SkepticLance

Prof. John Hawks of the university of Wisconsin has been involved in studying recent human evolution using current human genetic variability to show what changes have happened recently. Some of his thoughts are on : http://johnhawks.net/weblog/reviews/genetics/brain/lahn_2005_aspm_microcephalin_science.html The quote below shows several recent genetic changes, for two genes considered to be involved in brain development, showing evolution in the very recent past. "Haplogroup D for Microcephalin apparently came under selection around 37,000 years ago (confidence limit from 14,000 to 60,000 years ago). This is very, very recent compared to the overall coalescence age of all the haplotypes at the locus (1.7 million years). Some populations have this allele at 100 percent, while many others are above 70 or 80 percent. Selection on the allele must therefore have been pretty strong to cause this rapid increase in frequency. If the effect of the allele is additive or dominant, this selective advantage would be on the order of 2 or 3 percent -- an advantage in reproduction. The story for ASPM is similar, but even more extreme. Here, the selected allele came under selection only 5800 years ago (!) (confidence between 500 and 14,100 years). Its proliferation has almost entirely occurred within the bounds of recorded history. And to come to its present high proportion in some populations of near 50 percent in such a short time, its selective advantage must have been very strong indeed -- on the order of 5 to 8 percent. In other words, for every twenty children of people without the selected D haplogroup, people with a copy of the allele averaged twenty-one, or slightly more. "

Phi for All said "and now I know why creationists keep using this argument. You keep giving them permission to use it with statements like this. Sometimes clarification is really just equivocation in an ape suit." I do not want to be pedantic, but denying that humans evolved from apes is denying scientific truth. Humans are part of the Great Ape taxonomic group, and our ancestors were also apes. I don't care what arguments creationists use. We should not deviate from telling it as it is.

Actually, humans DID evolve from apes. In fact, we are still apes. That is our taxonomic grouping. The apes we evolved from are not modern apes, and none are still extant. I gave an example earlier - Pierolapithecus catalaunicus. - of a species of ape that may have been a direct ancestor of humans 13 million years ago. On Bigfoot. This is a situation where applying Occam's Razor is appropriate. Which is the simpler of two explanations? 1. There is a giant, largely unknown species of near human, living in North America, that avoids cameras. 2. Someone is playing a practical joke.

To POM Your futuristic space plane sounds good. Sadly, there is no sign it will appear, in the near future or far future. On the other hand, the space elevator is already being researched by a dedicated team. So far, they have built one a mile long and hung it under a balloon. OK, this is a long way from the 78,000 km long ribbon that will be needed - but it is a start, and the technology is possible in theory. This means that it is likely to appear in due course. The fact that orbit is achieved using just electricity has to be seen as a major advantage. No reaction mass required!

The problem with studies of human and ape evolution is the sheer lack of fossils. Most of the fossils discovered are mere fragments, and very few more complete skeletons exist. There are big gaps in the fossil record. I regard it as amazing that we know as much as we do.

One of the very likely common ancestors of apes and humans is represented by the fossil of Pierolapithecus catalaunicus. Definitely an ape, with no special human features. 13 million years ago. http://news.nationalgeographic.com/news/2004/11/1118_041118_ape_human_ancestor.html Modern apes (chimps, Bonobos, Gorillas, Orang Utan) separated from the human line more than 5 million years ago. Australopithecus was much more recent (say 2.5 million) and was definitely on, or close to, the line leading to humans.

For someone interested in human evolution, here is a good reference http://www.newscientist.com/channel/being-human/human-evolution

Vexer The two DNA's entwining, as you put it, is correct, though simplified. However, every living cell also needs mitochondria, and these pass only from the mother's side. In actual fact, the mitochondria reproduce quite separately. They divide from time to time, just like the bacteria they derived from. Their rate of division is finely adjusted to the needs of the cells they live in, but not directly linked to the parent cell rate of division. They divide enough to supply all the new cells with new mitochondria. When an egg is made inside mother's body, it retains a certain number of mitochondria, but only superior ones. There is a process of removal of mitochondria that have suffered harmful mutations, and the egg retains only pristine specimens. The sperm is too small for this, and normally (with rare exceptions) does not keep any mitochondria. When sperm and egg meet and fertilise, making a zygote, the zygote starts to divide to form the early embryo. The mitochondria also divide to make lots more mitochondria, so that all the daughter cells have enough.

