SMF

Cultured cells grow as a sheet on a flat plate because this is the only way all the cells can have access to oxygen and nutrients. Thicker tissues in a body are heavily invested with a capillary bed. You couldn't grow a golf ball sized lump, much less a swimming pool full. If you were to grow a massive volume of HeLa cells on plates and scrape them into a swimming pool it would be a semitransparent mass with the consistency of a thick gravy. If you were to do such a useless thing the family of Henrietta Lacks (HeLa), the woman from which the cell line was derived, might complain. You should do a little web research on Lacks because her story is interesting and an important ethical case. She died of the cancer from which the cell line was developed and the cells were collected without her knowledge so, because this is a widely used and important immortal line, there is probably more of her alive today than when there was just her. I think there was a lawsuit by the family to try to obtain some compensation.

Basement membranes are made of a fibrous material (mostly charged glycosaminoglycans and type 4 collagen) that, along with the capillary fenestrae and podocyte filtration slits, make the ultrafiltration membrane. SM

Cyclops, I was not irritated with you. On forums such as this many posters simply state the facts as they see them. This may sound unfriendly, but actually it is not. Without face-to-face voice inflection and facial expression the writing seems terse. SM

Jakson33, I was on the Tenure and Promotions Committee and the chair of the Salary Committee at a medical school and had access to LCME data. This site is more in line with the books I saw- http://www.merritthawkins.com/job-search/job-search-results.aspx?profession=Physician&specialtyId=9&regionId=-1#jobGridResults and these are actual advertisements for jobs nationwide. Family Practice is the lowest paid specialty and my current family practice physician in a rural area makes $180K. I know a medical student who paid off most of his student loans while a resident by moonlighting in an undesirable clinic. I know a resident (internal medicine) who started his first job in a practice at $235K. Keep in mind that the stated salaries you see often don't include “benefits.” The sickness I alluded to is reflected in the recent statistic that puts the US 33rd in the world for infant mortality (just below Cuba, Channel Islands, Brunei, Cypress, and New Caldonia), that our health care costs two to four times that in many other developed nations, that drug companies have been criticized for spending nearly as much on unethical practices intended to influence physicians regarding their products and paying them outright to hype their products than they spend on direct advertising and product R and D combined (story here- http://www.medicationsense.com/articles/jan_apr_06/conflict_of_interest_020306.html JAMA article here- http://www.nhmrc.gov.au/_files_nhmrc/file/health_ethics/hrecs/Health_Industry_Practices_that_create_conflicts_of_Interest.pdf ), that there were physicians lining up to collect from the drug companies and didn’t think that there was anything wrong, that people have to sneak across the border to find the very same drug sold in the US but at affordable prices, or how about medical insurance companies that cut off member insurance for arbitrary reasons when their costs are high. Blaming the above on mandates and regulations sounds a bit political to me. SM

I don't know, but I do think that there are some ethical issues that need to be cleared up regarding patenting genes and tissue. The Monsanto vs Schmeiser case and the development of the HeLa cell line come to mind. SM

Steevey, you say: If you are referring to the BBC article you linked, I did not say anything of the kind (this is getting very frustrating). I did say that no actual scientific evidence, that the skull changes were related to evolutionary processes, was presented. Because the evolutionary assertion is so unlikely I suggested possible alternative explanations. There was no reference to an actual published scientific study in the article that might have some further explanation and I couldn't find one on my own. If you wish to argue this, please provide a scientific reference. A BBC human interest piece by itself is not science, so without support it is just opinion. If you wish to argue about science, you have to actually talk about science. Mrs Zeta, you say: 1. Natural selection is not slow; it operates in a single generation on single individuals. Evolution can be very slow, especially in large populations, but when there is a small founder population that is reproductively isolated it can be quite fast. Both natural selection and evolutionary theory are not contrary to some futuristic theory. They are just a description of a collection of natural mechanisms. All the theory does is to describe the rules for what happens following a variety of factors. The rules are self-evident (e.g. if you die before you create young, your genes don't get passed on). For the future I presume you are referring to the possibility that some forms of natural selection will become less potent, and genetic mutation will become more controlled. This is not a competing theory. 2. Traditional natural selection and evolutionary theory do not necessitate anything. There are no time limits. The basic components of evolutionary theory at play are exactly the same for all species, so your emphasis on humans relative to evolutionary mechanisms is meaningless. If the age that members of a snail species can achieve was artificially increased to 300 years, this would result in an increase in the population. From this point on, how ongoing selection pressures on the snail might be altered as the result of the population increase is an ecological question. Human ecology includes the output of our big fat brains. I strongly suggest that you find two (for perspective) practicing evolutionary biologists to talk to. Practicing means that they are actively doing research. A friendly back and forth regarding evolutionary theory would very quickly help you with your misconceptions and help you present your futuristic ideas more clearly. SM

