Anthropology.net

Two days ago, Matt Ridley published a rhetorical editorial in the Wall Street Journal‘s column Mind & Matter. Ridley addresses the decline in incidence of inheritable diseases, overcoming infertility with in vitro fertilization (IVF), and other topics such as the impact of culture and brain expansion. The piece has gained a lot of attention in social media with over 1,900 Facebook shares and 650 Tweets at the time of writing this blog post. This is poignant discussion to be had but Ridley’s assessment falls short.

Ridley discusses relaxed selection by bringing up an IVF technique, intracytoplasmic sperm injection, used help men with immotile sperm to father children. Firstly, since he didn’t mention the cause of immobility of the sperm, I must mention that in any given man a significant portion of sperm are immotile. The ratio of immobile sperm to motile sperm is critical, as is the volume of or sperm count. The WHO standard for motility of sperm is about 50% of the sample, any less than the risk of infertility rises. However, if the sperm count is high, then having less than 50% motility is not an issue.

There are certain circumstances where almost all sperm are immobile, such as Kartagener’s syndrome. Kartagener’s syndrome is a primary ciliary dyskenesia. This is an autosomal recessive genetic disruption in the arms of the motor protein dynein. Kartagener’s syndrome is approximated to be present in 1 out of 15,000 – 32,000 men., of which infertility is not a primary concern. I write this because main result of impaired ciliary function is the impairment of clearing mucous to the lungs. Chronic respiratory infections due to progressive damage to the respiratory system, leads severe diseases like bronchiectasis beginning in early childhood. Prevention of these complications is more important than using IVF.

Ridley weakened his argument on relaxed selection, because he failed to discuss the details of what sperm immobility is and means. Furthermore, in an example of true spermatic immobility, surviving to reproductive age when respiratory complications hit is low. Why didn’t he address the relaxation on selection with the increase use of C-sections?

In the next half of the article, I can’t tell if Ridley was playing Devil’s advocate with this excerpt,

“Now, thanks to pre-implantation genetic diagnosis, parents can deliberately choose to implant embryos that lack certain deleterious mutations carried in their families, with the result that genes for Tay-Sachs, Huntington’s and other diseases are retreating in frequency. The old and overblown worry of the early eugenicists—that “bad” mutations were progressively accumulating in the species—is beginning to be addressed not by stopping people from breeding, but by allowing them to breed, safe in the knowledge that they won’t pass on painful conditions.”

Parents are still giving birth to children with known and unknown deleterious mutations. Post-implantation diagnosis of genetic diseases with techniques like such as amniocentesis or chorionic villus sampling are not offered to all expecting mothers, nor do all expecting mothers chose to these tests… Let alone pre-implantation! To say that these this practically non-existent option has directly caused a decrease deleterious traits to no longer be selected against is a bold and brash statement. The increase in admixture is a more impactful variable in the reduction of incidence in genetic diseases the pre-implantation diagnosis.

Ridley also brings up the differences of SNPs seen between people of European and African ancestry, attributing nothing of substance to the observation that Europeans have half as many SNPs as Africans. He implies, “larger population allow more variants [with] less severe selection against mildly disadvantageous genes,” and attributes the expansion of population in the last 5,000 years to this. But within a species, mutation rates are constant, regardless of the selective pressure.

Lastly, commenting on the slow rate of brain expansion and how modern advances in technology and culture will have an effect on evolution is akin to equating how the Kardashians will effect the Sun’s eventual implosion. The sum of the pressures of selection occur with drift. The time frames of history, in the thousands of years are too small to capture this phenomenon. A genetic example to outline this, is the Black Plague. European communities show much lower genetic diversity because of mass death that wiped out large populations, it had almost a nil effect on our genetic traits as a whole.

