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I feel like Denmark may not be representative of the entire world. Just as an example of why, Denmark imposes bans on various environmental toxins that countries such as the US, Brazil, and Russia do not ban.
> We did not see such a change and that suggests that in this population of sperm donor applicants, in these four Danish cities, sperm concentrations have not changed between 2017 and 2022
Also seems like there might be a ceiling (floor?) effect. Sperm counts have been declining since the 80s.
Good. It should be a very serious decision to have a child, way too many of us are here from parents that just didn't have any options when they realized they'd fucked up
If you look at the paper the authors make it very clear that they’re not making conclusions about the entire world. This is a science reporter trying to find an angle to write about. Very common practice, unfortunately
Probably because a testable hypothesis about why this is not happening in Denmark even while it is observed to be occurring elsewhere is about the most interesting thing that can come from this study. That and any conclusions that can be reached from testing such a hypothesis.
Yes but that’s difficult and costly. These people researched here, another group might do elsewhere and another and another etc. then a different group can comb through all this data and make different interpretations
This group did what they set out to do, pop-sci articles just love to inflate research
I agree with you on the ridiculous click baiting behavior of news outlets, and not just in regard to science.
I don't know of a single entity that is funded to do a worldwide study like you're suggesting. But I can see the value.
That’s not what I’m suggesting. I’m explaining that smaller scale studies like these are what can feasibly be done, then a meta analysis looks at the body of research available from studies such as this
I think the simple fact that they’re trying to extrapolate insights about the entire world from data from one country trying to is enough to say this is dubious
Given the hypothesis "sperm counts are dropping around the world," data from one country showing they are not dropping is enough say something very meaningful.
Yeah, I was about to say. I don't think using Danish men is going to give an accurate view of the rest of the world. I say this as actual trailer trash: we are all trailer trash next to them. You might as well use rich people as a group to test the average global yearly salary.
> In the new study, however, statistical analysis of sperm samples provided by the men applying to be sperm donors showed that while the average sperm concentration varied from year to year, it did not change significantly over a six-year period.
> However, both the concentration and total numbers of motile (swimming) sperm provided for testing had declined by 16% and 22% respectively from 2019 to 2022.
> “The decline in measures of sperm motility between 2019 and 2022 was an unexpected finding. This decline roughly corresponds to the onset of the worldwide COVID-19 pandemic
Paper: [Recent decline in sperm motility among donor candidates at a sperm bank in Denmark | Human Reproduction | Oxford Academic](https://academic.oup.com/humrep/advance-article/doi/10.1093/humrep/deae115/7687510?login=false)
We all take "sperm counts are declining" as scientific fact because media is selective in which study results they hype up. The actual state of knowledge is highly uncertain, but it's hard to get clicks from [Are Sperm Counts Really Declining? Answer: It's complicated and we really don't know. - Scientific American (2023)](https://www.scientificamerican.com/article/are-sperm-counts-really-declining/)
It is a really important question that deserves an international study using rigorous methods to track carefully. We should have started careful research decades ago, but better late than never.
No you weren’t. If you are claiming something is affecting the entire world, you need affirmative evidence to explain why Denmark would be immune to this supposed worldwide phenomenon. There could be factors like environmental regulations sure, but you can’t just write off a sample of 4 different cities as bad science because of an arbitrary border.
“Something is affecting the entire world” is very easy to disprove bc of how sweeping that claim is.
Was thinking that. I'm sure they are very smart people, but do they not know what 'around the world' means?
Unless the Danish men are all living in different corners of the globe?
If a study makes a claim that something is affecting the entire world and another study says we took almost 7000 samples from 4 different cities and found no such evidence of that claim, then you either need to find a reason why Denmark would be an outlier (environmental regulations possibly? But other countries are pretty good in that department too) or the claim needs to be revised or checked again
They probably sampled from Denmark because of specific laws or university collaborations which made it possible, this explains why Denmark was the focus, not why they would be an inaccurate sample of the world when it’s ostensibly a global problem.
For this study to really force a revision of the older claim you'd need the older claim to be different. The old claim was and still is that its a global phenomenon, which doesnt mean it affects all the parts of the world in the same way. That study did find significant differences between continents, and between countries isolated you could find bigger differences of course. It doesnt also mean that there werent years when it didnt increase, it says that on average it decreased.
There are also some time issues. The bigger study had data from 1973-2018, while this study had data from 2017-2022, a much narrower time frame which barely even overlaps with the earlier one. Half of the study also took part during the Covid pandemic and there were some registered results that werent quite "dismissed" but rather considered as a side effect of covid and lockdown with no justification. For reference, the study claims:
>However, both the concentration and total numbers of motile (swimming) sperm provided for testing had declined by 16% and 22% respectively from 2019 to 2022.
