Interspecies Grooming: Zanzibar Red Colobus and Cattle

I have written about interspecies grooming on this blog, a post that appeared sometime last October, Interspecies grooming at The Bronx Zoo. Interspecies grooming first peaked my interest after I realized that two of my cats would readily groom me (hair or skin). Of course, grooming held a special place in my heart. I wrote a thesis comparing grooming behavior in geladas and hamadryas baboons for my undergraduate thesis.

My blog post was featured and I was interviewed for this post on Environmental Graffiti, Monkeys Grooming Other Animals! earlier this October (almost a year after my interspecies blog post appeared). Interspecies grooming can occur among primate groups or among other non-primate groups. There are documented incidents where different primate species or primate and non-primate species (for example ruminants) groom each other. Interspecies grooming is not limited to the natural range of the animals as well. There are also documented bouts of interspecies grooming in captivity, mostly in zoos.

I received an email yesterday from Dr. Katarzyna Nowak, who is affiliated with Wildlife Conservation Research Unit (WildCRU) and the Udzungwa Elephant Project. She sent in a photo of an interspecies grooming in action between a few Zanzibar red colobus (Procolobus kirkii) and a cattle (Bos taurus).

Zanzibar red colobus grooming a calf outside of Jozani-Chwaka Bay National Park.
Photo by Dr. Katarzyna Nowak.

Dr. Nowak later filled me in on this photo.

Hi Raymond, 

The colobus and cows share this environment (it's a farm-field mosaic outside of the national park) so I presume that they compete at least to some extent over herbaceous vegetation as the colobus are largely terrestrial here. But it is only once that I observed this behavior (I was with primatologists Tom Struhsaker and Andy Marshall when we saw this) and I don't know of anyone else who has seen it before or since...but again, I imagine it happens more often. 

Interspecies grooming is a very fascinating interaction, at least to me. I think that it is easier to document interspecies grooming than to tease out why this behavior exist between individuals. But of course, each interaction is probably unique between the groomer and the one being groomed. I have wondered whether interspecies grooming in captivity is due to boredom. But of course I have no way of testing these hypotheses given that it's quite hard to proof that an animal is "bored". There are, of course, some ingenious ways out there to find out what these animals are thinking.

Please feel free to discuss or tell me why you think interspecies grooming occur and what types of studies can be used to further elucidate this phenomenon. Seen an interspecies grooming in action? Feel free to email me and tell me all about it. Emails with pictures will get a cookie!

Handedness in Humans and Geladas

I thought I’d share a paper I wrote from last semester’s Comparative Psychology class on handedness in humans and geladas. Debating if I should actually follow through with this preliminary report and do some data collection. There is a YouTube video that accompanies this paper, which will appear on the bottom of the page.

Handedness can be defined as the unequal distribution of fine motor skills between the left and right hands. Simply put, handedness is the preference to use left, right or both hands when performing tasks. Humans are mostly right-handed across cultures. Here, I compare handedness in humans (Homo sapiens) to handedness in geladas (Theropithecus gelada).

Right-handedness is predominant across cultures in humans. About 85% to 90% of humans report themselves as right-handers (10). In studies of great apes, comparative analysis indicates that chimpanzees and bonobos exhibit population-level preference in right-handedness while gorillas and orangutans do not exhibit population-level preference in handedness (10). However, right-handedness seems to be uniquely human as no other primate species has such a clear bias (1, 13 & 14). The objective of this preliminary study is to elucidate whether geladas exhibit preference in handedness.

A male gelada at The Bronx Zoo.

Geladas are Old World Monkeys and can be found in the high plateau of North Central Ethiopia and Eritrea (9 & 2). Geladas are sometimes referred to as “bleeding heart monkeys” due to the presence of a naked, pink patch of skin on the chest of males and females that looks like an hourglass (2). They exhibit sexual dimorphism; males have manes and are slightly larger than females. The maximum lifespan of a gelada is about 19 years in the wild (5) and well over 30 years in captivity (9). Geladas are gramnivores; they are unique among primates because grass is their main food source but is occasionally supplemented by seeds, roots, and bulbs (3).

There are many definitions of handedness. Here, I define handedness as the preference of left, right or either hand when performing tasks. In humans, those who have a preference for using their right hand are right-handed while those that prefer using their left hand are left-handed. Those that prefer to use either hand when performing tasks are ambidextrous.

Approximate location of Broca's area and Wernicke's area. Photo from Wikipedia.

Handedness is due to the lateralization (asymmetry) of the brain hemispheres. Those that are right-handed have a more dominant left hemisphere, while those that are left-handed have a more dominant right hemisphere. In most humans, the left hemisphere of the brain is more dominant. The left brain hemisphere is also involved in language and is where Broca’s area and Wernicke’s area are located. Broca’s area is involved in speech production while Wernicke’s area is involved in language comprehension.

Right-handed preference is deep-seated in hominid evolution. Analysis of stone tools from Lower Pleistocene sites in Koobi Fora, Kenya and Middle Pleistocene sites in Ambrona, Spain showed that there is a consistent pattern of tools being produced by right-handed Homo habilis and Homo erectus (15). Preference for right-handedness may have existed as early as 1.4 to 1.9 million years ago, and might hint that the hominid brain had lateralized and was well on its way to becoming more specialized for different functions (15). Analysis of scratch patterns in incisors and canines from archaic humans (Sima de los Huesos in Atapuerca, Spain) and European Neandertals (Sima de los Huesos in Atapuerca, Spain and Vindija, Croatia) also showed that there was a persistent pattern of right handedness (6 & 7).

The prevalence of right-handedness in humans has a linear correlation with left hemisphere dominance (12). Since the left brain hemisphere plays an important role in language, brain lateralization leads to right-handedness. Thus, the prevalence of right-handedness in humans is a byproduct of human language.

The left-handed Ned Flanders from The Simpsons. Photo from SF Weekly.