Like any progressing variable, time and culture offer different selective pressures upon the evolution of humans. While on one hand we maybe selecting for people with deleterious traits by offering IVF and C-sections to those who wouldn’t normally become parents, we on the other hand can prevent the births of offspring with such traits by early diagnosis. Additionally, as our population continues to expand and cultures admix, can we with certainty say we see an impact on the genetic and phenotypic makeup of humans?

These questions lead me to ask, “What Should Human Evolution Be?”

I am now two-thirds done with my psychiatry rotation. It has been a fascinating experience so far. I’ve seen the gamut of psychiatric cases, depressed people who cut their necks through and through, to florid schizophrenics worried that the Hiroshima bomb will go off any moment. The treatment of psychiatric conditions like depression or schizophrenia often revolves around regulating monoamine neurotransmitters like serotonin, norepinephrine and dopamine.

Dopamine is an important neurotransmitter that functions in a lot of behaviors and reactions, such as movement, lactation, aggression, fear, etc. In diseases like Parkinson, dopamine levels lower and movement becomes uncontrolled. In other diseases like schizophrenia, either dopamine levels are high or response to dopamine is higher, and paranoia & hallucinations manifest. Treating schizophrenia involves blocking dopamine receptors. As you can imagine, a common side effect of antipsychotics is movement disorders — or Parkinsonism.

So why am I on this neuropsychiatric kick on an anthropology blog? Our cultural and behavioral predisopostions ultimately boil down to chemicals in our brain interacting and stimulating other areas. One of the most important functions of dopamine is in the reward system of the brain, an area called the nucleus accumbens that primes pleasurable behavior to repeat, such as sex, eating, and drugs.

In this video, Robert Sapolsky of Stanford Neurology makes the distinction between how dopamine levels rise in the anticipation of pleasure and not as a response to pleasure. I especially like that comment he made regarding reward and religion, “There’s no monkey out there willing to lever press because St. Peter is down the line.”

By Jay Fancher

Oil transformed Dubai in the 1970s. The city now boasts the world's tallest building, giant malls, and some two million residents, who depend on desalinated seawater and air-conditioning—and thus on cheap energy—to live in the Arabian desert. (Credit: Jens Neumann/Edgar Rodtmann/NATIONAL GEOGRAPHIC)

To paraphrase Carl Sagan, science has a way of deflating human conceits.  Anthropology reveals that humans are special – just not for many of the reasons proposed throughout our history.  Thanks to biology, astronomy, and geology, we now know that:

• Modern humans are one species among many, not the pinnacle of all creation.

• We’re not the center of the universe; our planet orbits a fairly average star.

• We haven’t been around since the beginning of time – far from it.

On a 4.5-billion-year-old planet, with a 3.5-billion-year history of life, anatomically-modern Homo sapiens only go back about 200,000 years.  We’re brand new, a tiny blip on the geologic time scale!  Despite this, a new National Geographic article explores the possibility that the “Anthropocene” may have already begun.  Here is a brief excerpt:

Enter the Anthropocene—Age of Man It’s a new name for a new geologic epoch—one defined by our own massive impact on the planet. That mark will endure in the geologic record long after our cities have crumbled…Probably the most obvious way humans are altering the planet is by building cities, which are essentially vast stretches of man-made materials—steel, glass, concrete, and brick. But it turns out most cities are not good candidates for long-term preservation, for the simple reason that they’re built on land, and on land the forces of erosion tend to win out over those of sedimentation.

The author of the article, Elizabeth Kolbert, graciously agreed to an interview with Anthropology.net.  The text of our discussion, conducted via e-mail, follows:

Fancher: The greatest strength of anthropology is its all-encompassing view of humanity.  We’re proud of this breadth, frequently describing our work as the study of all people, in all times, and all places.  But, as you state in your article, stratigraphers take an extremely long view – the entire 4.5-billion-year history of Earth.  How can students of the human past benefit from this geological perspective?

