Various comments to various posts, not going to go through and quote everything since I can't look at the site while at work, but here goes.
According to the wiki article I linked Pete, the ratio of male to female births appears to be between 1.03 and 1.07 male to female. I know we tend to see a stable population around 48% male to 52% female, but actual birth ratio according to the article gives the edge to males. Also, for the western cultures and Japan, all countries have seen significant losses in the males due to wars since the mid 19th century into the mid 20th century. This has had to have a definite curtailing of the male population in western countries including Japan.
As to population stability, I've seen figures, using an exponential growth curve that state that given present death rates (this could easily change as humanity becomes more healthy and infant mortality in third world nations and devolping nations falls) that each generation needs to have 2.3 children per procreating pair to maintain the status quo on population levels, ie, no loss of population no gain in population. This means that countries like China and Western developed countries where birth rates are seen to be below 2.3 will see a lowering of the population over time. The more drastic the cut in births per procreating pair, the more drastic the population drop per generation (which is why I showed China dropping below 1 Billion in 3 to 4 generations if the one child law keeps up along with the imbalance seen of having more males to females, about 6 to 5 by China's count, more like 4 to 3 or even 3 to 2 according to other outside sources lowering the number of procreating pairs further).
As to supervolcanism, ie caldera volcanos, Yellowstone Caldera has a known cycle of 600,000 to 800,000 years. Geologists have noted a rise in the park of 6 inches in just 30 years time and 1 foot in the course of one century. The magma is definitely building in Yellowstone, but it is unknown when Yellowstone will go, but we're definitely seeing something going on with a definite increase in activity since the late 70s, early 80s compared the prior 70 years before that. Will Yellowstone go in our lifetimes, who knows, but it definitely is a sleeping giant ready to go much like Krakatoa did some 70,000 years ago which wiped out most of the Genus Homo at the time (scientists know that Species Sapiens dropped to just over 1000 individuals at the time from looking at mitochondrial DNA).
As to decline being linear, I'm not sure I agree with that. There are a lot of factors for the death of population besides general old age. You have to take into account infant mortality in third world and developing nations, you have to account for accidents, there is also the factor of general crime and/or warfare in a population, along with effects of disease, hazards in the environment either through human cause or through natural cause, and finally the amount of resources to produce food. Wealthier nations will show a propensity for a lower death rate while as poorer countries will show a rise in death rate. Again, these affects are less likely to be linear and more likely to be exponential much like birth rate.
According to the wiki article I linked Pete, the ratio of male to female births appears to be between 1.03 and 1.07 male to female. I know we tend to see a stable population around 48% male to 52% female, but actual birth ratio according to the article gives the edge to males. Also, for the western cultures and Japan, all countries have seen significant losses in the males due to wars since the mid 19th century into the mid 20th century. This has had to have a definite curtailing of the male population in western countries including Japan.
As to population stability, I've seen figures, using an exponential growth curve that state that given present death rates (this could easily change as humanity becomes more healthy and infant mortality in third world nations and devolping nations falls) that each generation needs to have 2.3 children per procreating pair to maintain the status quo on population levels, ie, no loss of population no gain in population. This means that countries like China and Western developed countries where birth rates are seen to be below 2.3 will see a lowering of the population over time. The more drastic the cut in births per procreating pair, the more drastic the population drop per generation (which is why I showed China dropping below 1 Billion in 3 to 4 generations if the one child law keeps up along with the imbalance seen of having more males to females, about 6 to 5 by China's count, more like 4 to 3 or even 3 to 2 according to other outside sources lowering the number of procreating pairs further).
As to supervolcanism, ie caldera volcanos, Yellowstone Caldera has a known cycle of 600,000 to 800,000 years. Geologists have noted a rise in the park of 6 inches in just 30 years time and 1 foot in the course of one century. The magma is definitely building in Yellowstone, but it is unknown when Yellowstone will go, but we're definitely seeing something going on with a definite increase in activity since the late 70s, early 80s compared the prior 70 years before that. Will Yellowstone go in our lifetimes, who knows, but it definitely is a sleeping giant ready to go much like Krakatoa did some 70,000 years ago which wiped out most of the Genus Homo at the time (scientists know that Species Sapiens dropped to just over 1000 individuals at the time from looking at mitochondrial DNA).
As to decline being linear, I'm not sure I agree with that. There are a lot of factors for the death of population besides general old age. You have to take into account infant mortality in third world and developing nations, you have to account for accidents, there is also the factor of general crime and/or warfare in a population, along with effects of disease, hazards in the environment either through human cause or through natural cause, and finally the amount of resources to produce food. Wealthier nations will show a propensity for a lower death rate while as poorer countries will show a rise in death rate. Again, these affects are less likely to be linear and more likely to be exponential much like birth rate.
Sith Warriors - They only class that gets a new room added to their ship after leaving Hoth, they get a Brooncloset
Einstein said Everything is Relative.
Heisenberg said Everything is Uncertain.
Therefore, everything is relatively uncertain.
Einstein said Everything is Relative.
Heisenberg said Everything is Uncertain.
Therefore, everything is relatively uncertain.