The subjects for this study are from a captive population of geladas at The Bronx Zoo (Wildlife Conservation Society). There were 7 individuals present during the observations and all were male. Observations were done on two separate days between 12 P.M. and 3 P.M. The geladas were recorded using a video camera, and the recordings were later analyzed.

Geladas spend a significant amount of their time foraging (8). Site studies show that geladas spend 35.7% to 81.6% of their time foraging (8). There is a positive correlation between altitude and time spent foraging; more energy is burnt at higher altitudes, therefore more time is spent foraging (11).

A male gelada foraging with both hands.

My observations showed that geladas use either hand while foraging. They use either their left or right hands to pick up bunches of grass to eat. As my observation progressed, I became concerned that their repetitive motion of picking up grass and putting it in their mouths was not a sufficiently varied behavior to indicate handedness. Therefore, I also observed the geladas grooming.

A female gelada grooming herself.

There are two types of grooming in geladas: autogrooming (self grooming) and allogrooming (social grooming). Grooming is not only important for hygienic reasons but also important for strengthening social bonds (4). A study by Dunbar suggests that the major reason for grooming is the satisfaction of physical contact between the groomer and the individual being groomed (4).

From my observations, allogrooming starts with the individual being groomed initiating eye contact with the groomer. Then, the individual lies down and presents the area that needs to be groomed. Sometimes, a groomer simply approaches the individual they want to groom and starts grooming them. My observations showed that there is also no preference for which hand is used by geladas during grooming. The geladas used either hand for both autogrooming and allogrooming. The decision to use their left or right hand seemed to be determined by the area of the body that needed grooming.

From my observations, it seems that the geladas use either hand for foraging and grooming. The geladas at The Bronx Zoo seem to exhibit ambidexterity because they have no preference for their left or right hand, unlike humans who are predominantly right-handed.

Handedness is correlated with brain hemisphere dominance. For most humans, the left brain hemisphere is dominant and is also involved in language. Thus, the prevalence of right-handedness is a byproduct of human language. None of the geladas I observed at The Bronx Zoo exhibited preference for handedness. This is probably due to the fact that geladas do not have language; therefore, their left brain hemisphere is not dominant and does not lead to right-handedness. Besides foraging and grooming, more behavioral repertoire should be used in future analysis to further elucidate the preference in gelada handedness.









 References

 1. Cashmore, L., Uomini, N., & Chapelain, A. (2008). The evolution of handedness in humans and great apes. Journal of Anthropological Sciences, 86, 7-35.

 2. Dunbar, R.I.M., &; Dunbar, P. (1975). Contributions to Primatology: Social Dynamics of Gelada Baboons (Vol. 6). Basel, Switzerland: S. Karger AG.

 3. Dunbar, R.I.M. (1984). Reproductive Decisions. Princeton, New Jersey: Princeton University Press.

 4. Dunbar, R.I.M. (2008). The social role of touch in humans and primates: Behavioural function and neurobiological mechanisms. Neuroscience and Biobehavioral Reviews, 34(2), 260-268.

 5. Falk, D. (2000). Primate Diversity. New York and London: W.W. Norton & Company.

 6. Frayer, W.D., Fiore, I., Lalueza-Fox, C., Radovčić J., & Bondioli, L. (2010). Right handed Neandertals: Vindija and beyond. Journal of Anthropological Sciences, 88, 113-127.

 7. Frayer, W.D., Lozano, M., de Castro, J.M.B., Carbonell, E., Arsuaga, J.L., Radovčić J., Fiore, I., & Bondioli, L. (2011). Laterality: Asymmetries of Body, Brain and Cognition, doi:10.1080/1357650X.2010.529451

 8. Gron, KJ. (2008, September 3). Primate Factsheets: Gelada baboon (Theropithecus gelada) Taxonomy, Morphology, & Ecology. Retrieved May 11, 2011, from www.pin.primate.wisc.edu/factsheets/entry/gelada_baboon

 9. Hiller, C. (2000). "Theropithecus gelada" (On-line), Animal Diversity Web. Retrieved May 11, 2011, from www.animaldiversity.ummz.umich.edu/site/accounts/information/Theropithecus_ gelada.html

10. Hopkins, W.D. (2006). Comparative and Familial Analysis of Handedness in Great Apes. Psychology Bulletin, 132(4), 538–559.

 11. Iwamoto, T., & Dunbar, R.I.M. (1983). Thermoregulation, Habitat Quality and The Behavioural Ecology of Gelada Baboons. Journal of Animal Ecology, 52, 257-366.

12. Knecht, S., Dräger, B., Deppe, M., Bobe, L., Lohmann, H., Flöel, A., Ringelstein, E.-B., & Henningsen, H. (2000). Handedness and hemispheric language dominance in healthy humans. Brain, 123 (12), 2512-2518

13. McGrew, W.C., & Marchant, L.F. (1997). On the other hand: Current issues in and meta-analysis of the behavioral laterality of hand function in nonhuman primates. American Journal of Physical Anthropology, 104(25), 201-232.

 14. Steele, J. & Uomini, N. (2009). Can the Archaeology of Manual Specialization Tell Us Anything About Language Evolution? A Survey of the State of Play. Cambridge Archaeological Journal, 19, 97-110.

15. Toth, N. (1985). Archaeological Evidence for Preferential Right-Handedness in The Lower And Middle Pleistocene, and Its Possible Implications. Journal of Human Evolution, 14(6,) 607-614.

Keeping up with the Hominin

In less than a week, some of you will be shuffling back to school as Fall session begins. Every new semester, without a doubt, you'll be able to pick out the smart ass in the class. You know, the ones that sit in front of the class and always have their hands up when the professor asks a question (think Hermione Granger). But what if you are the smart ass? Have no fear, you're reading the right post.

"Hominin - the group consisting of modern humans, extinct human species and all our immediate ancestors (including members of the genera Homo, Australopithecus, Paranthropus and Ardipithecus)."

- Australian Museum.