Kolbert: I’m not sure I have a good answer for this.  As all anthropologists know, we are a young species.  So human history doesn’t tell us much about earth history.  What is particularly alarming about a lot of recent discoveries in geology is that you have to go way, way back – i.e., tens of millions of years – to find analogues for some of the things we are doing today, like, for example, acidifying the oceans.

Fancher: I was surprised to read that our proudest technological achievements might not be easy to recognize in the geological record.  It’s humbling to think that urban centers will ultimately be as fleeting in the geological record as short-term hunter-gatherer camp sites are in the archaeological record.  Despite our human desire to leave huge, everlasting monuments, is it better not to be noticed in the geological record?

Kolbert: Well, it’s not clear that we will be noticed, because it’s not clear there’s going to be anything around to notice us.  But we will be noticeable.  And certainly from the standpoint of the other organisms on earth, it would be a lot better if our impact were not so obvious.

Fancher: Some issues of scientific classification appear to have little practical relevance.  For example, the debate over whether Pluto qualifies as a planet or not.  In your article, Dutch chemist Paul Crutzen concludes that the value of the Anthropocene classification goes far beyond textbook revisions.  Can you elaborate on the meaning of the Anthropocene?

Kolbert: Officially, we live in the Holocene, or “wholly recent” epoch.  The Anthropocene translates basically as the man-made epoch.  It’s an acknowledgment that humans, rather than what are sometimes quaintly called “the great forces of nature,” have become the driving force on the planet.

Fancher: How might recognition of a geological epoch called the Anthropocene influence human behavior?

Kolbert: I end the piece with a quote from Paul Crutzen, the Nobelist who coined the term.  Crutzen says, “What I hope is that the term ‘Anthropocene’ will be a warning to the world.”  I think what he means by that is: we are now in the driver’s seat.  Unfortunately, we don’t really know how to operate the vehicle.  So we’d better think about what we’re doing very carefully.

Many thanks to Elizabeth Kolbert for writing such a thought-provoking article, and for agreeing to this interview.  Enter the Anthropocene – Age of Man is part of National Geographic magazine’s year-long coverage of the global human population reaching 7 billion.

What do you think about the possibility of a geological epoch called the Anthropocene?

On the lighter side of anthropology…  The Onion takes a satirical look at what outrageously pseudoscientific research into human origins might look like.  Their headline reads:

“Anthropologists Trace Human Origins Back To One Large Goat”
‘Wait, That Can’t Be Right,’ Scientists Say”

In addition to being funny, the article, by contrast, helps show the strict standards of evidence, interdisciplinary collaboration, and peer-review process of actual paleoanthropological research.  Also, our close relationship with other primates is highlighted when one fake Onion researcher observes that “…humans don’t look like goats.”  In other words, don’t expect any presentations on “goat people” at professional anthropological conferences anytime soon.  Enjoy!

- Jay Fancher

Anonymous is not a force to be reckoned with. Scientologists have felt their wrath for sometime, Sarah Palin did as well, as have MasterCard & Visa post-Wikileaks fiasco. I’m sure Aaron Barr is now realizing the impact Anon has. Aaron Barr is head of an internet security company, HBGary Federal. His company was contracted by Bank of America as a counter Wikileaks impending release of cables that will incriminate BofA.

Anon vs. Scientology

Ars Technica has written up a 3 page account of the situation, which is absolutely fascinating. The tl;dr seems like its comes straight out of a B movie. Aaron’s ingenious plan was to ‘infiltrate’ Anon…He joined IRC channels in an attempt to sabotage Anon and get names of those in the organization.

His problems started here. Aaron failed to realize Anon is not a true organization. At its core, Anon is an anti-organization, as anarchist as you can be, with no leadership and an ever-changing membership. Aside from infiltrating the chat groups, Aaron attempted to flesh out members of Anon via a guilt-by-association method using something akin to 6-degrees-of-separation and social media. He revealed himself to the group, claiming to research them.

