Wikipedia:Reference desk/Archives/Science/2011 October 1

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October 1

Garfasil DNA contamination

I was reading a few articles about it and I was wondering what the possible risks can be since I have gotten the first two shots. — Preceding unsigned comment added by 76.87.48.142 (talk) 03:04, 1 October 2011 (UTC)

I suspect you mean Gardasil; you can find the patient product information here and the prescribing information here - Nunh-huh 03:16, 1 October 2011 (UTC)

I guess you could argue that since the antigenic material in the vaccine is influencing the prevalence of certain configurations of genes in the adaptive immune system it is "contaminating" but that would be a major stretch. Viruses like HPV are much messier when it comes to "contaminating" DNA, and there has been some speculation that a substantial percentage of human DNA (i.e. Introns) is nothing more than "contamination" by inactive viruses, though that's largely speculation. In short, if you want to preserve your genetic cleanliness (whatever the heck that means), getting vaccinated against viral infections is a good thing because the viruses will cause a lot more genetic damage than a little bit of the adaptive immune system doing what it's supposed to do. SDY (talk) 07:43, 1 October 2011 (UTC)

I didn't want to mention this per our policy on medical advice but I think it's likely the OP is thinking of the bullshit certain people and sites are spreading that is debunked here [1] not anything to do with effects on the adaptive immune system. Nil Einne (talk) 16:57, 1 October 2011 (UTC)

World after 100 years

Will industrial civilization, as we know today, collapse after 100 years due to peak oil? --DinoXYZ (talk) 06:07, 1 October 2011 (UTC)

No. HiLo48 (talk) 06:09, 1 October 2011 (UTC)

If capitalism is still the dominant economic system, then yes. →Σ ⚑  ☭  06:14, 1 October 2011 (UTC)

In many parts of the world large efforts are going into the development of alternative technologies for supply of energy. As oil prices rise, these will become viable options. HiLo48 (talk) 06:31, 1 October 2011 (UTC)

That's correct -- nuclear energy in particular appears promising, as well as coal-to-liquids technology and (to a lesser extent) wind energy. 67.169.177.176 (talk) 06:36, 1 October 2011 (UTC)

"to a lesser extent"? You might want to review Wind power#Cost trends: Wind is trouncing everything, including coal which used to be the least expensive, and is growing faster than ever. 75.71.64.74 (talk) 19:57, 1 October 2011 (UTC)

This does not take into account the maximum amount of wind power that can realistically be generated, which is still less than the the total level of energy consumption. So while wind power is a promising part of the mix, it cannot by itself meet our country's energy needs. 67.169.177.176 (talk) 00:46, 2 October 2011 (UTC)

Yes, it does. 69.171.160.45 (talk) 07:15, 3 October 2011 (UTC)

Only as long as the wind keeps blowing. Besides, it won't work for transportation -- only for electricity generation.67.169.177.176 (talk) 01:47, 4 October 2011 (UTC)

Please read http://windfuels.com -- their process produces transportation fuels at less than $55/barrel equivalent petroleum cost. You might want to look at pumped-storage hydroelectricity too. 69.171.160.201 (talk) 19:39, 4 October 2011 (UTC)

Boy, there's some POV on show here today, isn't there? ;-) I may have compiled a different list (nuclear is experiencing a bit of a hiccup in some areas right now), but the point is still valid. HiLo48 (talk) 06:41, 1 October 2011 (UTC)

If the amount of oil decreases significantly, the price of energy will probably go up, at least in the short term. The demand for energy will probably also go up. The ways around this are that if the price rises significantly, certain technologies which do produce energy today, but are not competitive with oil, will suddenly become competitive economically. Additionally, if the price of using energy goes up, then there will be additional incentive for using less of it. So in the end it is actually not that awful a thing for the oil to run out. Oil is addictive — it's cheap and bad for you (as a planet). There are lots of alternatives. They are not as cheap as oil (or coal), on the whole, at least in their current iterations. But many/most of them are a lot better for the environment than fossil fuels. (The really stupid but tempting thing to do would be to switch from oil to coal, of course.) Now this kind of transition, if it is very rapid, could cause significant economic disruption, which could cause significant political or social disruption if handled poorly by the powers that be. On the other hand, if the transition is anticipated, and the energy portfolio is diversified, then it's probably only a minor hiccup. I don't see total collapse of industrial civilization as a result in any case, though. This is obviously me gazing into a crystal ball, but it's based on fairly straightforward economic principles (and based on some article I read in Scientific American a long while back). --Mr.98 (talk) 13:30, 1 October 2011 (UTC)

