Saturday, April 25, 2009

"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)

Wednesday, April 22, 2009

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?

Monday, April 20, 2009

Photo of the day: Nom Nom Nom

Spectacled langur, dusky leaf monkey or spectacled leaf langur (Trachypithecus obscurus) at the PECO Primate Reserve, Philadelphia Zoo eating lettuce.

Saturday, April 18, 2009

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.

Tuesday, April 14, 2009

Study Confirms 3 Distinct Sub-Groups Of Neanderthals

Research by Fabre et al. (2009) in Genetic Evidence of Geographical Groups among Neanderthals using models from genetics, demography and paleoanthropology confirms that there are 3 distinct sub-groups of Neanderthals; ones in Western Europe, Southern Europe and Western Asia. The size of the three populations was not constant, possibly indicating migration between populations.

Read the press release and article from PLoS ONE: Genetic Evidence of Geographical Groups among Neanderthals

Sunday, April 12, 2009

New Orangutan Population Found In Borneo

Pongo pygmaeus morio or the Black Bornean Orangutan. Photo from Associated Press.

A population of the rare orangutan subspecies Pongo pygmaeus morio or the Black Bornean Orangutan named because of its black fur was found by scientists in a remote, mountainous area of Borneo. The population is estimated between 1000 to 2000 individuals though there is no confirmation of an exact number, said Erik Meijaard, senior ecologist at the The Nature Conservancy. There are currently two species of orangutans; Pongo pygmaeus sp. (Bornean orangutan) and Pongo abelii (Sumatran orangutan). Bornean orangutans are endangered and Sumatran orangutans are critically endangered according to the IUCN Red List of mammals.

This is indeed good news as Bornean orangutans are considered endangered and any newly discovered population is good news to conservation. I wonder what will they find in Borneo next. Read the rest of the article from Associated Press.

Wednesday, April 8, 2009

Wild Chimpanzees: Meat For Sex

An adult male chimpanzee holding the rib case of a red colobus monkey that he hunted. Photo from Discovery Channel News.

Wild chimpanzee males in the Tai National Park at Côte d'Ivoire, West Africa have been observed exchanging meat for sex on a long term basis, according to a new study. Cristina Gomes and Christophe Boesch found that males who share their meat with females increase their mating success.

For the females, meat is an important source of protein when they experience nutrition depletion, especially during estrus. So, it is beneficial for females to receive meat from males. Reproductive success then depends on good male hunting skills. The researchers also believe that there is a parallel between meat-sharing in hunter-gatherer societies and in chimpanzees. Hunters in hunter-gatherer societies tend to have more sexual partners.

Read the rest of the article from Discovery Channel News.

Did the evolution of meat-eating and meat-sharing in chimpanzees has anything to do with mating and reproductive success? Are these cultural behaviors since it is only observed in the Tai Forest National Park population?

Saturday, April 4, 2009

Female Orangutans Steal From Potential Mates

It seems that female orangutans steal from potential mates to test them, according to a new study. Females prefer males that do not fight back when they steal their food. This behavior evolved so that females can choose males that are not overly aggressive. Being aggressive towards other males to protect the females is a good thing. Males that are aggressive towards their females, however, is not. Male's aggression towards a female limits their choice to choose whom or when they mate, according to Maria van Noordwijk from the University of Zurich. So, when a female steals from her potential mate, it is an evolutionary adaption to test out their potential mate's aggression and tolerance towards her. Read the full article from National Geographic.

Friday, April 3, 2009

Were Neanderthals Cannibals?

Were Neanderthals Cannibals? Archaeological evidence from Krapina, Croatia shows that Neanderthal fossils exhibited signs of cannibalism, including cut marks. Did Neanderthals eat each other? Exploited a new "food" source when times were harsh? Not so fast, said paleoanthropologist and archaeologist Jörg Orschiedt from the University of Hamburg in Germany. He said that cut marks in the Krapina sample were randomly distributed and were not necessarily in locations where defleshing generally occurs, which is where the muscles attach themselves to the bones. Orschiedt thinks that the cut marks come from researchers that were measuring these bones with sharp measuring tools.

Read the rest of the article from Scientific American.