Steevey, I and the references I cite don't say what you think at all. In addition, I don't understand what the last two sentences you added mean. What skulls and what genome are you talking about? SM

Mr Skeptic, my response to your initial post is that your question presupposes that the pool of students that would make good doctors is tapped out and that the selection criteria are appropriate. My response to your second comment (#10) is- right on! If there were many more physicians their exorbitant salaries would come down (Jakson33, $180K is what the lowest tier physicians average), service would improve, and the ones that cause lawsuits wouldn’t be able to compete. The reason that clinics in most rural, inner city, and other undesirable locations have to use imported physicians is that there just aren’t enough US trained ones to go around. This is not a free enterprise system. Lemur, I think your idea is a good one but with the physician shortage I don’t think that there is any pressure to make less money in order to provide lower cost services. I also have to say that the entire US health care industry is sick because it is a cash cow for so many interests that are able to influence our government. I would really like to see a good cost analysis done in order to see where all the money goes. I agree with the idea of using more nurse practitioners and physician assistants. SM

Mr Skeptic, the Wired article is about a research article- http://www.pnas.org/content/104/52/20753.long that suggests that evolutionary rate has increased in the last 40,000 years relative to previous times by some interesting genetic mechanisms. They cite selection pressures that act on the genetic changes involve human migration that resulted in changes in skin pigmentation and adaptation to new environments, changes relative to transition to agriculture, increased disease mortality from the mixture of disparate groups that promote epidemics, and subsistence agriculture and changing diet that affected genes such as lactase. The original post here suggests that technology will greatly reduce all of these selection pressures and within this scenario, as a thought experiment, I agree. I just don’t agree that this will happen and in fact I think that looming problems secondary to overpopulation will radically increase differential survival and may accelerate evolutionary rate even further. SM

Steevey, I read the BBC and Time articles. They are both news items and don't actually provide any evidence of Evolution. In the BBC article the lead author of the report is Peter Rock, an orthodontist. I couldn't find any research article by him in Google Scholar that would demonstrate that his speculations have been published in a peer reviewed scientific journal. Most of what he reports can be explained by improved environment (e.g. nutrition or health). The Times article reports on a legitimate research article. Read it here- http://www.pnas.org/content/107/suppl.1/1787.full . This report demonstrates, with a statistical analysis, how differential reproduction rates have biased the frequency of some phenotypic traits by a very small amount in a population. This would take a very long time to change the genome and would only do so if the same reproductive advantage was consistent over time and there was no outbreeding. This sort of natural selection that alters gene frequency, not genes, is interesting, but is sort of like saying that humans as a whole are changing to be more like the populations of China and India because they have become a larger portion of the world population in recent years. It is also the type of selection that would be reduced for the reasons suggested by the original post in this thread. I also did a search for any research showing special genetic traits related to Inuit diet and could find nothing. This group migrated to the Americas 11,500 years ago and look pretty much like the Siberian group that they migrated from and to some north American native americans (e.g. Navajo). This is a difficult topic, and I suggest you read- http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.0030090#top to get some idea of the complexity involved in doing genetic analysis for evolutionary changes in humans. This is pretty hard going, but it references other research articles that you can follow up on if you wish to learn more. This article suggests that actual changes in genes occur on the order of tens of thousands of years. SM

Marat, in order to answer your query one first needs to know if this phenomenon is real. There is a lot of anecdotal evidence, which is notoriously unreliable, and there are also good researchers on both sides of the issue. If I remember correctly there are some Japanese researchers who have studied animal behavior relative to earthquakes and claim to have scientific evidence of a relationship while studies by others, such as USGS scientists, have been unable to find a reliable relationship. Personally, living in California, I have felt numerous earthquakes, big and small, and have never noticed any of my critters (chickens, cats, dogs, bees, hamsters, and so on) even take notice of the actual earthquake. SM

Steevey, I am beginning to think that you are trolling. You say say-- So, prove me wrong by providing any evidence whatsoever of genes that have died out, or any new genes that have appeared. Any peer reviewed scientific evidence will do. You seem to be just making this stuff up. SM

