On the origin of humans

Interesting observations regarding brain evolution

Homo sapiens distinguish themselves among the general primate lineage in three distinct ways- bipedalism, smaller modified jaws and teeth, and a very large brain. It is likely that at some point these principal developments coalesced functionally allowing for new opportunities in the game of evolutionary dynamics. It is not hard to imagine this unique combination beginning to form ever strengthening feedbacks with each other and eventually becoming the critical ingredients enabling, in time for the creatures we are today.

In fact, it may very well be this interplay that set one distant hominid ancestor off on the road to becoming Homo sapiens. The common belief that brain size or brain to body size relates to intelligence (at least the kind of intelligence we would consider human) is too simplistic. The elephant brain is four times larger than ours yet they posses no where near the interactive complexity of humans, therefore brain size does not equal complexity or correlate to human like intelligence. A straight brain to body size ratio do not work either as for example the mouse lemur has a brain to body ratio of 3% whereas humans come out at 2%.

Brain size grows as bodies become larger, albeit more slowly as body size increases, but ultimately there is no direct link to increased intellectual complexity and just larger brain size. The real relation between brain and body size is best described by a non-linear power ratio which is 0.75. With this ratio, humans indeed have the largest brains relative to body size.

Among all mammals, Homo sapiens have the largest brains, and primates in general tend to have larger brains than other mammalian species. It is interesting to note that there are exceptions and overlaps with other mammals though. For example, simian primates generally have relatively larger brains than prosimians but there is overlap at this level with some large brained prosimians and other mammals such as seals.

As primates go, contrary to what many think, the gorilla has a small brain size relative to body ratio compared to monkeys and the New World capuchin monkey has the highest non-human relative brain to body size ratio. This interesting capuchin fact offers researchers an opportunity for study that could potentially reveal some evolutionary insight into the brain expansion of our own ancestors.

One fascinating observation when considering brain size in mammals is, even though Homo sapiens have a much higher brain/body ratio (three times larger) than expected, it is not the fact that we have larger brains that stands out first from an evolutionary perspective.As previously implied, mammals in general tend to have larger brains, which seems to be a favorable quality for this branch of animals.

In fact, endocast studies of mammalian brain fossils has led to the incredible realization that, through time, brains have tended to increase in size across all lineages. This is indeed a humbling thought for the hominid line. The differences in modern species brain sizes have come about through differing rates of brain expansion. It seems what really set us apart in the mammalian world is the rate of expansion- just a few million years to gain our present brain size- that is truly unique.

The brain is a very expensive organ to develop and maintain. It seems the mammalian way of life facilitated the selection of a type of brain complexity that favored their survival. This then begs the question of how a hominid line was pressured towards attaining such a large brain.

Here, there is much speculative thought that revolves around the uniquely human evolutionary triage previously mentioned. Probably by serendipity and the inexorable flow of evolutionary pressure, this tiny hominid lineage stumbled upon a formula that allowed it the ability to feed its brain beyond the capacity of other mammals.

It seems then that our humanness is, at least in large part due to the inseparable interplay between bipedal walking, a remodeled jaw for eating high energy food, and a ready predisposition for large brains.

Ref:

Jones S, Martin R, et al. Human evolution. Cambridge university press. Cambridge, UK. Part three 107-108.

The lunar effect

Hard to keep a good myth down

A recent study done at the Colorado State College of Veterinary Medicine was reported this year in the July publication of the Journal of the American Veterinary Association. Canine and feline emergency room visits and the lunar cycle: 11,940 cases (1992-2002) evaluating whether the full moon influences activity at the emergency hospital is a retrospective study that includes 11,940 dogs and cats over an eleven year period. A variety of emergency admissions were associated with their corresponding lunar phase based on the date of the visit. The lunar phases were divided into new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, or waning crescent. The effect of lunar phase on the frequency of these visits was evaluated by calculating relative risk.

The authors conclude that there is indeed an association with emergency admissions and the lunar cycle. They identified a significant increase in admissions of both species during “fuller” moon days (waxing gibbous to waning gibbous). Interestingly, the clinical relevance section of the study notes that “It is unlikely that an attending clinician would notice the fractional increase in visits (0.59 and 0.13 more canine and feline visits, respectively) observed in this study at a facility with low caseload.” They do suggest that this data set implies that at a “larger facility with a robust emergency caseload, these results may lead to reorganization of staffing on fuller moon dates.” However, we need to take a step back and take a larger look at this whole lunar association issue before accepting these findings as relevant.

