Elephant Sense and Sensibility

by Michael Garstang

  Finding a mate, avoiding a predator, or effectively using sound to share food

  resources are all seriously impaired. Research shows that elephants on these sa-

  vannas, in common with a number of other animals, rarely use their loud, low-

  frequency calls during the middle of the day (Garstang et al., 2005).

  Predisposed by their evolution in forests, elephants are equipped with un-

  usually effective sound-producing and -detecting systems coupled with extraor-

  dinary olfactory sensors. Sound and smell for these species play a fundamental

  and pervasive role in their day-to-day lives and in the ultimate evolution as a

  species. When asking how an elephant’s mind works, these evolutionary under-

  pinnings must govern much of our thinking about elephant cognitive abilities.

  In our attempt to understand the mind of an elephant, we must think in terms

  other than those that guide the primates. Not only will this reveal evolutionary

  parallels between two quite divergent species but will surely provide us with a

  better understanding of the cognitive powers of this great animal.

  Chapter 3

  An Elephant’s Brain

  Current neural research has tended to move away from seeking to assign spe-

  cific functions to anatomically different parts of the brain. Evidence of the

  interconnectivity of the brain, the degree of feedback between different parts

  of the brain, and the speed and number of signals transmitted over very short

  time periods (seconds and less) all suggest that only limited understanding can

  be gained from the examination in isolation of any single part of the brain.

  Intelligence, which has always been difficult to define, now seems to reside

  everywhere and nowhere (Holdrege, 2001).

  The complexity of the brain is illustrated by our struggle to make computers

  simulate the brain. Early optimism in the wake of the development of computers

  (1960s) promised artificial intelligence that would begin to challenge humans.

  The multiple feedback loops operating in the brain could not be simulated by

  simple input–output devices. It was not until 50 years later when computers

  could be programmed to make choices based on statistical probabilities that an

  approach to “thinking” was achieved and demonstrated by the performance of

  IBM’s Watson on the television program Jeopardy in 2011.

  Having taken due note of the difficulties inherent in trying to think like an

  elephant and avoiding reliance upon a reductionist approach, we can, with cau-

  tion, draw some benefits through the comparison of component parts of the

  human and elephant brains.

  The elephant’s brain is three to four times larger than a human brain, weigh-

  ing an average of 5.0 kg (11 lbs) compared to 1.45 kg (3.8 lbs) for a human brain.

  Elephant female brains are slightly smaller than those of males (4.677 kg or

  10.3 lbs). This difference is displayed in the brains of humans (Shoshani et al.,

  2006). The heaviest known elephant brain on record weighed in at 9.0 kg or

  19.8 lbs. When the brain is scaled to the body weight, the ratio is 1/600–1/700

  for the elephant compared to 1/50 for a human and 1/40 for a dolphin. The en-

  cephalization quotient (EQ), which is the ratio of the observed brain size to the

  average brain size for the weight of the animal such that the average EQ = 1, has

  been used as a rough guide to intelligence. With EQ less than 1, intelligence is

  assumed to be less than average. With an EQ greater than 1, intelligence is as-

  sumed to be above average. Humans have EQs between 7.33 and 7.69, the next

  highest are chimpanzees, with EQs between 2.18 and 2.49. Elephants at the top

  end of their EQ scale (2.36) rank higher than the rest of the great apes, monkeys,

  Elephant Sense and Sensibility. http://dx.doi.org/10.1016/B978-0-12-802217-7.00003-X

  Copyright © 2015 Elsevier Inc. All rights reserved.

  9

  10 Elephant Sense and Sensibility

  lemurs, and other mammals measured. Intelligence, as stated above, remains

  difficult to define. Shoshani and Eisenberg (Holdrege, 2001) define intelligence

  as the “capacity to meet new and unforeseen situations by rapid and effective

  adjustment of behavior.” We progressively identify here behavior that can be

  related to intelligence.

  The brain of an elephant calf at birth may be as high as 53% of its final size,

  but it may not reach full weight before the 15th year. Human brains at birth are

  25% of their final weight, doubling in the first year and by the 6th year have

  reached 90% of final weight. The final weight of the human brain is reached in

  the 16th or 17th year. Brain size is certainly related to body size, motor skills,

  and the environment. The size of an elephant demands extensive motor controls.

  The tallest modern-day elephant, found as a skeleton in Namibia, measured over

  4 m (14 ft) at the shoulder. These tall, long-legged desert elephants are not the

  heaviest. The heaviest bull elephant, the African savanna elephant, probably

  weighs over 7 ton (14,000 lbs). Yet these giants can move through thick bush

  or forest in deathly silence. Elephants tend to use favored game trails, which

  can be centuries old (early aviators in Africa found game trails a reliable means

  of navigation in trackless regions of the continent). The surface of these trails

  is often a mixture of sand and fiber from centuries of droppings, producing a

  soft, spongy surface that can be trodden in silence. Elephants exercise consid-

  erable control over vegetation. By breaking branches and pushing over trees,

  they serve as a keystone species keeping savannas open to grasslands and sup-

  porting ungulate populations (Figure 3.1). Elephants have been termed mega-gardeners. Campos-Arceiz and Blake (2011) estimate that African elephants

  disperse seeds from at least 335 plant species and 213 genera. The acute olfac-

  tory sensors of elephants are used to locate seeds and fruit. Excellent spatial and

  temporal memories enable them to locate fruit when ripe. Savanna elephants

  are estimated to distribute over 2000 seeds per square kilometer every day.