A lot had happened this year with hominin research and some would redefine conventional understandings of this group. Below is a list of new studies that came out this year that I find quite interesting on hominin. Read up so you can show off in class with your knowledge of current hominin research. You know, just so you can make sure that your adjunct is really paying attention of what he/she is doing instead of begrudgingly teaching a class because he/she has to. Or maybe you have a geeky classmate you want to impress. Or if you're like me, you just wanna be the smartest in class because Asian Fail is not an option. So, enjoy ... and if they question you, tell them I said so.

Australopithecus africanus and Paranthropus robustus

• Male philopatry and female dispersal in both A. africanus and P. robustus. Is this a strategy to prevent inbreeding and mate choice by females? Ancient Hominid Males Stayed Home While Females Roamed, Study Finds

Paranthropus boisei

• Seems like we'll have to re-evaluate P. boisei's nickname, "Nutcracker Man". Recent study showed that P. boisei didn't eat nuts but instead used its big teeth to chew on grasses and sedges. No nuts for 'Nutcracker Man': Early human relative apparently chewed grass instead

From left to right: Comparison of upper jaw, P. boisei and H. sapiens. Photo from PhysOrg.

Homo erectus

• H. erectus were the first to controlled fire but it wasn't just used for warmth. New study shows that H. erectus were the first to cook their food (with fire) and process their food with tools. Homo Erectus Processed Food Like Humans, Harvard Scientists Say

• Stone artifacts, mostly flakes from stone tools, from the Dmanisi site in Georgia (the country, not the state) might suggests that H. erectus evolved outside of Africa. However, no conclusive evidence can be made due to the poor conditions of fossils found near these artifacts. Human ancestors in Eurasia earlier than thought

• H. erectus reached South Asia earlier than previously thought, between 1.5 to 1 million years ago according to Acheulean tools. Go east, ancient tool makers

• Findings from Solo River Terrace (SoRT) in Indonesia shows that H. erectus never coexisted with H. sapiens. Using three dating techniques: U-series, Electron Spin Resonance (ESR) and argon-argon, scientists found H. erectus went extinct between 143,000 to 550,000 years ago. H. sapiens are thought to reached Indonesia about 40,000 years ago. Human Ancestor Older Than Previously Thought; Finding Offers New Insights Into Evolution

An Acheulean hand ax found in India (South Asia) indicates that H. erectus moved to South Asia shortly after the invention of stone tools, around 1.6 million years ago. Photo from ScienceNews.

Homo neanderthalensis

• Neandertals probably died off because there were too many early humans to compete with. According to a statistical analysis, the Périgord region of southwestern France has the highest concentration of Neandertals and early humans. The ratio between Neandertal to early human was 1 to 10. There were just too many humans for Neanderthals to survive

• Mousterian culture might have lasted longer than previously thought and Neandertals might have spread as far as northern Russia in the mountains of Polar Urals, near the Arctic Circle. Last Neanderthals Near the Arctic Circle?

• Neandertals were predominantly right-handed, according to their teeth. Also, humans have been predominantly right-handed for at least 500,000 years. Neanderthal ancestors were mostly right-handed

Homo floresiensis (the Hobbits)

• The debate whether H. floresiensis is a separate species or just microcephalic H. sapiens continues on. New study shows that the measurement of the Hobbit skull is within the range of microcephalic H. sapiens. Taking the measure of a hobbit

From left to right: Homo floresiensis (LB1) and Homo sapiens.

Homo sapiens (early and modern humans)

• Early humans have been playing hanky panky with Neandertals and possibly the Denisovans. Proof? A toe bone and its DNA. Stone Age toe could redraw human family tree

• A particular segment of our X-chromosome were inherited from Neandertals. This supports the hypothesis that early humans interbred with Neandertal. However, only non-African humans have this segment. Confirmed: All non-African people are part Neanderthal

• Might not be a conscious decision, but apparently early humans that left Africa interbred with Neandertal to protect themselves against diseases. This is probably an unintended result more than an active thought process. First modern humans protected themselves against disease after leaving Africa by 'interbreeding with Neanderthals'

*Bouchra child, Homo sapiens*

• Dr. Harold Dribble and his team found the skull of "world's oldest human child" dated around 108,000 years old in Morocco and nicknamed it Bouchra. The boy died when he was 8 years old. This specimen has not been described in any scientific paper so watch out for it soon. World’s Oldest Child Found in Morocco

Someone Cited My Thesis!

Some time last week, a little birdie sent me a link to what appears to be a page from American Museum of Natural History (AMNH). Said birdie also mentioned that the link has to do with my honors thesis. Along with the link was a thumbnail of a male hamadryas baboon that looked rather familiar. It took me a few seconds to realize that I am looking at Fadi, or Moja as what he is referred to by the zoo. (Follow this link for who's who at Prospect Park Zoo) Confused as to what my honors thesis, Moja and AMNH have in common, I opened the link. The link directed me to one of AMNH's Young Naturalist Awards winner, a young gentleman by the name of Henry.

Henry's winning entry is Hamadryas Baboons, Papio hamadryas: Captive vs. Wild. His research was on hamadryas baboon behaviors, where he compares the Prospect Park Zoo troops with the ones from Larissa Swedell's field work in Ethiopia. And guess what, he cited my thesis! I'm excited that someone dug up my baby and used it in their research. This is the first time (that I know of) someone actually cited my research. I'm so glad I uploaded my honor thesis on Scribd instead of just letting the bound copy collect dust in my college's library. Anyway ...

Henry's research is quite interesting. He found that there are behavioral differences between captive and wild hamadryas baboons. Also, grooming was not the highest in frequency compared to other behaviors (sitting was the highest in frequency). This could be explained by the hot weather or the fact that data for this research was only collected for about 9 hours. Nonetheless, this is heading in a good direction and a pretty good research topic for a 15 year-old. Hopefully he'll stick to his passion for primates (baboons) and go on to be the next primatologist.

