Chimpanzees in west Africa observed indulging in habitual drinking

[jimmy olsen]

 

http://www.theguardian.com/science/2015/jun/10/chimpanzees-bossou-south-eastern-guinea-habitual-drinking

Chimpanzees in west Africa observed indulging in habitual drinking
Inhabitants of forests in Bossou, south-eastern Guinea, enjoy rich, alcoholic brew fermented from sugary sap


The boozing starts from 7am. Though large amounts are often drunk, the sessions are orderly, even sociable. A skinful later, and always before nightfall, enough is enough and they rest.

They are the chimpanzees of Bossou, south-eastern Guinea, and their secret is finally out. With 17 years of evidence in hand, scientists have declared the troop the first wild chimpanzees to indulge in regular, habitual drinking.


The west African chimps were observed in their natural forest habitat from 1995 to 2012. The action, captured on video, centred around raffia palms. Local communities harvest sugary sap from the trees, which ferments into a rich, alcoholic brew in hours.


To extract the sweet, white sap, tappers cut a wedge in the tree and suspend a container beneath. They leave it there to fill and lay leaves over the top to keep the bugs out. In a few weeks, a single tree can yield 50 litres of sap.


But the chimps have cottoned on. In a study published on Wednesday, scientists report 51 incidents of the chimps raiding the palm sap containers. The apes found a big leaf – often one covering the container – and chewed it to form an absorbent sponge or a folded scoop. They then plunged this into the sap, pulled it out and drank.


And drank some more. In their analysis, reported in Royal Society Open Science, the researchers observed the chimps necking on average a litre of fermented sap each time. One male, named Foaf, was a regular, appearing in 14 of the 51 sessions. He was an outlier though. Of the 26 apes observed, 13 were apparently teetotal.


Separate tests on raffia pam sap found that the alcohol content of the drink varied through the day, as the sugars increasing fermented to alcohol. On average, the liquid contained 3.1% alcohol by volume (ABV), the same as a pint of Bass mild. The most potent sap came in at 6.9% ABV, the same as Brooklyn East India Pale Ale.

Male and female chimps were equally keen on the drink, but apes varied individually in how much the imbibed. At one event, the scientists estimate that the amount of alcohol ingested reached 85 millilitres, the equivalent of about three pints of Stella Artois.

Kimberley Hockings, an author of the study at Oxford Brookes University, said they could not be sure if the chimps got drunk, but said the amounts they consumed were enough to "elicit behavioural changes in humans." On one occasion, an adult male seemed restless after a session and while his companions made for their nests, spent the next hour swinging from tree to tree "in an agitated manner."

The all-too-human behaviour adds weight to the "drunken monkey hypothesis", which states that natural selection favoured primates with a taste for alcohol, because it stimulated the appetite, helped them hunt for fruit and so boosted calorific intake. About 10 million years ago, our ancestors – and those of apes – gained a genetic mutation that improved 40-fold our ability to break down ethanol. Without it, consuming large amounts would be even more dangerous.


The chimps of Bossou are not the first to be caught partaking of the fermented sap. In 2008, scientists in the US reported chronic drinking in wild treeshrews. "It is yet unclear to what extent treeshrews benefit from ingested alcohol per se, and how they mitigate the risk of continuous high blood alcohol concentrations," the authors wrote. Other primates have found bolder ways to get their drink. In St Kitts, in the Caribbean, green monkeys steal tourists' cocktails.

Mareile Flitsch, director of the Ethnographic Museum of the University of Zürich, and author of the 2015 exploration of alcohol-based customs, Drinking Skills, said the challenge with palm sap wine was drinking it before it fermented too much and turned into vinegar. "It's very nice when it's fresh. It tastes like cider," she said.

[Jaron]

Are they sure they weren't just local blacks?

[jimmy olsen]

Take that bile and go troll somewhere else. 

Another interesting Chimp story I just read. Apparently unlike Humans, Gorillas and Orangutans, Chimps are almost pure muscle!

http://johnhawks.net/weblog/reviews/bonobos/zihlman-bolter-bonobo-body-fat-2015.html

Why do male bonobos have such low body fat?

10 Jun 2015

I can't be the only one surprised at how little body fat male bonobos have. A study of bonobo dissections by Adrienne Zihlman and Debra Bolter (2015) included data from six female and seven male bonobos collected over many years.  The females had very low body fat percentages, with the highest value only 8.6% and three of the six females under 1.2%. But the males were the interesting story, with no male among the seven measured as high as 0.01% body fat.

As Zihlman and Bolter explain, these are minimum estimates, since the necropsied bonobos did not necessarily include fat included in the viscera or near internal organs, and fat that could not be dissected as separate chunks was not weighed separately. But subcutaneous fat and other small adipose areas are included in this estimate, and comparable values for male humans are upward of 20%. They comment on the surprising finding:

The negligible measurable fat in all seven P. paniscus males was unexpected, overriding captivity, age, and body mass. Among wild chimpanzees, there is little indication of an ability to mobilize fat stores during times of caloric restriction, a key adaptive feature found in orangutans and possibly to a lesser degree in gorillas (24, 52, 53). Without selection pressure for storage fat, and with over half of body mass in muscle, the male P. paniscus does not easily accumulate body fat, even under optimal circumstances of captivity. Remarkably, none of the males and females manifested detrimental health as a consequence of having little fat, in stark contrast to H. sapiens.

I was interested in whether this is a bonobo-specific phenomenon. Zihlman and McFarland (2000) dissected four captive gorillas and found both males and females to have substantial body fat percentages, ranging from 19.4% to 44%. Wolfgang Dittus (2013) reported on the body fat distribution of wild toque macaques, finding that they had approximately 2.1% body fat, more than 80% carried within the viscera and other intra-abdominal areas and only a small amount subcutaneously. Males and females did not differ on average.

Interestingly, a study of zoo chimpanzees by Elaine Videan and colleagues (2007) found that no male chimpanzees could be categorized as overweight, and that they differed from females in skinfold and triglyceride levels. From that paper:

The range of serum triglyceride and glucose levels for male chimpanzees was considerably smaller than that of female chimpanzees (Figs. 2, 3). In fact, none of the male chimpanzees in this study had serum triglyceride levels above 150mg/dl (< 150 mg/dl 5 normal human reference range) despite having BMIs that ranged as high as 149.5. In addition, most of the mean skinfold measurements for male chimpanzees were half that of the female values (Table 1). We hypothesize that the high BMIs observed in many of the male chimpanzees in this study reflects high lean body mass (i.e., muscle mass) rather than high body fat.

So there does seem to be something about male chimpanzees and bonobos.

Lest you think that human body fat is just a post-agricultural phenomenon, Herman Pontzer and colleagues (2012) reported on body composition in the Hadza population of Tanzania, who live a hunter-gatherer lifestyle. In that population, women range from 12.4 to 27.7 percent body fat, and men range from 7.4 to 23.1 percent body fat. This is much less than in Westernized societies and is also less than in subsistence farmers, although the difference there is not so great as most might assume. There is a story of body fat in human evolution, and certainly the high body fat composition of humans—even human foragers—contrasts with most wild primate populations. It may be that bonobos and chimpanzees are not the appropriate comparison because of their own distinctive evolutionary trajectories.

[Eddie Teach]

https://www.youtube.com/watch?v=1KaWPYOLuT8
Monkey gets robot arm.

[Caliga]

Take that bile and go troll somewhere else. 

Yeah Jaron!

[Ed Anger]

Are they sure they weren't just local blacks?

I laughed

[Caliga]

[Ed Anger]

That giant head amuses me