People and giant snakes not only target each other for food -- they also compete for the same prey, according to a study co-authored by a Cornell University researcher.

More than a quarter of the men in a modern Filipino hunter-gatherer group have been attacked by giant pythons -- yet those same hunter-gatherers often target the pythons as their next meal. The study also finds that both the hunters and the pythons routinely eat local deer, wild pigs and monkeys. "Hunter-gatherers and other primates as prey, predators, and competitors of snakes," is published online in the Proceedings of the National Academy of Sciences.

"People have speculated for a long time that serpents have had a significant relationship with primates throughout their shared evolutionary history," said Cornell herpetologist Harry Greene, who conducted the study with Thomas Headland, an anthropologist at the SIL International in Dallas. "At least 26 species of non-human primates are eaten by snakes -- and there are many primates that eat snakes. This pattern of complex relationships is broader than those hunter-gatherers, and our paper provides the strongest evidence yet for those relationships." Greene is also a Cornell professor of ecology and evolutionary biology.

In the 1960s, Headland recorded ethnographic observations of the Agta Negritos, a modern hunter-gatherer group in the Philippines. An average Agta adult male weighs about 90 pounds, small enough to be eaten by the huge, native reticulated pythons that can grow to 28 feet. In one such attack, a father entered his dwelling to find a python had killed two of his children and was swallowing one of them headfirst. The father killed the snake with his bolo knife and found his third child, a six-month-old daughter, who was unharmed.

The study was funded by the Louis S.B. Leakey Foundation and the Lichen Foundation.