Tag Archives: cannibalism

Monogamous cockroaches practice minor cannibalism out of love

Adults of Salganea taiwanensis before (right) and after (left) mutual wing‐eating behavior. The right individual has long intact wings. The left individual has short wings. Most part of its wings has been eaten by its mate. Credit: Haruka Osaki.

The Taiwanese giant wood roach (Salganea taiwanensis) mates for life, spending the rest of its life inside rotten logs across Asia feeding and raising its young. A new study shows that this rare monogamous union is strengthened by minor acts of cannibalism, with the newlyweds taking turns munching each other’s wings down to stubs once they move into their new log together. According to researchers this consensual cannibalism has been facilitated and may have evolved thanks to the roaches’ monogamous bond.

This striking behavior has been identified for the first time in a new study published by Haruka Osaki from Kyushu University. The Japanese biologist first encountered wingless roaches six years ago while she was still a student. She noticed that their wings were chewed by something. Even then, she knew that it was highly unlikely that these marks were left by some predators, and rather were the result of the cockroaches eating each other’s wings. But why?

Years later, Osaki finally unraveled the mystery once she completed fieldwork for her Ph.D. She collected wild cockroaches from the forest and brought them to the lab, where she formed 24 couples. For three days, every move the roaches made was recorded by video cameras, including the moments when the insects started eating each other’s wings.

First, one of the bugs climbs on the other’s back and starts munching on the wings. When they’re ready to take a break, the bugs will swap positions before resuming. Sometimes, the roach having its wings eaten gives a violent shudder, which immediately causes the other to disengage and take a forced break before they’re ready to start again. Other than these rare moments, it didn’t seem like the roaches were in pain while they had their appendages eaten. Twelve of the couples partially ate each other’s wings, while the other twelve consumed the wings completely.

Cannibalism is rather frequent among insects and some spiders. Cannibals can benefit from a larger food supply following the elimination of competition, but also from the higher nutritional quality of feeding on arthropod body tissues rather than plant tissues. Some even cannibalize their mates, with the most notable example being praying mantises.

The Taiwanese roaches are radically different though. For them, cannibalism is a mutual thing, rather than only one mate being fed. Also, they don’t eat each others’ wings for nutritional value since there’s hardly any nutrients there.

The benefit lies in living more comfortably in tight quarters without having to deal with cumbersome wings. Since wings can also collect mold or mites, this minor cannibalism may also provide protection against diseases.

As for downsides, there don’t seem to be any since the roaches make a decision to mate for life, never again leaving their nest or seeking out other mates. You don’t need wings anymore if you don’t plan on flying again. Speaking to the New York Times, Osaki adds that in a natural world where the sexes typically have competing interests, the roaches are a rare example of mates that want the same thing.

The findings appeared in the journal Behavioural Notes.

An average-sized man could keep 25 people fed for only half a day. Credit: Wikimedia Commons.

How many calories does a human body have? Stone Age cannibals must not have been very satisfied

An average-sized man could keep 25 people fed for only half a day. Credit: Wikimedia Commons.

An average-sized man could keep 25 people fed for only half a day. Credit: Wikimedia Commons.

I can’t speak about taste but human meat doesn’t look that nutritious. That’s according to James Cole, an archaeologist from the University of Brighton in England, who for the past decade has been morbidly preoccupied with how many calories you’d get if you chowed down on a human.

Paleo diet anyone?

Cole isn’t some psychopath — he’s a real scientist who is trying to raise the shroud over the many instances of human cannibalism from the Paleolithic. Anthropologists will tell you cannibalism can occur out of ritual, cultural, social and nutritional considerations. We know from evidence such as butchered bones that our ancestors practiced cannibalism as well. It’s not always clear, however, whether a victim was eaten because someone was hungry or because someone with an even bigger appetite up in the heavens wanted a sacrifice.

Cole studied nine fossil sites where cannibalism was reported, ranging from 14,000 years to 900,000 years ago. Five of these sites involved cannibalism of Neanderthals, two sites involved our own species Homo sapiens, and the other two involved extinct human ancestors. Cole wanted to find out how many calories the bodies from each site could provide. So he used data from very old studies involving four male human cadavers to come up with the calorie content of an average-sized modern man then adapted the contents to the age ranges of the bodies.

His research suggests that eating an average-sized male yields about 144,000 calories. Specifically, the upper arms have about 7,450 calories, the forearms some 1,660 calories, while the heart has 650 calories. The lungs and liver seem higher in calories with 1,600 and 2,750 calories, respectively, while the kidneys have only 380 calories.

 Estimated total calorie values for male adults, adolescents, juveniles and infants. a

Estimated total calorie values for male adults, adolescents, juveniles and infants. Credit: Dr James Cole.


Is that a lot? Well, not really. According to Cole, if you’d cook a human you’d only be able to provide lunch to a group of 25 people. For comparison, a 3.6-million-calorie mammoth would have provided enough sustenance for 60 days. A bear or deer is a lot more nutritious than a human.

Cole argues that given the hassle of killing your own kind, which is presumably as fast and smart as the cannibal, why risk it? The point he’s trying to make is that most instances of cannibalism can’t be about nutrition and must be driven by some social or cultural factors instead. Sure, there will be instances when severe famine might have made some to resort to cannibalism but most of the time cannibalism just for the sake of food doesn’t add up in Cole’s book.