What ended up completely backfired on Aaron. Anon was pissed. In traditional hacking manner, they hacked his company’s site and replaced the front page. They also managed to get a hold of at least 44,000 of his emails and release them via torrents. They deleted 1 TB of his backups, wiped his devices and to top it all of, got a hold of his Twitter and LinkedIn accounts where they posted messages as him. For a company that was in the midst of a sale, Anon effectively ruined that.

This leads me to a open up a discussion regarding the Anthropology of Hackers, a timely piece that appeared in the Atlantic yesterday by NYU’s Gabriella Coleman. In her write up she outlines her 13 week curriculum on the culture of hacking, covering topics like open source, privacy & anonymity, and the dawn of the nerds. Ironically, almost all are relavent to HBGary Federal, given Aaron’s troubles. I wonder how they’d benefit from a crash course in Coleman’s class. Looking at Coleman’s course topics, there’s a lot to consider regarding hacking. The most relevant to this topic is the material covered in Weeks 11 & 12,

Week Eleven: Anarchism and the Politically Minded Hacker

Many hackers express some degree of ambivalence over the politics of hacking as Patrice Riemens has argued and as hackers themselves have raised. This is not the case with a small but well organized cadre of hackers located primarily in Latin America, Europe, and North America who havecharted collectives, many of them influenced by the political philosophy of anarchism. To grapple with anarchism as a political philosophy (which, similar to hacking, is plagued with a parade of misconceptions), we turn to David Graeber‘s fantastic pamphlet, Fragments of an Anarchist Anthropology. We also read Jeff Juris’s ethnographic work about technology activists during the counter-globalization era Networking Futures.

Week Twelve: Trolls and the Politics of Spectacle

If anyone has been paying attention to the Internet in recent years, it has been impossible to miss a class of provocateur and saboteur: the Internet troll, whose raison d’être is to be as offensive as humanely possible via raunchy (but often humorous and quite esoteric) language, images, pranks, and tricks, basically, doing it for what they call the “lulz.” To get a sense of the cultural logic and exploits of trolls we read “The Trolls Among Us” by Mattathias Schwartz. To help us grapple with the nature of spectacle, we read a couple of chapters of Dream: Re-imagining Progressive Politics in an Age of Fantasy by Stephen Duncombe. We read excerpts from Lewis Hyde’s magnificent book on tricksters to consider whether the troll might be an example of these mythical creatures that have dazzled countless societies with their trickery. We watch a talk on a protest movement against the Church of Scientology whose roots lie in the act of trolling buteventually turned into a morally serious protest movement, which nonetheless retained the tactics of spectacle as part of its political arsenal.

This is a very interesting time to be looking at the intersection of technology and culture. There are anthropologists doing some fascinating work researching the sense of identity in online communities like World of Warcraft and Facebook… These groups share an online space, often with avatars and complex long-lasting interactions.

But with Anon there’s no identity.

Anon remains behind ever-changing screen names and masked localities behind proxies. I’m sure if you’ve ever taken an Intro to Cultural Anthropology course you would have touched on Erik Erikson’s theories of personality, We know what defines identity is a loose association of markers like behavior, language, dress, shared spaces, etc. Anon is disparate to any modern definition of identity. They do not share the same space, language, or any other measure of similarity except for behavior and ideology…

“We are Anonymous.  We are Legion.  We do not forgive.  We do not forget.  Expect us.”

I’d really like to get to hear Coleman’s take on this current event, or any cultural anthropologist for the matter. So if you’re interested, please chime in on your take on this all — What do you understand on Anon and how are they similar/dissimilar to other groups?

Anyone remember 2 years ago, when Survival International released some photos of an uncontacted tribe at the border of Brazil and Peru? Well an update came out, a remarkable video showing the tribe and describing what’s being done to protect them. Oh and by the way, this is part of BBC’s Human Planet.

Check out the video here.

