New Under the Sun:
Volume 6, Issue 1
For the next several months, AnthroHealth News will be a series of linked essays on topics relevant to obtaining and maintaining optimal health the AnthroHealth way.
Letís get real here. There are no easy answers, no quick fixes, no magic cures or pills that are going to give you good health. Good health requires effort on your part. And, yes, it requires some sacrifices. We canít eat all the donuts and butterscotch sundaes we want to eat without paying for it. We canít sit in our office, our car, or on our couch thinking about exercise, but never doing it, without paying for it. If you eat too much, especially of the wrong foods, and exercise too little, you will have health to pay.
Good health takes hard work. Anyone who tells you otherwise is doing a con job to take as much of your money as possible before you realize youíve been scammed. I agree that it would be much more pleasant if the fairy tales were true. Wouldnít it be great if we could just say the correct spell or take the correct potion and the weight would melt away or the disease would be cured? Sadly, millions of Americans seem to believe more in magic and spirituality than in the rational analysis of science. Go to a bookstore and compare the size of the metaphysical section to the science section if you have any doubts.
But AnthroHealth News is for rational thinkers who arenít afraid to hear the hard truths and who are willing to put in the time and effort it takes to be truly healthy. Iíll let you in on a secret here. Humans are animals! Yup, we arenít some special creation that stands across an unbridgeable divide from the rest of the animal kingdom. Just as is true of every living thing, we are a part of nature. We get into trouble when we ignore this fact. Much of poor health and disease can be tied to beliefs and behaviors based on the proposition that humans are somehow not really biological organisms. Even many doctors fall into this trap. They become body mechanics who try to fix what goes wrong with the human machine, behaving more like engineers than biologists. When you accept the fact that humans are large animals and a part of nature, it will change how you think about and what you do to obtain and maintain good health.
Letís get real. Life is about choices, and some of them can be hard. If eating whatever you desire is what makes life worth living for you, then perhaps you are willing to have a short, but gastronomically full life. If the thought of exercise pushes you to settle more deeply into the sofa cushions, then perhaps you are willing to have a short, but well-cushioned life. But if living a long, maximally healthy life is your goal, then stick around. Letís show the others how itís supposed to be done!
Guess what! Dermatologists are wrong when they say there is no safe exposure to the sun. In fact, if you follow their advice and avoid all unprotected exposure to the sun you will seriously harm your health. Avoiding sunlight significantly increases your odds of developing a variety of health problems including prostate, breast, and colon cancers, and these odds are far higher than the odds that you may develop the most deadly form of skin cancer, melanoma. In fact, if you are a dark-skinned male your odds of developing melanoma are vanishingly small compared to your odds of developing prostate cancer. Why is that? Why are the dermatologists wrong? Well, that is what this essay is all about. Stay tuned.
It is not easy for life to get a toehold, and once it does, it is difficult to maintain. We look around us and see a planet brimming, overflowing with life and forget that this is the exception, not the rule. Out of eight planets (sorry, Pluto) in our solar system, ours is the only one with life. Just like Goldilocksí porridge, we arenít too hot or too cold, we are just right: just right for plants to directly use the sunís energy to provide us with food and oxygen. Without sunlight, life is impossible. But humans donít just need the sun for heat, and oxygen and energy via plant photosynthesis. Humans, as is true of all other animals, also require direct exposure to sunlight to maintain optimal health.
Science fiction writers who have humans living underground or on planets without sunlight do not have much familiarity with biology, the study of life, or they would know that they have created nonviable conditions. The inhabitants might not die immediately, but without sunlight, death is inevitable.
The largest organ in the human body is the skin. This is also true of other animals. Now, the skin does more than just hold all our other organs inside. It is a protective interface between our body and the environment. And one of its most important ďresponsibilitiesĒ is as the interface between our body and sunlight. Although we live on a ďjust rightĒ planet, the amount sun exposure we receive is not always just right for our individual conditions. To understand why, we need to go back in time and look at human evolution.