I love what mythbusters are doing. It is a fantastic concept and really good for science education. My only quibble is that the show is too damn slow! These days, no-one will watch a slow TV show. You gotta spend the money and make it fast paced and exciting.

Gold is very dense. Gold with silver added is less dense. If you can measure the density, you can tell if there is anything in it apart from gold. Archimedes had to weigh the crown (easy, even back in those days) and also measure its volume, since density is weight divided by volume. The problem was that he had no way to measure the volume of an irregular object like a crown. His 'eureka' moment came when he realised that even an irregular object would displace exactly its own volume in water. To measure volume, he filled a jug to the point of overflowing with water. He then lowered the crown very slowly and gently, on the end of a length of cord, into the water. The water overflowed. He collected the water that overflowed and poured it into a measuring vessel to measure its volume - something like a modern day measuring cylinder. He knew the displaced water would have the same volume as the crown. Thus, he had measured the volume of the crown. Density = wt/vol. Eureka! He had the density. He proved the crown was not pure gold, and the villains who were trying to cheat the king quite literally lost their heads.

If you take a look at the internet, you will find that there are literally thousands of references to the possibility of the LHC creating a planet-busting catastrophe. Dozens of people have been involved in those suggestions, including professional physicists. Even New Scientist had an item describing the theoretical risk. When I checked google under 'lhc+catastrophe' I got just under 100,000 hits. The more serious references suggest a chance of disaster of 1 in 50 million over 10 years. As we have said all along, this is small but non zero. Again, I find it hard to understand why, when we say something that is absolutely scientifically correct, we get met by sarcastic and emotional responses. This is the science forum, for Finagle's sake!

To Klaynos Yet no-one has actually said that. I am left wondering why the over-reaction.

It is kind of interesting to see the reaction to the statement that the risk is non zero. We are getting sarcasm, expressed emotion, and irrelevancies. I wonder why? It is hardly as if the 'non zero risk' statement is anything special, unscientific, or unusual. Somehow it has touched an emotional chord.

Interesting article in New Scientist (Australian printed edition 5 April page 36) by Prof. Michio Kaku - theoretical physics at City University of New York - and author of "Physics of the Impossible." He discusses what scientific and technological developments might occur in the future - which will happen soon, or later, and which are plain impossible. He points out that the history of science is full of luminaries that make lousy predictions. Examples are Lord Kelvin denying that heavier than air flight is possible, claiming that X-rays are a hoax, and that radio has no future. Ernest Rutherford denying that the A bomb will ever be possible. Prof. Kaku suggests 3 classes of development. 1. That which will be done within decades, or 100 years at latest. Examples include teleportation of small items - up to virus size, and invisibility. 2. That which will happen hundreds or thousands of years in the future. Examples include teleportation of large objects, including humans. 3. That which is totally impossible. Examples include precognition and perpetual motion machines. He discusses other interesting 'impossibilities' such as time travel, telepathy (assisted by electronic implants), travel through wormholes etc. Any other suggestions?

With polar bears into the Antarctic the problem is the opposite of lack of survival. They would thrive and devastate the place. The other animals there have no adaptations to polar bear predation. The bear population would explode and kill off the penguins, and seals. At that stage, the bears would mostly die of starvation. The result would be dreadful all around.

To Mr. Skeptic It has been said that sarcasm is the last resort of the incompetent. I am sure you are not incompetent or at your last resort, so the sarcasm is not appropriate.

