Elephant Sense and Sensibility
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52 Elephant Sense and Sensibility
expressing grief and was deeply aware of who it was that she was touching and
holding in her trunk. Not only was her behavior clear evidence of grief, but it
also showed that she perceived the depth of the relationship between who her
calf was and herself. Knobnose finally mated again, bore a healthy calf, re-
gained her equilibrium, and returned to lead her herd once again.
Numerous observers, including Darwin, believe that under extreme condi-
tions of stress, elephants can break down and weep, shedding tears and uttering
cries (see also Chapter 7).
Elephants visit the remains of their kind and have been shown (McComb
et al., 2001) to recognize the remains of elephants among the bones of other ani-
mals. In contrast to the account above, McComb found that there seemed to be
no particular recognition of kin, although when tusks were among the remains,
these drew special attention. She also found that elephants can distinguish the
bones of other elephants from those of large mammals and other nonelephant
remains.
Joyce Poole describes an incident involving Eleanor, one of the orphans
raised by Daphne Sheldrick. A woman wearing an ivory bracelet was warned to
hide the bracelet behind her back. She did so but Eleanor reached around behind
her, took her hand in her trunk, and raised it up close to her eye to look at it.
van Graan (cited in The Game Rangers Jan Roderigues, p. 56, 1992, per-
mission granted by Roderigues), in dealing with crop-raiding elephants on the
border of the Kruger National Park, had to shoot one of the bulls. The carcass of
this bull was dismembered for later use. However, as night descended, the feet,
tusks, trunk, and upper ear were moved and placed on an embankment some
distance from the carcass.
On return, shortly after sunrise the next day, there was no sign of the dis-
membered parts. Numerous tracks of elephants did, however, mark the spot
where the body parts were left. A search for these parts found them all back
in a neat pile beside the carcass of the elephant. They, and the carcass, were
partly covered with soil and vegetation. There were furrows in the soil where the
ground had been disturbed with clear prints of the feet of the elephants who had
done the work. Once again, there is clear recognition of who the dead elephant
is, that his being has been disturbed and what belongs to him violated. It is
more challenging to speculate on what motivated the other elephants to cover
the body and the dismembered body parts. Reports of such behavior, however,
are not uncommon (see, for example, the case of birth earlier in this chapter).
It is difficult not to conclude that elephants are aware of the distress of oth-
ers, empathizing with vocalization and other responses to their distress and at-
tempting to alleviate the suffering of others or restore others to a better state.
When this fails, they identify with the remains and may even treat them with
what could be called respect.
Elephants certainly recognize suffering and stress in other elephants and
respond in ways that attempt to relieve such conditions. This response is not
Empathy and Altruism Chapter | 8 53
restricted to kin but is a generalized response to suffering and death of conspe-
cifics. That elephants should show such a response is almost certainly related
to their highly social structure. The death of the matriarch Eleanor led immedi-
ately to the death of her calf and the loss of her knowledge to that family unit.
In a more generalized sense, altruistic behavior exhibited to kin promotes the
survival of the group. In evolutionary terms, natural selection of a beneficial
trait such as empathy or altruism within the gene pool of the family benefits
survival (Douglas-Hamilton et al., 2006; McComb et al., 2001).
More rarely elephants have been reported to respond to other species includ-
ing humans in distress. A nearly blind elderly woman returning to her village
was overtaken by nightfall. She was too frail to climb into a tree and resorted to
sitting with her back against the trunk of a large tree. Elephants arrived at this
spot during the night and, finding the woman, covered her with branches and
vegetation and remained around her for the duration of the night.
More recently, Hutto (2014), in Touching the Wild: Living with the Mule
Deer of Deadman Gulch, reports what he believes to be clear recognition by a
mule deer of the death of her fawn and even the deaths of others within a much
wider group of mule deer. Observing behavior of animals requires, as is demon-
strated by Hutto, both in the case of wild turkeys (Hutto, 2006) and mule deer
(Hutto, 2014), a significant commitment of effort and time.
The effort by Bates and her colleagues to examine elephant empathy under
controlled conditions in the wild points the way to how a significant part of
the research required to understand elephant cognition must be done. Failure
to place the elephant in its natural environment is likely to seriously bias if not
invalidate most experiments. The role played by elephant society and the full
spectrum of the environment prohibits acceptable design of experiments under
most artificial circumstances.
Experiments such as the mirror recognition test may be as invalid for
elephants as they would be for bats. We as scientists are further heavily influ-
enced by the need for rigor, recognizing the weakness of findings that cannot be
quantified and our tendency to believe in the reductionist approach. Elephants,
in particular, are likely to depend on multiple sensory inputs, are able to assimi-
late such multiple inputs, and deal with feedback between them resulting in a
response difficult to comprehend by humans that think primarily in terms of a
single sensory system: sight.
