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August 6 Information
Which human ancestors invented fire?
In the course of evolutionary history ,Which human ancestors invented fire?
Roasting, stewing, frying, and baking of food with fire could be considered "inventions," since at the time they were new and useful processes, resulting from happy accidents, or from observation and experimentation.
Edison (
talk)
14:47, 6 August 2013 (UTC)reply
There is also a distinction between those who used fire that they found in their environment (from forest fires, lightning, volcanoes, whatever) and those who created the means to make it from scratch. The latter would definitely be an "invention"...and I think that this is what we should probably be discussing here.
SteveBaker (
talk)
16:25, 6 August 2013 (UTC)reply
Generally, covalent network solids (like diamond, silicon, Bakelite, etc.) melt WITHOUT ionizing. Can you give an example of a covalent solid that ionizes as it melts?
24.23.196.85 (
talk)
04:56, 6 August 2013 (UTC)reply
Not generally, that is an over-simplification taught in secondary schools, just like "the conjugate of a weak base, is a strong acid" which is not strictly true either. See
aluminium fluoride for an example of a covalent metal fluoride.
Plasmic Physics (
talk)
05:51, 6 August 2013 (UTC)reply
It will be the other way around -- the solid will first break into neutral molecules, which may then self-ionize (but only to a small extent).
24.23.196.85 (
talk)
01:41, 7 August 2013 (UTC)reply
Is solid oxonium hydroxide stable under pressure, or does it require an applied electric field? I wonder how the density would be different from ice.
Plasmic Physics (
talk)
07:14, 6 August 2013 (UTC)reply
I ask because I know that an equilibrium shift can occur as a consequence of a change in pressure, I also know that this is only applicable to gases, as solids and liquids are incompressible. However, I also know that that last bit is only true for relatively small changes in pressure. Solids and liquids can actually compress under MPa pressures and higher. So, I wondered if MPa or greater pressures, could indeed shift the Kw away from water.
Plasmic Physics (
talk)
02:27, 7 August 2013 (UTC)reply
If you're looking for a solid composed entirely of H3O+ and OH- ions, you won't find it anywhere -- such a solid cannot exist because of energy considerations. Only in a
plasma can water be completely ionized!
24.23.196.85 (
talk)
04:11, 7 August 2013 (UTC)reply
I care to know what these energy considerations are - Gibbs, entropy, enthalpy, etc. (FYI I thought that the water decomposes into the elements before becoming a gas plasma.)
Plasmic Physics (
talk)
04:18, 7 August 2013 (UTC)reply
In the Jamestown colony, most of the settlers died their first year. Lack of food was a cause, but they also died from malaria, dysentery and "fevers." The local germs may have been strains they had not encountered back in Britain. The river water may have been nasty, but so were many rivers in England. The local natives were likely not only living in healthier locations, but probably had more natural resistance to the local pathogens.
Edison (
talk)
14:39, 6 August 2013 (UTC)reply
Jared Diamond wrote perhaps
the definitive work on this exact subject (at least as far as material that is accessible to a wide audience), if you're looking to understand the subject in detail. I recommend the book in any event as a must-read, but here's the long and the short of it - animal domestication. Most infectious diseases pass into the human population for the first time as a result of
zoonosis and as Eurasians had been living in close proximity with their domesticated species for many thousands of years by the point of time in question, they had built a healthy collection of diseases, but also had steadily built immunities to the same, limiting their virulence. Native Americans, by comparison, had only a handful of domesticated species (only a very small portion of all species on the planet possess a social nature and other features which make them good candidates for steady and lasting domestication through the methods that are available to a non-technologically advanced people), which were not very well dispersed geographically and as such had not developed nearly as extensive a collection of diseases/immunities. Unfortunately for these peoples, they also lacked the immunities necessary to protect them against the diseases brought with Europeans, and even the pathogens that had relatively mild effects on their Eurasian hosts of this era could in some cases prove deadly to their new American hosts, to say nothing of a disease like small pox, which spread well in advance of the Europeans themselves.
Snow (
talk)
00:27, 7 August 2013 (UTC)reply
Another factor was that indigenous Americans, having had little experience with deadly epidemics, did not have cultural coping techniques like
quarantine. They learned, to be sure, and survival rates went up when practices like quarantine were enforced. But at first the natural reaction was exactly the kind of thing that exacerbates epidemics. This is beside the point of why did not "american diseases kill the europeans?" Folks like Jared Diamond have tackled that quite well.
Pfly (
talk)
10:37, 8 August 2013 (UTC)reply
One codon equals three base pairs, so there is 1/3 of a codon per base pair. Estimates of the number of base pairs in the human genome vary a bit due to technical reasons, but the most recent value I've seen is around 6.3 billion (in women, with two X chromosomes rather than an X and a Y). Since each base pair contains two bits of information, that yields slightly under 1.6 GB of information.
Looie496 (
talk)
00:11, 7 August 2013 (UTC)reply
You can download each chromosome (or those for any of 50 or 60 other species)
here. If you grab the "GBK" file, you can unzip it and watch a sea of A's, G's, C's and T's scroll by. I was able to download the full set within a minute or so...and with compression - the whole thing fits comfortably onto a double-sided CD-ROM. You don't even need a DVD, let alone a BluRay disk. It's kinda humbling actually. :-)
SteveBaker (
talk)
02:36, 7 August 2013 (UTC)reply
Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the
current reference desk pages.
