4 ms·

Somewhat grim, but this has to be disregarding the humans who never reach the reproductive age or the ones who cannot keep their offspring alive. So there is so

by mertd 4y ago

Somewhat grim, but this has to be disregarding the humans who never reach the reproductive age or the ones who cannot keep their offspring alive. So there is some survivorship bias baked into the methodology.

tanbog5 4y ago
If I understand the method correctly, they are actually determining the age that the sample's parents generated dna material that went on to create them. So everyone who has a parent is included - which is everyone who ever lived.
- asgraham 4y ago
  They can't possibly be working with genomes spanning the past 250k years--- the oldest known human remains are only estimated to be ~230k years old, and I doubt they have parent/child trios nicely spanning the intervening few hundred thousand years. So they have to be working on mutation rate inferences. From a non-expert reading of the article, their pipeline is more like: modern human population genomes -> estimates of modern mutations' ages -> estimate of average historical parental ages. The first estimation (genome -> mutation ages) was carried out in a prior study "GEVA" [1], and this paper's contribution seems to be estimating the average parental ages based on those previously estimated historical mutation rates. I couldn't find any mention of using old DNA samples. The GEVA study pulls from two genome databases, TGP [2] and SGDP [3], both of which seem to be entirely modern genomes. I'm not an expert in the field, so maybe it's obvious to a population geneticist that these databases do include old genomes. Given that they're only using modern (surviving) genomes, the critique of survivorship bias seems valid. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992231/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992231/ [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750478/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750478/ [3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5161557/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5161557/
wolverine876 4y ago
It frustrates me that people on HN, an intelligent crowd, draw conclusions without a serious basis. Why not ask, 'Is this study disregarding the humans who never reach the reproductive age or the ones who cannot keep their offspring alive? Is there is some survivorship bias baked into the methodology?' You might find out - we might find out - rather than you guess wrong, never find out, and we all carry the error with us.
- MobiusHorizons 4y ago
  As I understand it, what the OP is saying is not something any study could ever control for without perfectly preserved DNA from a statistically significant sample of DNA from human populations going back to old generations. Any study that uses DNA collected from modern humans will weed out the DNA of humans whose descendants are not living today. Hence survivorship bias.
  - wolverine876 4y ago
    The problem is turning your 2 minute analysis into a conclusion instead of an informed question. The Internet is filled with such conclusions; another adds nothing.
    - ejb999 4y ago
      >>The Internet is filled with such conclusions; another adds nothing. reply Problem is, the internet is also filled with studies that prove or disprove anything you want, best to be skeptical. I personally don't put much credence into any studies that seriously thinks they can make any factual accurate statements about things that may or may not have happened 250,000 years ago. Science is never settled.
- usrusr 4y ago
  The study seems to look exclusively at the outcome in the contemporary gene pool. And not at archeological DNA samples, because then the x axis would be in years not in generations. There's nothing to compensate for or disregard, the study simply does not claim to describe anything it cannot (very indirectly) see.
james4k 4y ago
And maternal mortality rates.
AdrianB1 4y ago
By definition yes. "Average age of people who gave birth include people who never give birth?" or "Is a selection bias to include only people who gave birth in the selection of people who gave birth" sound completely different if asked this way, right?

by mertd 4y ago

tanbog5 4y ago

If I understand the method correctly, they are actually determining the age that the sample's parents generated dna material that went on to create them. So everyone who has a parent is included - which is everyone who ever lived.

asgraham 4y ago
They can't possibly be working with genomes spanning the past 250k years--- the oldest known human remains are only estimated to be ~230k years old, and I doubt they have parent/child trios nicely spanning the intervening few hundred thousand years. So they have to be working on mutation rate inferences. From a non-expert reading of the article, their pipeline is more like: modern human population genomes -> estimates of modern mutations' ages -> estimate of average historical parental ages. The first estimation (genome -> mutation ages) was carried out in a prior study "GEVA" [1], and this paper's contribution seems to be estimating the average parental ages based on those previously estimated historical mutation rates. I couldn't find any mention of using old DNA samples. The GEVA study pulls from two genome databases, TGP [2] and SGDP [3], both of which seem to be entirely modern genomes. I'm not an expert in the field, so maybe it's obvious to a population geneticist that these databases do include old genomes. Given that they're only using modern (surviving) genomes, the critique of survivorship bias seems valid. [1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992231/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6992231/ [2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750478/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4750478/ [3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5161557/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5161557/

wolverine876 4y ago

It frustrates me that people on HN, an intelligent crowd, draw conclusions without a serious basis. Why not ask, 'Is this study disregarding the humans who never reach the reproductive age or the ones who cannot keep their offspring alive? Is there is some survivorship bias baked into the methodology?' You might find out - we might find out - rather than you guess wrong, never find out, and we all carry the error with us.

MobiusHorizons 4y ago
As I understand it, what the OP is saying is not something any study could ever control for without perfectly preserved DNA from a statistically significant sample of DNA from human populations going back to old generations. Any study that uses DNA collected from modern humans will weed out the DNA of humans whose descendants are not living today. Hence survivorship bias.
- wolverine876 4y ago
  The problem is turning your 2 minute analysis into a conclusion instead of an informed question. The Internet is filled with such conclusions; another adds nothing.
  - ejb999 4y ago
    >>The Internet is filled with such conclusions; another adds nothing. reply Problem is, the internet is also filled with studies that prove or disprove anything you want, best to be skeptical. I personally don't put much credence into any studies that seriously thinks they can make any factual accurate statements about things that may or may not have happened 250,000 years ago. Science is never settled.
usrusr 4y ago
The study seems to look exclusively at the outcome in the contemporary gene pool. And not at archeological DNA samples, because then the x axis would be in years not in generations. There's nothing to compensate for or disregard, the study simply does not claim to describe anything it cannot (very indirectly) see.

james4k 4y ago

And maternal mortality rates.

AdrianB1 4y ago

By definition yes. "Average age of people who gave birth include people who never give birth?" or "Is a selection bias to include only people who gave birth in the selection of people who gave birth" sound completely different if asked this way, right?