Note that the male hamadryas photo "Simen, a 19-year-old Alpha Male" (above) is actually Moja, Simen's offspring. Simen can be identified with a mole underneath his left eye, which is absent in this photo. Click on the link to read my thesis, A Cross-Species Comparative Study: Grooming Patterns in Captive Populations of Hamadryas Baboons and Geladas.

20 million-year-old well preserved fossil skull: Ugandapithecus major

Map of Uganda showing the remote Karamoja region in the northeast of the country where a team of Ugandan and French paleontologists announced Tuesday they had found a 20-million-year-old ape skull, saying it could shed light on the region's evolutionary history. Illustration from PhysOrg.

A well preserved fossil skull of an ancient primate, Ugandapithecus major, has been excavated in the northeast region of Karamoja in Uganda (hence the genus name, Uganda monkey). The 20 million-year-old skull belongs to a male and probably died when it was about 10 years old, said researchers Pickford and Senut. The cranial size of Ugandapithecus major was about the same size as that of chimpanzees but its brain size is smaller. Ugandapithecus major is a tree-climbing catarrhine, an herbivore that lives around the Miocene. Although its genus name refers to it as a monkey, Ugandapithecus major is actually a hominoid (ape).

A well preserved skull of Ugandapithecus major. Photo from BBC News. 

The skull will be cleaned and prepared in France for about a year before returning it back to Uganda. Ugandapithecus major was described in 2000 by Senut et al. from a few dental and postcranial remains.

You can read Senut et al. (2000) A new genus of Early Miocene hominoid from East Africa: Ugandapithecus major (Le Gros Clark & Leakey, 1950) here (requires subscription).

AMNH Picturing Science Tweetup: In Living Colors

Atlantic Spotted Mackerel. Stained using red dye (bones) and blue dye (cartilage)

I was excited to be invited back to another tweetup at AMNH last night. This time, I was able to get Vance to come with me and I think he had a pretty good time. The tweetup was about "Picturing Science: Museum Scientists and Imaging Technologies", a vivid photo exhibition of specimens and phenomenon. And yet again, I have forgotten to bring my camera. You know, after I've got my Nexus S, I have barely used my camera. I just need to remember that sometimes my phone can't take pretty pictures. Anyway, we were treated to some behind-the-scene tour of some of the AMNH scientists at work using imaging technologies such as computed tomography (CT) scans, scanning electron microscope (SEM), infrared photography and even dyes to color bones and cartilage (staining technique). The latter was my favorite technique as I am quite fond of stained specimens.

We picked up a button when we arrived and on the brim of the button reveals the group that we will be part of. I subconsciously just chose the button of a upper mandible of a felid. Bones, bones, bones. So we were assigned to Group #2 for a behind-the-scene tour. But before the tour, we gathered at Akeley Hall of African Mammals to mingle. There was, of course, wine and cheese. Oh yea, it's classy like that.

Led by an ichthyologist and an entomologist graduate students, the first stop for this group was a classroom-like setting where we were treated to amber, flies, ants and stained fishes. Sweet. I got to hold a piece of Baltic amber that encases a pair of flies that are still in the heat of copulation. Pretty rad. There was also amber that encases a species of previously undescribed ant. That guy has a massive pair of mandibles. We also spent some time looking at stained fishes under the microscope, although the staining technique itself is sufficient to show the complexity of fish osteology. "Fish bones are jigsaw puzzle from hell". Yep, that pretty much sums it up along with articulating a snake. The staining technique uses red dye to color the bones and blue dye to color the cartilage. Here's a writeup on how to prepare a stained fish Hidden Blades, Glowing Scorpions and Bug Genitalia: Great Science Images From the American Museum of Natural History.

Using a microscope to looking inside an amber. This particular amber has an ant in it.

Vance loves ants. So he's particularly excited.

I hold in my hand a piece of amber that has encased a pair of copulating flies, hence the "IN LOVE" and an arrow pointing at the two amorous flies.

Next stop was the imaging technology area where we got to see some cool microscopes such as SEM and CT scan in action. The SEM was used to produce detailed close-up photos of goblin spider while the CT scan was used to take thousands of armadillo lizard x-rays. These x-rays are later incorporated into a 3D program to produce a comprehensive 3D image of an armadillo lizard. Pretty neat stuff. There was also a microscope that they dubbed "microscope on steroid" and is used to scan comet dust. They mean business there. LOL!

Scanning electron microscope (SEM) on the left. Image of the carapace of a goblin spider on the right.

Using a CT scan to look inside an armadillo lizard.

"Microscope on steroid". Scanning comet dust.

As the behind-the-scene tour ends, we were ushered back into the Akeley Hall of African Mammals and got to spend more time mingling and taking in the new photo exhibition. There was a photo exhibit of Chilecebus (Chilean Monkey), an extinct primate and the only specimen of its kind ever found. Using a CT scan, the researchers were able to look inside the skull of Chilecebus to reveal its brain size and the shape of its head's semicircular canal. 

Chilecebus photo exhibit. Using a CT scan to look inside the skull of the one and only specimen found.

Chilecebus skull (left). CT scan reveals the shape of its head's semicircular canal. 

Brownie points to Denton Ebel, the Curator-In-Charge of Department of Earth and Planetary Sciences for walking us through the exhibition and explaining to us in depth the "Warhol" meteorite photo exhibit. And also thanks for all the jokes "It's perfectly round, just like tears of astronauts in space ... because they missed home". Oh yes, I forgot about the swag. This time we were ushered away with some postcards from the photo exhibition and also a scorpion sucker! Hmm ... I dunno, I don't think I am gonna eat THAT. But thanks for another great tweetup, American Museum of Natural History! Looking forward to the next one.

Buttons for the group tour (left). Scorpion suckers as parting gift (right). I dunno, but I doubt it'll taste like chicken.