As a cautionary note to an earlier remark, Michael Finkel, in the July 2013
issue of National Geographic magazine, reported on Daniel Kirk who had lost
both eyes to retinal cancer at the age of 13 months. Daniel, at the age of 47,
has taught himself to navigate by echo location. He produces clicking sounds,
sometimes as fast as twice per second, which not only allow him to create im-
ages in his mind of objects as much as 30 m (100 ft) to 45 m (150 ft) away, but to
ride a bicycle on a city street. Close to 1000 blind students in over 30 countries
have been taught to use echolocation.
Chapter 9
Communication
Communication, especially in a highly social animal such as an elephant,
may have played a significant role in their evolution and in natural selection.
Animal communication favors callers whose vocalizations benefit their listen-
ers (Seyfarth and Cheney, 2003b). As is described here, elephants vocalize most
often in the presence of other elephants, emphasizing the social function of
communication. Although signalers may vocalize to change a listener’s behav-
ior, there is no general acceptance by researchers that animals call to inform oth-
ers. The concensus amongst psychologists is that listeners acquire information
from signals mainly by eavesdropping and not because the signaler intends to
provide such information (Seyfarth and Cheney, 2003b). Dawkins (1989, p. 57)
and Dawkins and Krebs (1978) believe that all animal communication repre-
sents manipulation of the signal-receiver by the signal-sender.
We show here and elsewhere that observed elephant behavior would suggest
that such a view may not be entirely valid. Similarly, there is fairly universal
agreement that the cognitive limitations of animals are responsible for the per-
ceived differences in animal communication and human language. While the
reach and extent of human language goes far beyond that of elephants, elements
of the understanding of an elephant receiving a signal of the signaler’s intent are
becoming increasingly apparent. The ability of elephants to recognize the men-
tal states of other elephants and to vocalize with the specific intent of informing
others and transmitting to those listeners knowledge that the signaler possesses
may equally well exist.
Individual recognition is central to social life. Elephants have knowledge of
members that are within their own family group as well as in the wider popula-
tion. This recognition, however, is primarily in the form of sound and smell and
not sight. McComb et al. (2003) show that adult female elephants are familiar
with and know the vocal identity of 14 families within the population, totaling
some 100 individuals. While the full range of low-frequency calling patterns of
elephants in the wild is unknown, it is likely that adult females maintain near-
continuous contact via these calls. Older females in the herd have the most ex-
tensive knowledge of the calls and identities of other elephants as well as sounds
emanating from other sources. Processing and storage of this range of auditory
input requires considerable cognitive ability.
Elephant Sense and Sensibility. http://dx.doi.org/10.1016/B978-0-12-802217-7.00009-0
Copyright © 2015 Elsevier Inc. All rights reserved.
55
56 Elephant Sense and Sensibility
Elephants generate and can detect sound over the widest range of fre-
quencies of all mammals (see http://people.eku.edu/ritchisong/RITCHISO/
infrasounddiagram.gif). The female Asian elephant tested by Heffner and Heffner (1982, 1984) was able to detect a 60 dB signal as low as 17 Hz and as high as
10.5 kHz, which is the widest range known for any nonhuman mammal tested. In
comparison, the range of human hearing is 20 Hz to 20 kHz (Soltis, 2010).
SOUND GENERATION
Sounds generated by vertebrates depend on lung capacity and the mass, length,
and elasticity of the vocal folds in the larynx. These fundamental sounds are
then modulated as they pass through and emerge from the passageways that
constitute the vocal tract. The vocal tract acts as a filter and operates indepen-
dently of the source (Fitch and Hauser, 2002).
This independence between the “source” and the “filter” is considered to be
the best current working hypothesis of how animals produce sound (Fitch and
Hauser, 2002). However, much of what is known about the relationship between
the source and filter has been learned from the study of humans, nonhuman pri-
mates, and other animals such as species of deer (Fitch, 2000; Fitch and Hauser,
2002; Fitch and Reby, 2001; Reby and McComb, 2003; Titze, 1994; Willmer
et al., 2000; Wilson et al., 2001). Little is known of the source-filter relationship
in elephants (Reby and McComb, 2003), yet it is useful to view the production
of low-frequency elephant calls in these terms (Garstang, 2004).