To John Cuthber If I, or anyone else, knew all the answers related to the LHC, we would be able to give a definitive risk probability. I do not know. Nor does CERN with 100% certainty, which is why the risk is non zero. However, as we said, the risk will be very low. Just not zero.

To excillium The underground habitat has to meet certain requirements, but is fairly flexible if it does so, 1. It has to hold atmosphere 2. It has to screen out radiation 3. It has to conserve heat. Atmosphere can be held in with a relatively thin (a few millimetres) of metal sheet. Radiation needs about 10 metres of soil or rock, or ice cover. Conserving heat is achieved by a foam layer. Perhaps three layers are needed to achieve all three points. Conserving atmosphere. What is often forgotten is the time factor. Mars has enough gravity to keep an Earth type atmosphere for many millions of years. Eventually the solar wind would blow a big chunk of it away, but only after millions of years. Even the moon has enough gravity to conserve an atmosphere of about that we have on Earth for up to a million years before it is lost. It is conceivable that a civilisation might break down ice to create an oxygen atmosphere on Ganymede or a similar moon, and keep it for tens of thousands of years. It could be replenished with more ice electrolysed.

I have encountered this idea before, and thought it a bit impractical. Apart from anything else, it is terribly wasteful. Most of the energy is radiated out away from the place where it is most useful. In addition, to set up a self-sustaining fusion reaction would require a much larger object, so that the inward pull of gravity can balance the outward thrust of the ongoing fusion explosion. I have always felt that complete terraforming is probably not needed. Especially on a small moon. For example, how would you screen out the hazards of cosmic radiation, which can induce lethal cancer within 3 years? On Earth we have a thick atmosphere and magnetic fields. Not on a moon. My feeling is that humans do the adapting. Not the moon. We become troglodites, and build underground habitats, or even whole cities underground. We use nuclear fusion power stations for energy. Ten metres of rock and soil overhead will screen out lethal radiation, and the fusion energy is channelled in a much more efficient way into electricity which is used to provide light and heat. Humans are highly adaptable, and could survive and thrive well in that environment.

Welcome to the forum. It is your knowledge rather than formal qualifications that counts. I will look forward to your questions, queries and comments.

Hi Watcher. I am from New Zealand. Do you have qualifications in biology? Just asking because it relates to your favourite topic.

To John Both Mark and I agree that the probability of that kind of disaster is small. The point is that it is not zero. Cosmic rays are not the same as colliding streams of high energy particles. In all probability, there will be no catastrophe. However, as said, it is not zero probability.

To iNow The relevance is that Al Gore is a career politician. To politicians, truth is a variable that can be altered to achieve specific goals. Politicians do not have the same reverence for objective scientific truth that I hope most of the contributors to this forum have. As a result, most smart people treat the utterances of politicians with some suspicion.

Have you ever known a politician who was a stickler for exact scientific truth? If so, please let me know, and I will add it to my list of known miracles.

To Mark That was a very nice, comprehensive and informative post. I think it is very good to see someone playing Devil's advocate. Thank you. I am not keen on conspiracies or catastrophes. Thus, what I am about to say is not something I really take too seriously. One of the great puzzles has been called the Fermi Paradox. This is the query as to why no civilised star travelling alien species has visited Earth, and left traces of that visit. It does not take much to calculate that, if such species are common, one would have visited Earth before now. Lot's of different explanations for the Fermi Paradox have been suggested, but few are really very tenable. It occurred to me a while back, that one reason might be that all intelligent life gets killed off by a booby trap set by Mother Nature, before they can become star travellers. All developing intelligences are likely to follow a similar path to scientific understanding. For example ; they are all likely to invent prisms for splitting light into colours before they make different coloured lasers. If all such development follows more or less the same path, perhaps one step on that path is lethal, but not able to be predicted. An all devouring black hole that inevitably appears for a certain size particle accelerator might be such a booby trap that inevitably kills off the developing species. As I said, I do not really believe that, but it is probably worth thinking about.