The Evolution Of Brain Size In Primates And Homo Floresiensis

Skull of LB1 (Homo floresiensis) and modern human.

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

A White-collared Mangabay (Cercobebus torquatus)

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

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

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

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

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

EurekAlert!: Does evolution always lead to bigger brains?

Wired Science: Evolution Shrank Some Primates’ Brains.

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).

Hobbits Might Not Be A Homo After All

The controversies over the hobbits or Homo floresiensis just refuse to end. It seems that the hobbits might not be a Homo after all. I guess they found the index and ring fingers of the hobbits (Sorry, inside joke. Read this post if you want).

 Homo floresiensis (LB1) skull. Photo from Science Museum.

Homo floresiensis, LB1, skull (left) and human skull (right). Photo from BBC.

Anyway, Peter Brown from the University of New England who first described Homo floresiensis said that he is considering of stripping the hobbits from the genus Homo. Brown and his colleague, Tomoko Maeda, said that the Homo floresiensis lineage possibly left Africa before the evolution of the genus Homo. Their paper had been accepted and will be published in an upcoming special Homo floresiensis edition of the Journal of Human Evolution.

I can't wait for the paper to come out. In the meantime, you can read this article from The Australian.

Hobbit in the Haystack: Homo floresiensis and Human Evolution - Watch it Online!

Earlier this year, I've blogged about the 2009 Human Evolution Leakey Symposium at Stony Brook that I went to. For more about that blog post, click here.

The symposium, entitled "Hobbit in the Haystack: Homo floresiensis and Human Evolution" can now be streamed live through the Stony Brook website. The website also includes previous Human Evolution Leakey symposia. Click here to watch.

Thanks to Afarensis: Anthropology, Evolution and Science for the heads up!

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

"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?

First Ever Casts Of Homo Floresiensis To Be Unveiled At Stony Brook University

Photo from Science Museum

Apparently, the first ever casts of Homo floresiensis or "Hobbit" will be unveiled at the 7th Annual Human Evolution Symposium at Stony Brook University on Tuesday, April 21st, 2009 courtesy of the National Research and Development Center for Archaeology in Jakarta, Indonesia. This symposium will be convened by Richard Leakey, famous paleoanthropologist and Anthropology professor of Stony Brooks. “Hobbits in the Haystack: Homo floresiensis and Human Evolution,” is hosted by the Turkana Basin Institute at Stony Brook.

Click here for the press release from Stony Brook. This all-day symposium is open to the public. Check website for ticket pricing and questions. I HAVE to be there ...

Karen Baab and Kieran McNulty: Modern Procrustes

I found this while searching for news articles on "The Hobbits" or "Homo floresiensis". Sometimes taxonomy gives me headaches. I don't know why humans are so obsessive compulsive about putting things in categories. I guess that same reason is why I put labels on my blog posts.

Anthropologists Karen Baab from Stony Brook University Medical Center and Kieran McNulty from University of Minnesota published "Size, shape, and asymmetry in fossil hominins: The status of the LB1 cranium based on 3D morphometric analyses" in the Journal of Human Evolution last July. Click for .pdf version of the article.

Photo from the Science Museum

Using principal components analysis in shape space and in Procrustes form space, they shrank skulls of modern humans, fossil hominins and apes proportionate to their body so that they can use these new simulated models to compare LB1's skull. They found that LB1's skull closely resembles those of the genus Homo, too different to be those of modern human but close enough to be related to Homo erectus or something more primitive.

"You can't just make things bigger or smaller," McNulty explains. "When things change size, they need different mechanical properties." Or, there could be certain spatial requirements for the brain. A host of factors determine the proportions of the "shrunken" skull.

They concluded from their study that LB1 was more primitive than those of the Asian Homo erectus and perhaps LB1 (Homo florensiensis) was a descendent of a hominin population that predates Asian Homo erectus which underwent a process of size reduction.

Read the press releases from University of Minnesota and Stony Brook University.

I think a lot of people see LB1 as modern human because the skull looks like a shrunken modern human skull. They try to explain why LB1 is so small in stature, from microcephaly to dwarfism. But sometimes looks can be deceptive. LB1 might look like a modern human but it's not. I think that Homo floresiensis is a species of its own and it seems that more and more evidence is surfacing to prove so.

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?