The number of synaptic connections in the brain, while very large, is not a very useful statistic. A cortical pyramidal cell may receive 20K synapses, but they only have one axonal output. Synapses on the cell may have excitatory or inhibitory input and these inputs sum to create the action potential output of the cell. For some cells the output is an action potential or not, while others have a relatively constant action potential rate that is modulated by the sum of inputs. I find it useful to think of each neuron as an analog Boolean logic gate. It is easy to see how an AND, OR, NOT, and so on, decision can be represented by the output of a neuron. Neurons in which modulation of output frequency is regulated can also display logic decisions, but they are mostly observed in finely tuned sensory systems. Each neuron as a simple decision maker can get complicated because of the analog component. Excitatory and inhibitory synaptic inputs to a neuron can vary in frequency, timing, and position on the cell. A higher action potential frequency of an excitatory input can overwhelm an inhibitory input (and the reverse). An excitatory input can be blocked if an inhibitory one occurs at the same time (and the reverse) but if, for example, the inhibitory one arrives just after the excitatory one there will be a short burst of output action potentials that is shut off and prevented for some time afterward (pulse generator?). There may be a large number of excitatory inputs to a cell via the terminal ends of its dendritic tree that can sum to create, or modulate, action potential output, but if there is inhibitory input very near, or on, the axon hillock (where action potentials are initiated) all of the excitatory inputs are negated. And then there are interneurons that don’t produce action potentials. The brain she is not so simple. SM

If you are just talking about the energy source the output of our giant fusion reactor, 93 million miles away, is enormous. Obviously it is the cost at the pump or meter or whatever that really counts. SM

I have not heard this term in reference to a specific structure and it isn't in Steadman's medical dictionary. It probably is just an anatomical description. All blood vessels have an outer connective tissue layer called the adventitia, and I suspect that this is what is referred to, but it could also refer to the larger regions of connective tissue that contain and protect larger arteries, veins, and nerves. SM

Steevey, you still haven't presented any evidence. Evidence is not some columnist or blog site or news item. I am quite aware of some of the studies that show small differences between human groups, but you haven't presented anything but your own opinion. Greater lung capacity can be a developmental or a conditioning phenomenon and to claim that it is due to a genetic change requires evidence of genetic change, not your opinion. If what you are saying is true, then there should be scientific support. Why don't you find some good published scientific journal articles, it would be a good exercise. SM

Apparently the way that elements will be displayed in the future in, for example, the periodic table will be changing to reflect different isotopes more accurately. The International Union of Pure and Applied Chemistry commission in charge of atomic weights are suggesting that atomic weights should be displayed as ranges, or more accurately as pie charts that represent the abundance of the different isotopes. There is a good short review of this proposal, its advantages, and some history regarding chemistry by committee in Science News, 2011, Jan 29, pp 5. SM

When you breath in through your nose or mouth the air is traveling to a region of lower pressure. Pressure is lowered in the lungs by movements of the ribs and diaphragm. In my experience most little 6 to 8 year old boys learn how to lower the pressure in their stomach in order to inhale gas for making rude burbs, especially when their parents are having a visit from their adult friends or relatives. SM

Steevey: You have not provided any scientific evidence of evolutionary change. This would require some published science that involved genetic analysis and an attempt to attribute this to evolutionary processes. You have provided some evidence for the remarkable abilities of humans to adapt and persevere in some activities. A Belgian recently completed running 365 marathons in one year. Do you now think that Europeans evolved to become excellent runners? http://edition.cnn.com/2011/SPORT/02/05/marathon.record.engels.365/index.html I don’t know what surviving the plagues or Inuit dietary practices have to do with anything. I think you should get a beginning evolutionary textbook or take a class. SM

OK Steevey, please provide the references that show that what you say has been proven. Science only please, no speculation by non experts. SM

Mr Skeptic: Ball valve. SM

Steevey, there are some differences between groups of humans for which genetic differences have been linked to the evolutionary process. I don't know where you got your list of group differences, but did they provide any scientific evidence for these claims? SM

Swansont: I did it. Thanks. I gave you one also. SM

Mrs Zeta. A significant change that is affecting evolution in current developed nations is the reduction in selection pressure by diseases that kill prior to breeding and child rearing age. This is, of course, due to increased health care and sanitary conditions worldwide. This is not a cessation of evolutionary change. The Neutral Mutation Theory, originated by Kimura, has been fleshed out and added to the evolutionary theory synthesis. Apparently most of the point mutations that occur in DNA have no effect whatsoever. For example, there are quite a few single amino acids and whole regions of large proteins that can be altered without affecting the functioning of the protein at all. These changes accumulate slowly and can be compared between two species to get estimates of evolutionary distance and time. In addition to this process, changes in genes from which selection pressure has been released are retained, rather than being selected out, and they accumulate because they are now neutral. Overall this process is often called random genetic drift and these silent changes can suddenly become important when the protein product changes enough to be important for survival again. Also, in instances in which the original selection pressure returns from, for example, the return of a previously banished disease, the silently changed gene may now be ineffective. Evolutionary change operates on very long time scales relative to human society. For example, cave animals loose vision when the development of their eye is disabled by random changes of 10 or 12 genes. This often results in a degenerative vestigial cyst below the skin that only contains some random eye elements. Such a change probably takes somewhere between 10K and 100K years. SM

Thank you DH. Your description is clear and helpful. SM