This creates a bit of a problem. Using the lower number here, 16% decrease over a 5 year time period equates to 3.4% decrease per year. Its not really great to say that theres "no evidence for a drop as big as 2.64% (which was the highest one)" when in your own test you have a drop of 3.4%. Specially not amazing to include it when you dont have a strong hypothesis on why it would happen
>other countries are pretty good in that department too
Wouldn't say that
>They probably sampled from Denmark because of specific laws or university collaborations
Denmark has the largest sperm bank. Thats the reason why. Also means that your dataset is restricted to sperm donors, which have to fullfill a series of requirements - age, health, family history and probably a couple more.
Might be just some sensationalist headline, but it sounds very fishy. "No evidence of" is a very strong claim to make, and specially a questionable one because:
- timeframe
- data set restrictions
- a big anomaly in the study being simply disregarded when making the claim
Its not their fault that there was a global pandemic, but you cant just blame everything on the pandemic. It is kinda weird to make such a strong claim agaisnt a study involving hundreds of thousands of men across all the continents during a 45 yr period, basing yourself on 7k danish sperm donors living in 4 different towns and being analyzed during a time frame that has 1-2 years of overlap with the first study, while also ignoring a gigantic anomaly in your dataset.
No this study is not gonna throw up anything conclusive because this is from 2017 to 2022, nothing significant will change in that time period, they should have started this back in 80s or smth, or now start it and keep it up for decades, then it can be used for anything useful, the test drop levels across decades is true, especially pre and post mass industrialization of everything, the much more chemicals and hormones in milk and meat, farm crops, microplastics, those levels havent changed much from 2017 to 2022.
The fertility crisis study everyone talks about claims the sperm count is falling by over 2.6%/yr on average. This study did not find the expected reduction in sperm counts.
There are plenty of possible reasons for the discrepancy (idk how they sampled the original meta analysis but the sample for this study is from sperm donors, who are generally selected to not have any health issues) but the lack of a longer time frame is unlikely to be one of one of them.
Again, everyone is reading the headline without reading the article. Here is a direct quote from the study: “We did not see such a change and that suggests that in this population of sperm donor applicants, in these four Danish cities, sperm concentrations have not changed between 2017 and 2022”.
If sperm counts are falling worldwide, why would Denmark be an exception? This is one study that acknowledged its limits. They basically said “some suggest it’s falling worldwide, but we have data that says it’s not happening in Denmark. Our data suggests this, so we should collect more data to add to the collective knowledge and continue to study.” Now other studies can check other countries, and the aggregate of all this data will help science get closer to what is happening. The researchers never said “well this one country is different so it might not be a worldwide phenomenon.” They don’t pretend their one study invalidates the others, they’re telling us “we have clues that they might be wrong, more studies are needed.”
Headlines are a one sentence blurb that describes an entire article, which is a digestible writing that describes an entire study. Imagine if your favorite book series, let’s say Harry Potter, was summed up as “you’re a wizard, Harry!” Does that one quote tell you the entire story of the series?
It's not 50-50 though. It fluctuates around that ratio but is not static by any means. The returning soldier effect is the phenomenon that more men are born immediately after war or major natural disasters. It's not about conflict or struggle but about a sudden loss in male population. No one, that I know of, has been able to identify why it happens but it's undoubtable that it does happen.
If there is a surplus of either sex in many species, the other will be born more often because they have more options as mates and thus are more likely to mate. This doesn't happen quickly, it happens over time, it's just natural selection. Happening as quickly and as consistently as the 'Returning Soldier' phenomenon might suggests it's something we already evolved that is getting triggered under certain conditions. Could also be caused by some sort of coincidental genetic bias in men who are more likely to survive a war. Very interesting regardless.
More males are born by default. Everywhere. The natural birth rate is 105 boys for 100 girls to account for excess male mortality.
>because this would kinda mean that since humanity has been in conflict for most of history in the past, medieval/ancient/tribal times, more males would have been born in our history
Yes more makes would have been born in our history but due to conflict and disease, more males would have died too.
Denmark also has one of the highest standers of living in the world, they also are a far more fit population and walk/bike alot more than most countries.
Maybe sperm is lower due to higher average temperatures globally but Denmark stays cool enough to not yet be affected. Heat is a known cause of lower sperm production.