Synthetic fuel is now less expensive than petroleum-derived fuels in some electricity markets (see wind power above) due mostly to improved plating alloys for electrolysis anodes, so expect it to become very much more popular in the next few years. 75.71.64.74 (talk) 19:57, 1 October 2011 (UTC)

Electrolysis? I work in the field of synthetic fuel technology, and while many synthetic fuel production methods involve the use of hydrogen, I don't know of any where the hydrogen is produced by electrolysis. In fact, in most processes that I know of, hydrogen is produced either by the water-gas shift reaction or by steam reforming. Are you sure you didn't mean "improved catalysts"? Or that you didn't actually conflate synthetic fuel production with wind power (where electrolysis is indeed used for energy storage)? 67.169.177.176 (talk) 00:37, 2 October 2011 (UTC)

Yes. See http://windfuels.com 69.171.160.45 (talk) 07:15, 3 October 2011 (UTC)

The future is solar power. When the earth becomes unified and invests resources into creating one of those things where they put millions of satellites with solar panels on them in orbit around the sun (d[a-z]+ spheres, or something, I forgot) solar power will become the principal source of energy. →Σ ⚑  ☭  02:04, 2 October 2011 (UTC)

Wrong again -- solar power is much more expensive than any other kind, and space-based solar is even worse. Besides, switching to exclusively solar power would give an unfair advantage to savages and greatly hurt civilized countries. 67.169.177.176 (talk) 02:12, 2 October 2011 (UTC)

He's referring to futuristic, sci-fi style plans like Dyson spheres Ah, yes, that's what it was called! →Σ ⚑  ☭  02:49, 2 October 2011 (UTC) or rings or bubbles and the like. It's pretty speculative. Anyway, considering the first part of the statement involves a politically unified planet, it's not happening anytime soon by any other indications. (I've also no idea what you're getting at with the idea that solar will help third world countries or something like that. Perhaps you haven't noticed, but oil hasn't exactly propelled the third world into great arenas, despite it being rather plentiful there.) --Mr.98 (talk) 02:20, 2 October 2011 (UTC)

What I'm getting at is that meeting the per-capita energy demand here in the USA with solar power alone would require several HUNDRED square meters of solar panels for EACH AND EVERY PERSON in the country, at prohibitive economic costs, while meeting the energy demand somewhere in Kenya would only require a solar-panel area measured in square decimeters. Does this sound even remotely fair to you, especially considering all the great achievements that the civilized nations have reached due to their use of their energy resources? 67.169.177.176 (talk) 02:31, 2 October 2011 (UTC)

Maybe it would be lower if the USA citizens didn't waste so much energy on supersizing everything rather than aiding the aforementioned nation. →Σ ⚑  ☭  03:13, 2 October 2011 (UTC)

What makes you think that aiding Kenya and other third-world ingrates who want to see our country weakened and humiliated is more important than maintaining a high standard of living for OUR OWN PEOPLE? 67.169.177.176 (talk) 02:02, 4 October 2011 (UTC)

Is it humiliating to stretch a helping hand to another, more unfortunate country? Does a nation's border truly define what one variety of "people" is? →Σ ⚑  ☭  04:39, 5 October 2011 (UTC)

(ec) My sense, not based on any careful analysis, is that the contribution of solar power for the forseeable future will be decentralized, point-of-use photovoltaics. Their price has come down I think quite a lot and should drop still more. Solyndra folded but the basic idea is good, just needs different market conditions that will show up sooner or later. These can make a significant contribution to residential and business power supply; doesn't mean you can cut off ties with your local power company, just that you won't have to buy as much of their product.

Centralized solar I don't think is in the cards. The power density just isn't high enough, you need too much land, and the plant stops delivering power just at the time everyone's turning their lights on.

