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.

The Menstruation Story

In keeping with yesterday's post on sexual maturation, here's an interesting find from YouTube. The Menstruation Story was produced by Disney circa 1946. Quite an interesting video, I might say. With interesting take on the video by Shameless and NYmag.

Having Brothers Delays Menstruation and Sexual Activity in Sisters

Hey girls, your brother will not only pull out your Barbie's head but he will also delay your sexual maturation as well ... allegedly. A interesting study by two behavioral ecologists (Milne & Judge, 2010) on contemporary western society of Australian adults found that:

Girls with older brothers experience a delay in menstruation.
Girls with older brothers (but with no older sisters) started their menstruation at a mean age of 13.6 years while girls with older brothers and older sisters started their menstruation at a mean age of 13.3 years. Girls with no older brothers (with or without older sisters) started their menstruation at a mean age of 12.7 years. The more older brothers the girls had, the older they were when they started their periods. However, the age of the brothers does not effect the results.

Girls with younger brothers experienced a delay in first sexual activity.
Girls with one or more younger brothers experienced their first sexual activity up to two years later than girls without any younger brothers.

Neither younger nor older brothers influenced the fitness of their sisters. 
Brothers do not affects number of pregnancies, number of children, age at first pregnancy or the firstborn of their sisters.

It is thought that having boys in subsistence and preindustrial societies require more resources than girls, therefore imposing a constraint on lifetime reproductive success. Results from Milne & Judge (2010) were unusual for a society that has plenty of resources because it shows evidence that having brothers negatively affect their sister's sexual maturation. However, having brothers do not influence the reproductive fitness of their sisters. The authors posit that brothers in contemporary Australian are not associated with reproductive fitness due to their sisters having a long period of independence before child bearing. Dr. Judge said that she prefer not to speculate too much of the study as the study was very basic and straightforward. She emphasized that the delay in sexual maturation should not be interpreted as something negative.

Possible reason why younger sisters are experiencing a delay in first sexual activity.

Important to note that the study interviewed only 273 (n) adults between the age of 18 - 75. Out of the total 197 are females and 76 are men. It would be interesting to see results of the study from a bigger sample size because the study essentially represents the western society of Australia (N) as a whole, so the sample size (n) should be bigger. I don't know off hand the population size of western society of Australia, but the Australian population is currently 22,434,156 (current as of August 24, 2010 from Australian Bureau of Statistics). So I would be interested to see if the trend holds up to a bigger sample size, where (n) is at least over 1000. Also, would sisters of twins (with younger twin brother or older twin brother) exhibit the same delay in sexual maturation as well?

References:
Milne, F.H. Judge, D.S. 2010. Brothers delay menarche and the onset of sexual activity in their sisters. Proceedings of The Royal Society B DOI: 10.1098/rspb.2010.1377

Edwards, L. 2010. Having brothers delays sexual maturation in women. Physorg.com Retrieved August 23, 2010 http://www.physorg.com/news201419637.html

There are some Neandertal in us

Two papers published by Science on the May 7th 2010 issue posit that Neandertal genes exist in all of us (modern humans). The paper by Green et al. drafts the sequence of the Neandertal genome from three Neandertal individuals and compared them with the genomes of five modern humans, while the paper by Burbano et al. explains the method for sequencing target regions of Neandertal DNA.

John Hawks from John Hawks Weblog has a detailed write-up of these two papers. Check out his post, NEANDERTALS LIVE! Also check out Zacharoo's post from Lawn Chair Anthropology, Neandertal Nuclear Genome: Multiregional Evolution is the new Out of Africa.

The sequencing of the Neandertal genome brings back the age old question of human evolution: Multiregional or Out of Africa?

Link to papers:

• A Draft Sequence of the Neandertal Genome by Richard E. Green et al. (2010)
• Targeted Investigation of the Neandertal Genome by Array-Based Sequence Capture by Hernán A. Burbano et al. (2010)

Unearthed finger bone points to the possible discovery of an unknown hominin

DNA analysis from a finger bone unearthed from Denisova Cave, Siberia might lead to the discovery of an unknown hominin. Dubbed "X-Woman", information from her mitochondrial DNA suggests that she shared a last common ancestor with modern human and Neanderthals about one million years ago.