August 6 Information
Which human ancestors invented fire?
In the course of evolutionary history ,Which human ancestors invented fire?
Roasting, stewing, frying, and baking of food with fire could be considered "inventions," since at the time they were new and useful processes, resulting from happy accidents, or from observation and experimentation.
Edison (
talk)
14:47, 6 August 2013 (UTC)reply
There is also a distinction between those who used fire that they found in their environment (from forest fires, lightning, volcanoes, whatever) and those who created the means to make it from scratch. The latter would definitely be an "invention"...and I think that this is what we should probably be discussing here.
SteveBaker (
talk)
16:25, 6 August 2013 (UTC)reply
Generally, covalent network solids (like diamond, silicon, Bakelite, etc.) melt WITHOUT ionizing. Can you give an example of a covalent solid that ionizes as it melts?
24.23.196.85 (
talk)
04:56, 6 August 2013 (UTC)reply
Not generally, that is an over-simplification taught in secondary schools, just like "the conjugate of a weak base, is a strong acid" which is not strictly true either. See
aluminium fluoride for an example of a covalent metal fluoride.
Plasmic Physics (
talk)
05:51, 6 August 2013 (UTC)reply
It will be the other way around -- the solid will first break into neutral molecules, which may then self-ionize (but only to a small extent).
24.23.196.85 (
talk)
01:41, 7 August 2013 (UTC)reply
Is solid oxonium hydroxide stable under pressure, or does it require an applied electric field? I wonder how the density would be different from ice.
Plasmic Physics (
talk)
07:14, 6 August 2013 (UTC)reply
I ask because I know that an equilibrium shift can occur as a consequence of a change in pressure, I also know that this is only applicable to gases, as solids and liquids are incompressible. However, I also know that that last bit is only true for relatively small changes in pressure. Solids and liquids can actually compress under MPa pressures and higher. So, I wondered if MPa or greater pressures, could indeed shift the Kw away from water.
Plasmic Physics (
talk)
02:27, 7 August 2013 (UTC)reply
If you're looking for a solid composed entirely of H3O+ and OH- ions, you won't find it anywhere -- such a solid cannot exist because of energy considerations. Only in a
plasma can water be completely ionized!
24.23.196.85 (
talk)
04:11, 7 August 2013 (UTC)reply
I care to know what these energy considerations are - Gibbs, entropy, enthalpy, etc. (FYI I thought that the water decomposes into the elements before becoming a gas plasma.)
Plasmic Physics (
talk)
04:18, 7 August 2013 (UTC)reply
In the Jamestown colony, most of the settlers died their first year. Lack of food was a cause, but they also died from malaria, dysentery and "fevers." The local germs may have been strains they had not encountered back in Britain. The river water may have been nasty, but so were many rivers in England. The local natives were likely not only living in healthier locations, but probably had more natural resistance to the local pathogens.
Edison (
talk)
14:39, 6 August 2013 (UTC)reply
Jared Diamond wrote perhaps
the definitive work on this exact subject (at least as far as material that is accessible to a wide audience), if you're looking to understand the subject in detail. I recommend the book in any event as a must-read, but here's the long and the short of it - animal domestication. Most infectious diseases pass into the human population for the first time as a result of
zoonosis and as Eurasians had been living in close proximity with their domesticated species for many thousands of years by the point of time in question, they had built a healthy collection of diseases, but also had steadily built immunities to the same, limiting their virulence. Native Americans, by comparison, had only a handful of domesticated species (only a very small portion of all species on the planet possess a social nature and other features which make them good candidates for steady and lasting domestication through the methods that are available to a non-technologically advanced people), which were not very well dispersed geographically and as such had not developed nearly as extensive a collection of diseases/immunities. Unfortunately for these peoples, they also lacked the immunities necessary to protect them against the diseases brought with Europeans, and even the pathogens that had relatively mild effects on their Eurasian hosts of this era could in some cases prove deadly to their new American hosts, to say nothing of a disease like small pox, which spread well in advance of the Europeans themselves.
Snow (
talk)
00:27, 7 August 2013 (UTC)reply
Another factor was that indigenous Americans, having had little experience with deadly epidemics, did not have cultural coping techniques like
quarantine. They learned, to be sure, and survival rates went up when practices like quarantine were enforced. But at first the natural reaction was exactly the kind of thing that exacerbates epidemics. This is beside the point of why did not "american diseases kill the europeans?" Folks like Jared Diamond have tackled that quite well.
Pfly (
talk)
10:37, 8 August 2013 (UTC)reply
One codon equals three base pairs, so there is 1/3 of a codon per base pair. Estimates of the number of base pairs in the human genome vary a bit due to technical reasons, but the most recent value I've seen is around 6.3 billion (in women, with two X chromosomes rather than an X and a Y). Since each base pair contains two bits of information, that yields slightly under 1.6 GB of information.
Looie496 (
talk)
00:11, 7 August 2013 (UTC)reply
You can download each chromosome (or those for any of 50 or 60 other species)
here. If you grab the "GBK" file, you can unzip it and watch a sea of A's, G's, C's and T's scroll by. I was able to download the full set within a minute or so...and with compression - the whole thing fits comfortably onto a double-sided CD-ROM. You don't even need a DVD, let alone a BluRay disk. It's kinda humbling actually. :-)
SteveBaker (
talk)
02:36, 7 August 2013 (UTC)reply