A hunter-gatherer mother sits stirring a pot of stew over an open fire.  Her young son, eagerly anticipating the evening meal, approaches the pot and asks, “What are we eating?”  “Not sure.  Meat, I think.  Probably some other stuff,” she replies.

Okay, I made that up.  The preceding exchange would never occur between hunter-gatherers.  Or horticulturalists.  Or pastoralists.  Or most of the other subsistence systems that anthropologists study.  The mother, and usually the son, would know what was in the pot because they took part in hunting, gathering, raising, growing, or processing the ingredients.  And that’s pretty much the way it’s been for the vast majority of human history.

So how did we end up here?  An Alabama law firm is suing Taco Bell, claiming that the meat used in Taco Bell’s products does not meet the U.S. Department of Agriculture definition of “beef.”  In fact, the lawsuit alleges that the company’s meat filling is only 35% beef, with the remainder comprised of non-meat ingredients such as water, oats, modified corn starch, maltodextrin, etc.

Taco Bell asserts that their products contain 100% beef.

That’s a big difference in percentages.  Someone’s not telling the truth, or is at least being very disingenuous.  Thankfully, we humans have an established method for evaluating evidence-based claims…SCIENCE!  Yes, I can turn anything into an advertisement for science, and I hope the legal proceedings rely on solid data to resolve this dispute.

From an anthropological perspective, this issue highlights the wide, historically-unprecedented, gap between food production and food consumption in 21st Century developed nations.  We’re all food consumers, far fewer of us are food producers.  The production of our food most often occurs out of sight.  Michael Pollan [In Defense of Food and the film Food, Inc.] argues that much of what we eat is not even food in the strict sense, but rather “food products,” manufactured from food and the “other stuff” I mentioned before.

Many people seem repelled by the idea of unidentifiable “meat.”  But, like our Paleolithic ancestors, we crave fat, salt, and sugar [Martin Jones' Feast: Why Humans Share Food and Richard Wrangham's Catching Fire: How Cooking Made Us Human].  Fast food provides massive quantities of all three for a low, low price.  I had Taco Bell a few days ago, so I understand the allure of quick, cheap calories.  How we got to this point is a fascinating story, well-covered by anthropological research (please see included links and share your own in the comments).  Since we are so removed from the production of our own food products, I think it’s reasonable for consumers to know what’s in the pot – even if laboratory analysis is required to figure out the ingredients.  What do you think?

- Jay Fancher

The American Anthropological Association (AAA) is a strange organization. I often wonder how it operates, but then I realize I don’t even wanna know because there’s often no real logic to their madness. Take into consideration these cases:

Case 1: About 4 years ago the AAA decided to close access to almost all their journals, directly against the Federal Research Publication Access Act. This spurned a lot of discussion regarding ownership of publication, author’s rights and the AAA’s motivation behind it. Most of us wondered how could the AAA, who didn’t fund the research, produce the data, and write up the analysis, close off the information to the world? Here was a bit of my outcry over the matter, archived by afarensis in June of 2006,

“The hypocrisy that surrounds the AAA when it begged for anthropologists to protest to the US government to not cut funding but their recent resiliency to not give back is outstanding in this matter. I don’t get why the AAA won’t open their eyes and see that this form of publishing helps to ensure long-term access to scholarly articles. Unlike articles that are licensed in traditional article databases, like their closed AnthroSource, public libraries and institutions of the people (like universities) can create local copies and repositories of these resources. People, by working together to make repositories of open access literature, can ensure continued access to these scholarly publications into the distant future.”

From this idiocy, a nice project spun off but hasn’t in my opinion been a viable alternative. Unfortunate.

Case 2: Once upon a time the AAA was an organization that scoffed at social media and Web 2.0, specifically blogs. It’s hard to dig up exact references since many links have died… But I do distinctly remember them issuing a statement saying blogs are useless forms of communication, with a little wink wink nod nod to this said blog.

