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

Australopithecus sediba and "missing link"

Skull of juvenile male Australopithecus sediba. Photo from National Geographic.

The announcement last week of a new hominin, Australopithecus sediba, garnered a lot of media attention and of course among the academic circle. The remains of an adult female and a juvenile male was found deposited inside a cave in Malapa, South Africa by Lee Berger and his 9 year-old son. These fossils are thought to date about 1.9 million years ago and are probably a descendant of Australopithecus africanus.

Brain scans reveals the possibility that a chunk of brain is still intact inside the brain case, along with some fossilized bugs. Google Earth was also credited for discovering these fossils. Lee Berger have been used Google Earth to map out known fossil deposits and caves. Armed with these knowledge, Berger found 500 previously unidentified fossil deposits and cave sites.

For more about A. sediba, read:

• Kambiz's post on Anthropology.net, Australopithecus sediba (UW88-50) of Malapa, South Africa.
• Jackaroo's post on Lawn Chair Anthropology, Holy Effing Crap II: Australopithecus from Malapa.
• John Hawk's post on John Hawks Weblog, What, if anything, is Australopithecus sediba?
• Scientific America: Discoverer of "Lucy" raises questions about Australopithecus sediba, the new human species from South Africa.
• Science/AAAS: Special Feature: Australopithecus sediba.

The discovery of A. sediba, along with the "Denisova hominin" and Homo floresiensis, sparked a lot of media coverage but unfortunately the lingo "missing link" seems to be almost always paired with such discoveries. One should be cautious when using the term "missing link" as most links among known fossil records are not really "missing". Our evolutionary past is not a long linear chain but more like branches coming out of a tree trunk. Remember the missing link, "Aunt Ida" (Darwinius masillae) who turned out to be just a fossil primate on the dead end of an evolutionary branch? Some of these branches indeed lead to evolutionary dead ends, so claiming that all new discoveries are "missing link" is false. For more on the etymology of the phrase "missing link", read John Hawks's "A missing etymological link" and Carl Zimmer's "Yet Another 'Missing Link'".

Why Did Our Early Ancestors Ate Nuts And Seeds?

A team of researchers, led by Professor Gerhard W. Weber from the Department of Anthropology at the University of Vienna in Austria, thinks that our early ancestors (specifically the australopithecines) probably started eating nuts and seeds because they were hungry and that was the only food available.

These adaptations are important in an environment where food is scarce. While being able to adapt to new food source is important, it probably would not be possible if they can't process these foods mechanically (chewing and processing). Adaptations such as large molars, robust teeth or thick enamel (morphological adaptation) are also important. Read more here: European scientists crack the mystery of why we eat nuts.

Also read, The feeding biomechanics and dietary ecology of Australopithecus africanus by Strait et al. (2010)

Taung Child - Virtual Skull

A partial skull and brain endocast of an Australopithecus africanus child. Photo from Australian Museum.

Through the Australian Museum, you can now access the virtual skull of Taung Child, an Australopithecus africanus. This interactive replica includes the partial skull and brain endocast found in Taung, South Africa in 1924. Raymond Dart published this discovery in 1925.

Click here to look at the interactive Taung Child.

"Whence Homo floresiensis? Clues From The Brain." By Dean Falk, Florida State University

During the 7th Human Evolution Symposium, Hobbits in the Haystack: Homo floresiensis and Human Evolution at Stony Brook, Dean Falk presented her lecture entitled "Whence Homo floresiensis? Clues from the Brain". She concluded that Homo floresiensis is a species of its own, LB1 did not suffer from microcephaly and Homo floresiensis is not a diminutive form of Homo erectus or Homo sapiens.


Falk commented that LB1 had a small-sized but "fancy" brain and that there was a "global reorganization" of the brain. Comparing LB1 with 9 modern human microcephalic skulls, Falk came to the conclusion that LB1's skull is nothing alike from a microcephalic and that LB1 was not a microcephalic.

A computer image depicts the brains (red) of a microcephalic modern human (left), and the fossil specimen of the Homo floresiensis (right). Microcephalics are also called "pinheads" due to the "pin-like" shape of their frontal lobe. Photo from National Geographic.

The shape of LB1's brain matches closely to those of Homo habilis. Falk thinks that LB1 might share ancestral history with Homo habilis and australopithecines. This is due to the characteristics that are found in LB1's brain.