You can follow American Museum of Natural History on Twitter at @AMNH for more info on the museum, upcoming events and also future tweetups. The photo exhibition, Picturing Science: Museum Scientists and Imaging Technologies, opened June 25, 2011 and ends June 24, 2012. It is free with museum admission and opens daily.

Maternal Infanticide and Cannibalism in Moustached Tamarin

Infanticide and cannibalism are two extreme behaviors seen in primates. Though extreme, the persistence of these behaviors in primates suggest that they are adapted for and had evolved to serve different purposes. Infanticide and cannibalism can be considered as both reproductive and survival strategies. Infanticide has always been associated with males killing off the progeny of former dominant males to make females more sexually receptive and to shorten the birth interval. Cannibalism, on the other hand, is not as sinister as it has always portrayed to be but just a coping mechanism. Ingestion of body parts, usually own offspring, is a response to cope with food scarcity. Lack of food resources would inevitably result in the death of the offspring thus cannibalization returns the caloric investment back into the mother. A new paper by Culot et al. (2011) has documented a case of infanticide and cannibalism in a wild female moustached tamarin (Saguinus mystax).

Moustached Tamarin (S. mystax) from The Bronx Zoo, New York City. Photo from Wikipedia.

S. mystax belong to the Callitrichid family, and like all Callitrichids has an interesting reproductive strategy unlike those of other primate families. Callitrichids form multimale-multifemale group and has a polyandrous (one female, multiple male) mating system. Callitrichids are the only primate family that consistently give birth to twins. The gestation period for S. mystax is 6 months. Usually, only one dominant female is reproductively active and shares offspring rearing responsibilities with multiple males in the group. However, an unstable dominance hierarchy among females might lead to multiple births within the group and will compromise the survivability of both the group and the offspring from stress, less parental investment and lack of food resources.

The researchers were studying how help from male moustached tamarins in the same group and the absence of female competition ensure the survival of offspring when they observed a female cannibalizing an infant. Necropsy and genetic analyses were used to rule out diseases and to determine paternity. They found that the infant has no diseases and did not die from trauma (falling from tree). Instead, it was a healthy infant and was being cannibalized by its own mother.

The mother was seen biting and then eating the head of its own infant during a period when another female was pregnant and gave birth just 1 month later. Before that, the perpetrator had given birth to twins three times successfully when four to five adult and subadult males were present in the group. Although we do not know for certain that the infant was alive when the mother started biting it, our field observations preceding the event suggest it probably was. The possible infanticide case and the two cases of births and early death of the infants occurred while only two to three adult males were present in the group. This could be the second case of maternal infanticide reported in the genus Saguinus and the similar circumstances suggest a common pattern. Culot et al. (2011).

Five common hypotheses proposed by Hrdy (1979) were used by the authors to try to explain maternal infanticide and cannibalism in this scenario. These hypotheses are resource competition, sexual selection, social pathology, exploitation, and parental manipulation.


The resource competition and sexual selection hypotheses were rejected because it was maternal infanticide, and not infanticide from another female. The social pathology hypothesis was rejected because it predicts infanticide restricted in areas that are disturbed by humans. The study group was habituated and had many successful births, therefore social pathology was ruled out. The exploitation hypothesis was also reject because the mother did not kill her infant to exploit its meat. Observation shows that the mother only consumed the brain and parts of the infant's neck. 


The parental manipulation hypothesis was accepted because the authors think that it best explains the scenario. The offspring was not pathological nor did it fell from the tree. Instead, it was a healthy infant that was killed by its own mother. According to Hrdy (1979), victim of parental manipulation does not necessarily have to be defective but also born "at the wrong place in the wrong time".

The authors concluded that parental manipulation is the best explanation for this possible maternal infanticide scenario. Parental manipulation strategy can happen in a group with poor capacity to raise the offspring from multiple breeding females, birth intervals that are shorter than 3 months, and low infant survival probability due to physical injuries or weakness.

References:

Culot, L. Lledo-Ferrer, Y. Hoelscher, O. Lazo, FJJM. Huynen, C. Heymann EW. 2011. Reproductive failure, possible maternal infanticide, and cannibalism in wild moustached tamarins, Saguinus mystax. Primates 52(2): 179-186.

Hrdy, SB. 1979. Infanticide among animals: A review, classification, and examination of the implications for the reproductive strategies of females. Ethology and Sociobiology 1(1): 13-40.

New adapiform species discovered in West Texas

Do you know that fossil primates once roam North America? I didn't know either so this discovery was a shock and a "d'oh" moment at the same time.

Lingual view (side that touches the tongue) of Mescalerolemur horneri partial mandible.

Scale bar equals 2 mm. Photo from Kirk & Williams (2011).

Anywho ... A fossil primate from the Eocene Epoch was discovered in Devil's Graveyard badlands of West Texas by Anthropologists Christopher Kirk and Blythe Williams. Named Mescalerolemur horneri, this new fossil primate lived about 43 million years ago is a member of the extinct group, adapiforms, that are found all over the Northern Hemisphere. Mescalerolemur looked like a modern-day greater dwarf lemur and weighs about 370 grams.

Interestingly enough, Mescalerolemur are more closely related to Eurasian and African adapiforms than those from North America. Darwinius masillae, famously known as Aunt Ida, was a Eurasian adapiform. Another interesting fact to point out is that Mescalerolemur had unfused mandibular symphysis, similar to those of Strepsirrhines (lemurs, lorises and galagos). The authors posit that this is definitive evidence that adapiforms are more similar to Strepsirrhines than Haplorrhines (humans are Haplorrhines). Kirk &Williams (2011) published their findings on Journal of Evolution: New adapiform primate of Old World affinities from the Devil’s Graveyard Formation of Texas.(PDF)

You can also read more about the discovery at EurekAlert: Anthropologist discovers new fossil primate species in West Texas.