The idea that there is some association between the fluctuating phases of the moon and animal or human behavior goes back eons and is fairly well established within the pages of common folklore crossing all kinds of cultures and continents. Even now, in modern times it is not uncommon to associate the phases of the moon with changes in any number of activities, including those found in a medical setting such as emergency visits at a veterinary hospital.

Therefore, this Colorado study joins a long and interesting lineage of similar studies that concern themselves with the possible effects of the lunar cycle with animal or human medical events. This is an important detail as it will become apparent that this particular study needs to take its place among the plethora of other such studies and be considered a small part of a larger body of information before actions such as adjusting the veterinary staff can be made.

A comprehensive review by Kelly et al ¹ went over a variety of human studies that examined a possible relation between the cycles of the moon and abnormal behavior. Using statistical methodologies including meta-analysis and additionally reanalyzing previous published studies, the authors found a variety of significant errors that biased many conclusions in favor of a positive association. As noted by the authors, a meta-analysis is only as good as the information on which it is based (garbage in/garbage out), and it is crucial to make an effort to evaluate each study for any statistical errors. Besides being only one study, the Colorado conclusion needs to be evaluated carefully for errors or confounding factors. All these items will help shake out its ultimate value among the sea of data out there.

Another non-meta-analysis review² in humans found “no evidence of a trend for more calls to be reported around the full moon. The majority of studies yielded no relationship between lunar phase and crisis calls and the positive findings contradicted each other.” Interestingly a 1996 study³ as well as others found a correlation between weekly, annual, and semi-weekly cycles (i.e.; Time of day and weekdays- makes sense) but no relation to lunar cycles. Additionally, a variety of related studies (birth rates, personality traits, aggression in sports) also reveal no significant relationship between lunar cycle and the data points being considered.

This year, there was another recent animal study regarding the full moon and veterinary emergency visits done at the University of Melbourne Veterinary Clinic and Hospital Australia. This retrospective study evaluated 12,102 animal admissions between 2003 and 2006 on full moon and non-full moon days adjusting for the day of the week and public holidays.

This study found no significant difference between the number of animals presented to the emergency clinic between full and non-full moon days. This study is especially interesting because of the adjustments they make for days of the week and holidays which may be a confounding factor in the Colorado study not accounted for.

As a whole, these findings put a damper on any definite positive conclusions the Colorado study might have found, however slight. The overall conclusion at this point then continues to be that there is no significant relation between the lunar cycle and a variety of associations in humans or animals including emergency admissions.

1 The Moon was Full and Nothing Happened. Skeptical Inquirer Winter 1985-86, updated 1996.

2 Byrnes, G & Kelly, I. Crisis calls and lunar cycles: A twelve year review. Psychological Reports, 71,779-785.

3 Bickis M , M Kelly I, et al. Crisis calls and temporal and lunar variables: a comprehensive examination. The journal of psychology 1995 , 129,701-711.

Scientific consensus: a communal crossword puzzle

Always open for re-assessment, it’s the best we got

There are some interesting posts today regarding the difference between a skepticism bound by reasoned evidence and that which broaches these confines extending deep into denialism and crankery.

The discussion belies a level of skeptical angst due to the existence of a broad general consensus, a “super structure” of knowledge if you will, upon which we must rely that helps define the scientific community. This might immediately bring to mind a rigid and dogmatic towering institution hell bent on world domination.

Fortunately, these dark thoughts quickly dissipate as it becomes quite clear that the concept of a scientific consensus acts much more like a communal effort; like many people working on a huge crossword puzzle. This analogy, put forth by Susan Haack (Defending Science: within reason) is not a bad analogy because it takes into account the critical essence that describes scientific consensus.

That is, gathering data, observations, evidence, and then combining these to form coherent theories that actually work and explain things - and are examined by others doing similar things. This slow building up of interrelated information indeed resembles a jigsaw puzzle. Dogma not required, needed, nor wanted.

It is important to note that there are different levels and strengths of consensus depending on the level of knowledge or field of study. There might be weaker consensuses on the fringe of that knowledge, or regarding the less science based fields such as the social sciences. Even so, these areas need to rely on the preponderance of the evidence as the basis for whatever level of consensus it allows. In other words, it is important to follow a critical methodology that takes away as much of ones bias and personal ideologies in the interest of getting closer to the truth of things.

The all important communal quality of scientific consensus safeguards it against the ever present pitfalls of dogmatic thought and belief. In this way an honest skeptic can retain their status as inquirers and still confidently rely on a consensus that can flex and grow like a living breathing organism.