As Iíve said before, and will probably say again, humans are animals. Specifically, we are primates and, precisely, we are in the same family as the great apes: orangutans, gorillas, and chimpanzees/bonobos. Primates are a tropically-adapted group. In the wild, none of the great ape species are found outside the tropics. Only a very few monkey species are subtropical. From this, it can be concluded that humans were originally a tropically-adapted species.
Now, there may be some readers who question my statement that humans fall in the same family with great apes, let alone that we are primates, so it is important to review the evidence here. There are several characteristics that define a primate. One is that vision is more important to primates than the sense of smell. This is obvious if you look at the face of a monkey or ape or human. The eyes are relatively large, close together, and vertically positioned on the face. This allows the individual to have over-lapping fields of vision and provides depth perception, a necessary trait for climbing trees and leaping from limb to limb. However, our improved visual acuity means that the ability to have a heightened sense of smell is severely diminished. The olfactory lobe, the portion of the brain used to process scents, sits right between the eyes. Large, closely-spaced eyes mean that there is little room for the olfactory lobe. Fortunately, scents are not particularly important high in the tree canopy, so the loss of that ability is more-than-compensated for by the increased visual acuity.
Primates have retained a generalized limb structure from the earliest mammalian ancestor. Instead of the specialized hooves of horses, for instance, we have the more ancient form of five digits on our hands and feet. This allows primates to more readily manipulate their environment than is possible among more specialized species. Another aid to manipulation is that instead of having digits that end in pointed claws, primates have flattened digits with nails. The generalized structure also allows the upper and lower limbs to have a much wider range of movement than is possible in other species. When at rest (not sleeping), primates tend to sit upright. Again, this allows them to more readily manipulate their environment with their generalized hands and arms.
Another ancient retention of primates is their generalized dentition. Primates have four different types of teeth (incisors, canines, premolars, molars) while more specialized animals may have only two types. Having different types of teeth allows primates to eat a varied diet. While some primates do specialize in a particular type of food such as fruits or leaves, they are able to eat a more varied diet and most do so. Those with the most varied diet, eating leaves, fruit, nuts, small animals, eggs, etc., are called omnivores, a group that includes baboons, chimpanzees, and humans.
When matched to a non-primate animal of similar body size, primates have a larger brain-to-body ratio. While there is not a direct correlation of brain size to intelligence within a species, there is such a correlation across species. For instance, baboons and chimpanzees are smarter than non-primates of a similar body size. One of the reasons for this increased intelligence is that primates must learn everything they need to know in order to survive in their environment. Since this learning period requires a large investment of time and energy on the part of the mother, primates tend to have only one offspring at a time. This is especially the case for the larger monkeys and the apes. When twins are born, generally one or both will die during infancy because the motherís resources are over-taxed. Apes (chimpanzees, gorillas, and orangutans) have a particularly long developmental period, comparable to that of humans, and are, with the exception of humans, the smartest of the primates.
If you want to know how to differentiate a monkey from an ape, the best thing to do is to look at yourself. Most of the traits that differentiate you from a monkey also differentiate an ape from one. For instance, apes and humans are much larger than monkeys. Apes and humans donít have a tail, but most monkeys do have one. Apes and humans have a much larger brain-to-body ratio than is true of monkeys. Apes and humans have a much longer lifespan. The average lifespan of an ape is 45 Ė 50 years. That of a human forager is also about 45 Ė 50 years, while that of a baboon, the largest monkey, is 25 Ė 30 years. Apes, particularly chimpanzees, actively teach their young how to do certain activities such as crack hard nuts using a hammerstone and anvil, or fish for termites using a specially-prepared wand. Humans also actively teach their young how to do various tasks. Monkeys do not do so. Next time you are at the zoo, spend an hour carefully watching the behavior of monkeys and another hour watching the behavior of chimpanzees. It should be an insightful experience.
I mention chimpanzees frequently because they are our nearest relative. We are not descended from chimpanzees any more than you are descended from your first cousin. But we do share a common, many greats-grandmother. Around six million years ago, the ancestors of humans and chimpanzees were one big family. Something happened to isolate a small portion of the population from the rest of group. This founder group did not encounter members of the original group for tens of thousands of years. Over that period of time, the two groups gradually became so distinct that they could no longer mate. The original population became the chimpanzees and the smaller founder group became us.