Since Neanderthals and modern humans split at about 500,000 year ago, it suggests that she did not originate from that divergent. Instead, she represents an unknown hominin lineage, presumably an unknown migration out of Africa. "X-Woman" is too young to be a descendant of Homo erectus (which migrated out of Africa to Asia about two million years ago) yet too old to be a descendant of Homo heidelbergensis.
 

"Whoever carried this mitochondrial genome out of Africa about a million years ago is some new creature that has not been on our radar screens so far," said co-author Professor Svante Paabo, also from the Max Planck Institute for Evolutionary Anthropology.

Read more about this discovery on BBC News, DNA identifies new ancient human.

Said article can be found on Nature, The complete mitochondrial DNA genome of an unknown hominin from southern Siberia (Krause et al., 2010). Unfortunately I do not have access to said journal so if you have a copy I'd appreciate it A LOT if you can send it to me. Thanks Mark, for the pdf.

*Edit* Here's a pdf from Nature, Fossil finger points to new human species.

New Exhibit At Warsaw Zoo, Poland: Cavemen!

Visitors at Warsaw Zoo in Poland are being reminded this week that humans are animals too when they walk past the "cavemen" exhibit. Two volunteers, a 24 year-old man and 18 year-old woman, dressed themselves in animal hide behind an old monkey cage. The exhibit runs till this Sunday.

Two volunteers in a former monkey cage and dressed as cavemen, are photographed by a visitor at the zoo in Warsaw, Poland, Friday, Nov. 27, 2009. The zoo has opened a week-long display where two volunteers - a man and a woman - spend time in the cage to remind visitors that humans are animals too. (AP Photo/Alik Keplicz)

"Organizer Maria Mastalerz says the weeklong "performance" aims to attract interest in a play, "Caveman," showing in the Polish capital. But she says it also carries a message that humans today are not all that different from their prehistoric ancestors" - Associated Press.

"They are very calm and gentle. They don't bite. And they're keen to watch all the strangers passing by their home. You can try to communicate with them, or even offer them food ... a playful attempt to inspire people to think about the place of humans in the universe", said the zoo's deputy director Ewa Zbornikowska, AFP.

Hobbits Are Indeed A Separate Species, Said Researchers.

 Researchers from Stony Brook University Medical Center in New York confirmed that the Hobbits, or Homo floresiensis, are indeed a separate "human" species instead of a population of diseases Homo sapiens. The 7th Human Evolution Symposium, Hobbits in the Haystack: Homo floresiensis and Human Evolution was held this year at Stony Brook.

A recent full-body reconstruction of LB1, the ‘little lady of Flores’, by the Parisian paleoartist Elisabeth Daynès. (©2009, S. Plailly/E. Daynès—Reconstruction Atelier Daynès Paris). Photo from The geometry of hobbits: Homo floresiensis and human evolution.

Cranial comparison between LB1 (Homo floresiensis) and modern human. Photo from www.bbc.co.uk

Height comparison between modern humans and Homo floresiensis. Illustration from www.amnh.org

According to the press release, researchers William Jungers and Karen Baab used statistical analysis on the skeletal remains of LB1 (nicknamed Flo) to determine that Homo floresiensis are indeed a distinct species. A few characteristics of LB1 that makes her and her kind a separate species than modern humans.

• LB1's cranial capacity is about 400cc, about the same size as a chimpanzee.
• The skull and jawbone of LB1 is more primitive looking than any normal modern humans.
• The thigh bone and shin bone of LB1are much shorter compared to modern humans including Central African pygmies, South African KhoeSan (formerly known as 'bushmen") and "negrito" pygmies from the Andaman Islands and the Philippines. Jungers and Baab believe that these are primitive retentions as opposed to island dwarfing.
• Using a regression equation developed by Jungers, LB1 was about 3 feet, 6 inches (106cm) tall, far smaller than modern human pygmies whose adults grow to less than 4 feet, 11 inches (150cm) tall.

The nearly complete left foot of LB1 next to the right tibia (shin bone, which is ~235 mm long). The foot is relatively very long and has unusual intrinsic proportions; its footprint matches no other species (photo: W. Jungers) The geometry of hobbits: Homo floresiensis and human evolution.

Read more about the Hobbits at The geometry of hobbits: Homo floresiensis and human evolution (Free Wiley Interscience PDF).

Modern Humans Are Still Evolving But Will Modern Men Get Wimpier?

Two interesting articles that went into my inbox today: Modern man a wimp says anthropologist and Darwin Lives! Modern Humans Are Still Evolving.

