A Japanese biologist studying the social structure of sperm whales has discovered that the phrase "Saturday's for the boys," translates into echolocation.

His research reveals that male sperm whales form strong platonic social bonds among other, normally solitary males-shedding light on the mammalian evolution of bromance.

Famous for spending time hunting in the depths of the ocean, or roaming it lone-wolf style, male sperm whales are not easily researched. Their female halves normally live together in pods of matriarchal leadership, casting males out, much like elephants, when they reach sexual maturity.

It's long been thought that this was the whole story for male sperm whales, but they actually maintain close male-to-male relationships that can stretch not only across years, but across meetings.

The first evidence that this was the case were mass stranding events that consisted only of males, which led whale biologist Hayao Kobayashi to spend thousands of hours aboard whale-watching vessels collecting observational data.

In total, his study reports that twenty pairs of sperm whales observed between 2006 and 2017 in the Nemuro Strait, Japan, were repeatedly seen associating with each other for periods between 2 and 5 years. One pair was found to have spent 26 days hanging out over a period of 5 years. Elephant males associate in similar ways, pairing together for poorly understood reasons outside of the mating season.

Kobayashi's study reporting the findings suggests that the behavior is down to habitat, and that in areas where food is unreliably available, or where predators are numerous, male sperm whales start associating together.

A whale is a huge animal for any predator to tackle, plus the sperm whale has massive conical teeth. Two together puts them essentially beyond reckoning for even the largest squid or shark.

In terms of hunting, Kobayashi told Hakai Magazine that two males could hunt more effectively or share information about hunting environments through echolocation.

Friendship is a complex animal trait, and understanding it outside of primates is difficult, but knowing whales get the lads together for a weekend fishing trip is a fascinating discovery, and Kobayashi feels that the more we discovery about whales, the more similarities we will discover between them and us.

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