Orac nicely describes the difference between an honest skeptic as compared to those that work the data with prejudice and make empty claims against this living communal scientific consensus.

“Scientific skepticism looks at the totality of evidence and evaluates each piece of it for its quality. Cranks are very selective about the data they choose to present, often vastly overselling its quality and vastly exaggerating flaws in current theory, in turn vastly overestimating their own knowledge of a subject and underestimating that of experts. This is perhaps the key characteristic of cranks and the biggest difference between a crank and a true skeptic...

...What a lot of this distinction boils down to is that crankery, denialism, pseudoskepticism, or whatever you want to call it tends, either intentionally through ideology or unintentionally through an ignorance of the scientific method, to conflate and/or confuse nonscientific, ideological arguments with scientific arguments. This is not to say that scientists and skeptics are free from their own biases, whether ideological or simply a desired result that they hope to find. Far from it. However, skepticism means applying the scientific method to claims, whatever its faults, scientific method is the best method thus far devised to minimize these biases. As scientists, the reason we use the scientific method is not because we consider ourselves superior to the cranks, but rather because we recognize that we are human too and thus just as prone to falling into the same traps as they. Moreover, we know that science is a work in progress and that what is considered correct today may well be modified tomorrow. This change, however, is not brought about by cranks cherry-picking data but by rather skeptical scientists probing for weak spots in our current understanding, making hypotheses, and then testing whether current theory or the new hypotheses make the better prediction.”

NOTE: In a past post “The Skeptic’s Dilemma” , I touch on some of the pitfalls that impede the skeptic from achieving an honest intensity of inquiry

On the Stem Cell Controversy

Crossing the rubicon

During a recent conference this summer in Aspen, Colorado Sam Harris described human happiness as falling into a “region” within a spectrum or gradient of human behaviors that tended to embrace more optimal cooperative and altruistic qualities of social interaction. In this way, he noted true happiness is separable- not necessarily independent - from the many cultural, religious, and political pressures that may pull human behavior away from this probabilistic “ideal” region.

Although addressing the many pitfalls and dangers of religious dogma, Harris speaks to other forms of thinking that create similar inflexible positions. As such, when debating a sensitive topic, there are certain intractable opinions; especially those oblivious to the concept of gradients and spectrums, nor those aware of just how messy biology can actually be that one is immediately confronted with nonstarters- debate dies before it can even begin.

So it is with the “hot button” controversy of stem cell research in this country. The necessarily arbitrary "lines in the sand" today’s society struggles to declare as acceptable, as in the abortion issue, have created an epic struggle between dogmatic and pragmatic decisions. This is another area where scientific education and an honest and dispassionate consideration of the information would prove invaluable towards reaching a prudent determination.

One way to begin a truly constructive dialogue would be to become better informed of the issues surrounding stem cell research. Michael Ruse and Christopher Pynes book “The Stem Cell Controversy” seems to provide an important resource towards this end.

According to a review in the July/August Skeptical Inquirer Magazine by Kenneth Krause, this book provides “a balanced anthology recent commentaries, official decrees, and, most important, expert analysis addressing each of these crucial issues.”

Ruse and Pynes describe some of the fascinating advances in stem cell research involving adult stem cells (i.e.; skin cell & umbilical origin) and addresses both their current limitations such as small numbers and lack of pluripotency as well as some potential advantages including a greater specialization- a possible advantage in certain cases such as in central nervous transplants.

On the other hand, the sheer power of embryonic stem cells pluripotency provide the promise of offering a wider range of treatments for a plethora of diseases. These cells also offer a glimpse into the etiological mechanisms of cancer and genetic disorders.

The current US stem cell policies confine embryonic stem cell research to those currently in existence while conversely allowing parents to utilize in vitro fertilization, where many embryonic stem cells are discarded in the process.

The authors go on to describe the complex political and ethical landscape of what a stem cell is and where they fall within the realm of research, treatment, and cures. This will increasingly become that “rubicon” that needs to be crossed in order for this country to attain a reasonable base for stem cell advancement.

This struggle is reminiscent of Sam Harris’ description of that region or spectrum where, through open dialogue and honest assessment of the facts, modern society might attain a balanced and educated position, albeit arbitrary, allowing stem cell research to flower and reach its great promise.

Remembering the Legacy of Sagan

Belated tribute to Carl Sagan

Carl sagan passed away on December of 1996. A great and gentle mentor for so many of us, he still sparks the embers of honest inquiry and fires the excitement of our imaginations. May those of us standing on his shoulders continue the quest for truth and honor a legacy bigger than all of us.