A cover illustration from Australian anthropologist Peter McAllister's new book entitled "Manthropology" and sub-titled "The Science of the Inadequate Modern Male." Photo from REUTERS/Hachette Publishing/Handout.

Modern man a wimp says anthropologist  from Reuters, summarizes Peter McAllister's book Manthropology: The Science of the Inadequate Modern Male. Using various data from Neanderthals and ancient aboriginal populations, McAllister concludes that modern men are inferior than their predecessor in running, jumping, and even sheer brute. "Any Neanderthal woman could have beaten former bodybuilder and current California governor Arnold Schwarzenegger in an arm wrestle", McAllister said. John Hawks from John Hawks Weblog has a lot to say about this in his post Is modern man a "wimp"? I think Hawks is spot on with his post.

The Time article, Darwin Lives! Modern Humans Are Still Evolving, is about a study in a contemporary Massachusetts population led by Stephen Stearns and his team of scientists from Yale University. Using correlations between women's physical characteristics such as height, weight, blood pressure, and cholesterol levels with the numbers of offspring produced, they found that "stout, slightly plump, but not obese" women tend to have more offspring as oppose to women with very low body fat count, as well as women with lower blood pressure and lower cholesterol levels.

Stearns explains that women with very low body fat count, low blood pressure and low cholesterol levels do not ovulate. Ovulation is, of course, when the matured ovarian follicle ruptures and discharge an ovum (or the egg). While human females ovulate about once a month, female chickens ovulate once a day. Of course, we refer to chicken ovum as chicken eggs.

Stearns and his team thinks that the characteristics for producing maximum offspring (stout, slightly plump, higher blood pressure and cholesterol levels) were passed down from mothers to daughters. Separating social and cultural factors using statistical analysis, Stearns and his team were able to conclude that these characteristics were passed down genetically. "Variations in reproductive success still exist among humans, and therefore some traits related to fertility continue to be shaped by natural selection" Stearns says. So women who have more children are more likely to pass down these traits to their offspring.

It explains the notion that modern humans are still evolving because variation in reproductive success means that there are selective pressure that favor certain traits. Interesting to note that while fertility is being shaped by natural selection (as per Stearn and his team's study), artificial selection is also shaping the width of female pelvis and the average brain size of infants being born. Mothers with a narrow birth canal (smaller pelvis size) puts both her and her infant in jeopardy during childbirth. The infant will be stuck in the birth canal due to restricted space. An infant with a larger than average brain size will also get stuck in the birth canal. Both scenarios will likely kill the infant and mother. However the advent of Caesarean section negates the restriction of a narrow birth canal and allows infant with larger brain size to be born.

So, we can see that modern humans are evolving through variation in reproductive success, female pelvis size and average infant brain size is also evolving through artificial selection though it is too early to say which direction the selection is favoring.

Can I See Your Fingers Please?

That is what University of Liverpool's Emma Nelson probably would have said if she were to meet our hominan ancestors in person. Known to hold true in anthropoids (humans, apes and monkeys), the index (second digit) to ring (fourth digit) fingers ratio or 2D:4D is an indication of how much an individual were exposed to androgen (such as testosterone) in the womb. The more androgen you are exposed to, the longer the ring fingers are (and the shorter the index fingers are compared to the index fingers).

Photo of a human's left hand. From left to right: thumb, index, middle, ring and little finger. Photo modified from Wikipedia.

Nelson et al. believe that a high ratio (longer index finger, shorter ring finger) suggests monogamy (or pair-bonded) while a low ratio (shorter index finger, longer ring finger) suggests polygamy (or non pair-bonded). Simply put, individuals with high androgen level is likely to be non pair-bonded and the telltale sign is in the index and ring fingers. Also, some controversial studies had suggested that both men and women who receive high levels of androgen in the womb are more likely to be stronger, faster, and more sexually competitive.

Nelson and her researchers recently looked at the fossils of two Neandertals and one Australopithecus afarensis with complete index and ring fingers to determine their 2D:4D. They found that Neandertals had long ring fingers, suggesting that they were polygamous just like modern day primates that live in groups. A. afarensis on the other hand, had long index fingers. Nelson is puzzled by this discovery. "These were small creatures that probably lived in groups and were being eaten by predators. How do you keep from mating with different members of the group?", she said.

