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Nine species of giant, flightless birds, known as moas, suddenly went extinct within two
centuries of humans’ first arrival to New Zealand. Coincidence? No, a team of geneticists,
biologists and archeologists recently wrote. The scientists found evidence that moas thrived
before Polynesians colonized the islands in the 13th century.
The scientists analyzed genetic remains from 281 individual birds from four species of
moa. The researchers looked for signs of dwindling moa populations in the 4,000 years before
humans arrived. When animal populations shrink dramatically, their genetic diversity also
decreases. Instead, the moa had a healthy variety of DNA, which suggested strong populations.
For example, the 3.6 meter (12 ft.) tall South Island giant moa (Dinornis robustus) had an
estimated population of 9,200 individuals that may have been growing. Although another
species, the 1.5 to 1.8 meter (4.9–5.9 ft.) tall eastern moa (Euryapteryx crassus), showed
signs of a major historical die-off, that reduction in numbers likely occurred more
than 17,900 years ago, thousands of years before humans arrived. Euryapteryx crassus
had recovered and seemed to be thriving in the eastern lowland forests of New Zealand
by the time humans arrived. “These findings point strongly toward human
contact as the only factor responsible for the extinction,” wrote the scientists in
Proceedings of the National Academy of Sciences. “Elsewhere the situation may be more complex,
but in the case of New Zealand the evidence provided by ancient DNA is now clear: The
megafaunal extinctions were the result of human factors,” said lead author Mike Bunce
of Curtin University in Australia in a press release. “We need to be more aware of the
impacts we are having on the environment today and what we, as a species, are responsible
for in the past.”