Our earliest ancestors are found in the Rift Valley region of East Africa, practically on the Equator. Therefore, we know that we evolved in a region of plentiful sunshine. It is improbable, then, that sunshine is solely a danger to health. Actually, when we speak about sunshine we need to break it down into the components most important to us: visible light and ultraviolet radiation. What is of interest to us in this discussion is ultraviolet radiation, in particular, the mid-range or UVB. The UVB range is from 280 nm to 320 nm. Although UVA radiation is involved in skin aging effects and tanning, the UVB range is associated with burning, skin damage, and skin cancers. The UVC radiation is even more damaging, but as almost no radiation in that range reaches the earth, it is not important to this discussion.
Ultraviolet B radiation is not equally distributed over the earth either geographically or throughout the year. This is due to two factors: the angle of the earth to the sun and the varying thickness of the ozone layer around the earth. In the equatorial zones, the sunís rays are essentially perpendicular to earth for the entire year and the ozone layer is at its thinnest. This means that this region has continuous and abundant exposure to UVB radiation. For each ten degrees of latitude one moves north or south from the Equator, the exposure to UVB radiation dramatically decreases due to an increasingly acute angle of the earth relative to the sun and an increasingly thick layer of ozone, which is thickest at the poles. Therefore, much less UVB radiation is able to penetrate the atmosphere to strike earth. Someone living in London, England or Paris, France receives 300 times less UVB radiation than does someone living in Accra, Ghana or Nairobi, Kenya. However, someone living at both high altitude and high latitude receives more UVB radiation than does someone living at sea level at the same latitude because the ozone is thinner at higher altitudes. Each 1000 meters a person climbs in altitude increases UVB radiation exposure by 19%.
The best way for a primate, human or ape, to adapt to high levels of UVB radiation is either to have a dense, very dark pelt of hair, as do chimpanzees, or very dark skin color, as do humans with long ancestry in the tropical zones of Africa. The reason for this is that melanin, the dark pigment in skin and hair, which is found in melanosomes (organelles of varying size occurring in skin and hair cells, produced by melanocytes), diffuses the UVB radiation striking it, allowing very little to penetrate. Individuals with very dark skin have large, closely-spaced melanosomes that provide a very effective barrier to UVB radiation, somewhat similar to wearing continuously a SPF 15 sunscreen.
At this point, you may be thinking, OK, so all this is saying is that the sun is bad and that dark skin is a good thing. If this is the case, then why would I, the author, say that sun is a good thing? And why donít all humans have dark skin? The answer to both is that humans need UVB radiation. Yes, we need UVB radiation, especially in the range of about 290 nm. We need it because UVB radiation striking unprotected skin and penetrating to the lower levels of the skin activates a hormonal cascade that goes by the misnomer of vitamin D. Vitamin D was discovered in 1919 in cod liver oil just at the time that vital amines were being discovered in food. This was thought to be one of them, and as it was the fourth to be discovered, was given the name vitamin D. Much later, it was found that it occurs naturally in very few food items, that it has several different components, and that the active form is a hormone (1,25-dihydroxyvitamin D), but the name has stuck.
Vitamin D is essential for proper skeletal growth and maintenance. But its effects are more far-reaching as it has been shown to be involved in tumor suppression, and in the proper regulation of the immune system. Individuals with deficient levels of vitamin D may suffer from a variety of skeletal disorders including rickets, osteomalacia, and osteoporosis. Inadequate levels of vitamin D have also been associated with autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, and diabetes. Vitamin D has been used as a tumor-suppressant in the treatment of prostate cancer, and inadequate levels of vitamin D may be associated with breast and colon cancers. Individuals with hypertension and tuberculosis have seen improvement in their diseases when their vitamin D levels have been dramatically raised. Adequate levels of vitamin D are necessary to the maintenance of good health.
This essay, The SunÖExposed! will continue next month. Until then, bone up on the virtues of vitamin D.
© 2001-2009 Kathleen E. Fuller, PhD. All rights reserved.