Finding the motivation behind something as gruesome as cannibalism in instances that occurred hundreds of thousands of years ago seems practically impossible. At the same time, it’s clever analyses such as this that can sometimes be an eye opener.

Though there are some shortcomings like the small sample size and the inherent limitation of inferring a Neanderthal’s calorie yield from a human’s, it’s possible many sites where cannibalism was proved present could be revised.

Cole’s paper appeared in the journal Scientific Reports.



Archaeological finding could confirm gruesome Greek legend

Archaeologists working on top of a Greek mountain have made a sinister discovery: they found the skeleton of a teenager, amid several other bones and a mound of ashes. This was likely a sacrifice for the god Zeus and could confirm one of the most gruesome Greek legends.

Zeus turning the Greek king Lycaon into a wolf for sacrificing and eating another human being. Engraving by Hendrik Goltzius.

The headless skeleton was uncovered with the bones laying on the East-West, a position thought to have a ritual significance. The skeleton was laid on top of a pile of ash made from centuries of burnt animal remains. The gruesome site was estimated to be 3,000 years old, and the sacrifices were made at a temple of Zeus, the most significant god in the Greek pantheon.

The teenager was in the supine position and buried with ceramic pottery, located on a panoramic position of the Lykaion Mountain.

“Written sources mention human sacrifices on the altar of Lykaion Mountain, but the excavations had been carried out to date in the area had not found human bones,” said the Greek culture ministry in an announcement.

Archaeologists working at the site confirmed that this is the first time human remains had been found in the area:

“Several ancient literary sources mention rumors that human sacrifice took place at the altar, but up until a few weeks ago, there has been no trace whatsoever of human bones discovered at the site,” excavation leader David Gilman Romano, a professor of Greek archaeology at the University of Arizona, told the Associated Press.

A sinister legend

The finding seems to fit with a legend written by the ancient writer Pausanias (A.D. 110-180). Pausanias wrote of a king, Lycaon, who was turned into a wolf after sacrificing a young boy. It was a common belief at the time that cannibalism would turn people into wolves.

“Lycaon brought a human baby to the altar of (Zeus) and sacrificed it, pouring out its blood upon the altar, and according to the legend, immediately after the sacrifice, he was changed from a man to a wolf,” Pausanias wrote in a book on the geography of Greece (translation from a “Description of Greece with an English Translation” by W.H.S. Jones, Litt.D., and H.A. Ormerod, Harvard University Press, 1918).

Mount Lykaion was for centuries associated with the most nefarious of Greek cults, Plato himself writing about the human sacrifices made in the name of Zeus. There may be some facts behind this myth, but it’s still too early to draw any conclusions.

“Scientific study of the skeleton is in progress and despite the fact that it is still too early to draw conclusions about the circumstances of the death, the prominence of the orientation of the oceans and the altar demonstrates the importance of the burial,” they said in their announcement.

Lifestyle of the Gibraltar Neanderthals. Credit: Wikimedia Commons

Neanderthals in Belgium were cannibals and fashioned tools out the bones of their own kind

Lifestyle of the Gibraltar Neanderthals. Credit: Wikimedia Commons

Lifestyle of the Gibraltar Neanderthals. Credit: Wikimedia Commons

In the Goyet caves near Namur in Belgium, researchers made a gruesome find: Neanderthal bones which carried the marks of intentional butchering. Moreover, tools made from Neanderthal bones were also found, suggesting our hominid relatives didn’t frown from doing what’s necessary to survive in desperate times. They were also very practical about it, apparently.

This isn’t the first time Neanderthals were shown to engage in cannibalism. Eight 43,000-year-old Neanderthal skeletons excavated from an underground cave in El Sidrón, Spain in 2000 were filled marks and evidence that the bones were torn apart. These skeletons also bore teeth which showed evidence of periods of starvation or minimal nutrition, particularly during difficult life transitions like weaning or adolescence.

Overview of the anthropogenic modifications observed on the Neandertal remains from the Troisième caverne of Goyet (Belgium). Credit: Nature

Overview of the anthropogenic modifications observed on the Neandertal remains from the Troisième caverne of Goyet (Belgium). Credit: Nature

Something very similar was found in the caves from Belgium. Anthropologists report the remains show the victims were skinned, cut up and even had their bone marrow extracted. One thighbone and three shinbones were used to shape stone implements, similarly to how animal bones were fashioned. Nothing went to waste.

“These indications allow us to assume that the Neanderthals practised cannibalism. The many remains of horses and reindeer found in Goyet were processed the same way,” said Prof Hervé Bocherens, from the University of Tübingen in Germany.

The fact that some Neanderthals were cannibals shouldn’t be surprising — after all, they’re the closest extinct relatives to homo sapiens, and human cannibalism can happen to this day.

“Goyet not only provides the first unambiguous evidence of Neandertal cannibalism in Northern Europe, but also highlights considerable diversity in mortuary behaviour among the region’s late Neandertal population in the period immediately preceding their disappearance,” the scientists involved in the excavations said.

The findings were documented in the journal Nature.