Falk ended her lecture by talking about "insular dwarfism". Brain size and relative body size shrinks proportionately in the case of insular dwarfism. In the case of Homo floresiensis, its brain size did not shrink proportionately with its relative body size when compared to Homo erectus or Homo sapiens (based on the argument that Homo floresiensis is a diminutive version of Homo erectus or Homo sapiens)

Hobbits In The Haystack: Homo floresiensis And Human Evolution

The 7th Human Evolution Symposium, Hobbits in the Haystack: Homo floresiensis and Human Evolution was held yesterday at Stony Brook. Turnouts were great despite damp and rainy weather. Convened by Richard Leakey, the symposium was an all day event where researchers share their findings on Homo floresiensis. The highlight of the symposium is the first ever complete cast of LB1, or Flo and a host of Homo floresiensis researchers.

The symposium ended with questions and issues for discussion by Richard Leakey. Then, the floor was opened for general Q&A session with the panel. I will write about each presentations tomorrow, I'm currently swamped with school work!

"Accepting it (Homo floresiensis) will require us to rewrite the textbooks." - William Jungers, Stony Brook University.

Here is a list of topic presented by speakers during the symposium:

"Hobbits in context: life, times and death of Homo floresiensis" by Michael J. Morwood, University of Wollongong, Australia.

"Digging up Hobbits: The Excavations at Liang Bua" by Thomas Sutikna, National Research and Development Centre for Archaeology, Indonesia.

"Stone Tools and Hominins on Flores" by Mark Moore, University of New England, Australia.

"Whence Homo floresiensis? Clues from the brain." by Dean Falk, Florida State University.

"Her Teeth Were Sharp, Her Gums Were Raw, and Spit Was Dripping From Her Jaw: The Little Things That Make Us Human" by Peter Brown, University of New England, Australia.

"Why the Tiny Wrist Bones of a Hobbit Tell Us So Much About a Big Chapter in Human Evolutionary Theory" by Matthew Tocheri, Smithsonian Institution.

"The Hobbit Shrugged: The Shoulder of Homo floresiensis and its Implications For Human Evolution." by Susan Larson, Stony Brook University.

"Can Island Dwarfing Explain Hobbit Body Size and Shape?" by William Jungers, Stony Brook University.

"Virtual Hobbits and Health in Homo floresiensis" by Charles Hildebolt, Washington University in St. Louis.

A list of what Richard Leakey commented and asked during the symposium:

We should be careful when using Lucy as model for comparison because Lucy is not representative of the genus Australopithecine in general.

We don't have Homo erectus feet in our fossil record. The fossilized foot prints that were found in Ileret, Kenya has been suggested that it was left behind by Homo ergaster, an earlier version of Homo erectus.

There should be more discussion on the types of dating methods used on Homo floresiensis and the artifacts found in association with it.

There should be more discussion and research to link lithic materials to the Hobbits, or Homo floresiensis.

What were the geographic isolation of Flore? How did the Hobbits ended up in Flores?

Were there large carnivores in Flores or lack thereof? Hobbits have ape-like feet that were built for walking but not for running. Did they survive despite that because they have no need for speed to get away from predators?

Little Foot: The Australopithecine

Little Foot's skull and upper left arm. Photo from The Witness.

10 years later, Little Foot will finally be given a species name. Read about the discovery Little Foot in 1998 from Washington Post here.

Professor Ron Clarke of the Institute for Human Evolution and School of Anatomical Sciences at the University of the Witwatersrand will start identifying Little Foot for the latest issue of the South African Journal of Science. According to Clarke, Little Foot does not belong to the species Australopithecus afarensis or Australopithecus africanus, but to a unique Australopithecus species previously found at Makapansgat and Sterkfontein Member Four. Read the article from The Witness here.

Donald C. Johanson, The Man Who Discovered Lucy

Paleoanthropologist Donald C. Johanson, discoverer of the oldest fossil bones of erect walking humans on record, displays a plaster-cast skull of a female skeleton he named "Lucy." Photo from Time magazine.

Time magazine had a Q&A with paleoanthropologist, Dr. Donald C. Johanson on his new book, Lucy's legacy: The Quest for Human Origins, a continuation of his previous book, Lucy: The Beginning of Humankind and his discovery of "Lucy" the female Australopithecus afarensis.

To set the record straight, it was the Beatles' song "Lucy in the Sky with Diamonds" that gave birth to the hominid's name, correct?

Yes, the whole camp was listening to Beatles' tape because I was a great Beatles fan, and "Lucy in the Sky with Diamonds" was playing and this girl said, well if you think the fossil was a female, why don't you name her Lucy? Initially I was opposed to giving her a cute little name, but that name stuck.

Read about the Q&A here.

