You are currently browsing the tag archive for the ‘primates’ tag.

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Primates evolved in a forest habitat of many complex colors and shapes where a failure to properly judge depth perception meant painful injury or death.  Vision is therefore a paramount sense for monkeys, apes, tarsiers, lemurs, and lorises.  Primates are social animals.  After evolving highly acute sight and keen color vision, they then evolved to be the most colorful order of mammals.  As with cuttlefish and birds of paradise, primate colors carry all sorts of social cues.

 

We will talk about all of this more (although, to be frank, we have always been talking about it), but today we are concentrating on the color red, which is of enormous importance to most primates because it is involved in status relations and thus in mating. Red is an important color for primates!  For example, among mandrills, red coloration of the face correlates directly with a male’s alpha status: the redder the face the more exalted the mandrill.  Primatologists have found this pattern vividly true in many species of monkey (and to other very different creatures like octopuses and cardinals, where red holds similar dominance significance).  To quote a particularly eye-opening line from Wikipedia, “Red can also affect the perception of dominance by others, leading to significant differences in mortality, reproductive success and parental investment between individuals displaying red and those not.”

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Humans beings are primates.  I suspect that it is not news to you that red is heavily involved in our own status and sexual selection preferences (for the sake of chivalric euphemism I will hereafter say “romantic” preferences).  Although this is readily evident in the red dresses of supermodels, the flashy Ferraris of celebrities, and the power ties of senators, the subconscious sway it holds over our lives is more pervasive than you might realize.

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In studies where men rated the general attractiveness of photographs of women, the women wearing red were rated as more desirable, even when the experimenters stacked the deck with pictures of the same women in different colors.  The same sort so f experiments revealed similar preferences among women looking at pictures of men.  It might be speculated that this has something to do with blushing, blood flow and suchlike visible markers of fertility/interest (although when asked, men said that women in red were more attractive, and women said that men in red were more “dominant”).

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Wearing red uniforms has been linked with increased performance in competitions (particularly physical competitions such as sports). Controlled tests revealed that red conferred no physical advantage during non-competitive exercise, so the effect is purely one of perception among opponents, teammates, and referees. Referees and judges seemed to be a particular focus of the psychological effects we are discussing here, rating red-garbed performers much more highly/favorably than similar peers in other outfits.

One needs to pause and think of how much more frequently the hateful Boston Red Sox and the despicable Atlanta Falcons would be justly drubbed if they wore dun uniforms.

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All of this might seem like bad news for people without a great deal of red in their wardrobe or in their clubhouse lockers, but there is a counterposing effect too.  In studies which involved paying attention and focusing on achievement-type events like the SATs or IQ tests (or essay questions about the Byzantine empire), red proved to be a nuisance and a hindrance.  Exposure to red decreased performance during such events (although my source does not say what this constitutes…maybe the experimenters had a huge red flashing light or a ringing red phone or some such gimmick that would unequivocally mess up one’s GREs).

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If all of this sounds wrong or suspicious to you, I guess it is the middle of the 2018 World Cup.  According to primatologists, Russia, England, Belgium, and Serbia should all win in the quarterfinals (so as long as they are not wearing their white or yellow “beta” uniforms).  If that test seems too nonsensical for you, you could always put on a British naval uniform and walk down to the local bar.  I would be very curious to learn how your experiment goes, and I will tally up the results as soon as I finish ordering a few new shirts…

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It is leap day! Every four years the niceties of the calendar give us this extra day. In the past, leap day has caused me to reflect about history, the calendar, and the ineluctable nature of time in general, but this year I am going a different direction. Instead of concentrating on the calendar aspect of the day, we will concentrate instead on “leaping.” And from there it is a short cognitive leap to the microcontinent of Madagascar where we find the masters of leaping, the lemurs.

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Ring-tailed Lemur jumping (Lemur Catta) photo by Luc V. de Zeeuw

Lemurs are strepsirrhine (wet-nosed) primates endemic to the island of Madagascar. They are ancestral primates—the monkeys, apes, and hominids evolved from them (though of course these branches diverged in the Eocene and the lemurs have been evolving in their own directions for 50 million years). In fact, let me say that last sentence differently and better: monkeys (and apes and people) descended from a very lemur-like ancestor.