What I think people need to take on board is that the demand for electricity is going to go way up as electric cars come on line. I don't think solar is going to cut it for that; people are going to want to charge their cars at night. That's one reason I think we're likely to need new nuclear capacity, and quite a lot of it. --Trovatore (talk) 02:42, 2 October 2011 (UTC)

In an earlier post I said about alternative technologies that "THESE will become viable options". Rather than having almost total dependence on what is really one source of energy, fossil fuels, many differnt sources will be developed, as apporopriate to particular needs. The criticisms here of solar are at least partly valid, so we won't depend on solar alone. A combination of new technologies will evolve - solar, wind, tidal, thermal, even cleaner nuclear, etc, etc, etc. Attacking one of these doesn't prove we won't use it. HiLo48 (talk) 02:56, 2 October 2011 (UTC)

I wasn't attacking solar! I just think its main use will be decentralized, not from power plants. One of the best things about solar is that it can be generated in a decentralized fashion. --Trovatore (talk) 06:08, 2 October 2011 (UTC)

The reaction you get, when you try to build one little 10KW thorium reactor for your personal use.... --Trovatore (talk) 06:12, 2 October 2011 (UTC)

Yes, good point. Solar can work right beside where you want to use it. That doesn't apply to many technologies. (It would for your thorium reactor of course.) HiLo48 (talk) 06:30, 2 October 2011 (UTC)

Did I not mention unifying the planet, or did your eyes jump to the glorious and enlightening hammer and sickle in my signature? →Σ ⚑  ☭  03:05, 2 October 2011 (UTC)

That hammer and sickle in your signature is more than enough proof that you want to (among other things) turn Wikipedia into Commiepedia, and (as your threats to me earlier in this discussion clearly show) forcibly suppress anyone who tries to stand in your way! And BTW, here's more evidence that your plans to "unify the planet" involve having my country destroyed in the process! There's no reasoning possible, nor indeed any good reason to have any sort of intelligent discussion, with America-hating social-fascists like you and your ilk! Maybe I should go back to boycotting this whole travesty altogether, as well as reporting this and other incidents on Wikiwatch... 67.169.177.176 (talk) 02:35, 4 October 2011 (UTC)

Good for you, because I stopped caring 3 days ago. Anyway, I responded to your more rationale comment above.

Note that this is your final warning. The next time you make personal attacks on other people, you may be blocked from editing without further notice. →Σ ⚑  ☭  04:39, 5 October 2011 (UTC)

Oh-My-God particle & force

1. According to our article on ultra-high-energy cosmic rays, occasionally particles hit the atmosphere at 1.0×10²⁰ eV+, with the vast majority (~99.9995%) of energy in these collisions going to kinetic energy, and the rest going to "interaction with a proton or neutron." Where exactly would the kinetic energy go? As in, which particles, if not protons or neutrons?
2. If this particle were to crash into a sunbather, would it be cancer inducing? My understanding is that most cancer comes from photons in electromagnetic radiation. If the answer to my previous question was "photons", I imagine the answer would be a resounding "yes" because the collision would produce some very high energy gamma rays.

Magog the Ogre (talk) 06:36, 1 October 2011 (UTC)

(1) AFAIK the kinetic energy goes into inducing high-speed movement of air molecules in the ionosphere, as well as their ionization; the other 0.0005% actually goes into transmuting a proton or neutron into any of a whole bunch of exotic particles, along with gamma ray emission.

(2) Yes, any kind of ionizing radiation is potentially cancer-inducing; however, a single cosmic-ray particle would definitely not suffice to cause even one cell to become cancerous. 67.169.177.176 (talk) 06:43, 1 October 2011 (UTC)

Clarification to part 1: the 0.0005% of the energy goes into transmuting the proton or neutron into such exotic particles as mesons and hyperons, while the other 99.9995% goes into propelling said exotic particle at very high speeds through the upper atmosphere while it collides with other protons/neutrons, transmuting them as well. Eventually all the exotic particles formed in this cascade reaction decay back to protons and neutrons, with emission of gamma rays and neutrinos.

Clarification to part 2: None of the exotic particles formed in the aforementioned cascade reaction ever actually reach the surface -- they all decay in the upper atmosphere, while the gamma rays emitted during the decay process are absorbed by air molecules in the ionosphere, which become ionized in the process and form ozone among other things, as well as re-emitting the absorbed energy as visible light, particularly in the form of Northern lights. 67.169.177.176 (talk) 07:06, 1 October 2011 (UTC)

Or Southern Lights Please try to remember that the earth has two magnetic poles. Roger (talk) 12:34, 1 October 2011 (UTC)

You mean, the Northern hemisphere doesn't have a monopole-y on Aurorae? {The poster formerly known as 87.81.2301.95} 90.197.66.221 (talk) 16:27, 1 October 2011 (UTC)

While most charged particles don't reach Earth, I wonder if a particle at such a high velocity might be going at a quick enough speed to overcome the Earth's magnetic poles. Magog the Ogre (talk) 20:50, 1 October 2011 (UTC)