Here's a trivia for you: Do you know that Australopithecus afarensis means the Southern ape of Afar, named after the area where Lucy was found (Afar, Ethiopia).

Walk Like A Modern Human: 1.5 Million-Year-Old Footprints Found In Ileret, Kenya

Fossilized footprints were found between two sedimentary layers in Ileret (Rutgers' Koobi Fora Field School), Kenya that dates back about 1.5 million-years-ago. These footprints show that its owner was walking upright, bipedally and the foot already had the anatomy like those of modern humans: relatively adducted hallux (big toe), medial longitudinal arch and medial weight transfer before push-off. The size of the footprints corresponds to the stature and body mass of Homo ergaster, an earlier version of Homo erectus (Bennett et al., 2009).

Cover of Science, 27 February 2009. Optical laser scan of early hominin footprints at Ileret, Kenya, color-rendered to illustrate depth; reds indicate areas of high elevation, blues lower elevation. The footprints are 1.5 million years old and were probably made by Homo ergaster/erectus. Two right footprints and a partial left are visible along with a range of animal prints. Image processing in Rapidform^TM: Matthew Bennett/ Bournemouth University.

These footprints are distinct from the "famous" Laetoli footprints, discovered by Mary Leakey in 1976 at Laetoli, Tanzania which dates to about 3.5 million-years-ago. The Laetoli footprints belong to Australopithecus afarensis and at least two individuals were present, walking side by side.

Laetoli footprints. Photo from www.pbs.com

The Ileret footprints are different and similar to the Laetoli footprints in many ways. Laetoli footprints are more ape-like, Ileret footprints are more human-like. Both, however, do not have an opposable toe like those of chimpanzees. Both footprints indicate that its owner was walking bipedally or has a bipedal gait.

Comparison between a chimpanzee footprint and Australopithecus afarensis (Laetoli) footprint. Photo of chimpanzee footprint from www.elucy.org and photo of Laetoli footprint from www.columbia.edu




Comparison between Homo ergaster (Ileret footprint) and modern human. Photo of Ileret footprint by Matthew Bennett from www.nationalgeographic.com

Read more on "Prints Are Evidence of Modern Foot in Prehumans" by John Noble Wilford.
Rutgers' Press Release: 1.5 Million-Year-Old Fossil Humans Walked on Modern Feet.

Citation:
Bennett MR. Harris JWK. Richmond BG. Braun DR. Mbua E. Kiura P. Olago D. Kibunjia M. Omuombo C. Behrensmeyer AK. Huddart D. Gonzalez S. 2009. Early Hominin Foot Morphology Based on 1.5-Million-Year-Old Footprints from Ileret, Kenya. Science 323 (5918): 1197 - 1201. [DOI: 10.1126/science.1168132]

Australopithecus Africanus Were Nutcrackers

Large and heavy premolars from fossil hominins are traditionally viewed as indications of a diet consisting of small, hard objects or massive amount of food.

Using finite element analysis in conjunction with comparative, imaging, and experimental methods, Strait et al. (2008) came up with a modified conclusion: these large and heavy premolars served as nutcrackers to break open hard nuts and seeds. A shift to nuts and seeds diet may explain that A. africanus were exploring new food resources, possibly due to a scarcity of preferred food source. Early Humans Had Nutcracker Jaws.

What are the implications of this research?

Does it mean that our hominin ancestors (A. africanus) were forced to exploit new food resources earlier than we had thought?

Were there environmental changes that lead to lower production of preferred food sources (possibly fruits)?

Exponential increase of Australopithecine population in a shrinking forested habitat forced some individuals with larger and heavy premolars to exploit new food resources (nuts and seeds)?

Cranial facial morphology A. africanus. Photo from PNAS

Computer simulations showed the compressive stress of biting in the cranium of A. africanus. Bright colors indicate high stresses, and show that a bone running alongside the opening of the nasal cavity acts as a strut to reinforce the face against premolar loads. Credit: Arizona State University and the Hominid Feeding Biomechanics research team. Photo from LiveScience.com

Citation:
Strait DS. Weber GW. Neubauer S. Chalk J. Richmond BG. Lucas PW. Spencer MA. Schrein C. Dechow PC. Ross CF. Grosse IR. Wright BW. Constantino P. Wood BA. Lawn B. Hylander WL. Wang Q. Byron C. Slice DE. Smith ML. 2008. The Feeding Biomechanics and Dietary Ecology of Australopithecus africanus. Proceedings of the National Academy of Sciences of the United States of America 106 (8) 2124-2129.

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?