Indeed it does not make sense for A. afarensis to be monogamous if they live in groups. Notice that Nelson et al. only used one A. afarensis fossil to get the 2D:4D. Perhaps it is not their fault that only one A. afarensis specimen had complete index and ring fingers but such are the dilemma of using fossil specimens to generalize a whole species.The result might just be a statistical outlier. However, I can't speculate the result or the implications but anyone that are familiar with statistical data knows that a small sample size leads to a higher sampling error. Also what would a 2D:4D = 1 (same index and ring finger length) be?

Interesting enough, John Hawks at John Hawk's Weblog mentioned the correlation of 2D:4D with male homosexuality (Robinson and Manning, 2000). I would know about this. In fact, my 2D:4D is indeed low.  Robinson and Manning predicted right! Maybe ...

I do find both Nelson et al. and Robinson and Manning (2000) research interesting but I would like to stress that the results are mere predictors and correlations. Take it with a grain of salt. Don't go measuring 2D:4D of your future spouse, boyfriend or girlfriend and accuse them of not being monogamous or a homosexual.

Emma Nelson and her team presented their research at this year's Society for Vertebrate Paleontology meeting held in Bristol, United Kingdom. Read more about Emma Nelson's research.

References:

Reilly M. 2009. Human Ancestors Conflicted on Monogamy. Discovery News. Retrieved September 25, 2009, from http://dsc.discovery.com/news/2009/09/24/human-monogamy.html

Robinson SJ. Manning JT. 2000. The ratio of 2nd to 4th digit length and male homosexuality. Evolution and Human Behavior 21(5): 333-345. [doi:10.1016/S1090-5138(00)00052-0]

Frans de Waal: A Helping Hand Or A Stab In The Back - Which Is More Human?

Dr. Frans de Waal will be having a lecture and book signing tomorrow (Thurs, Sept 24) , 7pm at The Kaye Playhouse at Hunter College. For all you Facebook users, Dr. De Waal has a Facebook fan page as well! You really should go become his "fan" on his page. Really.

Below is the description from Hunter College's website:

Thursday, September 24, 2009
7:00 PM
A Helping Hand Or A Stab In The Back - Which Is More Human?

World-renowned primatologist Dr. Frans de Waal will discuss his ground-breaking book The Age of Empathy: Nature's Lessons for a Kinder Society.

An exploration of the origins of human morality that challenges many of our most basic assumptions, The Age of Empathy has been written by one of the world's leading primatologists, Dr. Frans de Waal, called one of the world's 100 most influential people by Time magazine and the winner of the Los Angeles Times Book Award. De Waal's newest book looks at the question of whether competitive, selfish behavior is really "instinctive" and "natural," an outgrowth of evolution and the survival of the fittest. However, using research from anthropology, psychology, neuroscience, and animal behavior, de Waal argues that humans are equally hard-wired for empathy. We are, he says, group animals - cooperative, sensitive to injustice, and mostly peace-loving - just like other primates, elephants, and dolphins. De Waal's findings have profound implications for politics, office behavior - and perhaps our very survival.

The Kaye Playhouse at Hunter College
(68th Street between Lexington and Park Avenues)

Program is free and open to the public.
To RSVP, click here or call (212) 772-4007.

Contagious Yawning in Chimpanzees

Animation of chimpanzee yawning from Emory University. Illustration from BBC News.

I'm sure we are all familiar with this scenario: Someone yawns and we would "catch" it or vice versa. This is the phenomenon of contagious yawning.

A new paper from The Proceedings of The Royal Society "Computer animations stimulate contagious yawning in chimpanzees" suggests that the phenomenon of contagious yawning and empathic response to animation occurs in chimpanzees. Computer animations of yawning chimpanzees (see illustration above) can be use to stimulate contagious yawning in chimpanzees. Previous researches have documented contagious yawning in chimpanzees through video-recorded footage.

Dr. Matthew Campbell, lead author of the paper from Emory University's Yerkes National Primate Research Center said that they would also like to learn more about behaviors that are related to empathy such as consolation (when an individual does something nice to the victim of aggression). They want to know if individuals that are good contagious yawners are also good consolers. Understanding how chimpanzees empathize and imitate animations can help us understand how we, as human beings, empathize and imitate animations as well, said Dr. Campbell.

