Macaques Like To Keep Their Conversations Short

Formosan macaques. Photo from Wikipedia.

Macaques, like humans, seem to prefer conversing in short calls (or using short words) rather than lengthy vocalizations. In humans, we use the words "the", "a" and "of" often and they do not take long to say. The calls used often by macaques (greetings, grunts and coos) are also short.

The relationship between the length of a word and how often we use it can be explained by the "law of brevity", which states that the words we use very often are very short and the words we use very rarely are long, said Dr. Stuart Semple from Roehampton University, UK.

The vocal repertoire of the Formosan macaques (Macaca cyclopsis) conforms to the law of brevity, indicating a commonality in the basic structure of communications in humans and non-human primates. The article by Semple et al. (2010), Efficiency of coding in macaque vocal communication is published on Biology Letters (free pdf)

Read more on BBC News: Monkeys keep chatter 'short and sweet'.

The Evolution Of Brain Size In Primates And Homo Floresiensis

Skull of LB1 (Homo floresiensis) and modern human.

A few links and papers on Homo floresiensis brain size and the evolution of primate brain size. It seems that the evolution of brain size in primates is not one directional (always leading to larger brain) but instead body size and brain size is subjected to separate selective pressure. In the evolution of Homo floresiensis, evolution shrunk its brain size much like how evolution shrunk the brain size of Mouse Lemur, Marmosets and Mangabeys. So, the small brain size in Homo floresiensis is not pathological but instead a product of evolution. There's a good write up at A Primate of Modern Aspect.

A White-collared Mangabay (Cercobebus torquatus)

A Pygmy Mouse Lemur (Microcebus myoxinus). Smallest primate in the world. Photo from National Geographic.

A Pygmy Marmoset (Callithrix pygmaea). Photo from Wikipedia.

Links to paper and articles:
Reconstructing the ups and downs of primate brain evolution: implications for adaptive hypotheses and Homo floresiensis (Montgomery et al, 2010)

Scientific American: What the small-brained hobbit reveals about primate evolution.

EurekAlert!: Is the Hobbit's brain unfeasibly small?

EurekAlert!: Does evolution always lead to bigger brains?

Wired Science: Evolution Shrank Some Primates’ Brains.

Ready, Set, Chimp! Movie Made By Chimps To Be Aired On TV

A movie made by chimpanzees?! Yes, you read it right ... a movie shot entirely by chimpanzees will be aired on BBC Two on January 27th, 2010. PhD student Betsy Herrelko at the University of Stirling, UK thought of this idea and introduced "video technology" to a group of 11 chimpanzee individuals that live in Edinburgh Zoo, UK. This project is part of a scientific study on how chimpanzees perceive the world and each other. Follow link to the BBC Earth News website, with photos and videos of the chimpanzees.

One of the chimpanzees at Edinburgh Zoo using a "Chimpcam".

Chimpanzees are not the only great ape who's famous for using modern technology. Nonja, the orangutan the from Schönbrunn Zoo, Vienna is famous for using her camera to take pictures of herself and her enclosure.

A New Theory On The Origin Of Primates

A new theory on the origin of primates was published on Zoologica Scripta. The paper, Evolution and biogeography of primates: a new model based on molecular phylogenetics, vicariance and plate tectonics by Michael Head, argues that the distribution of major primate groups are correlated with the Mesozoic tectonic features. The range of these primate groups correspond to them evolving locally from a widespread ancestor on the supercontinent of Pangea about 185 million years ago.

Read more about this from Science Daily, New Theory on the Origin of Primates.

Allogrooming in Verreaux's Sifaka

Finally a paper about grooming patterns! On "early view" in American Journal of Primatology, is Rebecca J. Lewis's Grooming Patterns in Verreaux's Sifaka (free abstract). If you would like to read the article, let me know and I can send you the whole article in pdf.

I can definitely relate to the first sentence of this paper's abstract, "Lemur grooming has received very little attention in the literature". It has became apparent to me when I was visiting different graduate schools that professors would comment "Well, there aren't much grooming going on in the species that I study so you'll just be wasting time". While it is important to collect data on species that groom a lot, it is also important to document grooming patterns in species that don't groom a lot so that we can compare these data. Why don't these species groom as much? What alternative strategies are they using instead of grooming?

Well back to the article. As you might have guessed, it's about grooming patterns in Verreaux's Sifaka (Propithecus verreauxi). What's unique about prosimians grooming is that they don't groom with their fingers, instead they groom with their dental comb. In her paper, Lewis found is that these sifakas:

• Spend very little time allogrooming. 
• Allogrooming happens on parts of the body that can be easily autogroomed (self groomed). 
• While ectoparasite loads are greater in the rainy season, the rate of allogrooming did not increase.
• Allogrooming rates are influenced by sex and rank. Sifakas groom up the rank with females receiving more grooming than males. Males also tend to groom others more than females do.
  
• Allogrooming rates increased by 50-100% during mating season. Males tend to initiate grooming during mating season but generally are not reciprocated by females.

These results suggest that Verreaux's Sifaka used grooming as a social function, not as a health function. Lewis also posits that lemur grooming patterns do not differ from anthropoid grooming patterns as much as previously thought.

Greetings From Yale University: Peabody Museum Of Natural History

Hi all. Sorry for not posting for a bit (it's been a week!) but I've been busy being sick and getting everything ready for my grad school application which was due yesterday.