You can derive this ratio approximately just from special relativity, without knowing anything about particle physics. A high-energy cosmic ray comes in with a (energy, momentum) four-vector of (E, E) relative to the lab frame. The particle it strikes is more or less at rest (relatively speaking), with a four-momentum of (m, 0). In the center-of-momentum frame their four-momenta are (E'/2, E'/2) and (E'/2, −E'/2), where E' is the center-of-mass energy. The dot products of vectors in different coordinate systems (reference frames) are the same. This gives $E'={\sqrt {2Em}}$, which is roughly the geometric mean. In other words, you lose half of the orders of magnitude of the cosmic ray energy in the center-of-momentum frame. Assuming both particles are protons (mass = 10⁹ eV) and the cosmic ray energy is 10²⁰ eV, the interaction energy is only about 10^14.7 eV. The rest, about 1 − 10^5.3 = 99.9995%, is conserved kinetic energy. This is why circular colliders collide beams circulating in opposite directions instead of using a stationary target. This is a purely relativistic phenomenon—in Newtonian physics this ratio never goes above 7550% for like particles, no matter how high the speed. -- BenRG (talk) 21:04, 1 October 2011 (UTC)

Imaging ripples

What is the word to describe the effect whereby the degree to which something like longitudinal or transverse structures in a 3D ripple pattern are visually enhanced (by light and shadow contrasts) depends on the position of the light source ? For example, if you are looking down on a 3D ripple pattern that has superimposed fairly regular londitudinal N-S structures and fairly irregular transverse E-W structures, a light shining from the east will tend to emphasize the regularity of the N-S longitudinal structures and the pattern will look pretty regular whereas a light shining from the north will tend to emphasize the irregularity of the transverse structures and the pattern will look pretty irregular. I get the feeling that this is some obvious word that I should already know but I can't think of it. Here's an example, the same ripple pattern with 1. left image - light shining from the east, and 2. right image - light shining from the north (although there is a very slight horizontal offset between the images). Sean.hoyland - talk 08:33, 1 October 2011 (UTC)

May I ask, are those images created with an emboss function, and were the ripples created algorithmically? --George100 (talk) 08:53, 1 October 2011 (UTC)

Those are real ripples created with sand on a plate that was moved in a water tank by a motor repeatedly to reproduce the effects of a current. Sean.hoyland - talk 09:04, 1 October 2011 (UTC)

I don't know the correct answer, but Anisotropy might figure in it. {The poster formerly known as 87.81.230.195} 90.197.66.221 (talk) 16:31, 1 October 2011 (UTC)

automated blood draw

Is there yet a machine that can draw blood? --DeeperQA (talk) 10:44, 1 October 2011 (UTC)

It is easier to provide a precise answer when the question is specific. What step in blood drawing are you asking about? A pheresis machine draws blood out of people once connected to a catheter that has been inserted into a vein. My guess is that you're asking about venipuncture, and if so I don't think there's a machine that will find and puncture a vein. -- Scray (talk) 12:09, 1 October 2011 (UTC)

If there are machines that can perform surgery then there must be machines that can find and puncture a vein and avoid the many possible mishaps technicians have when taking sample after sample per hour and per day. I have seen many mishaps with needles sliding out for instance and the technician using the wipe to clean blood from the arm rest before wiping the arm to reinsert the needle - a process an automated system would likely not perform no matter how many samples it took a day. --DeeperQA (talk) 19:22, 1 October 2011 (UTC)

There aren't machines that can perform surgery. There are machines that surgeons can use to perform surgery. The surgeon is still in control. --Tango (talk) 19:25, 1 October 2011 (UTC)

No, finding a good vein and walking the patient through the draw is skilled labor requiring human empathy. It's not outside the realm of possibility, but self-service is orders of magnitude easier than automation at this stage. 67.21.131.22 (talk) 21:08, 1 October 2011 (UTC)

Water-added chicken breast

In this week's circular at a local supermarket is chicken breast with 20% added water. Is there a problem of insufficient disclosure in the United States of this added water, or is it well regulated? (If this question belongs in law, please move it.) Thanks. Imagine Reason (talk) 13:16, 1 October 2011 (UTC)

See plumping.--Shantavira|^{feed me} 14:55, 1 October 2011 (UTC)

