Sunday, May 30, 2010

TedMed Talk on Health of Brain

This is an excellent talk on one of the most important areas of scientific research today: how to develop healthy and happy minds. This topic should interest every educator, every parent and every person.

The Hawn Foundation site is here.


Monday, May 24, 2010

Play Menu (May 2010)

Recent posts at "In Search of Enlightenment" include the following series of posts on the importance of play:

Part 1

Part 2

Part 3

Part 4

Part 5

Part 6

Cat Stevens captures the essence of play in this great song:


Wednesday, May 19, 2010

Climate Change and Malaria

One of the purported harms of global warming is an increase in the prevalence of malaria. Given that malaria is a tropical disease, it makes sense to assume that warmer temperatures would bring an increase in malaria.

As I noted before, the actual data on this point doesn't match onto our intuitions. And the latest issue of Nature has a study that suggests that temperature rises do not impact malaria risk. Here is a sample from the News summary of the study:

Of the many climate-change catastrophes facing humankind, the anticipated spread of infectious tropical diseases is one of the most frequently cited — and most alarming. But a paper in this week's Nature adds to the growing voice of dissent from epidemiologists who challenge the prediction that global warming will fuel a worldwide increase in malaria.

On the surface, the connection between malaria and climate change is intuitive: higher temperatures are known to boost mosquito populations and the frequency with which they bite. And more mosquito bites mean more malaria.

Yet when epidemiologists Peter Gething and Simon Hay of the Malaria Atlas Project at the University of Oxford, UK, and their colleagues compiled data on the incidence of malaria in 1900 and 2007 (see page 342), they found the opposite: despite rising temperatures during the twentieth century, malaria has lost ground. According to the models the researchers used to tease out the factors affecting the incidence of malaria, the impact of public-health measures such as improved medications, widespread insecticide use and bed nets have overwhelmed the influence of climate change. "Malaria is still a huge problem," says Gething. "But climate change per se is not something that should be central to the discussion. The risks have been overstated."

And here is the abstract of the paper:

The current and potential future impact of climate change on malaria is of major public health interest1, 2. The proposed effects of rising global temperatures on the future spread and intensification of the disease3, 4, 5, and on existing malaria morbidity and mortality rates3, substantively influence global health policy6, 7. The contemporary spatial limits of Plasmodium falciparum malaria and its endemicity within this range8, when compared with comparable historical maps, offer unique insights into the changing global epidemiology of malaria over the last century. It has long been known that the range of malaria has contracted through a century of economic development and disease control9. Here, for the first time, we quantify this contraction and the global decreases in malaria endemicity since approximately 1900. We compare the magnitude of these changes to the size of effects on malaria endemicity proposed under future climate scenarios and associated with widely used public health interventions. Our findings have two key and often ignored implications with respect to climate change and malaria. First, widespread claims that rising mean temperatures have already led to increases in worldwide malaria morbidity and mortality are largely at odds with observed decreasing global trends in both its endemicity and geographic extent. Second, the proposed future effects of rising temperatures on endemicity are at least one order of magnitude smaller than changes observed since about 1900 and up to two orders of magnitude smaller than those that can be achieved by the effective scale-up of key control measures. Predictions of an intensification of malaria in a warmer world, based on extrapolated empirical relationships or biological mechanisms, must be set against a context of a century of warming that has seen marked global declines in the disease and a substantial weakening of the global correlation between malaria endemicity and climate.


Sunday, May 09, 2010

Who are We?

The veil of ignorance is slowing being lifted.

This report in Naturenews suggests that the genomes of most modern humans are 1–4% Neanderthal. A sample from the report:

"This will change our view of humanity," says John Hardy, a neuroscientist at University College London who was not involved in the research but studies genetic neurodegenerative diseases.

The drive to sequence the complete Neanderthal genome began about five years ago following the invention of better, faster methods for sequencing DNA. From three Neanderthal bones found in Vindija Cave in Croatia, the team extracted a total of about 300 milligrams of bone. The bones date to between 38,300 and 44,400 years ago, and some have been broken open posibbly to remove their marrow — a sign of cannibalism.

.... Using the Neanderthal genome for comparison, Pääbo and his colleagues were also able to identify genes that occur frequently in modern humans, suggesting that such genes are the result of selection pressure.

The report notes genes that affect metabolism, cognition and skeletal development show similar signs of such positive selection in modern humans. And there was positive selection for three genes, that when mutated, have been implicated in Down syndrome, autism and schizophrenia1.

The Neanderthal draft genome provides "a powerful method to shine a light on our evolutionary history", says Green — a technique that will reveal the genomic regions and genes that are keys to our human identity.

There couldn't be a more exciting time to be working in the humanities or social sciences than there is now!


Saturday, May 08, 2010

Fossil Records: Past and Present

Fossil records provide some of the most valuable bits of information about the past. These records provide us with a sense of the diversity of species that once, but no longer, roamed this planet. They provide valuable information about the migration, biology, diet, etc. of different species.

Fossil records can also help provide us with a sense of the risks that our species historically faced in different places, and at different times, in the 150-200 000 years that homosapiens have roamed the planet.

Looking at our species' history through the lens of fossil records can also help us get a better sense of our priorities, with respect to public policy. Here I offer a few reflections on how they can do this.

Looking back over our species' history, as told in fossil records, what do we find? This insight from Hayflick is important:

Prehistoric human remains have never revealed individuals older than about 50 years of age, and humans had a life expectancy at birth of 30 years or less for more than 99.9% of the time that we have inhabited this planet.

For 99.9% of our species' existence most humans died in early or mid-life. The extrinsic risks of infectious disease (1415 species of infectious organisms in the world have been identified as causing disease in humans) , poverty, war, etc. meant that our species' survival depended on high fertility rates. And our biology reflects this reality.

Comparative biology teaches us that reproduction is life’s solution to the inevitability of death in the hostile environments of Earth (source). Reproduction is thus made a higher biological priority than the longevity of a parent.

So for most of our species' history there was little progress in terms of increasing life expectancy at birth. But things began to change in the 19th century. Advances in technology (e.g. the sanitation revolution), medical knowledge, material resources and changes in behaviour helped change the future course of our species. The hard work and innovation of people like Chadwick, Snow, and Jenner, Pasteur, helped humanity escape a world dominated by early and mid-life morbidity and mortality.

The fossil records of the 21st century will be unique in our species' history for two reasons. Firstly, there will be more human remains this century than in any other century (because of the size of the human population). Furthermore, the vast majority of these deaths will be caused by chronic disease and will afflict people after the age of 60.

Isn't it odd, given how many people are projected to suffer and die from chronic disease and given the rapid progress that is being made in the biomedical sciences, that we don't invest more of our energies into tackling the leading cause of chronic disease? Namely, aging.

When future generations look back at the 21st century they will wonder why we didn't act sooner to try to ameliorate the high risks of morbidity and mortality that currently ravage our bodies and minds. They will wonder why we were so easily distracted by the stories that dominate the evening news. And why so many bright academics who were employed to educate future generations seemed so detached from the realities of their own time.

If only a population could see, analyze and react to, fossil records in "real time". That might help us take a more rational approach to improving the health prospects of today's aging populations.