When they redesigned their homepage a couple of years ago, they deployed several blogs. They even sent me emails asking for link exchange. Sure people are allowed to change their minds, but I wondered what’s with the change in heart? Suffice to say, I didn’t add them back.

Case 3: The AAA just had their annual meeting and yes, everyone’s reporting that decided to do away with science. It’s true, Peter Wood of the Chronicle, writes on them actively deciding to nix science out of the Mission Statement. I’ve copied and pasted the presumed edits to the mission statement he provided below the read more link.  Another related decision made is defining the role of AAA, away from ethnography and scientific experiments and observations to anecdotal and subjective journalism… Again without ethnology and ethnography — what is cultural anthropology?

Alice Dreger of Fetishes I Don’t Get, writes on some of the anger she experienced from other scientific anthropologists,

“The primatologist Sarah Hrdy (a member of the National Academy of Sciences) wrote, “My reaction is one of dismay-actually, even more visceral and stronger than that-albeit not surprise.” The scientists I talked to want to know (as I do) exactly what is the AAA Executive Board’s justification for all this. They are confused about whether they should bother to fight, or just give up and depart the AAA already.”

The Society for Anthropological Sciences, a division of the AAA, objected to these changes, I am sure most do. I don’t understand why this change is being done. In a time and age when we need to strive to objective data to make informed decisions, this organization is moving away from that, and consciously. Why?

Could it because anthropology is largely not considered a science outside of the discipline — so the AAA chooses embrace what most think of us?

Again it is hard to get into the minds of such a dysfunctional organization. They seem to never make the right decision. An analogy that works in my mind is the AAA is to anthropologists as the Clerical Theocracy of the Islamic Republic are to Iranian population. As many governments help make decisions to move forward and advance their society, both the AAA and the mullahs regress their organizations further back in time.

Read the rest of this entry »

I haven’t bothered to translate this page, but I’ve stumbled across a collection of 56 family portraits from East Asia that I wanted to share with you. The images give us a quick glimpse of all the different cultures and ethnicities that make up the far East, along with the lat/long of where these people are found. Check it out.

Ethnic Mongol

See also: Is Homo floresiensis really that strange? – Zinjanthropus@ A Primate of Modern Aspect

A new, detailed and freely accessible paper, Reconstructing the Ups and Downs of Primate Brain Evolution: Implications for Adaptive Hypotheses and Homo floresiensis (provisional PDF) has just come online at BMC Biology, in which Stephen H. Montgomery et al discuss the reduced brain-size of Homo floresiensis, and suggest she is unlikely to have descended from Homo erectus, for which this is the abstract:

Background

Brain size is a key adaptive trait. It is often assumed that increasing brain size was a general evolutionary trend in primates, yet recent fossil discoveries have documented brain size decreases in some lineages, raising the question of how general a trend there was for brains to increase in mass over evolutionary time. We present the first systematic phylogenetic analysis designed to answer this question.

Results

We performed ancestral state reconstructions of three traits (absolute brain mass, absolute body mass, relative brain mass) using 37 extant and 23 extinct primate species and three approaches to ancestral state reconstruction: parsimony, maximum likelihood and Bayesian Markov-chain Monte Carlo. Both absolute and relative brain mass generally increased over evolutionary time, but body mass did not. Nevertheless both absolute and relative brain mass decreased along several branches. Applying these results to the contentious case of Homo floresiensis, we find a number of scenarios under which the proposed evolution of the Homo floresiensis brain appears to be plausible, dependent on body mass and phylogenetic position.

Conclusions

Our results confirm that brain expansion began early in primate evolution and show that increases occurred in all major clades. Only in terms of an increase in absolute mass does the human lineage appear particularly striking, with both the rate of proportional change in mass and relative brain size having episodes of greater expansion elsewhere on the primate phylogeny. However, decreases in brain mass also occurred along branches in all major clades, and we conclude that, while selection has acted to enlarge primate brains, in some lineages this trend has been reversed.