Ann Druyan, in "Billions and Billions: Thoughts on Life and Death at the Brink of the Millenium" offers this touching account of Carl's last days that reflects who he was to the end:

"Contrary to the fantasies of the fundamentalists, there was no deathbed conversion, no last minute refuge taken in a comforting vision of a heaven or an afterlife. For Carl, what mattered most was what was true, not merely what would make us feel better. Even at this moment when anyone would be forgiven for turning away from the reality of our situation, Carl was unflinching. As we looked deeply into each other's eyes, it was with a shared conviction that our wondrous life together was ending forever." D. 1996.

i of the vortex

With an often mischievous smile and penetrating eyes, well known neuroscientist Dr Rodolfo Llinas elaborates an incredible tale of how the "i" in us came to be. He discusses the importance of movement as a primal trigger for the kind of cellular evolution that eventually allows for colonization and cooperation and the subsequent development of the nervous system.

The Science Studio put together this fascinating conversation where Dr Llinas touches on some of the conclusions his neurological research has revealed. He weaves an enticing and plausible tapestry threading together the simple to the complex and deftly describes what the very core of human consciousness might actually be.

Indeed, some of the conclusions of his research may have breathtaking implications regarding free will and whether human consciousness as we sense it is in fact something real or a spectacular illusion.

Listen to "A conversation with Rodolfo Llinas". It is well worth considering as part of ones study of human consciousness.

A small case of cognitive dissonance

This recent commentary on a skeptic thread reveals how polarized thinking can be offered up as “balanced” reasoning:

"The following is a direct quote from the Dec. 6th issue of NEJM:

In recent weeks, over-the-counter cough and cold medications for children have received unprecedented attention from regulators, physicians, the media, and parents. This scrutiny represents a long-overdue reassessment of products that were purchased by 39% of U.S. households during the past 3 years. It also reflects an important evolution in the standard of evidence for medications used in children.

Over-the-counter cough and cold preparations include various combinations of antihistamines, decongestants, antitussives, and expectorants. There is no standard for describing these products; two products marketed similarly may have different types of ingredients. Consumers purchase about 95 million packages of such medication for use in children each year. Within the pediatric community, however, concern over the effectiveness and safety of such drugs has been growing for more than two decades.”

“I think there's a similarity here with some of the criticisms made of CAM products on this List. Not identical, nor perhaps as extensive, but similar; in particular market driven, and taking decades to rectify, while clearly taking advantage of citizen's vulnerabilities in the area of health care. Most notable perhaps is the much greater degree of harm caused here as compared to CAM treatments; much less of an effort to hold anyone accountable as compared to the reactions to lesser frequencies and/or degrees of harm when these occur from CAM; and, it seems to me, the much greater level of tolerance or permissiveness over a prolonged period toward direct harms from these cough and cold products as compared to problems occasionally reported from direct harms from CAM products.”

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Here are a few comments with respect to some of the cognitive dissonance noted in these remarks:

"Most notable perhaps is the much greater degree of harm caused here as compared to CAM treatments"

Imperfect though it may be this process seems to reflect a critical scrutiny not often observed in non evidence based modalities. These substances have real actions and as harms are measured, evaluated, and taken into account, there are mechanisms for change.

It appears to me that non evidence based approaches (homeopathy prevention for Malaria and AIDS, chiropractic for subluxations, nutrition schemes for cancer cures....) open doors for significant harms of their own. What critical mechanisms are in place to scrutinize them (The NCCAM hasn't seemed to have had much impact yet)?

"much less of an effort to hold anyone accountable as compared to the reactions to lesser frequencies and/or degrees of harm when these occur from CAM"

Not so sure about this. Accountability is critical, so is honesty and transparency in scientific endeavours. Pharmaceuticals & industry have lots of dirty laundry here. In the same vein though, "CAM" has been given huge leeway and liberty to ply all kinds of questionable practices and make a lot of $$ under a veneer of "science". This is significant harm.

"and, it seems to me, the much greater level of tolerance or permissiveness over a prolonged period toward direct harms from these cough and cold products as compared to problems occasionally reported from direct harms from CAM products."

This "direct" harm comparison is confusing. How do we compare a treatment with known effect (implying risk/benefit) with a placebo for example? If a placebo harms even one person, doesn't that have huge implications?

Anecdotally, we just referred a client’s dog to surgery for known disk herniations being treated with homeopathy and acupuncture...and this morning I talked to a new mother who refuses to vaccinate her child (doesn't "believe" in them)preferring the "immune boosting effects" of aromatherapy.

It seems harms loom heavy all over...