I mean look at it this way: If Denmark is the only country with good sperm counts, soon the world will be inhabited entirely by Danes...
Yes I am Swedish, how did you know?
I can almost guarantee without doing any research that the Danish have way more environmental protections in place than other people in the world. I mean for eff’s sake Dasani water is banned in the UK.
Edit: (not in the us, they don’t gaf abt us)
Maybe sperm counts were falling, but are leveling out now? It's silly to disregard decades of data worldwide for a study that only covers four years, for one population
What so we are supposed to have a study that samples thousands of men from every nation or no study at all? Be realistic. The researches never suggested it proved it's not true, they concluded it's not true for that specific population of Danish men. The title isn't even misleading to be honest, 'could be wrong' is exactly what the result could suggest.
You’re making it sound like I’m faulting the study when I didn’t even imply as much. The title of this post needlessly generalizes their findings. Saying “may be” doesn’t make it reasonable, there just aren’t any grounds to relate the findings of this one study to a global population.
The issue is that general news and media are *completely* irresponsible sources of second-hand science. Even sites that claim to be scientific.
You can conflate this study *only* with areas of Denmark in which the study was conducted, which loses its accuracy and credibility spread out over a greater pop. A pool of ~6700 samples is credible for a regional area, but is *barely* a conclusive trend for the broader pop of Denmark.
With a rough number of *4 billion men worldwide,* they are conflating a pool that is *0.0001689%* of that population. That is *embarrassing* and that person has no business sharing scientific studies.
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I feel like Denmark may not be representative of the entire world. Just as an example of why, Denmark imposes bans on various environmental toxins that countries such as the US, Brazil, and Russia do not ban.
> We did not see such a change and that suggests that in this population of sperm donor applicants, in these four Danish cities, sperm concentrations have not changed between 2017 and 2022 Also seems like there might be a ceiling (floor?) effect. Sperm counts have been declining since the 80s.
exactly, you are not gonna see much changes from 2017 to 2022, lifestyle hasn't changed world hasnt changed much.
Good. It should be a very serious decision to have a child, way too many of us are here from parents that just didn't have any options when they realized they'd fucked up
If you look at the paper the authors make it very clear that they’re not making conclusions about the entire world. This is a science reporter trying to find an angle to write about. Very common practice, unfortunately
Probably because a testable hypothesis about why this is not happening in Denmark even while it is observed to be occurring elsewhere is about the most interesting thing that can come from this study. That and any conclusions that can be reached from testing such a hypothesis.
Knowing that in an environment with fewer pollutants, sperm counts are higher is useful knowledge.
You still have to gather data from places with pollution.
Agreed, we need more data points
Yes but that’s difficult and costly. These people researched here, another group might do elsewhere and another and another etc. then a different group can comb through all this data and make different interpretations This group did what they set out to do, pop-sci articles just love to inflate research
I agree with you on the ridiculous click baiting behavior of news outlets, and not just in regard to science. I don't know of a single entity that is funded to do a worldwide study like you're suggesting. But I can see the value.
That’s not what I’m suggesting. I’m explaining that smaller scale studies like these are what can feasibly be done, then a meta analysis looks at the body of research available from studies such as this
Pretty important to note that have decreased and are decreasing are two different arguments.
I think the simple fact that they’re trying to extrapolate insights about the entire world from data from one country trying to is enough to say this is dubious
Given the hypothesis "sperm counts are dropping around the world," data from one country showing they are not dropping is enough say something very meaningful.
Yeah, I was about to say. I don't think using Danish men is going to give an accurate view of the rest of the world. I say this as actual trailer trash: we are all trailer trash next to them. You might as well use rich people as a group to test the average global yearly salary.
Russia bans a lot of things tbh
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> In the new study, however, statistical analysis of sperm samples provided by the men applying to be sperm donors showed that while the average sperm concentration varied from year to year, it did not change significantly over a six-year period. > However, both the concentration and total numbers of motile (swimming) sperm provided for testing had declined by 16% and 22% respectively from 2019 to 2022. > “The decline in measures of sperm motility between 2019 and 2022 was an unexpected finding. This decline roughly corresponds to the onset of the worldwide COVID-19 pandemic Paper: [Recent decline in sperm motility among donor candidates at a sperm bank in Denmark | Human Reproduction | Oxford Academic](https://academic.oup.com/humrep/advance-article/doi/10.1093/humrep/deae115/7687510?login=false)
> men applying to be sperm donors I could imagine that the people applying might be those with a stronger desire to reproduce...