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There are nearly 100 species of lemurs and they have spread through all sorts of evolutionary niches in Madagascar. It is hypothesized that they reached the island micro-continent by rafting there on masses of floating wood and vegetation. On Madagascar they were free to evolve in their own direction, as other primates back in the ultracompetitive African homeland went down different pathways. When humankind finally reached Madagascar 2000 years ago (from Indonesia!) there were even more strange lemurs, including some as large as gorillas, but the violent humans quickly snuffed them out (and indeed we are rapidly eating the remaining smaller lemurs out of house and home as well (or just eating them outright).

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Female Sclaters lemur with open mouth  (photo by “Tambako the Jaguar”)

Lemurs live in many habitats and specialize in many lifestyles. They are diurnal or nocturnal or crepuscular. They are fructivores, or herbivores, or insectivores. Some are omnivorous. With many different lifestyles come different habitats, but lemurs, like most other primates tend to be arboreal. While some lemurs imitate lorises and sloths and move with deliberate glacial slowness, the majority of lemurs have a different and far showier way of getting around—they leap from tree to tree like acrobats.

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Perhaps I should say acrobats are like lemurs. Not only were the latter here first, but they are also capable of thrilling flights that would cause the most air-worthy flying Wallenda to fall down dead (literally). Using their long powerful back legs, lemurs hurl themselves into the air and then flatten out. They can thus leap up to 10 m (33 feet). And this is not an isolated leap. They can leap again and again and again…thus springing through whole jungles in a series of breathtaking bounds.   The real masters of leaping—the ring-tailed lemur and Verreaux’s sifaka, hardly seem suited for any other sort of locomotion. When Verreaux’s sifaka is stranded in a tree island and is forced to cross open ground the poor creature looks quite ludicrous (see the gif below). It holds its arms above its head and leaps plaintively and swiftly across the hated land.   But Verreaux’s sifaka looks utterly at home in its preferred habitat—hurling itself between spiny trees covered with razor sharp needles.

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The more I read about lemurs, the more I realize I will have to come back and write more about them. It may be four years before the next leap day, but we will be back to lemurs before then!

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DeBrazza’s monkey (Cercopithecus neglectus) Photo by In Cherl Kim

So far, Primate Week has been a huge success! The Year of the Fire Monkey has featured the loudest land animal, the immortal magician monkey god, and the disconcerting calculus of Dunbar’s number. There is still another topic which I wanted to address—an important primate post which I have planned to write for a long time–but it is almost midnight on Friday night, so I am going to bunt with a quick gallery post about color. Last week I wrote a piece about humankind’s love for the color red. I blithely assured everyone that primates are the most colorful mammals…however I didn’t back that up with any images.

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Northern owl monkey (Aotus trivirgatus) photo by Mogens Trolle

Therefore, here are some beautifully colorful primates. I am only listing the species and the source (where available) so that you can revel in the beautiful color of these monkeys. If you want to learn what these colors betoken and how each species evolved such lovely patterns, you will have to look elsewhere. I have done my best to label each picture, but the WordPress function which allows a a blog’s creator to label images has been broken a long time (at least for the template I use). If you have any questions, just ask in the comments!

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The mandrill (Mandrillus sphinx)

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The Golden Langur (Trachypithecus geei)

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The golden snub-nosed monkey (Rhinopithecus roxellana)

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Emperor Tamarin (Saguinus imperator)

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Bald-headed uakari (Cacajao calvus) photo by Luis Louro

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Zanzibar Red Colobus monkey (Procolobus kirkii) Olivier Lejade

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Golden lion tamarin (Leontopithecus rosalia)

 

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It is a pretty intense rainbow! Look at how expressive their faces are. It is possible to read the personality of each monkey. Some of them remind of acquaintances from secondary school or world leaders, but of course we humans are not quite so colorful. Still we can pull off a mean combination of orange pink and brown in our own right. We also change colors somewhat when we are aroused, angry, or afraid! Colorful mammals indeed!

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Human (Homo Sapiens) photo by Luis Aragon

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Robin Dunbar is an anthropologist/primatologist who discovered a correlation between the size of a primate’s brain (or really its neocortex) and the size of that animal’s social network. For example, clever chimpanzees tend to live in groups of 60 or so individuals, who maintain complex intimate social relations (yet chimpanzees don’t really care about outsiders without elaborate introductions). Howler monkeys tend to live in groups of 6 or 7. Dunbar studied primate brains until he believed he found the correlation index… then he applied it to human beings based on our own neocortices (is that the right word?). The number he arrived at was around 150. He posited that this is the average number of stable meaningful social relationships we can have at once. Here is a humorous (yet oddly serious) article which explains the concept elegantly (albeit with some fairly salty language and preachy talk).