Further analyses of the phylogenetic position of Homo floresiensis and better body mass estimates are required to confirm the plausibility of the evolution of its small brain mass. We find that for our dataset the Bayesian analysis for ancestral state reconstruction is least affected by inclusion of fossil data suggesting that this approach might be preferable for future studies on other taxa with a poor fossil record.

There’s a pretty good write-up over at A Primate of Modern Aspect, from which this is excerpted:

It’s extremely important for most of your organs to increase with body size.  For example, a bigger animal needs to pump more blood, so it needs a bigger heart.  A bigger animal eats more food and needs a bigger liver.  There are certain areas of the brain that increase allometrically with body size- usually areas that are in charge of motor skills.  If you’ve got bigger legs, you’ve got bigger muscles, and you need more neural projections in order to control them.  But does a larger animal need to think more?  Will it benefit from an extra few cubic centimeters of neocortex?  Probably not, so it’s not worth the extra time and energy it takes to develop that neocortex.

And that sort of brings us to an important question in evolutionary neurobiology: Does absolute brain size matter, or is it solely brain size relative to body size?  Brains that are absolutely larger have more neurons, which could have important cognitive implications.  But how many of those extra neurons are just being used to control the physiological functions of the body?

Does size even tell us anything at all?  Any way you look at it, brain size is a crude measurement of cognitive ability.  In an ideal world, we would know the proportion of each of the different regions of the brain in each species and go from there.  But, those kinds of measurements are hard to obtain in living species, and impossible in fossils.  Ralph Holloway has been saying since 1967 that there has got to be a better way than just plain ol’ cranial capacity… but other than noting the relative position of different sulci and gyri on endocasts, there isn’t too much else to be done.

The diminished brain size of LB1 has been remarked upon ever since the initial discovery, at is generally supposed that the stone tools found in context would have required a hominid with a larger brain in order to deploy the cognitive capacity needed for such behaviours, leading some to suggest that they were copies of others made by unknown AMH others present on the island of Flores. This in turn raised the question of from what or whom Liang Bua 1 had descended – according to the interpretation by zinjanthropus, if LB1 is descended from either H.georgicus found at Dmanisi, or H.habilis, the size of her brain is much more in accordance than had the descent been from the H.erectus from Ngangdong. Here’s a related note from the paper, which I’m sure will be the subject of extended discussion in the near future:

From our analyses  of evolution of H. floresiensis brain size under different phylogenetic  hypotheses, we conclude that the evolution of H. floresiensis is consistent with  our results across the primate phylogeny if it either evolved from populations  of H. habilis or Dmanisi hominin by insular dwarfism, or under Argue et al.’s  [43] proposed phylogenetic scenarios, and if H. floresiensis had a body mass  towards the lower end of the range of estimates obtained from skeletal  remains. In this respect we note that Brown et al. [26] suggested the lower  body mass estimates are probably most appropriate, assuming H. floresiensis  shared the lean body shape typical of Old World tropical modern humans.

If  this were true we estimate the evolution of H. floresiensis involved a  reasonable decrease in absolute brain mass, but an increase in relative brain  size.  Our analysis, together with studies of brain size in island populations of living primates[41, 42], therefore suggests we should perhaps not be  surprised by the evolution of a small brained, small bodied hominin, although  further clarification of the relationships between H. floresiensis and other  hominins are required to confirm this observation. Finally, our analyses add to  the growing number of studies that conclude that the evolution of the human  brain size has not been anomalous when compared to general primate brain  evolution [59, 61 91-94].

Reference:

Reconstructing the Ups and Downs of Primate Brain Evolution: Implications for Adaptive Hypotheses and Homo floresiensis

Abstract – Provisional PDF

Stephen H Montgomery , Isabella Capellini , Robert A Barton and Nicholas I Mundy

BMC Biology 2010, 8:9doi:10.1186/1741-7007-8-9