Rise of the Planet of the Apes

This trailer makes me wish it's August already! If you don't know what it is, it's the prequel to Planet of the Apes. The movie adaptation was first made in 1968 with a remake in 2001. I expect to not see mistakes that were made in previous Planet of the Apes movies, among some of them, non-human apes were portrayed walking upright with a human gait. All the non-human apes in this movie will be CGI so I expect the designers to have done their homework. Though one seem to wonder, did these non-human apes (from the movie) evolved a bipedal gait just like those of human? What do you think?

Are you as excited as I am about this movie? I am interested to see how this movie portray the ethnics and "consequences" of primate testing in labs. I think I might Netflix the previous movies before I watch this one in August.

New study shows that gay orangutans are more common than previously thought

EDIT: IN CASE THE DATE OF THIS POST IS NOT ABUNDANTLY CLEAR, THIS IS AN APRIL FOOL'S POST.

A recent study shows that homosexual behaviors in orangutans occur more frequent and could possibly mean that there are more homosexual orangutan that we previously thought. The study by Smith et al. (2011) found that, statistically, 1 out of 10 orangutan is actually gay. One of the example from the study described two male Sumatran orangutans (Pongo abelii) whom the authors believe are "totally gay".

Two male Sumatran orangutans were first observed making a nest together for the night. Orangutans make makeshift nests to sleep at night which they abandon during the day. Every night, orangutans make a new nest. Not only was it peculiar that two male orangutans would sleep together in the same nest, they seem to have taken a liking to their nesting site as well. The duo returned to their nest every night to sleep and would leave together during the day to forage for food, swinging side by side.

An example of orangutan nest. Siegfried and Roy's nest are much bigger, elaborate and fabulous.
 Photo by Mongabay.com.

The researchers nicknamed the two males "Siegfried" and "Roy" and posit that Siegfried and Roy were most probably attracted to each other's large cheek pads. Telling Siegfried and Roy together is not hard. Roy has a scar on his face, a reminder of his escape from the jaw of a Sumatran tiger. Not wanting to release the identity of "Siegfried" and "Roy" for fear of homophobic retaliations from other orangutans, the authors released a sketch (below) that was included in their paper.

This is what Siegfried and Roy supposed to look like. Smith et al. (2011).

Researchers were puzzled at first as to why these two males would bring objects back to their nest. Periodically, these two orangutans would bring back flowers and "kitschy" forest objects like dried twisted twigs or moss balls. Immediately after bring these objects back to the nest, they would then meticulously decorate their nest with them. "The objects that they bring back to the nest, it's like straight out of a Crate and Barrel store", Smith jokes. Remarkably, one of Smith's field assistant, Dorothy, fell in love with the orangutan couple and had decided to continue the study for her PhD dissertation. Friends of Dorothy were not shocked. "Dorothy simply adore those flaming apes", said one of them.

Siegfried and Roy would bring moss balls like these (pictured above) back to their nest.
Photo from Crate and Barrel. Real moss balls sold by Crate and Barrel, $12.95 for all 9, excluding tax.

Smith et al. (2011) reached out to Kanzi, a bonobo that uses lexigrams to communicate with human primates, for comments about their findings. Despite multiple attempts to ask Kanzi questions, he seemed to be fixated to only two lexigram combination. "We asked Kanzi questions like 'What do you think of these gay orangutans?'" said Smith and all Kanzi said was "Bi-Winning". "Maybe Kanzi was trying to tell us that bonobos are mostly bisexual but we're not sure why Kanzi kept giggling and saying 'Bi-Winning'", Smith added. Results of this study will be presented at a primatology convention this year. However, the authors are hesitant to present their findings anywhere near the Bible belt due to homophobic protests.

The homophobic Rat Pobertson (above), planned to protest the authors' findings. Pobertson claims that gay orangutans should be send to palm oil plantations as slaves.

Reference:
Smith, JO. Fuqua, K. Gilman, I. Vagell, N.Dorothy, G. 2011. Flaming Apes: An Observation of Gay Sumatran Orangutans. Der Primaten 41(2011): 20-25.

Difference between monkeys and apes FAIL!

Snapped a photo of this T shirt when I was at the aquarium this weekend. Can you figure out why the explanation is a fail? Hint: First sentence.

The Semantics of Vervet Monkey Alarm Calls: Part II - The Experiment

Last week, I blogged about the semantics of alarm calls in vervet monkeys. This post will focus solely on the ingenious experiment by Robert Seyfarth, Dorothy Cheney and Peter Marler (1980) to test whether vervet monkey alarm calls convey information or if these calls were just an uncontrollable auditory response to predators. Their question was simple. Would vervet monkey alarm calls alone elicit different responses?

A vervet monkey. Photo from Wikipedia.

Here's what the researchers did in the field. They used playbacks of recorded vervet monkey (subjects) alarm calls from concealed speakers. Equal amount of alarm calls for leopard, eagle and snake were used. These alarm calls were recorded from known adult male, adult female and juvenile vervet monkeys in the field. Trials were done when subjects were on the ground and also when they were in the trees. These trials were conducted in the absence of predators to eliminate visual cues from the caller.

Alarm calls were broadcasted in different amplitudes to mimic natural alarm calls. In succession from loudest to lowest amplitudes are alarm calls for leopard, eagle and snake. Subsequently, leopard calls have the lowest pitch while snake calls have the highest pitch. To control for the possible effects of amplitude, the researchers broadcasted alarm calls that do not differ significantly in the amplitudes for all three predators.

Table from Seyfarth et al. (1980). Click on illustration for its original size.

The alarm call playbacks showed two types of responses. First, subjects of any sex and age looked at the direction of the speaker and spent more time scanning their environment once an alarm call was made for more than 10 seconds. The researchers believe that they might be scanning for additional cues from the "caller" and the subject's surrounding.

Second, each alarm calls seem to elicit a distinct response from the subjects. Remember the trials were done when the subjects were on the ground and on the trees? When subjects were on ground, leopard calls were more likely to make them run up into the trees and eagle calls made them look up and run into cover (bushes) Snake calls made them look down. When subjects were on the trees, leopard calls were more likely to make them run higher in trees and to look down. Eagle calls made them look up and sometimes run out of trees. Snake calls made them look down.