Air driven from the lungs sets the vocal folds in the larynx in motion. With
their own elasticity and mass, these folds, responding to the air flow over them,
act as mechanical vibrators that can generate self-oscillation (Fitch and Hauser,
2002; Titze, 1994). When the folds close to the appropriate “phonatory” posi-
tion, they generate acoustic energy. The period and thus the frequency of the
opening and closing of the vocal folds produces the fundamental frequency
(FO). This frequency is set passively by muscle tension, mass of the vocal
cords, and lung pressure. There are small nonlinear oscillations around this
fundamental frequency. These nonlinearities in the periodic vocal production
provide structure to the morphology of the call and have been described in
terms of deterministic chaos (Reby and McComb, 2003). Because the length,
mass, and elasticity of the vocal folds are related to body size, the FO can
be related to body size. However, these parameters (length, mass, elasticity)
can change (e.g., with age) and the relationship between FO and body size is
not robust (Fitch, 1997; McComb, 1991; Reby and McComb, 2003; Rendall,
1996; Riede and Fitch, 1999). The inverse relationship between the length
and mass of an elephant’s vocal folds predicts that it is capable of producing
lower-frequency sounds than any other terrestrial animal. The prediction that
larger animals produce lower frequencies than smaller animals of the same
species has not been well verified by observations (McComb, 1991; Reby and
McComb, 2003).
Communication Chapter | 9 57
The supralaryngeal vocal tract of the elephant is the respiratory tract from
the larynx to the tip of the trunk. For the elephant the pharyngeal pouch, nasal
cavity, membrane near the tip of the trunk, the highly mobile tip of the trunk
and the length and ability to change the length of the trunk are, in combination,
unique Elephantidae features (Garstang, 2004) (Figures 9.1 and 9.2). Their individual and collective role in controlling the air column in the vocal tract has
not been carefully studied.
Recent work, however, at the University of Vienna on an excised larynx of
a 25-year-old female African elephant has both confirmed earlier supposition
and described a number of new phenomena within the elephant vocal anatomy
including the generation of vibrations of the vestibular folds, which increased
the sound pressure levels by 12 dB. The study also showed that the anatomy of
the elephant’s larynx is more complex than that of a human and is capable of
producing multiple wave patterns (traveling, standing, and irregular vocal fold
vibrations) (Herbst et al., 2013).
The air column in the vocal tract has elasticity and mass that will vibrate
preferentially at certain frequencies termed normal modes or resonances.
In the simplest terms this column of air acts as though it is in a tube closed
at one end such that the length of the tube is one-quarter of the wavelength.
Wavelength is directly related to the speed of sound and inversely related to
FIGURE 9.1 The vocal tract of an adult elephant including the trunk, the nasal cavity seen as a bump on the forehead, the pharyngeal cavity, and the larynx can amount to a length of nearly 4.4 m (15 ft). Both the exterior trunk and the larynx can be extended by another foot.
58 Elephant Sense and Sensibility
FIGURE 9.2 A cavity in the throat of the elephant called the pharyngeal pouch can be filled with water (up to 4 or 5 L) and used as an emergency drinking or cooling supply of water and influence the sound emerging from the vocal tract of the animal. (Pen and ink watercolor on wood by author.) the frequency. Thus, for the average speed of sound in the atmosphere near the
ground of 350 m (1148 ft) per second and a frequency of 20 Hz, the wavelength
is 350/20 m = 17.5 m (57 ft), and the vocal tract length would be (1/4)(17.5 m) or
4.4 m (15 ft). As we have seen, this is a realistic length of the vocal tract for an
adult African elephant.
The vocal tract will act as a filter depending on the transit time of the sound
waves up (and down) the column. The speed of sound in this tract will govern
the transit time and thus will depend on the composition of gases in the tube and
the temperature of those gases (Pierce, 1981).
The filter will act upon all of the frequencies being generated in the larynx
(i.e., the FO and the nonlinear oscillations about the FO). The filter will thus shape
the final form of the vocal signal. Prominent in this ultimate form of the signal
will be “formants.” These formants are selectively amplified parts of the vocal
signal, clearly visible in the sonogram of the call of an elephant as nearly equally
spaced bands of acoustic energy (Figure 9.3). Embedded in this signal envelope but independent of the formants is the FO and the integer harmonics of the FO.
The vocal tract length governs formant spacing. Formant spacing is a better
predictor to body size than the size of the vocal folds or larynx (Fitch, 2000;
Fitch and Hauser, 2002; Reby and McComb, 2003). In addition to changing
the length of the vocal tract by extending its trunk, the elephant may be able to
elongate the vocal tract by contraction of the larynx or laryngeal descent (Fitch
and Reby, 2001; Reby and McComb, 2003). The presence or absence of water
in the pharyngeal pouch may also influence vocal tract length. The function of
the narrow connective strip of tissue dividing the lower part of the trunk into two
Communication Chapter | 9 59
500
400
300
F4
Frequency (Hz) 200
F3
F2
100
F1
F0
0
0
2
4
Time (s)
FIGURE 9.3 Waveform of a female contact call showing the fundamental frequency (F0) and harmonics and the position of the first four formants (F1–F4). Based on Garstang (2004); from McComb et al. (2003).