Humpback whales: Are they altruistic mammals?
Humpback whales have been found to protect other species from killer whales, even when fresh krill is nearby.
In black-and-white uniforms, humpback whales are the ocean's first responders, at least when it comes to orca attacks.
Marine ecologist Robert Pitman observed this behavior in 2009 when a pod of killer whales knocked a seal off an ice floe in Antarctica, but was prevented from killing it by a humpback, who lifted the seal and placed it on its belly to keep it out of water until it was out of harm’s way.
Dr. Pitman and his team analyzed 115 such rescue incidents from published and unpublished sources for a paper published in last month’s issue of Marine Mammal Science. Their goal: To understand exactly how and why humpback whales go out of their way to become small-creature-saving heroes.
Are the whales responding based on personal history or experience with orcas? The study finds that only 11 percent of orca victims that humpback whales tried to save were humpback whale calves; they aren't just protecting their own. Other marine creatures that humpbacks have saved include gray whales, harbor seals, California sea lions, and ocean sunfish, raising questions about whether the ocean giants are altruistic toward other species.
“Interspecific altruism, even if unintentional, could not be ruled out,” the researchers report.
Humpback whales are the “only cetacean that deliberately approaches attacking [mammal-eating killer whales] and can drive them off,” the study notes. Studies have recently shown that orcas regularly attack humpback calves and juveniles, but rarely the adults.
Still, personal history could influence a humpback’s decision to intervene. Many that do attack orcas bear scars from their younger years, Alisa Schulman-Janiger, a whale researcher with the California Killer Whale Project who coauthored the study, told National Geographic. As adults, they could act protectively to help younger whales make it through their most vulnerable stage. Responding to non-humpback victims could be accidental: humpbacks could be responding to the killer whale’s auditory signal, rather than to the species in trouble, for example.
Humpbacks, however, could truly be altruistic. “Although this behavior is very interesting, I don’t find it completely surprising that a cetacean would intervene to help a member of another species,” Lori Marino, an expert in cetacean intelligence and president of the Whale Sanctuary Project, told National Geographic.
Ms. Marino described humpbacks as intelligent problem-solvers and communicators. “So, taken altogether, these attributes are those of a species with a highly developed degree of general intelligence capable of empathic responses,” she said.
Altruism is not unique to humans. As The Christian Science Monitor reported, even rats have been found to display altruistic and prosocial behavior.
Scientists are moving toward a startling conclusion: humans can no longer claim that they are the only ones with an elevated sense of morality. For instance, studies have found that chimpanzees will give food to one another when given the opportunity. So will dogs.
Scientists are learning that prosocial behavior, that is helping others with no direct personal benefit for oneself, is far more common than previously imagined in the animal kingdom.
Because it’s difficult to conduct controlled experiments with 30- to 50-ton humpback whales, however, no conclusions can yet be drawn about their motives. “As biologists,” Pitman told National Geographic, “that is where we should start our search for explanations.”