  Some 15 tree species have been found dispersed by elephants over distances as

  great as 50 km (31 mile). Such dispersal is far more successful than germination

  around the parent tree. Seeds dispersed by elephants germinate 57% of the time,

  whereas only 3% of the seeds fallen under the parent tree germinate.

  In the Salonga National Park in the Democratic Republic of the Congo,

  Beaune and colleagues (2013) found that seeds from most plant species are

  dispersed by animals rather than by wind, water, or ballistic mechanisms.

  Elephants and bonobos were found to be the largest seed dispersers. They es-

  timated that 85% of all plant species and 88% of tree species but 95% of indi-

  vidual trees were dispersed by animals in the forest that they studied. The loss

  of animal species and, in particular, elephants could result in a radical change in

  the composition of the forest.

  Evidence of the exquisite and delicate motor control of these giant animals

  can be observed at almost any time in watching a family group. Mothers and

  aunts, weighing 5 ton and towering over their newborn calves who they are un-

  able to see under their wide bodies,
can be gently nudged onto their feet or

  An Elephant’s Brain Chapter | 3 11

  FIGURE 3.1 The strength of the trunk, with some 1400 muscles, is considerable. It can be used to break branches by twisting or bending, push over large trees, and, with the aid of its tusks, strip bark and gouge out softer fibrous materials.

  moved aside by legs as large as tree trunks and feet the size of dining chair seats.

  At water holes, it is not unusual to see a full-grown elephant gently step over a

  tortoise no bigger than a small dinner plate.

  At the Elephant Sanctuary in Hohenwald, Tennessee, an adult female

  elephant (Tarra) had made firm friends with a dog named Bella. Bella liked to

  have her tummy rubbed. Tarra would oblige using a front foot to do so. Tarra’s

  front foot was half the size of Bella (Buckley, 2009).

  The trunk of an elephant contains no bone or cartilage, giving this unique or-

  gan an almost unlimited range of motion all coordinated by muscle movements.

  The trunk is in almost continuous use while feeding (Figure 3.2). It is used to select parts of plants, clean food, fold and manipulate food into rolls or bundles,

  even use fibrous material to stop up holes dug for water, access water in deep

  fissures, spray water and mud over the body, snorkel, throw objects, and manu-

  facture and manipulate tools. The prehensile tip can pick up objects as small as

  an unshelled peanut and detect cracks or grooves no more than a quarter of a

  millimeter wide. The elephant can use the strength of its trunk to push over siz-

  able trees, strip bark off trees using both its trunk and its tusks, lift logs perhaps

  12 Elephant Sense and Sensibility

  FIGURE 3.2 The trunk is in almost continuous use as an effective organ to gather the amount of vegetation to meet the daily needs of an adult elephant.

  as heavy as half a ton, and use the trunk as a deadly weapon that can disable a

  full-grown lion or kill a human. Finally, the trunk of an elephant as part of its

  long vocal tract may be critical to the production of loud, low-frequency calls

  as well as serving as an organ extremely sensitive to touch and to smell. Mental

  control of this complex organ occupies a large fraction of the elephant’s brain

  (Shoshani et al., 2006).

  The cerebellum of the elephant’s brain is proportionally larger than a hu-

  man’s (18.6% of the brain vs. 10.3%) with gyri and sulci that have complicated

  folia and many subconvolutions that are all related to coordinating movements,

  locomotion, and posture. The large cerebellum and basal ganglia favor the ability to perform complex and coordinated motor functions like those carried out

  with the trunk.

  In humans, the temporal–parietal junction gathers information from many

  senses (visual and tactile) to construct a single image. It is unknown but likely

  that elephants have a similar capability (de Waal, 2013, p. 92).

  The large and bulbous temporal lobes including anterior temporal gyrus,

  together with a well-developed neocortex and large olfactory bulb and paleo-pallum, all support an excellent ability to smell. The olfactory region of an

  An Elephant’s Brain Chapter | 3 13

  elephant’s brain includes complex functions such as flehmen (reproduction)

  and Jacobson’s (vomeronasal) organ housed in the roof of the mouth as well as

  a highly tuned sense of smell in the trunk. The very large temporal lobe of the

  cerebrum of the elephant may be related to the complex forms of communica-

  tion including infrasound used by the elephant.