From the results, Seyfarth et al. (1980) posit that vervet monkey alarm calls alone do elicit different responses. It's hard to tease out whether these alarm calls symbolize the predator "leopard" or a command "run up tree". However, we can postulate that these alarm calls are rudimentary semantic signals used to warn other conspecific of impending danger. For those that are not familiar with semantics, it refers to the meaning of a symbol, sign, word or phrase. In this case, vervet monkey alarm calls are semantic signals because it conveys a specific meaning.

Here's an interesting video by Robert Seyfarth summarizing his research with the vervet monkeys.

Reference:
Seyfarth, RM. Cheney, DL. Marler, P. 1980. Monkey responses to Three Different Alarm Calls: Evidence of Predator Classification and Semantic Communication. Science 210(4471): 801-803.

The Semantics of Vervet Monkey Alarm Calls: Part I

Anti-predatory alarm calls are important  for social animals to alert others of approaching predators. Without the presence of "language", some non-human primates are known to give out different predator-specific alarm calls to alert conspecific. These non-human primates include ring-tailed lemurs (Zuberbühler et al., 1999), white-faced capuchin monkeys (Fichtel et al., 2005), Diana monkeys (Zuberbühler, 1999), Campbell's monkeys (Ouattara et al., 2009) and vervet monkeys (Seyfarth et al., 1980).

Alarm calls are typically high frequency sounds because these calls are hard to localized by predators. On the other hand, low frequency sounds are easier to localized by predators. Calls that are hard to localized by predators are selected for because conspecific can pick up on the warning but predators cannot identify the location of the caller. If an individual successfully alert its social group of approaching predator yet does not reveal its location, it will significantly decrease the chance of the caller to be detected and increase the chance of its social group to avoid predation.

Vervet monkeys. Photo from Wikipedia.

Here, I will focus on the study of predatory alarm calls in vervet monkey (Chlorocebus pygerythrus) by Seyfarth et al. (1980) in the Amboseli National Park, Kenya. Vervet monkeys are Old World monkeys that range between Eastern and Southern Africa. These monkeys are diurnal and live in closely-knit social groups. They are quadrupedal and are both terrestrial and arboreal. Like all Old World monkeys, vervet monkeys have the characteristic cheek pouches that enables them to forage and store food to be eaten later. Male vervet monkeys have blue scrotal area and a red penis. Males and females are sexually dimorphic, with males slightly larger than females.

Male vervet monkey with blue scrotal area and red penis. Photo from Something Up Her Sleeve.

Vervet monkeys are known to elicit predator-specific alarm calls. Three well-documented vervet monkey alarm calls are those for leopard, martial eagle and python. Leopard alarm calls are short tonal calls produced in a series of inhalations and exhalations. Eagle alarm calls are low pitched grunt while python alarm calls are high pitched "chutters". Different alarm calls seem to evoke different responses to individuals that heard the alarm calls. However, the first reaction of a vervet monkey upon hearing an alarm call is to look at the direction of the caller. Looking at the direction of the caller gives them clues as to why the alarm calls were made and also where the caller is facing reveals the direction of the approaching predator. You can listen to these different alarm calls on this site.

As we said before, different alarm calls evoke different responses. Leopard alarm calls would make the monkeys run up into the tree to avoid being ambushed by the leopard. Also, these monkeys would sit on the branches further away from the tree because, even though leopards can climb trees, the branches could not support the leopard's weight. When an eagle alarm call is given, vervet monkeys would make them look up, run for the nearest bush or both to avoid an approaching aerial attack. Python alarm calls would the monkeys stand bipedally and look down on the ground.

A martial eagle. Photo by Jacques S G from Flickr.

Adult vervet monkeys are more discriminatory when eliciting alarm calls. Infants and juveniles calls however, are less discriminating as they attribute most terrestrial mammals with leopard calls, flying birds with eagle calls and stick-like figures with snake calls (although, compared to infants, juveniles are more discriminant when making alarm calls). In spite of that, adult vervet monkeys seem to elicit eagle alarm calls to different species of raptors and non-raptors (see illustration below). We can infer that adult vervet monkeys attribute eagle alarm calls to birds with the same silhouette as martial eagles. As vervet monkeys get older, they seem to have a better association between predator species and types of alarm calls. Vervet monkeys generally pay more attention to adult alarm calls than those of juveniles or infants.

Alarm calls made by infant, juvenile and adult vervet monkeys in response to sightings of birds of prey (raptors) and non-raptors. The number of calls cited for each age group refers to the total number of calls that were analysed (Gould & Gould, 1999). Click on illustration for larger view of the image.

The study of vervet monkey alarm calls by Seyfarth et al. (1980) laid an important ground work to better understand the complexity of animal communications. By showing that vervet monkeys make different alarm calls to different predatory species, we can posit that vervet monkeys have the ability to categorize different species. The ability to discriminate between terrestrial mammal, flying birds and snake-like objects starts during infancy in vervet monkeys. As they get older, they are better at associating predators with specific alarm calls.

An infant vervet monkey with its mother. Photo by Lip Kee from Flickr.

The ability to over generalize during infancy is evident in both vervet monkeys and humans. For example, upon learning the word "dog", human infants would refer to quadruped mammals they see as "dog". As the infant grows, so does the ability to associate the semantic meaning of words they learned. However, the acquisition of alarm calls in vervet monkeys is different than the acquisition of speech (language) in humans. Alarm calls in vervet monkeys are instinctual and not learned. Humans, however, have to learn their language. Failing to do so during the "critical period" generally will result in the inability to learn language in later years. Feral child are examples of human infants that lack linguistic input during their critical period of language acquisition.

