Another failed Darwinian prediction XX

Cell death

According to evolutionary theory, biological variation that supports or enhances reproduction will increase in future generations—a process known as natural selection. The corollary to this is that biological variation that degrades reproduction will not be selected for. Clearly, natural selection could not result in destructive behavior. Here are two representative statements from Origins:

we may feel sure that any [biological] variation in the least degree injurious would be rigidly destroyed. (Darwin, 63)

Natural selection will never produce in a being any structure more injurious than beneficial to that being, for natural selection acts solely by and for the good of each. (Darwin, 162-3)

But are not examples of such “injurious” behavior obvious? When the rattlesnake rattles its tail, is this not injurious to its hunt for food, and ultimately to its reproductive chances? Darwin argued that this and other such examples are signals to frighten away enemies, not warn the intended prey.

But today we have many examples of injurious behavior that falsify Darwin’s prediction that natural selection “will never produce in a being any structure more injurious than beneficial to that being.” In bacteria, for example, phenomenally complicated mechanisms carefully and precisely destroy the individual. Clearly, this suicide mechanism is more injurious than beneficial to the bacteria’s future prospects.

One such mechanism consists of a toxic gene coupled with an antitoxic gene. The toxic gene codes for a protein that sets the act of suicide into motion and so ultimately kills the bacteria. The antitoxic gene inhibits the toxic gene from executing its mission. Except, that is, when certain problems arise. Lack of proper nutrients, radiation damage and problems due to antibiotics can all cause the antitoxin to be diluted, thus allowing the toxin to perform its mission. (Chaloupka, Vinter; Engelberg-Kulka, Hazan, Amitai; Engelberg-Kulka, Amitai, Kolodkin-Gal, Hazan; University Of Nebraska)

This bacterial suicide is probably good for the bacteria population on the whole. If nutrients are running low, then better for some bacteria to die off so the neighbors can live on. Not only will the reduced population require less nutrients, but the dismantled bacteria help to replenish the food supply. Therefore evolutionists can explain the suicide mechanism as having evolved not for the individual bacteria, but for the population. But the explanation introduces major problems for the theory.

Suicide is probably good for the bacteria population, on the whole, in challenging conditions. Since gene sharing within a bacteria population is at its maximum, evolutionists have no problem explaining such altruism as a result of kin selection (see Altruism). Such a facile response, however, misses the profound problem of how such a design could arise in the first place, for the mechanism is immensely complex.

In this example of bacteria suicide, the antitoxic gene normally inhibits the toxic gene from executing its mission. When the antitoxic gene is diluted then the toxic gene can perform its mission. The toxin does not, however, single-handedly destroy the cell. The toxin is an enzyme that cuts up the copies of DNA (i.e., messenger RNA, or mRNA) that are used to make other proteins. By slicing up the mRNAs, the cell no longer produces the proteins essential for normal operation. But the toxin does not cut up all mRNAs. Some mRNAs escape unscathed, and consequently a small number of proteins are produced by the cell. These include death proteins that efficiently carry out the task of disassembling the cell.

Death proteins are not the only proteins that the toxin allows to be produced. As researchers reported, the toxin “activates a complex network of proteins.” (Amitai) While some of the proteins bring death to the bacteria, others can help the cell to survive. The result is that most cells in the population are destroyed, but a fraction is spared. This of course makes sense. The suicide mechanism would not help the bacteria population if every individual was destroyed. Instead, some survive, and they can be the founders of a new population when conditions improve.

This suicide mechanism and “behavior” is altruistic. Some bacteria die off to save others. And the explanation that this bacteria suicide is due to kin selection adds tremendous complexity to the theory of evolution. Kin selection can select from only that which is available. This elaborate suicide mechanism must have just happened to arise from some combination of random mutations, and then remained in place until the time when it would succeed in surviving a stressful environment. The toxin and antitoxin genes with their clever functionality, the death and survival proteins, the inter cellular communications—all these were needed to be in place and to be coordinated before the kin selection could even begin to act. This is highly unlikely and adds considerable complexity to the theory.

References

Amitai, Shahar, Ilana Kolodkin-Gal, Mirit Hananya-Meltabashi, Ayelet Sacher, Hanna Engelberg-Kulka. 2009. “Escherichia coli MazF leads to the simultaneous selective synthesis of both ‘death proteins’ and ‘survival proteins’.” PLoS Genetics 5:e1000390.

Chaloupka, J., V. Vinter. 1996. “Programmed cell death in bacteria.” Folia Microbiologica, 41:6.

Engelberg-Kulka, Hanna, Ronen Hazan, Shahar Amitai. 2005. “mazEF: a chromosomal toxin-antitoxin module that triggers programmed cell death in bacteria.” J Cell Science 118:4327-4332.

Engelberg-Kulka, Hanna, Shahar Amitai, Ilana Kolodkin-Gal, Ronen Hazan. 2006. “Bacterial programmed cell death and multicellular behavior in bacteria,” PLoS Genetics 2:e135.