Why do vegetables cooked quickly in Pressure Cooker

Can anybody pls explain my query -Thanking you Navneeth

Have you read our article pressure cooker, which explains how the increased pressure allows water to boil at a higher temperature? Mikenorton (talk) 15:50, 1 October 2011 (UTC)

It's because of how water boils. If you just have a pot of water at sea level and boil it, no matter how much heat you apply, the water will never get hotter than 100 degrees centigrade. Instead, the water will just boil faster. But if you increase the pressure, the boiling point of water is increased, so you can get the water hotter than 100 degrees, which cooks things a lot faster. Rabuve (talk) 17:23, 1 October 2011 (UTC)

Yes. Essentially, if it were to be at sea level, at 100 degrees, all the heat would go in making steam, rather than cooking the rice. At a higher pressure, the BP is raised, so the heat goes to the rice instead of trying to make steam. Lynch7 17:35, 1 October 2011 (UTC)

(And, magically, vegetables turn into rice :-)

(--DaHorsesMouth (talk) 00:56, 2 October 2011 (UTC))

Rice doesn't come from a plant? News to me! {The poster formerly known as 87.81.2301.95} 90.197.66.70 (talk) 12:48, 2 October 2011 (UTC)

The corollary is that, for similar reasons, you can't make decent tea in the mountains, because the water boils at too low a temperature, because of the lower air pressure. Mitch Ames (talk) 04:27, 2 October 2011 (UTC)

Does the higher temperature mean that nutrients in the food are more likely to be destroyed ? 115.241.26.140 (talk) 08:59, 5 October 2011 (UTC)

Miller indices and reduction to lowest integers?

In the 8th edition his book "Materials Science and Engineering: An Introduction", Callister states in a footnote on page 64 that "On occasion, index reduction is not carried out (eg., for x-ray diffraction studies that are described in section 3.16); for example, (002) is not reduced to (001). In addition for ceramic materials, the ionic arrangement for a reduced-index plane may be different from that for a nonreduced one."

I am not able to fully understand why this is the case, and hence, would really appreciate it if anyone could provide me with more details about this kind of "special" cases. If anyone has a document that discusses this kind of issues with respect to either x-ray diffraction or ceramics that would be great.

Thank you in advance. — Preceding unsigned comment added by 69.11.30.122 (talk) 16:41, 1 October 2011 (UTC)

Sometimes you can deduce the structure without index reduction, and sometimes index reduction will give you an incorrect structure. You have to check your results with what you know about the composition to make sure it makes sense. 75.71.64.74 (talk) 19:52, 1 October 2011 (UTC)

Reproductive isolation of humans?

If Bushmen man married Fuegian woman, can they have common children?

Their tribes have divided tens (hundreds?) of thousand years ago; they have a lot of different mutations and no gene exchange all this years etc.

I think they can have children, its probably not enough time for real reproductive isolation, but i`m not sure.

Maybe some sort of "weak" reproductive isolation? (For example, hight rates of mortality of infants)

P.S. I'm not a racist. I love Bushmen, Fuegians and all other nations. I'm just curios. - Ewigekrieg (talk) 23:03, 1 October 2011 (UTC)

The human group separated from the rest for the longest period was probably the Australian Aboriginal people. 40,000 years is the widely accepted figure. There have been absolutely no problems with them interbreeding with other humans. HiLo48 (talk) 00:13, 2 October 2011 (UTC)

There are different levels of reproductive isolation - from "no children" to "slightly heightened rates of mortality of infants". We can`t be sure about total absence of problems with interbreeding without data of the health of the "mixed" children - Ewigekrieg (talk) 00:31, 2 October 2011 (UTC)

Why should they marry? Anyway, 40,000 sounds like a lot, but it's not a lot of time in an evolutionary context. We had billions of common evolution before that. Wikiweek (talk) 00:28, 2 October 2011 (UTC)

Twu wuv? -- Obsidi♠n Soul 03:23, 2 October 2011 (UTC)

Geographic isolation doesn't necessarily mean reproductive isolation. While it may have eventually resulted in speciation from genetic drift given enough time; like Wikiweek say, it's simply too short (estimated beginning of human migration out of Africa is 70,000 to 50,000 years ago at the earliest).

The ability to interbreed successfully (produce fertile offspring) is also a plesiomorphic character, and may be retained within closely-related taxa. In Botany such closely related interbreeding groups of "semispecies" are called syngameons. Homo neanderthalensis and Homo sapiens, for example, despite having an evolutionary gap of ~400,000 years, were still not completely reproductively isolated, and were able to hybridize successfully. Modern human non-African populations still have traces of neanderthal genes from contact with them after radiation out of Africa.