I went to Connecticut this weekend and I think you guys should check out Yale University's Peabody Museum of Natural History if you haven't. Their "Hall of Mammalian Evolution", "Primates" and "Fossil Fragments: The Riddle of Human Origins" are worth checking out.

 
My favorite was the primate exhibit, of course, but I also like the cast of Nariokotome Boy (An 8 year-old Homo erectus found in Lake Turkana, Kenya).

Attention To Elders' Voice In Campbell's Monkeys

Campbell's Monkey. Image: Patricio Robles Gil/Minden Pictures/FLPA from Newscientist.

A new paper from Biology Letters by Lemasson et al. (2009) observed that Campbell's monkeys (Cercopithecus campbelli) pay more attention to the vocalization of older individuals. The authors posit that attention to vocalization of older individuals not only exist in humans but also in non-human primates. Since aging is sometimes synonymous to wisdom in human culture, the authors think that the propensity for younger individuals to pay more attention to the vocalization of elders has a biological basis both in humans and non-human primates. Younger individuals simply listen carefully what the older individuals have to say because they are wiser and more accountable.

Read about the article, Attention to elders' voice in non-human primates on Biology Letters. Also, NewScientist has an article on this too, Respect for elders 'may be universal' in primates.

As some of you might remember, these are the monkeys that are said to understand primitive form of syntax.

Oldest Anthropoid Fossil Hails From Thailand, Said Thai Officials

So supposedly a newly publicized paper back in November 2009 confirms that the oldest primate anthropoid fossil comes from the southern province of Krabi, Thailand (according to some Thai news articles, which unfortunately I cannot find where they cited their primary sources). It was discovered 14 years ago by Thailand's Mineral Resources Department archaeologists. Siamopithecus eocaenus supposedly roamed the earth 35 million years ago and is in fact currently the oldest primate anthropoid fossil from the fossil record (again, can't find where they cited the primary source). Thanks to Mae Kai Fa for pointing out that it is the oldest "anthropoid" fossil not primate fossil, which makes more sense.

Siamopithecus eocaenus or the Siam Ape gets its name from the country it was found. Siam was the official name of Thailand until 1939, although it is still somewhat used synonymously with Thailand.

Fragments of the fossil includes the lower right molars and upper left and right molars that are attached to the eye bone. Researchers think that S. eocaenus is about the size of a gibbon, weighs around 7kg and belongs to the Amphipithecidae family.

So, I don't know. This sounds a bit like the Darwinius massilae fiasco all over again. I also wonder why no one picked up this news, except a sprinkle of Thai news websites. What do you think? The paper pointed out by these articles is possibly The Face of Siamopithecus: New Geometric-Morphometric Evidence for Its Anthropoid Status by Zollikoffer et al. (2009) that was published in The Anatomical Record on November. Unfortunately I do not have access to that journal so I can't verify whether the paper did point out that S. eocaenus is indeed 35 million years ago.

Some Thai news article:
Oldest primate fossils found by Bangkok Post.
35-mn-year-old fossil raises questions on primates' origin by Prokerala.com.
Oldest primate fossils found in Krabi by National News Bureau of Thailand (NNT).

Brucellosis In Australopithecus Africanus Skeleton: Evidence Of Meat Eating In Early Hominin?

Brucellosis is an infectious disease cause by the bacteria, Brucella sp. These bacterias localize in the reproductive organs of the host animals and are shed in large numbers through the animal's urine, milk, placental fluid and other fluids. Exposure to infected animals and animal products causes brucellosis in modern humans.

Does possible brucellosis diagnosis in early hominin skeleton Stw 431(Australopithecus africanus) from Sterkfontein, South Africa suggests that A. africanus occasionally eat meat? Maybe. That is what the paper Possible Brucellosis in an Early Hominin Skeleton from Sterkfontein, South Africa (D'Anastasio et al., 2009) is about. The presence of lesions on the vertebral bodies of Stw 431 was diagnosed as spondylosis deformans due to trauma but the authors suggest that these lesions were actually pathological changes from the initial phases of brucellosis.

Reference:
eMedicine. 2010. Brucellosis. Retrieved January 05, 2010, from http://emedicine.medscape.com/article/213430-overview

Happy New Year Y'all. Dolphins Smarter Than Chimps?

Happy New Year to all my readers, humans and non-humans alike (I've caught my cat reading my blog more than twice). Sorry for not posting this few days but I've been sick since New Year. Suffice to say, 2010 didn't really start on a good note for me.

Apparently 2010 did not start on a good note with my fellow primate, the chimpanzees, either. Lori Marino, a zoologist at Emory University in Atlanta, Georgia claim that the second most intelligent creature after humans are dolphins, not chimpanzees as many researchers believed. Diana Reiss, a psychology professor from Hunter College (CUNY) in New York City found that bottlenose dolphins can recognize themselves in front of the mirror and learn rudimentary symbol-based language. Both Marino and Reiss will present their findings at a conference in San Diego, California, next month. These findings have tremendous implications on human-dolphin interactions, specifically the use of dolphins for entertainment in marine parks.

Sad chimpanzee is sad because he is no longer the second smartest after humans.

Read the article Scientists say dolphins should be treated as 'non-human persons' from Times Online. I wonder if both had any papers that will be published soon about this topic. I've only found Marino & Reiss (2001) Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence and Marino (2002) Convergence of Complex Cognitive Abilities in Cetaceans and Primates. Why is this story being published in 2010, almost 8 years since the papers were published? Something is fishy here (no puns intended because dolphins are in fact mammals, not fish).