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When one starts looking for the number 150, it crops up all over the place. Hunter gatherer tribes were (and still are) limited to about that number. Military companies of all sorts of different armies throughout history have been that size. Business consultants say that this is an ideal size for companies (come to think of it there are 150 people at the company where I work) or for departments of companies.

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But of course the 150 people I work with are not the entirety of my social interactions. I have 500 or so Facebook friends and not a one of them is from work….and the people I am closest to are not always on Facebook. And there are people I know about but have never (and will never) meet (like Susanna Hoffs, the emir of Qatar, and…Robin Dunbar). High functioning individuals like Presidents, CEOs, and world famous artists probably know many thousands of people—or at least know the one or two key pieces of information which makes each contact useful.

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So there are lots of troubles and quibbles with Dunbar’s number…yet if you really write out everyone you have a true worthwhile meaningful relationship with you will probably come up with about 150 (if you are a gregarious adult with a full life in a big city—you can have many fewer close relations and there is nothing wrong with that…it doesn’t mean you are a capuchin monkey or something).

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(Not that there is anything wrong with that either)

There is a line we draw around our tribe. Within this line are people we care about and need, outside it are… others—people we may care about in the abstract, or because they share a language, or a characteristic, or a nationality with us…but who are not dear to our heart in the same way as our intimate associates. The writer I linked to in the first paragraph up there asks us to imagine having a beloved pet…or two beloved pets…or six, or 23. How long would it be before our love and our attention were so diluted that we only cared about them in the most general abstract terms (or just outright despised them as a furry horde)? Whether you accept the premise of Dunbar’s number or not, it is a worthwhile question. If our brains are built by evolution in such a way as to make an “us” and a “them” what does it mean for all of us?

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Happy Chinese New Year! It is year 4713! The Year of the Fire Monkey. Monkeys are intelligent and clever but mercurial and swift. Our in-house oracle thus prognosticates that this year will be intense and intellectual…yet scattered and jumpy (and, it goes without saying, that it will rush by swiftly). 2016…er….4713 is therefore a good year for fresh starts and running leaps. However scrying is not really this blog’s metier: let’s talk about monkeys!

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One of Ferrebeekeeper’s favorite and best topics is mammals, however I have (largely) avoided writing about primates. This is not because I dislike primates (although some species of monkeys and apes dwell in the uncanny valley where they are simultaneously so human and yet inhuman that the effect is deeply disconcerting), but because primates are very difficult to write about. Not only are they generalists who make their living through a wide range of complex behaviors, they also have elaborate social lives which require attention, sympathy and discernment to understand and present. Even primate taxonomy is complicated. There is a great divide between prosimians and anthropoids (which is now being reconceived as a divide between wet-nosed primates (non-tarsier prosimians) and the dry-nosed primates). There is a great geographic divide between New World and Old World Primates. There are 72 genera and hundreds of species–and that is only the ones that are extant—I am leaving out the extinct fossils.

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Primates have a similarly complex place in society, art, and mythology. Just look at Sun Wukong AKA Monkey King, the trickster god of classical Chinese mythology who is simultaneously Buddhist and animist, wicked and saintly, immense and infinitesimally miniscule. The Indian monkey god Hanuman is similarly protean and complex. And these are only the two monkey gods…the nimble arboreal creatures are found everywhere in religion, literature, and art.

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Finally, and above all, we..the readers and the writer…are primates. When the silverback from marketing comes by and harasses the trapped office women before displaying his dominance by making me move his stupid credenza around, I tell myself it is just the world economy. That may be true, but it is really all stupid monkeyshines. History is an intricate tapestry of primates desperately contending for privileged status. Here in America we are seeing lots of primate behavior—after all, it is an election year, and primates are ferociously hierarchical and tribal. Primates are also stupendously aggressive. Sometimes this trait combines with that big brain to make for horrendous violence. We are going to start unpacking some of this throughout the remainder of this week, which I dub “Primate Week” in honor of the fire monkey.

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Dusky leaf monkey, Trachypithecus obscurus - Kaeng Krachan National Park, Thailand. Photo by Thai National Parks.

