Can elephants smell danger? Dr. Lucy Bates and her colleagues at the Amboseli Trust for Elephants demonstrate that elephants have a unique combination of cognitive capacities: great senses of smell, impressive memories, strong social bonds and relatively sophisticated communication skills.
"People often think of elephants as being very intelligent," Bates said. "The research so far does support the old adage that elephants have good memories ('elephants never forget') but the evidence also suggests that elephant memory is far more impressive and complex than simply remembering lots for a long time."
Image courtesy of Tom Curtis/FreeDigitalPhotos.net. African Elephant.
Bates wanted to find out if elephants utilize their powerful memories to recognize potential threats. The more than 1400 African Elephants (Loxodonta africana) in the Amboseli National Park in Kenya encounter various humans, including members of two ethnic groups, the Maasai and the Kamba.
The Kamba people, agriculturalists who eat a variety of foods such as meat, vegetables, and maize meal, don't hunt or otherwise hurt the elephants. On the other hand, young Maasai men, who traditionally wear bright red garments, have been known to spear elephants, especially those elephants that attack the Maasai cattle. Maasai culture relies on cattle; the Maasai drink cow's milk and eat cow meat and blood and use animal fat as body paint. Further, because their animals are so important to their survival, they often keep them inside their villages and even in their homes. Such close contact with cattle "does give their homesteads a distinctive smell and I think it is also reflected in their body odor," said Bates.
To discover whether elephants associated these distinctive smells with the two ethnic groups, Bates and her colleagues studied the elephants' reactions to three different shirts: one unworn, one worn by a Maasai man for five days, and one worn by a Kamba man for five days. The researchers then placed the shirts in a field and set up video camera to record the elephants' reactions.
The elephants' fear (as measured by the speed and distance they ran directly away from the shirt, the time it took them to relax again, and whether they chose to head for the relative safety of tall elephant grass) varied significantly for the three different shirts. Fear was greatest for the shirt worn by the Maasai man and least for the unworn shirt.
The elephants never got within 10 meters (about 30 feet) of any of the shirts, and were probably unable to see them. Thus, the researchers concluded that their reaction was based on odor alone.
That's an impressive feat of smelling, but sensory perception far beyond that of humans is relatively common in the animal kingdom. The surprising part is that the elephants were able to use that information in a rational, intelligent way; they were able to react according to the magnitude of the threat. Part of this ability comes from learning through personal experience; all of the elephants studied have probably had some exposure to Maasai and Kamba people, who live in the areas around Amboseli National Park and the Maasai sometimes bring their cattle into park areas. "Most of these interactions are not violent or aggressive," Bates said, "but they probably all are negative in some way for the elephants." Remember: even the odor of the harmless Kamba agitated the elephants more than the odor of an unworn shirt; they ran away much faster and took much longer to relax again.
Still, how did the elephants know that the Maasai odor posed a greater danger than the scent of a Kamba man? After all, only some of the elephant groups studied had members who had been speared by a Maasai, but all groups reacted more strongly to the Maasai-worn shirt than to either of the other two.
This knowledge is probably shared with all of the elephant groups in the area through social learning. "Elephant groups spend quite a lot of time with other families, so there is plenty of opportunity for them to observe the fearful reactions of families that do have direct experience of spearing," Bates said. "From watching the intensity of the fear reaction (quickly running far away, into tall grass, and taking a long time to relax) of groups that have been speared, the other families would quickly learn to associate the smell of Maasai with serious danger, and react the same way themselves."
"Therefore, this experiment also demonstrates that communication and 'social memory' have to be employed," Bates said. "Elephants rely heavily on shared knowledge, even between different family groups."
In a second experiment, Bates and her colleagues showed that elephants react more aggressively to red cloth than to white cloth. Well, you might say, that's not too surprising; we often think of red as being an "aggressive" color. (Of course, bulls are actually colorblind, and so are not reacting to the color the matador's red cape, but that's another discussion). However, as the article mentions, red looks fairly drab to an elephant's eye. Thus, Bates and her colleagues have concluded that the elephants connect the color red to the Maasai and their traditionally red clothing, and therefore to danger.
It appears that the elephants' ability to classify people into categories is both a result of social bonds and caused by them. "It is probably based on the same kind of brain architecture/cognitive processing which allows elephants to learn and remember the identities of so many other elephants, and so be able to work out which elephants are familiar, and which are strangers," Bates said. "Elephant families can range over such large distances and not always be close together. They use contact calls that can travel up to 10km to remain in contact, so it is important that they can classify the calls they hear as being from known individuals or strangers. Perhaps their classification ability actually evolved because of these social pressures."
Neuroscientists are always interested in how the structure of the brain relates to its function (in other words, how structure relates to cognitive abilities). "The ability of elephants to distinguish between two groups is based on their sensory perception and their learning and memory ability," Bates said. The olfactory bulb (which processes scents) and the hippocampus (which plays an important role in memory consolidation) are disproportionately large in elephants. Could this play a role in elephants' excellent olfactory senses and their impressive memories? Indeed, they do seem to surpass humans in both respects, but more research is needed. Still, "So far, the elephant's ability to split members of a single species into further sub-groups is a unique one," Bates said.