Mikroskopic Posted January 27, 2011 Posted January 27, 2011 (edited) Ancient body clock discovered that helps to keep all living things on time The mechanism that controls the internal 24-hour clock of all forms of life from human cells to algae has been identified by scientists. Not only does the research provide important insight into health-related problems linked to individuals with disrupted clocks - such as pilots and shift workers - it also indicates that the 24-hour circadian clock found in human cells is the same as that found in algae and dates back millions of years to early life on Earth. Two new studies out tomorrow, 27 January, in the journal Nature from the Universities of Cambridge and Edinburgh give insight into the circadian clock which controls patterns of daily and seasonal activity, from sleep cycles to butterfly migrations. One study, from the Institute of Metabolic Science at the University of Cambridge, has for the first time identified 24-hour rhythms in red blood cells. This is significant because circadian rhythms have always been assumed to be linked to DNA and gene activity, but - unlike most of the other cells in the body - red blood cells do not have DNA. Akhilesh Reddy, from the University of Cambridge and lead author of the study, said: "We know that clocks exist in all our cells; they're hard-wired into the cell. Imagine what we'd be like without a clock to guide us through our days. The cell would be in the same position if it didn't have a clock to coordinate its daily activities. ! Moderator Note Quote snipped; copyrighted material. Use the link to read the whole article Edited January 30, 2011 by swansont copyright 1
TonyMcC Posted January 27, 2011 Posted January 27, 2011 (edited) Quite surprising when the length of a day has just about doubled since life first began on earth. http://www.scribd.com/doc/9498374/Length-of-DayEarth-rotation http://wiki.answers.com/Q/How_did_life_on_earth_start Edited January 27, 2011 by TonyMcC
Marat Posted January 27, 2011 Posted January 27, 2011 Experiments with human subjects kept for extended periods of time at the bottom of a mineshaft with no natural light sources and no clocks, and thus no ability to receive cues from the environment as to what time it is, have shown that they all quickly adjust to a 25-hour wake-sleep cycle. This finding has been cited to explain why humans need alarm clocks to wake up at the same time every day, while other animals seem to maintain a 24-hour cycle naturally. So how can this latest discovery be reconciled with those previous results suggesting a natural 25-hour diurnal cycle for humans?
CharonY Posted January 27, 2011 Posted January 27, 2011 You have to understand that these circadian clocks are not precise. One single cycle has individual-to individual variation, as well as day-to-day variation. 24h is just the approximate for the diurnal cycle. The studies that analyzed human behavior found anything between 23-27h cycles, with an average close to 25. 1
Mr Skeptic Posted January 27, 2011 Posted January 27, 2011 Experiments with human subjects kept for extended periods of time at the bottom of a mineshaft with no natural light sources and no clocks, and thus no ability to receive cues from the environment as to what time it is, have shown that they all quickly adjust to a 25-hour wake-sleep cycle. This finding has been cited to explain why humans need alarm clocks to wake up at the same time every day, while other animals seem to maintain a 24-hour cycle naturally. So how can this latest discovery be reconciled with those previous results suggesting a natural 25-hour diurnal cycle for humans? If anything if the days used to be shorter, than our cycle would be expected to be shorter than a full day, not longer.
Sisyphus Posted January 27, 2011 Posted January 27, 2011 Experiments with human subjects kept for extended periods of time at the bottom of a mineshaft with no natural light sources and no clocks, and thus no ability to receive cues from the environment as to what time it is, have shown that they all quickly adjust to a 25-hour wake-sleep cycle. This finding has been cited to explain why humans need alarm clocks to wake up at the same time every day, while other animals seem to maintain a 24-hour cycle naturally. So how can this latest discovery be reconciled with those previous results suggesting a natural 25-hour diurnal cycle for humans? It doesn't seem credible that humans would naturally have a 25 hour cycle while all other animals would naturally have a 24 hour cycle. Do other animals, when kept for extended periods of time at the bottom of mineshafts, maintain 24 hour cycles? How consistent is the 25 hour cycle for humans? Is it merely an average in a wide range? Do all other animals, in fact, keep rigid schedules by clock's time, or do they, for example, go by sunrise and sunset? Furthermore, just anecdotally, I get up at the same time every day, without an alarm clock. (I have one, but I haven't failed to wake up shortly before it goes off in probably years.)
CharonY Posted January 27, 2011 Posted January 27, 2011 Bottom line, molecular rhythms have (surprise!) inherent variability that can adapt to external stimuli.
Marat Posted January 28, 2011 Posted January 28, 2011 Sisyphus: There is a group of scientific outsiders who claim that the 25-hour diurnal cycle experimentally revealed for humans in contrast to all other beings suggests that we really come from Mars, not the Earth, as other species do.
Paradox of Vigor Posted January 29, 2011 Posted January 29, 2011 Sisyphus: There is a group of scientific outsiders who claim that the 25-hour diurnal cycle experimentally revealed for humans in contrast to all other beings suggests that we really come from Mars, not the Earth, as other species do. That is interesting. Does Mars have a 25-hour revolution or spin cycle?
Sisyphus Posted January 30, 2011 Posted January 30, 2011 Sisyphus: There is a group of scientific outsiders who claim that the 25-hour diurnal cycle experimentally revealed for humans in contrast to all other beings suggests that we really come from Mars, not the Earth, as other species do. So in other words, it is not even true, as I suspected. The 25 hour thing for humans was based on flawed and now discredited research, and humans are not at all unique in not keeping perfect 24 hour time themselves: http://en.wikipedia.org/wiki/Circadian_rhythm
D H Posted January 30, 2011 Posted January 30, 2011 Quite surprising when the length of a day has just about doubled since life first began on earth. http://www.scribd.co...yEarth-rotation http://wiki.answers...._on_earth_start The first article is from Progress in Physics, which is a wacko journal. The author pulled numbers from a 1963 study rather than using more recent data. His equation does not jibe with the physics of tidal recession. All other things being equal, tidal torque varies with the inverse of the cube of the Earth-Moon distance. The vast majority of the lengthening of the length of day occurred when the Earth-Moon system was very young. His curve has this backwards. A better estimate is that length of day has increased by about 1/4 since complex life first formed. When you incorporate CharonY's observation the issue with the increasing length of day disappears.
TonyMcC Posted January 30, 2011 Posted January 30, 2011 The first article is from Progress in Physics, which is a wacko journal. A better estimate is that length of day has increased by about 1/4 since complex life first formed. When you incorporate CharonY's observation the issue with the increasing length of day disappears. I stand corrected. I knew the length of a day had increased and accepted what I found on the web.
Oldman Posted February 27, 2011 Posted February 27, 2011 I can sort of prove that a system has its own clock -- employing physics. The following is from my research work in physics. Time is meaningless in the absence of mass. Time exists in the presence of mass. Time runs slower closer to mass. Time virtually stops in the vicinity of an infinitely high point-dense mass. That is, the run of time depends on the quantity of and proximity to mass, or on the strength of gravitational interaction. Perhaps the genesis of time lies in interactions; perhaps an interaction works with its own time. If so, two systems (inanimate or animate), for they have interacting constituents, have different internal clocks; as interactions between the constituents of a system change, its internal time run changes also. Time in other fundamental fields is not clear. Given the relative strengths of the fundamental interactions (g : w : e : s ≈ 1 : 1030 : 1040 : 1042), time periods should be dilated in similar proportions under them. (Electrons and protons could be ‘immortal’ after all.)
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