Recent comments in /f/Showerthoughts

SpecialistAd5537 t1_jaa9ous wrote

Reply to comment by batsofburden in There's been tens of thousands of generations of humans, yet even those just 3 generations back are already forgotten by most living humans. by batsofburden

There have been a number of evidences recently that the human race is very young. For example, a recent issue of Science (Collins, F., M. Guyer, and A. Chakravarti, "Variations on a Theme: Human DNA Sequence Variation," Science 278:1580-1581, 28 November 1997, page 1581) said that the age of the human race is roughly 1,000 to 10,000 generations: ... 1000 to 10,000 generations old, which is roughly the age of the human population, ...

We review some of this evidence for the youth of the human race, including recent findings concerning mitochondrial DNA mutation rates which give even a much younger age than 1,000 generations. Age estimates are obtained by observing differences between the DNA of different individuals, and are calculated using estimates of mutation rates. Mitochondrial DNA is often used for this; it is separate from the bulk of the human DNA, which is found in the cell nucleus. Mitochondrial DNA has about 16,000 base pairs and mutates, apparently, much faster than the nuclear DNA. Human mitochondrial DNA has been completely mapped, and all the coding regions are known, and the proteins or RNA for which they code. Some of the mitochondrial DNA does not code for anything, and is known as a control region. This region appears to mutate faster than any other region, because the variation among humans is greatest here.

Recently, mitochondrial DNA mutation rates were measured directly (Parsons, Thomas J., et al., A high observed substitution rate in the human mitochondrial DNA control region, Nature Genetics vol. 15, April 1997, pp. 363-367). The mutation rate in a segment of the control region of mitochondrial DNA was directly measured by comparing mitochondrial DNA from siblings and from parents and their offspring. Mitochondrial DNA was found to mutate about 20 times faster than previously thought, at a rate of one mutation (substitution) every 33 generations, approximately. In this section of the control region, which has about 610 base pairs, humans typically differ from one another by about 18 mutations. By simple mathematics, it follows that the human race is about 300 generations old. If one assumes a typical generation is about 20 years, this gives an age of about 6000 years.

I guess your opinion discredits DNA science all together...

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Showerthoughts_Mod t1_jaa972r wrote

Reply to A version of each of us lives in the minds of other people - from a person who briefly sees us out on the street, to our closest loves ones who know us for decades, and everyone in between. by Ibrake4tailgaters

This is a friendly reminder to read our rules.

Remember, /r/Showerthoughts is for showerthoughts, not "thoughts had in the shower!"

(For an explanation of what a "showerthought" is, please read this page.)

Rule-breaking posts may result in bans.

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xanthraxoid t1_jaa741k wrote

Reply to Someone who lets you in their lane may be using your car as a body shield for the large truck in front of them instead of the kindness of their heart by The_Expidition

Another possibility is that they're not "letting you in" to use you "as a body shield" but they're leaving a sensible amount of empty space "as a body shield" and you've just put your car in the middle of a potential collision zone.

LPT: leave a good healthy gap in front of you. Remember that "two second rule"?* Try counting it out some time, it's probably further than you think. 90+% of drivers I see are within a second, and an alarmly non-zero amount significantly closer than that!

And it's really not as patronising as it feels, either. Even if you're focussed on driving (and let's face it, it's very easy to have your attention divided or entirely displaced for short periods while driving) it'll take you about a second to respond to a sudden need to slow, so if you're within a second of the vehicle in front, there's a good chance you'll hit it even in the most favourable of circumstances.

I've had a couple of accidents where I've used up all of my two second gap and more - including one recently. Please take this seriously!

* Oh, and that's for dry roads. Double it for wet, triple it for salted, and multiply it by ten for ice/snow.

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