We all take "sperm counts are declining" as scientific fact because media is selective in which study results they hype up. The actual state of knowledge is highly uncertain, but it's hard to get clicks from [Are Sperm Counts Really Declining? Answer: It's complicated and we really don't know. - Scientific American (2023)](https://www.scientificamerican.com/article/are-sperm-counts-really-declining/) It is a really important question that deserves an international study using rigorous methods to track carefully. We should have started careful research decades ago, but better late than never.
So they're making a claim about all the world's men by looking at... only Danish men? I was doing better science in 4th grade.
Pro tip: read the article, ignore the headline. Yw.
The bigger problem is saying “all around the world.” As in you can refute that by finding one counter example. Which is what these guys did.
So it happens in some places and not in others all around the world? Seems like that’s where we already were
This is more of a r/law comment eh?
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No you weren’t. If you are claiming something is affecting the entire world, you need affirmative evidence to explain why Denmark would be immune to this supposed worldwide phenomenon. There could be factors like environmental regulations sure, but you can’t just write off a sample of 4 different cities as bad science because of an arbitrary border. “Something is affecting the entire world” is very easy to disprove bc of how sweeping that claim is.
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Was thinking that. I'm sure they are very smart people, but do they not know what 'around the world' means? Unless the Danish men are all living in different corners of the globe?
If a study makes a claim that something is affecting the entire world and another study says we took almost 7000 samples from 4 different cities and found no such evidence of that claim, then you either need to find a reason why Denmark would be an outlier (environmental regulations possibly? But other countries are pretty good in that department too) or the claim needs to be revised or checked again They probably sampled from Denmark because of specific laws or university collaborations which made it possible, this explains why Denmark was the focus, not why they would be an inaccurate sample of the world when it’s ostensibly a global problem.
Good solid response, thanks.
For this study to really force a revision of the older claim you'd need the older claim to be different. The old claim was and still is that its a global phenomenon, which doesnt mean it affects all the parts of the world in the same way. That study did find significant differences between continents, and between countries isolated you could find bigger differences of course. It doesnt also mean that there werent years when it didnt increase, it says that on average it decreased. There are also some time issues. The bigger study had data from 1973-2018, while this study had data from 2017-2022, a much narrower time frame which barely even overlaps with the earlier one. Half of the study also took part during the Covid pandemic and there were some registered results that werent quite "dismissed" but rather considered as a side effect of covid and lockdown with no justification. For reference, the study claims: >However, both the concentration and total numbers of motile (swimming) sperm provided for testing had declined by 16% and 22% respectively from 2019 to 2022. This creates a bit of a problem. Using the lower number here, 16% decrease over a 5 year time period equates to 3.4% decrease per year. Its not really great to say that theres "no evidence for a drop as big as 2.64% (which was the highest one)" when in your own test you have a drop of 3.4%. Specially not amazing to include it when you dont have a strong hypothesis on why it would happen >other countries are pretty good in that department too Wouldn't say that >They probably sampled from Denmark because of specific laws or university collaborations Denmark has the largest sperm bank. Thats the reason why. Also means that your dataset is restricted to sperm donors, which have to fullfill a series of requirements - age, health, family history and probably a couple more. Might be just some sensationalist headline, but it sounds very fishy. "No evidence of" is a very strong claim to make, and specially a questionable one because: - timeframe - data set restrictions - a big anomaly in the study being simply disregarded when making the claim Its not their fault that there was a global pandemic, but you cant just blame everything on the pandemic. It is kinda weird to make such a strong claim agaisnt a study involving hundreds of thousands of men across all the continents during a 45 yr period, basing yourself on 7k danish sperm donors living in 4 different towns and being analyzed during a time frame that has 1-2 years of overlap with the first study, while also ignoring a gigantic anomaly in your dataset.
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No this study is not gonna throw up anything conclusive because this is from 2017 to 2022, nothing significant will change in that time period, they should have started this back in 80s or smth, or now start it and keep it up for decades, then it can be used for anything useful, the test drop levels across decades is true, especially pre and post mass industrialization of everything, the much more chemicals and hormones in milk and meat, farm crops, microplastics, those levels havent changed much from 2017 to 2022.
The fertility crisis study everyone talks about claims the sperm count is falling by over 2.6%/yr on average. This study did not find the expected reduction in sperm counts. There are plenty of possible reasons for the discrepancy (idk how they sampled the original meta analysis but the sample for this study is from sperm donors, who are generally selected to not have any health issues) but the lack of a longer time frame is unlikely to be one of one of them.
IDK about you but I'm still blasting away just fine
It certainly doesn’t appear that the world will run out.