Homo floresiensis Walked Out of Africa

Skull of LB1 (Homo floresiensis, or the hobbit). Photo from Science Museum

New analysis by a team led by Australian National University doctoral student Debbie Argue showed that Homo floresiensis, nicknamed hobbits, were early hominin and walked out of Africa to Flores. Their findings supports the argument that Homo floresiensis had a unique wrist anatomy that originated from a lineage that lived long before the common ancestor of Homo sapiens and Neanderthals.

With Mike Moorwood from University of Wollongong and Thomas Sutikna from Indonesian Center for Archaeology, Debbie Argue compared 60 skulls and skeletal features from two individual hobbits to those of hominins, chimpanzees and gorillas using cladistic analysis. The result shows that Homo floresiensis "probably took one of two evolutionary paths from Africa to Flores. One began 1.66 million years ago, the other 1.9 million years ago".

Read more here: Hobbits Walked Out of Africa

The Face Of The First European

The face of the first European, reconstructed by forensic artist Richard Neave. Photo from Telegraph.

Using the incomplete skull and jaw bone in a cave in the southwest of the Carpathian Mountains in Romania, scientists had revealed for the first time the face of the first European.

Scientists doesn't know if this modern human is a male or a female but using radiocarbon analysis they found that this individual lived around 34,000 to 36,000 years ago. Around this time, Europe is home to both Neanderthals and modern humans. Modern humans first arrive to Europe from Africa.

The skull of this individual is human-like, though there are also some archaic traits such as large molars. Some scientists speculated that this skull belongs to a Neanderthal and modern human hybrid though it was disproved by many experts.

Richard Neave, a forensic artist used clay to reconstruct this individual for a BBC program about the origins of the human race and evolution.

Garden of Eden: The Origin Of Modern Humans

A new genetic survey by Dr. Sarah A. Tishkoff of the University of Pennsylvania and her team has found that modern humans originated in an area between Namibia and Angola, on the coast of southwest Africa. Read the New York Times Article: Eden? Maybe. But Where’s the Apple Tree?

However, this harsh and inhospitable area is nothing Eden-like, they said. The origin of a species, like modern humans, is generally pinpointed to a place where its individuals show the highest genetic diversity. After comparing genetic data from populations around the world, the researchers pinpointed the population with the highest genetic diversity - somewhere on the coast of southwest Africa near the Kalahari Desert. The Bushmen or San people currently call this area their home.

The researchers have also calculated the exit point of modern humans that left Africa about 50,000 years ago. The exit point lies in an area of the African coast of the Red Sea. If the "Out Of Africa" theory holds true, this tribal group of about 150 people that left Africa at that exit point displaced other archaic Homo sapiens populations from different continents, giving rise to the current modern human populations.

Human Ancestors Were Not Good Tree Climbers, Said Researcher

A new study by Jeremy DeSilva, anthropologist at Worcester State College in Massachusetts suggests that human ancestors may not have been good tree climbers. He suggests that our ancestors traded in arboreal adaptations to evolve bipedality.

By recording how wild chimpanzees climb tree in Uganda's Kibale National Park, DeSilva found that chimpanzees flex their ankles 45 degrees from normal resting position while modern humans flex their ankles a maximum of 20 degrees while walking. Flexing any more than that and a modern human's ankle will suffer serious injuries.

DeSilva then compared the ankle joint, the tibia and the talus, in great apes and fossil hominins between 4.12 million to 1.53 million years old. He found that all of the hominin ankle joints resembled those of modern humans rather than those of apes, suggesting that this joint "form" took on its current configuration early in human evolution.

Read the full ScienceNOW article.

Questioning The "Out-Of-Africa" Model

The "Out-Of-Africa" Model is something that all Biological Anthropology students get drilled into their heads in Anthropology 102. Some Homo erectus migrated out of Africa to different regions. Archaic Homo sapiens then evolved from Homo erectus. Archaic Homo sapiens from Africa migrated out and displaced other archaic Homo sapiens from different regions. These archaic African Homo sapiens then evolved and became anatomically modern humans (Homo sapiens sapiens) Academically it is also call the recent single-origin hypothesis (RSOH), the Replacement Hypothesis or the Recent African Origin (RAO) model. These hypotheses came from the discovery of mitochondrial DNA, a kind of DNA that's only passed down by females to their offspring. Tracking this mitochondrial DNA, we can all draw our lineage back to a single female aptly named Mitochondrial Eve. Read about the "Out-Of-Africa" Model from a wiki entry.

