Thursday, July 18, 2013

Elephants Never Forget

People often ask, ‘do elephants really never forget?’ Quite simply, yes an elephant never forgets. Elephants are extremely intelligent, social, long-lived and large brained animals. They possess remarkable memories of migration routes, water and feeding spots and they can remember the scents and vocalizations of many different individuals (both elephant and human). Thus, this is not just another elephant ‘myth’. This blog will look into the body of evidence surrounding this saying.

The elephant brain

Elephants have the largest brains among all land mammals, averaging 5 kg in weight. In theory, the larger the brain, the more cognitively complex it is. While we cannot judge brain efficiency on size alone, it can give us an indication of the power of elephant memory. One method of measuring intelligence and brain power among animals is to look at the ‘Encephalization Quotient’ (EQ). EQ compares the actual size of brain mass to the expected brain mass of a typical animal of that size (Jerison, 1973). Elephants have an average score of 1.88 (Shoshani et al, 2006), whereas chimpanzees have an EQ of 2.5 and humans 7.

Elephants have complex brain structures. They have the greatest volume of cerebral cortex available for cognitive processing of all land mammals. This enables them to have greater capabilities for learning and knowledge retention. Elephants also have a large neocortex, which is the part of the brain that is used for a working memory, planning and spatial orientation.

                                                                  Public Domain Clip Art

Memory of water and feeding sites

African elephants are known to travel vast distances in search of food and water. They can remember many different water sites which are thousands of kilometers apart. For example, in Namibia and Mali, the elephants have extremely large home ranges of up to 11,000 square kilometers. These large home ranges are due to the sparse distribution of water sources, which can be over 60 km apart. These elephants must remember the location of all these water sources in order to survive, even when some are only used once a year. This example indicates that elephants have exceptional cognitive mapping skills.

The elephants of the deserts of northern and southern Africa also provide another impressive example of the ecological memory of elephants.  They have been found to travel hundred of kilometers in order to reach remote water sources shortly after a period of rain. Sometimes they use routes which have not been used for many years, highlighting the incredible mental mapping memory of the matriarch (oldest and most knowledgeable elephant who leads the herd), which is dependent upon long-term memory of these matriarchs who have travelled on these routes previously, or who have been passed down this knowledge (McComb et al, 2001).

Memory of people

Elephants also have a great memory of people.  One study in the Amboseli, found that African elephants react negatively to the scent and sight of clothing belonging to the Maasai tribe. In Kenya, young Masaai men demonstrate their manhood by spearing elephants. Thus, the elephants are able to remember and associate the smell of the Massai with spearing, which is a threat to them (Bates et al, 2007).

My good friend and vet at GTAEF, Dr Cherry, always amuses me with her stories about her relationships with the elephants. One story which comes to mind, and highlights that elephants really never forget, is that of a little 6 year old elephant called Pumpui. A few years ago, Dr Cherry had to treat a hip abscess that Pumpui had. The treatment was probably quite memorable as, for a long time after the treatment, Pumpui would not let Dr Cherry approach her, maybe from fear of having the treatment again. Pumpui has now got over this event and she now lets Dr Cherry approach her. This sort of story is not uncommon for elephant vets, as it seems the memory of injections and other treatments is quite vivid for elephants!

As for me, after having worked here for over a year, there are elephants that seem to remember me. For example, whenever I see one elephant called Poonlarb, she will immediately open her mouth and expect food from me. She will just stand there with her mouth open, waiting. If I don’t have food, I will just rub her tongue, which she likes too! I think she formed this mouth opening habit and association with me through food because she remembers me from research. At research, we use Poonlarb frequently, and elephants that come to research always get lots of tasty food rewards for completing different tasks. I definitely see the forming of such elephant relationships as a perk of being a researcher!

                                                               Poonlarb and I              

Memory of other elephants

Elephants recognize each other even better than humans! It is believed that elephants are able to keep a mental record of many different individuals. Elephants use contact calls to stay in contact with each other. One study in Africa found that female elephants are able to remember and distinguish between the contact calls of closely related females (family and extended family) and non-related individuals outside the extended family. They can remember contact calls from around 14 different families in the population, which is approximately 100 adult females (McComb et al, 2000). Elephants are also able to keep track of individuals by their incredible sense of smell. They can identify at least 17 individuals by the scent of their urine. This is a useful technique for keeping track of the positions of individual family members (Bates, et al, 2008).

There are countless stories of elephants (related and non-related) who have been separated from each other, and then years later being reunited and remembering each other. For example, at ‘The Elephant Sanctuary’ in Tennessee, when two elephants were reunited, they displayed very enthusiastic greetings towards each other. One of the elephants called Shirley, also displayed unusual mothering behaviors towards the other elephant, called Jenny. Later on, it was discovered that these two elephants, Jenny and Shirley, had previously known each other. They were kept together in a circus while Jenny was only a calf and Shirley was 30 years old. They were then separated and reunited and were able to still remember each other 23 years later!

Memory of deceased elephants

Elephants have also been seen to display a variety of different reactions towards the bodies of dead elephants or elephant remains. It has been reported that elephants investigate elephant bones or tusks that they encounter. It has also been suggested that they visit the bones of dead relatives, suggesting a long term memory of individuals that had previously died.

Elephants really are quite remarkable animals. They really do ‘never forget’, which is quite a rare trait in the animal kingdom and suggests that elephants are not too dissimilar from ourselves. 


References
  • Bates, L.A., Sayialel, C.N, Njiraini, N.W, Poole, J.H., Moss, C.J. & Byrne, R.W. 2008. African elephants have expectations about locations of out-of-sight family members. Biology Letters: 4, 34-36.
  • Bates, L.A., Sayialel, C.N, Njiraini, N.W, Poole, J.H., Moss, C.J. & Byrne, R.W. 2007. Elephants classify human ethnic groups by odour and garment colour. Current Biology. 17, 1-5
  • Jerison, H.J. 1973. Evolution of the Brain and Intelligence. New York: Academic Press.
  • McComb, K., C. Moss, S. Durant, S. Sayialel, L. Baker. 2001. Matriarchs as repositories of social knowledge. Science 292: 491-494.
  • McComb, K., C. Moss, S. Sayialel, L. Baker. 2000. Unusually extensive networks of vocal recognition in African elephants. Anim. Behav. 59:1103-9
  • Shoshani, J., Kupsky, W.J. & Marchant, G.H. 2006. Elephant brain. Part I: gross morphology, functions, comparative anatomy, and evolution. Brain Research Bulletin 70: 124-157



2 comments:

  1. Elephants may be able to recognise themselfes better by smell, but humans have superior vision, so you can't compare two different species

    ReplyDelete
  2. Elephants may be able to recognise themselfes better by smell, but humans have superior vision, so you can't compare two different species

    ReplyDelete