Tuesday, August 17, 2010

Genetic Basis of Tibetans’ Adaptation to High Altitude

The ability of native Tibetans to tolerate high altitude is, of course, legendary. Tibetans living on the Tibetan plateau at elevations that exceed 4000 meters are exposed to an atmosphere that has oxygen concentrations that are approximately 40% lower than that which is available at sea level. From a biological perspective it is of interest to know how this has been achieved.

From the evidence accumulated by Jian Wang and his associates from the University of California at Berkeley, Tibetans have acquired a number of inherited adaptations to this extreme environment, including – higher birth weight, higher hemoglobin – the protein found in red blood cells that binds oxygen - levels, higher oxygen saturation in the blood of infants and adults following exercise when compared with a control group of Han Chinese who moved to Tibet and are genetically distinct. Tibetans have occupied the Tibetan Plateau for over 25,000 years, possibly enough time to accumulate genetic adaptations through natural selection.

In an attempt to delineate the genetic characteristics of these adaptations, the investigators analyzed the DNA from both Tibetans and the control group. There results demonstrated, in fact, a single-nucleotide polymorphism (SNP) – a single point variation in the DNA studied – from a gene that encodes for the EPAS1 protein. This protein has been shown to be involved in the body’s response to hypoxia – low oxygen environment. This change occurred at a much higher frequency in native Tibetans than in the control group of Han Chinese.

These results represent a very important finding in regards to the fact that this beneficial genetic modification occurred over a very brief interval of time as compared to previously studied human genetic adaptations.

Saturday, August 7, 2010

An Argument for a Dramatic Improvement in the Science Education of Our Children

The technological wonders of the modern age are quite spectacular. One of the most profound of these is the Hubble telescope. Many human lives are saved and horrific diseases are averted daily due to the great strides made in the arena of health and medicine. The additional examples that could be cited are too numerous to mention here. Technological improvements are a direct outcome of the application of scientific enquiry and discovery.

The human world is beset with many problems that demand solution – the most urgent of these being climate change. There is a growing body of scientific evidence that supports this contention, including:

•Record setting high temperatures during the last ten years
•Erratic, severe and unusual weather conditions
•Increase in the frequency and severity of forest fires
•Increased acidity in the world’s oceans that has impacted the health of coral, phytoplankton and shelled creatures especially oyster larvae
•Melting and receding of glaciers worldwide
•Melting of the ice in the Arctic Ocean during the summer months.

The science that has established the relationship between the increased concentration of carbon dioxide and methane, the so-called greenhouse gases, resulting from human activity is clear and irrefutable.

In spite of these data, there is a marked resistance in this country to accept not only the obvious implication of these observations, but the meaningfulness of the observations themselves. This, to me, is extremely disturbing, for inaction or lack of sufficient resolve to confront this issue will inevitably result in disastrous consequences for future generations.

This inability to grasp the urgency of the issues that confront us is a direct result of the failure to educate our children in the realm of science. Science has some essential characteristics that make it exceedingly well suited for problem solving. It is cooperative effort; scientific advances are a direct result of strides made by investigators in the past as well as the present. Science depends on a growing body of knowledge; it builds upon all that has been already discovered. In addition, the scientific process is open-minded; any hypothesis or law must fit the data that is accumulated through observation. If new data does not fit the interpretation then the conclusions need to be modified to accommodate the newly acquired facts. Science requires a rigorous thought process that relies on higher-order functions in the human brain.

In my judgment, it is not possible to meet the challenges we face in this technologically-driven world without a sufficiently adequate education in the sciences. We have failed abysmally in this regard in the United States. Ignorance is not bliss by any stretch of the imagination. Ignorance will inevitably lead to erroneous conclusions and ultimate disaster.

Wednesday, August 4, 2010

Dangers of Increased Acidity in the World’s Oceans as a Direct Result of Human Activity

The effect of increased carbon dioxide resulting from human activity on the oceans is quite clear. There is a direct relationship between increasing levels of carbon dioxide in the atmosphere and the increasing acidification of the oceans. The chemistry has been well documented. Carbon dioxide (CO2) when dissolved in water (H2O) forms carbonic acid (H2CO3). This acidification has been implicated in the destruction of coral. Recent evidence has also demonstrated that increased acidity in the oceans also has a deleterious impact on oyster larvae as well.

As I have reported earlier, it has been shown that increased acidity in the oceans has placed increased stress on phytoplankton, an organism that is a fundamental part of the food web in the world’s oceans. They account for one-half of all oxygen production as a result of photosynthesis on the planet.

In this article we will review the impact increased acidity is having on the world’s oceans in greater detail. Currently, human societies are collectively depositing gigatons of carbon dioxide per year into the earth’s atmosphere - a gigaton is equivalent to one billion tons. According to Lee Kump, a geochemist at Pennsylvania State University, this kind of growth in the level of carbon dioxide emissions as a direct result of human activity on the earth may be considered, “as one of the most notable, if not cataclysmic events in the history of the planet.”

It is estimated that there has been a drop of 0.1 pH unit in the global ocean since the beginnings of the industrial revolution with a .026 drop within the last fifteen years. These are disturbing data. Computer modeling predicts that if this trend continues the pH will have dropped to 7.8 from the 8.2 value in the pre-industrial age, where pH is a logarithmic measure of the concentration of hydrogen ions – a solution having a pH below 7.0 is considered to be acidic. By way of comparison, the pH of the stomach is around 2.0.

According to Richard A. Kerr in an article published in the June 18 2010 Science, decreasing pH impacts species that build shells or skeletons of calcium carbonate in the following way, “These organisms include tropical corals, echinoderms, mollusks, microscopic foraminifera floating in surface waters and certain algae. When the hydrogen ion concentration of seawater gets high enough, the calcium carbonate in these organisms begins to dissolve.”

The oceans provide much of the world’s supply of food. These data taken together with the warming effect on the earth’s oceans as a result of increased carbon dioxide in the earth’s atmosphere and its resulting effect on weather patterns, paints an alarming picture in regards to the changing natural environment and the future of humanity.