The "Out-Of-Africa" Model. Illustration from Raritan Valley Community College

Well all that is fine and dandy. We were even told that the "Multiregional" Model is pretty much not accepted in academia nowadays. However, this dude begs to differ.

The "Multiregional" Model. Illustration from Wikipedia.

Akhil Bakshi, an Indian "explorer" led a multidisciplinary Gondwanaland Expedition across the 17 countries of South Asia, West Asia and Africa. He questions the "Out-Of-Africa" Model and in favor of the notion that anatomically modern humans were the byproduct of interbreeding between archaic Homo sapiens across different regions. He is actually in favor of the "Multiregional" Model.

Read his article here (text or .pdf). What do you think?

A Cure For Malaria

Do you know that the difference between human and chimpanzee genome is only 2% ? That genetic difference involves mostly genes that are related to the immune system, infectious disease and also vulnerability to parasites (Sapolsky, 2006). Chimpanzees are resistant to malaria while we humans are scrambling to find a cure for this epidemic.

Researchers are now trying to understand how chimpanzees are resistant to malaria and use that knowledge to find a cure.

Erica Tassone, a biology graduate student, is currently working on malaria research with Stone and Vellerri for her dissertation project, which she started in fall 2007.

“I look at genes associated with malaria resistance in chimpanzees and see how they’re the same or different from those genes in humans,” Tassone said.

Although Tassone said she is also interested in doing research on how genes act in a cell, her main concentration now is the disease research.

“[I hope] to get a better understanding of how humans and chimpanzees have evolved and developed resistance to diseases,” Tassone said.

Click here to read the full news article.

Citation:
Sapolsky R. 2006. The 2% Difference. Discovermagazine.com http://discovermagazine.com/2006/apr/chimp-genome/article_view?b_start:int=1&-C=

Our Toes Were Made For Running

Ever wonder why our toes are stubby instead of long and slender like our fingers? Long toes require more energy and generate more shock as compared to short toes, according to biomechanical analysis. Shorter toes are an adaptation favored by natural selection. Australopithecines, our first bipedal ancestor, had longer toes than our genus Homo but smaller than those of great apes.

"When you're walking, before you push off to start the next step, your other foot has already hit the ground. You've transferred some of your body weight. Your toes have to do much more work in running, to push you." (Rolian et. al, 2009)

Click here to read more.

Citation:
Rolian C. Lieberman DE. Hamill J. Scott JW. Werbel W. 2009. Walking, Running And The Evolution of Short Toes in Humans. Journal of Experimental Biology 212 (5): 713-721.

Homo Floresiensis: Hobbits of Southeast Asia

What is Homo floresiensis? This question has plagued scientists since the 2003 discovery of these hominids in the remote island of Flores, Indonesia. A few specimens, found only inside the cave of Liang Bua in Flores, were given the names LB1, LB2 and so on. Their small stature, thought to be no taller than a three-year-old human child, led to them being nicknamed “Hobbits” by scientists after J.R.R. Tolkien's tiny “Lord of The Rings” characters. Homo floresiensis is thought to have co-existed with modern humans starting from about 18,000 years ago to about 13,000 years ago -- pretty recent in geological time. What Is The Hobbit?

Height comparison between Homo sapiens sapiens and Homo floresiensis. Illustration from www.amnh.org

Cranial comparison between LB1 (Homo floresiensis) and modern human. Photo from www.bbc.co.uk

A recent article suggests that Homo floresiensis existed alongside modern humans (Homo sapiens sapiens). If Homo floresiensis were indeed contemporaneous to modern humans, then they could have been the sourceof local myths such as the “Ebu Gogo” and “Orang Pendek”. Cryptozoology and mythology aside, scientists are still debating whether Homo floresiensis is a species of its own or just a small population of Homo sapiens sapiens that suffered from cretinism.

Putting a face to the hobbit (Facial reconstruction from LB1 cranial). Photo from www.blogs.discovermagazine.com

So who really were Homo floresiensis? A species of their own or just individuals that suffered from cretinism? We still do not know.

If Homo floresiensis were indeed a species of their own, did they evolve out of Austrolopithecine, Homo erectus or even archaic Homo sapiens?

If Homo floresiensis were actually archaic Homo sapiens suffering from cretinism, how did they survive well pass adulthood and use stone tools to hunt?

Currently there is no consensus whether Homo floresiensis were a separate species or just individuals who suffered from cretinism. What do you think?