http://blog.oup.com/2014/02/proving-polybius-wrong-about-elephants/
Proving Polybius wrong about elephants
Posted on Thursday, February 27th, 2014 at 3:30 am SHARE:
By Adam L. Brandt and Alfred L. Roca
Do conservation genetics and ancient Greek history ever cross paths?
Recently, a genetic study of a remnant population of elephants in Eritrea
has also addressed an ancient mystery surrounding a battle in the
Hellenistic world. After Alexander the Great died unexpectedly in 323 BC,
his generals divided his territory, founding several empires. Their
successors ended up fighting each other during the next few centuries,
often using elephants to intimidate the enemy and disrupt military
formations. The Seleucids, heirs to the lands neighboring India, traded
treasure and territory for access to Indian war elephants. They fought the
Ptolemaic dynasty of Egypt, seeking control of the lands between the two
empires during the Syrian Wars. The Ptolemaic pharaohs, desperate for their
own pachydermal tanks, established outposts in what is today the country of
Eritrea, to capture African elephants for warfare.
Elephants from the two continents were put to the test at the Battle of
Raphia in 217 BC, between Antiochus III and Ptolemy IV Philopater. In The
Histories, which includes the only known account of African and Asian
elephants meeting in warfare, the Greek historian Polybius described the
resulting fiasco:
"Most of Ptolemy's elephants, however, declined the combat, as is the habit
of African elephants; for unable to stand the smell and the trumpeting of
the Indian elephants, and terrified, I suppose, also by their great size
and strength, they at once turn tail and take to flight before they get
near them. This is what happened on the present occasion; when Ptolemy's
elephants were thus thrown into confusion and driven back on their own
lines."
As every school child knows, Asian elephants are smaller than African
elephants. So why did Polybius get this wrong? One British writer, perhaps
unconsciously affected by the corporal punishments meted out by Classics
teachers to disruptive students at English schools, decided that Polybius
must after all be correct. He pointed out that, although African savanna
elephants are larger than Asian elephants, there is a different species of
elephant that lives in the tropical forests of Africa, and which is smaller
in size than the Asian elephant. Thus began the tale that the war elephants
of the pharaohs were actually African forest elephants, ignoring the
thousands of kilometers that separate the range of forest elephants from
places where the Egyptians captured their war elephants. This tale was then
perpetuated by subsequent authors, each citing authors before as definitive
sources.
A savanna elephant in Kruger National Park, South Africa
In a recent conservation genetics study, we examined the elephants of
Eritrea, the descendants of the population that was the source of Egyptian
war elephants. Eritrea currently has the northernmost population of
elephants in eastern Africa. Perhaps one or two hundred elephants persist
there, in isolated and fragmented habitat. Using DNA isolated from
non-invasively collected dung samples we examined three different genetic
markers. First we looked at slow-evolving nuclear gene sequences in the
Eritrean elephants. In every case the sites always had the same sequence
found in hundreds of savanna elephants, and in no case did we ever get a
match to sequences found across all forest elephants. This established that
Eritrean elephants were savanna elephants.
When we then looked at very fast evolving regions of the nuclear genome,
the Eritrean elephants proved to be a close match to savanna elephants in
East Africa, and again were genetically unlike forest elephants. Finally,
we looked at mitochondrial DNA, which often has a different pattern than
other genetic markers in elephants. Mitochondrial DNA is transmitted only
by females, and these females do not geographically disperse away from the
natal heard. Very often, one can infer a signal of ancient genetic events
that persist only in the pattern of the mitochondrial DNA. Yet in this
case, the mitochondrial DNA agreed with the nuclear results: these were
savanna elephants, and there was not the slightest trace of any ancient
forest elephant presence in Eritrea.
Given this result, why did Polybius claim that the Asian elephants were
larger than African elephants? It turns out that in the ancient world there
was a legend that, due to the wet climate, animals were always larger in
India than they were elsewhere. This legend was widespread among authors
before and after Polybius. Go back and look at the way the translation of
the Polybius text is worded. Even in translation, it is evident that
Polybius has interjecting his own beliefs onto the account, and not
recounting an actual observation.
Our genetic study indicated that the isolated population of elephants in
Eritrea has low genetic diversity. Habitat loss and human-wildlife conflict
are major concerns for conservation of this population, which luckily has
not yet been impacted by China's lust for illegal ivory. Increasing and
protecting suitable habitat for their long-term survival is critical, and
in the very long run it may become possible to create habitat corridors to
other surviving but distant populations. Luckily, the government of Eritrea
is committed to protecting the country's natural environment, and has
recently reported an increase in the range and number of elephants.
Adam L. Brandt is a PhD candidate, and Alfred L. Roca is an Assistant
Professor, in the Department of Animal Sciences of the University of
Illinois at Urbana-Champaign. They are the authors of the paper 'The
elephants of Gash-Barka, Eritrea: Nuclear and mitochondrial genetic
patterns' published in Journal of Heredity.
The Journal of Heredity covers organismal genetics: conservation genetics
of endangered species, population structure and phylogeography, molecular
evolution and speciation, molecular genetics of disease resistance in
plants and animals, genetic biodiversity and relevant computer programs.
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Image credit: Savanna elephant in Kruger National Park, South Africa. By
Felix Andrews (CC-BY-SA-3.0) via Wikimedia Commons.
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Received on Thu Feb 27 2014 - 09:06:12 EST