University Of Nebraska. 2007. “New Hope For Fighting Antibiotic Resistance,” ScienceDaily April 27.

Darwinism vs.the real world XXVII

Temperature Control: Too Hot, Too Cold, or Just Right?
Howard Glicksman

Editor's note: Physicians have a special place among the thinkers who have elaborated the argument for intelligent design. Perhaps that's because, more than evolutionary biologists, they are familiar with the challenges of maintaining a functioning complex system, the human body. With that in mind, Evolution News is delighted to offer this series, "The Designed Body." For the complete series, see here. Dr. Glicksman practices palliative medicine for a hospice organization.

Since the body is made from matter, it must follow the laws of nature that affect the atoms and molecules making up its trillions of cells. These laws tell us that heat is the transfer of energy from one object to another and temperature is a measure of the random motion within an object or its internal energy. The body's core temperature is directly related to how much heat it produces from its metabolism, whether at complete rest or with activity, and how much heat it loses to or gains from its environment. The body must control its core temperature because, if it isn't just right, it can adversely affect enzyme function, the integrity of the plasma membrane, and other cellular structures.

The body's normal core temperature is set by the hypothalamus at 97o-99oF (36o-37oC). It receives data from the central thermoreceptors and keeps the core temperature at this set-point

using both voluntary and involuntary means. When your core temperature rises or falls outside the normal range, and you feel too hot or too cold, there are things you can do, like take off or put on warm clothes, to help bring the core temperature back towards normal. At the same time, the hypothalamus, using the sympathetic nerves, automatically sends out messages to the blood vessels and sweat glands in the skin to either promote or limit heat loss. Using both of these mechanisms, the body is usually able to keep its core temperature where it should be while staying active. Let's look at what happens when the numbers dictating core temperature just aren't right.

The commonest cause of an elevated core temperature is fever, also called pyrexia. Thistakes place when, under the influence of pyrogens, the hypothalamus increases the set-point. The body responds by reducing heat loss through the skin and increasing production through shivering to preserve this abnormally high temperature. That's why you feel chilly and shake prior to developing a fever. Pyrogens are chemicals released by invading bacteria, immune cells involved in inflammation and fighting infection, and even some types of cancer cells.

Hyperthermia, another common cause of high core temperatures, is when the core temperature is above 99oF (37.2oC) despite having normal thermoregulatory mechanisms in place. This usually takes place when a person is working or playing hard, generating excessive amounts of heat within a hot and humid setting, and the mechanisms for thermoregulation become overwhelmed.

Whether due to a very high fever (hyperpyrexia) from illness or heat stroke from physical and environmental factors, a core temperature above 107oF (42oC), means that several life-threatening reactions are likely to take place. These include things like protein and enzyme breakdown, impairment of mitochondrial function, and loss of plasma membrane stabilization. All of this culminates in severe brain dysfunction, muscle breakdown, loss of thermoregulation, and multi-organ system failure, resulting in death.

Hypothermia exists when the body's core temperature drops below 95oF (35oC) despite having normal thermoregulatory mechanisms in place. This usually happens when people are in a very cold environment without adequate protection. Hypothermia affects every tissue in the body by reducing cell metabolism and diminishing enzymatic activity, including the enzymes needed for energy production and usage. As the core temperature drops below 91oF (33oC), mental confusion is soon followed by loss of consciousness and thermoregulation itself.

Based on our knowledge of how the body works, the ability for our earliest ancestors to survive and reproduce depended on their ability to maintain the right core temperature no matter where they were or what they were doing. For if the system of control they used allowed the core temperature to drop below 91oF (33oC) or go above 107oF (42oC), they would have died. Real numbers have real consequences when it comes to dealing with the laws of nature. Not just any core temperature works for survival. It has to be the right one to preserve protein integrity and cell function in order to keep the brain and all the other organs and tissues in the body working properly.

Just because a system is irreducibly complex does not automatically mean that it will be able to function well enough to allow for life. Besides being irreducibly complex, systems that allow for life must also have natural survival capacity. By this I mean that each system must take into account the laws of nature. This involves having an inherent knowledge of what is needed to keep the organism alive and the ability to do what needs to be done.

The system that uses thyroid function and uses the sympathetic nervous system to adjust the blood vessels and sweat glands in the skin to keep the body's core temperature between 97o-99oF (36o-37o C) seems to naturally know how to get the job done. The same can be said for each of the control systems discussed in this series that manage things like oxygen, carbon dioxide, hydrogen ion, hemoglobin, iron, water, sodium, potassium, glucose, respiratory and heart rate, and blood pressure. Not only do each of these systems demonstrate irreducible complexity with natural survival capacity, but the absence or serious dysfunction of any one of them results in death.

Given what you have learned so far about what it actually takes to keep you alive, are you, like Richard Dawkins, intellectually satisfied about the explanatory power of evolutionary biology?

The more you understand what it takes for life to survive within the laws of nature, the more you will come to realize how inadequate and overly simplistic the theories of evolutionary biologists. How cold-blooded animals evolved into warm-blooded ones is a case in point. That's what we'll consider next time.