Most of us interpret animal alarm calls as an uncontrollable auditory response to fear or pain, akin to humans yelping if we had our finger caught in a door. While this is not entirely false, some animal calls actually convey information from the caller to the listener. Seyfarth et al. (1980) posit that vervet monkey alarm calls are actually basic semantic signals or symbolic signals because each alarm calls seem to mean something to these vervet monkeys. While we don't know if these alarm calls actually mean "leopard" or "run up to the tree", we do know that it conveys specific information to their conspecific about approaching predators.

I will be blogging Part II of this post later this week, where I will explain in details the experiments done by Seyfarth and Cheney on vervet monkey alarm calls.

References:
Cawthon Lang KA. 2006 January 3. Primate Factsheets: Vervet (Chlorocebus) Taxonomy, Morphology, & Ecology. http://pin.primate.wisc.edu/factsheets/entry/vervet. Accessed 2011 March 9.

Fichtel, C. Perry, S. Gros-Louis, J. 2005. Alarm calls of white-faced capuchin monkeys: an acoustic analysis. Animal Behaviour 70(1): 165-176. doi: 10.1016/j.anbehav.2004.09.020.

Gould, JL. Gould, CG. 1999. The Animal Mind. Scientific American Library.

Ouattara, K. Lemasson, A. Zuberbühler, K. 2009. Campbell's Monkeys Use Affixation to Alter Call Meaning. PLoS ONE 4(11). doi:10.1371/journal.pone.0007808.

Seyfarth, RM. Cheney, DL. Marler, P. 1980. Monkey responses to Three Different Alarm Calls: Evidence of Predator Classification and Semantic Communication. Science 210(4471): 801-803.

Zuberbühler, K. Jenny, D. Bshary, R. 1999. The Predator Deterrence Function of Primate Alarm Calls. Ethology 105: 477–490. doi: 10.1046/j.1439-0310.1999.00396.x.

Zuberbuhler, K. 2000. Referential labelling in Diana monkeys. Animal Behaviour 59(5): 917-927. doi: 10.1006/anbe.1999.1317.

AMNH Dinosaur Tweetup: It Was Dino-mite!

So there I was last night, at American Museum of Natural History (AMNH) for my first tweetup event. Hosted by AMNH, it was a dinosaur tweetup to preview their upcoming exhibit, The World's Largest Dinosaurs (read the press release here). Apologies for bad photo quality. I forgot my camera and had to use my phone camera instead, which incidentally is running out of battery life as well!

The event started with us signing in at the Theodore Roosevelt Rotunda and were greeted by two of the museum's famous dinosaur articulation: the Barosaurus and the Allosaurus. After getting our name tags, we were whisked up to the 4th floor on the Hall of Saurischian Dinosaurs where the reception is held. Cheese and wine, oh my ... très sophistiquée! To those are familiar with the museum, this is where the Tyrannosaurus rex articulations are located. Of course, these articulations include both modern and outdated interpretation of the T. rex.

The outdated interpretation of T. rex is that its body is 45 degrees or less from the ground and its tail dragging along (imagine a kangaroo). However, by 1970s, paleontologists realized that this interpretation is wrong. Instead, T. rex's body is almost parallel to the ground and its tail is lifted up from the ground to balance its head. If you're visiting AMNH, the outdated interpretation can be seen next to the wall inside a sheet of plaster while the modern interpretation can be see fully articulated towards the center of the exhibit.

Oh, right. The behind-the-scene tours. We had to choose two out of three that were offered, although I really wish they would just let us do all three. I went on the tour to meet paleontologist Mark Norell and to the Big Bone room while opted out to visit the Exhibition Design Studio. I would later found out that the Exhibition Design Studio is way cooler than I thought and regretted not being able to be there personally.

On the table (picture to the left) are Silly Bandz with colors that correspond to the behind-the-scene tour you chose. The blue screen is one of the two screens that streams live twitter feed with (hashtag) #AMNHTweetup. Someone actually stopped me and told me that he enjoyed the last tweet I sent out (@PrancingPapio I have yet to verify if dinosaurs are Jesus ponies, as per suggestion of Sarah Palin #amnhtweetup).

My first behind-the-scene tour was to meet Mark Norell. His office was actually a turret and the view is to die for. Mark does most of his research in China and Mongolia. Some interesting facts from Mark:

• Birds are actually dinosaurs, much like humans are primates.
• T. rex might have feathers.
• Cross section of dinosaur bones (usually the leg bone is used) can be used to determine the age of the individual. 

The second behind-the-scene tour was to the Big Bone room with Carl Mehling. Carl was a really fun guy and I think the ladies were swooning over him (OK, guilty) and we didn't know his wife was actually in the group with us! 

Carl told us that melanosomes are present in feathers and can be used to determine the colors that appeared in the feathers. This is especially important because fossilized feathers of dinosaurs were found and melanosomes can be used to determine its color(s). Some cool detective work there.

The Big Bone room was an impressive room with big bones (d'oh!). Also calling the Big Bone room their home are these fossilized bird-like dinosaurs and a Hadrosaurid skin cast. We were actually allowed to touch the skin cast. This skin cast came from a fossilized skin on the back of a Hadrosaurid.

This is a very interesting fossil. The individual is in a brooding position (like modern birds) with eggs all around it. The paired capsule-like objects on the bottom left of the fossil are its eggs. Some dinosaurs have paired oviducts which explains why their eggs are always paired. However, what makes this fossil interesting is that its bones does not show signs of calcium depletion, a sign that the individual had just laid eggs. This individual might either be a male or another female from the same group, indication of allomothering.

After the tours, we had about an hour to mingle before the event ended. We were given a swag bag and everyone had their very own Pastasaurus, the spaghetti strainer dinosaur, to bring home. So glad to finally meet Krystal (@Antinpractice) and Brian (@Laelaps) in person. Also, a big HELLO to all the new friends I made at the Tweetup.

Thank you AMNH for the experience. I had a wonderful time. Actually to say that I had a wonderful time is an understatement. You can follow AMNH on Twitter at @AMNH for more information about the museum and events. There will be another AMNH Tweetup next month so stay tuned.