 7 in the journal Nature Communications that describes these findings.
Sperm whale ABCs
With some of the largest brains of any species on Earth, sperm whales have complex social behaviors. They travel in pods and have various cultural groups that dive and hunt together and even take turns looking after younger whales. They do this all in almost complete darkness, so they need strong communication to coordinate their lives in the ocean’s deepest depths.
[Related: Science Says Sperm Whales Could Really Wreck Ships.]
Sperm whales use a complex system of codas–short bursts of clicks–to communicate. In this study, the team collected 9,000 codas from sperm whale families in the Eastern Caribbean sperm observed by The Dominica Sperm Whale Project. They used acoustic biologging tags, called D-tags that were deployed on whales. The D-tags captured details of the whales’ vocal patterns.
The team found that these short groups of clicks vary in structure depending on the conversational context. With this data in hand, they used a mix of algorithms for pattern recognition and classification, and on-body recording equipment. It revealed that the communications were not random or simple, but more structured and complex.
The sperm whale’s essentially have their own phonetic alphabet. Various auditory elements that the team call rhythm, tempo, rubato, and ornamentation work together to form a large array of distinguishable codas. Depending on the context of the conversation, the whales can systematically modulate certain aspects of their codas. They may smoothly vary the duration of the calls–rubato–or add in some extra ornamental clicks. The team also found that the building blocks of these codas could be combined in various ways. The whales can then build many distinct vocalizations from these combinations.
“The sperm whale communication system is a combinatorial coding system,” says Sharma. “Looking at a wider communicative context allowed us to discover that there is fine-grained variation in the structure of the calls of sperm whales that are both perceived and imitated in the course of their exchange.”
Using AI
The team developed new visualization and data analysis techniques that found individual sperm whales could emit various coda patterns in long exchanges. Using machine learning is important for pinpointing the specifics of their communications and predicting what they may say next.
[Related: How bomb detectors discovered a hidden pod of singing blue whales.]
Scientists are interested in determining if these signals vary depending on the ecological context they are given in and how much the signals follow any potential rules similar to grammar that the listeners recognize.
“The problem is particularly challenging in the case of marine mammals, because scientists usually cannot see their subjects or identify in complete detail the context of communication,” University of Pennsylvania Psychology Professor Emeritus Robert Seyfarth said in a statement. “Nonetheless, this paper offers new, tantalizing details of call combinations and the rules that underlie them in sperm whales.” Seyfarth was not involved in this study.
Alien communication on Earth
In future studies, CETI hopes to figure out whether elements like rhythm, tempo, ornamentation, and rubato carry specific intentions when communicated. This could provide insight into a specific linguistic phenomenon where simple elements are combined to present complex meanings. This “duality of patterning” was previously thought to be unique to human language.
Research like this also parallels hypothetical scenarios in which humans contact alien species and need to communicate.
“It’s about understanding a species with a completely different environment and communication protocols, where their interactions are distinctly different from human norms,” says Sharma. “Essentially, our work could lay the groundwork for deciphering how an ‘alien civilization’ might communicate, providing insights into creating algorithms or systems to understand entirely unfamiliar forms of communication.”