Dusky leaf monkey, Trachypithecus obscurus – Kaeng Krachan National Park, Thailand. Photo by Thai National Parks.

I have been wanting to expand Ferrebeekeeper’s “mammals” categories by writing more about primates…but primates are really close cousins.  They are so near to us on the tree of life that it is tricky to write about them.  Monkeys and apes venture into the uncanny valley…that uneasy psychological chasm that contains things that are very much like humans, but clearly are not humans.

The Dusky leaf monkey (Trachypithecus obscurus)

The Dusky leaf monkey (Trachypithecus obscurus)

Therefore, in order to ease us into the subject of primatology, I am going to start with the spectacled langur aka dusky leaf monkey (or, more properly Trachypithecus obscurus).  This is a beautiful langur which lives in the dense rainforests of Malaysia, Burma, and Thailand, but realtively little seems to be known about the creatures. Adult male dusky leaf monkeys weighs approximately 8.3 kilograms (18 pounds). Females are somewhat smaller.  The monkeys live in troops of about ten or a dozen and they subsist on a variety of tropical fruits and nuts (supplemented perhaps occasionally with other vegetables or small animals).  Infants are born orange, but quickly turn dark gray with the distinctive “spectacles” for which the species in known. I don’t really have a great deal of information about these monkeys, but I am blogging about them anyway because they are adorable!  Just look at these young langurs.  This is exactly the sort of cute introduction which we need to get us started on the topic of primates.  We will work on the serious grim monkeys later!

Dusky Leaf Monkey (Trachypithecus obscurus) photo by Petfles

Dusky Leaf Monkey (Trachypithecus obscurus) photo by Petfles

The Eocene (Illustration by Bob Hynes for the Smithsonian Institution)

The Eocene epoch (which lasted from 56 million ago to 34 million years ago) was hot!  Temperate forests ran all the way to the poles.  Steamy tropical jungles grew in the latitude where Maine is now and the equatorial regions of earth were (probably) sweltering. Tropical reefs formed in the coastal waters around a heavily forested and ice-free Antarctica. Since there was not year-round ice at each pole, the sea levels were much higher.

A Global Map of the Early Eocene (map by Dr. Ron Blakey)

The Eocene was a time when most of the contemporary mammalian orders first appeared.  The earliest artiodactyls, perissodactyls, rodents, bats, probiscideans, sirenians, and primates all originated during this time.  Of course mammals were not the only story: the Eocene was also a time of great diversification for birds and many familiar orders of avians developed then.  Reptiles begin to put the setbacks which marked the end of the Cretaceous behind them and several giant new species emerged including an immense tropical ur-python and a host of crocodiles and turtles. It is harrowing to think that the first wee dawn horses and cute little early atiodactyls were forced to contend with a 13 meter long super snakes and giant crocodilians (which flourished in the great hot swamps of Alaska), but such is the case.

Titanboa with Ancient Crocodilian (painting by Jason Bourque)

The high temperatures of the Eocene are perplexing to scientists.  By contrast, the temperatures of the Paleocene (which was the first era of the Cenezoic and had directly preceded the Eocene) were much more temperate. In fact the temperature spike of 56 million years ago seems to have ended the Paleocene and brought about the diversification of Eocene life.  The rapid warming is known as the Palaeocene-Eocene thermal maximum and scientists have been vigorously debating what caused the climate change.  An immense amount of carbon seems to have entered the atmosphere at this time, which in turn led to greenhouse warming.  It remains controversial as to how such a large quantity of carbon got into the atmosphere.  Comet/meteorite impact, massive peat fires, and volcanic activity have been suggested as triggers, however supporting evidence is lacking.  The release of globally significant quantities of hydrocarbons–which had been trapped in undersea clathrates seems like a more feasible hypothesis, as does the idea that the earth’s orbit brought the planet closer to the sun for a time.

Phenacodus, a goat-sized grazer of the Eocene era (painting by Heinrich Harder)

The end of the Eocene was also linked to the carbon cycle.  Reduced carbon dioxide in the atmosphere seems to have led to global cooling and newly evolved varieties of grasses began to invade large swaths of the world.  Additionally two massive meteor strikes in Siberia and Maryland combined with substantial volcanic activity to finish off the long hot summer. But during the Oligocene, the era which followed the Eocene, the world was a much more familiar place inhabited by orders of animals which are still here with us today (or are us–since primates first evolved during the Eocene).

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