  Elephants and humans have the highest degree of convolutions in the brain

  of the 13 mammalian taxa. The relative weight and surface area of the ele-

  phant’s cerebral cortex and temporal lobe is the highest among mammals, including humans (Holdrege, 2001). These features of the elephant brain favor

  hearing, learning, memory, and emotion, all of which relate to communication

  and socialization. Similarly, elephants have an unusually large and convoluted

  hippocampus compared to primates and cetaceans. In humans, the hippocampus

  and formation of the hippocampus relate to recent memory of facts and events

  as well as emotions. In elephants this may also equate to social and chemical

  memory in which the identity of individuals is recorded and remembered.

  Elephants can be right-handed or left-handed. When eating grass the ele-

  phant will grasp a clump of grass by the end of its trunk, preferentially insert the

  right or left tusk under the grass, and break the tuft by lifting and tearing with

  the tusk. Such persistent use wears a notch in the tip of the tusk, marking it as

  the preferred tusk.

  In contrast to humans, the occipital lobe, composed of the primary visual

  cortex and association cortex, are small and ill-defined in elephants. These parts of the brain are related to a well-developed sense of vision. As mentioned earlier, an elephant’s vision is one of its least-developed senses.

  Finally, species with large average brains relative to their body size show

  greater ability to process and utilize complex information. We pursue this in the

  following chapters, showing and emphasizing in particular that the two senses

  discussed here, smell and hearing, play a major role in the functioning of an

  elephant.

  In the above brief overview of the elephant’s brain, there is evidence to sup-

  port the role of smell, hearing, taste, and touch as important sources of input

  to the functioning of an elephant. Of the five recognized senses, the elephant’s

  brain, in comparison to that of humans, is least well developed for sight. The

  prominence of smell and hearing over sight in the elephant’s brain accords

  with the evolution of the species in dense, closed-canopy rain forests. It further

  stresses the fact that if we are to penetrate the mind of an elephant we must

  think in terms of smell and hearing and to a lesser degree in terms of sight. It is

  further likely that we will need to expand our conception of how olfactory and

  auditory signals as well as touch and taste are processed and used. In particular,

  it is likely that the elephant processes signals from multiple sources simultane-

  ously and that an integrative rather than a reductionist viewpoint must be taken

  to penetrate elephant cognition.

  Chapter 4

  Functioning of the Brain

  The brain of an elephant is a complex interactive organ that has been receiving,

  sending, interpreting, and storing millions of signals at rates exceeding many hun-

  dreds of pulses per second over millions of years (Eagleman, 2011). Much of the

  brain is a closed hard-wired system that runs internal functions such as breathing,

  digestion, and motor controls. This unconscious system operates without the in-

  tervention of the conscious but is not decoupled from conscious modulation. The

  unconscious is a repository for all of the preceding conscious lessons of survival.

  No brain of a newborn elephant is a blank slate. Instead, it is equipped by evolu-

  tion to survive. The newly born calf will struggle to its feet within minutes of

  birth, it will find its legs and its mother’s breast, and it will immediately imprint on

  its mother’s voice and smell, shelter between its mother’s legs, and follow her and

  the herd. Newly born zebra foals are believed to imprint upon the black-and-white

  striped patterns un
ique to its mother’s hind quarters, allowing the calf to find its

  mother among dozens of other zebras within the herd. This survival instinct has

  evolved within the context of the elephant’s immediate environment—its umwelt.

  Its umwelt includes not only the physical and living environment, but complex

  relationships of a highly social animal.

  The senses of smell, hearing, touch, taste, and sight built by the conscious

  and stored in the unconscious are learned responses. We know from humans

  that the interpretation of the signals sent to the brain by these senses are in the

  form of electrical pulses. While the eye has complex receptors in the retina, it

  does not project an image on the brain analogous to that produced on the film in

  a camera. Instead, it generates a host of neural signals that must be interpreted

  by the brain as an image. The brain makes assumptions about what is seen. For

  example, for the human, light normally comes from above and shadows are

  cast below. The human brain automatically adjusts to that assumed distribu-

  tion of light. Reverse this situation and all sorts of tricks can be played on the

  brain, including “seeing” water flowing uphill (see the lithograph of Dutch artist

  M.C. Escher titled Waterfall [1961]).

  In the case of animals, we cannot be sure. While elephants use their eyes

  as we do, it is quite possible, given the relative role of sight and hearing for an

  elephant, that they may construct images from sensory systems other than or in

  addition to optical signals. In rare instances, such as Mike May who was blinded

  Elephant Sense and Sensibility. http://dx.doi.org/10.1016/B978-0-12-802217-7.00004-1

  Copyright © 2015 Elsevier Inc. All rights reserved.

  15

  16 Elephant Sense and Sensibility

  at 3 years old but had his sight restored 40 years later, he was unable to construct

  images (Eagleman, 2011, p. 38). It took time for his brain to learn to see.

  Hägstrum (2000) has suggested that homing pigeons use the earth’s low-level

  seismic noise to navigate. Continual movement of the earth’s crust produces a

  low-level seismic signal, which is recorded on a seismograph as a band of low-

  level noise. This low-level noise may be reflected and enhanced by the surface