It has actually been argued that premodern humans (including H. neanderthalensis) which diverged within around 1 million years ago, should be considered the "true" races (subspecies) of modern humans rather than separate species as they did/can not achieve reproductive isolation yet (Larsen, 2010. A Companion to Biological Anthropology. pp.372–373). The 1-million-year minimum is an approximation based on the average amount of time reproductive isolation/speciation occurs in other similarly-sized eutherian mammals (Cartmill & Smith, 2009. The Human Lineage. p. 412). Neanderthals, after all, did not truly become extinct. They were assimilated into modern humans.

The differences between modern humans even from such geographically isolated populations, in comparison, is exceedingly recent and minor. -- Obsidi♠n Soul 03:23, 2 October 2011 (UTC)

I understand, there is not enough time for complete reproductive isolation. But what about partial reproductive isolation?

For example, almost all species of Bovine can be hybridized. But some hybrids:

1. dying in womb

2. completely sterile and dying in youth

3. completely sterile

4. females are sterile, but not males

5. fertile, but have weak health

6. fertile and have average health

7. fertile and healthy.

Its a whole spectrum of reproductive isolation.

Human-neandertal hybrids can be, for example, at "stage" 4.

Is it enough differences between modern humans for "stage" 5? -Ewigekrieg (talk) 08:06, 2 October 2011 (UTC)

As there are no known cases of any human geographical populations having problems producing offspring together. The answer obviously, is no.

Animal species which show problems producing fertile offspring actually already have achieved reproductive isolation. In rare instances, though, fertile offspring from such unions can go on to create a hybrid species, like the domestic sheep Ovis aries. Your stages 5 to 7 are also subjective. Health of the offspring varies even within populations and is really not a very good indicator of reproductive isolation. Furthermore, what is 'unhealthy' and disadvantageous for one population, may be very advantageous in another. Hereditary diseases can also be passed on whether or not the parents belong to the same population.

It also happens in the opposite direction just as frequently. In hybridization between species and reproduction between differently adapted populations, mixing can result in stronger offspring able to take advantage of other habitats their parents can not, a fact taken advantage of in animal husbandry & horticulture. Modern bananas, for example, are the result of two species - Musa acuminata bear sweet fruits, but can not grow in more adverse conditions; Musa balbisiana is very hardy but produces starchy fruits. Hybridization between the two allowed early human farmers to spread the cultivation of bananas throughout the world. Population bottlenecking on the other hand, can cause inbreeding, which is usually detrimental. Early human cultures took great pains in avoiding this, even resorting to abducting wives from neighboring tribes.

Unless we're talking about obvious genetic defects here, everything else is basically eugenics when applied within a species and driven more by social attitudes as to what characters constitute a 'healthy' or 'acceptable' individual. The basis for genocides. -- Obsidi♠n Soul 09:28, 2 October 2011 (UTC)

Ok, one example. Some of Pygmy peoples have average hight of almost 1 meter. If Pygmy woman married white man, can she give birth without problems? Is her pelvis broad enough? Should she use Caesarean section more often than average?

My mother is Turkish woman and my father is German. I really don't have anything against mixing of nations. I try to understand human evolution. -Ewigekrieg (talk) 10:18, 2 October 2011 (UTC)

She's not exactly going to be giving birth to a six foot baby, heh. In fact, pygmy peoples give birth to newborns of the same average birth weight as that of taller peoples (Average North American birth weight is 7.5 lbs). Here's an account of birth among the Efé people. Besides, the fact that she had gotten pregnant already makes the question of reproductive isolation moot. Pygmy peoples also intermarry with neighboring Bantu peoples, whose heights are similar to European populations. Though it's rather infrequent. AFAIK the only real problems are social/cultural as Mitch Ames also mentions below. And those are not biological per se.-- Obsidi♠n Soul 11:10, 2 October 2011 (UTC)

Yes, I daresay you are right. Thanks for informative discussion -Ewigekrieg (talk) 11:26, 2 October 2011 (UTC)

There may have been "absolutely no biological problems with [Australian Aborigined] interbreeding" with other people, but there were a few social problems - see Half-Caste Act, Stolen Generation. Mitch Ames (talk) 04:24, 2 October 2011 (UTC)

No doubt, but what does that have to do with the biological nature of the original question? Googlemeister (talk) 14:17, 3 October 2011 (UTC)