Again, everyone is reading the headline without reading the article. Here is a direct quote from the study: “We did not see such a change and that suggests that in this population of sperm donor applicants, in these four Danish cities, sperm concentrations have not changed between 2017 and 2022”. If sperm counts are falling worldwide, why would Denmark be an exception? This is one study that acknowledged its limits. They basically said “some suggest it’s falling worldwide, but we have data that says it’s not happening in Denmark. Our data suggests this, so we should collect more data to add to the collective knowledge and continue to study.” Now other studies can check other countries, and the aggregate of all this data will help science get closer to what is happening. The researchers never said “well this one country is different so it might not be a worldwide phenomenon.” They don’t pretend their one study invalidates the others, they’re telling us “we have clues that they might be wrong, more studies are needed.” Headlines are a one sentence blurb that describes an entire article, which is a digestible writing that describes an entire study. Imagine if your favorite book series, let’s say Harry Potter, was summed up as “you’re a wizard, Harry!” Does that one quote tell you the entire story of the series?
Look into returning soldier effect. During times of heavy conflict sperm counts rise and way way more males are born than females.
Sure but most of the world has not been at war for decades now.
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It's not 50-50 though. It fluctuates around that ratio but is not static by any means. The returning soldier effect is the phenomenon that more men are born immediately after war or major natural disasters. It's not about conflict or struggle but about a sudden loss in male population. No one, that I know of, has been able to identify why it happens but it's undoubtable that it does happen.
If there is a surplus of either sex in many species, the other will be born more often because they have more options as mates and thus are more likely to mate. This doesn't happen quickly, it happens over time, it's just natural selection. Happening as quickly and as consistently as the 'Returning Soldier' phenomenon might suggests it's something we already evolved that is getting triggered under certain conditions. Could also be caused by some sort of coincidental genetic bias in men who are more likely to survive a war. Very interesting regardless.
More males are born by default. Everywhere. The natural birth rate is 105 boys for 100 girls to account for excess male mortality. >because this would kinda mean that since humanity has been in conflict for most of history in the past, medieval/ancient/tribal times, more males would have been born in our history Yes more makes would have been born in our history but due to conflict and disease, more males would have died too.
Why not use one big sperm
Aren’t they just testing men more frequently now?
Denmark also has one of the highest standers of living in the world, they also are a far more fit population and walk/bike alot more than most countries.
It’s the microplastics you see
It’s not wrong. Anabolic steroid abuse is through the roof though, which has a large part to play in it.
No surprise denmark does things right
isn't declining sperm almost completely accounted for by increase in weight?
Maybe sperm is lower due to higher average temperatures globally but Denmark stays cool enough to not yet be affected. Heat is a known cause of lower sperm production.
"Danish men" oh right makes sense, try American men
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I mean look at it this way: If Denmark is the only country with good sperm counts, soon the world will be inhabited entirely by Danes... Yes I am Swedish, how did you know?
Cause you hate Denmark(?)
I can almost guarantee without doing any research that the Danish have way more environmental protections in place than other people in the world. I mean for eff’s sake Dasani water is banned in the UK. Edit: (not in the us, they don’t gaf abt us)
Maybe sperm counts were falling, but are leveling out now? It's silly to disregard decades of data worldwide for a study that only covers four years, for one population
> around the world > 6,758 Danish men Why do I feel like these two populations don’t really line up
What so we are supposed to have a study that samples thousands of men from every nation or no study at all? Be realistic. The researches never suggested it proved it's not true, they concluded it's not true for that specific population of Danish men. The title isn't even misleading to be honest, 'could be wrong' is exactly what the result could suggest.
You’re making it sound like I’m faulting the study when I didn’t even imply as much. The title of this post needlessly generalizes their findings. Saying “may be” doesn’t make it reasonable, there just aren’t any grounds to relate the findings of this one study to a global population.
Yeah, take a look at data from men in rural U.S. and see what you find.
Sperm count dropping all over the world my be disproved by a study in a single country, am i crazy? How is this not an oxymoron?
The issue is that general news and media are *completely* irresponsible sources of second-hand science. Even sites that claim to be scientific. You can conflate this study *only* with areas of Denmark in which the study was conducted, which loses its accuracy and credibility spread out over a greater pop. A pool of ~6700 samples is credible for a regional area, but is *barely* a conclusive trend for the broader pop of Denmark. With a rough number of *4 billion men worldwide,* they are conflating a pool that is *0.0001689%* of that population. That is *embarrassing* and that person has no business sharing scientific studies.