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11

This meta-analyis examines 50 years of sperm count data and finds that time is a weak predictor of sperm count. They fitted a linear (straight) and quadratic (curved) line to the data. Note that in the scatterplots each data point is a study, not an individual. The result was: Our assessment of sperm quality over time leads to the conclusion that ...


11

No, it takes more than one sperm. The egg has multiple barriers which take up to 100 sperm, co-operating, to penetrate. The fusion of the egg with its three barriers (cumulus-oocyte complex, zona pellucida and finally the plasma membrane) takes approximately 10 sperm to clear the first two barriers of the oocyte referring to De Jonge and up to 100 sperm to ...


10

Martial law was in operation in Poland from 13 December 1981 to 22 July 1983, so the article might suggest an increase in births in 1982 and a further increase in 1983, followed by falls in 1984 and 1985 It is true that birth rates were higher in 1983 in Poland than in the immediately preceding years or the immediately following years, which is consistent ...


7

The Telegraph article may be correct. There was a study that showed that sitting on a heated car seat increases scrotal temperatures by about 0.5°C. https://www.ncbi.nlm.nih.gov/pubmed/17919605 It is known that 'raised testicular temperature has a detrimental effect on mammalian spermatogenesis and the resultant spermatozoa' https://www.ncbi.nlm.nih.gov/...


4

Research referred by Emily Martin in her 1991 paper 'The Egg and the Sperm: How Science Has Constructed a Romance Based on Stereotypical Male Female Roles' show that the sperm and egg are mutually active partners who do interact on more mutual terms. There is a take 2 for the egg and the sperm tale coming up with Richard Cone according to her CV present here....


3

That study was published in Germany in 2003. As Nate Eldridge says, the reference is "Time to pregnancy: results of the German prospective study and impact on the management of infertility"; C. Gnoth, D. Godehardt, E. Godehardt, P. Frank‐Herrmann, G. Freundl. Human Reproduction, Volume 18, Issue 9, 1 September 2003, Pages 1959–1966, doi.org/10.1093/humrep/...


2

Yes, although it is generally said that humans do not have estrous cycles in the way most mammals do, there are indeed multiple peer-reviewed studies suggesting that people (not just men, and in some cases other women especially) find ovulating women more attractive. The mechanisms for this are multiple, including both physical and behavioral changes. ...


2

It seems legit. LiveStrong and the BBC both reference a 2009 Cordoba study. I believe those are talking about "Sperm morphology normalcy is inversely correlated to cycling kilometers in elite triathletes" which concludes: The main finding of the present study is that cycling training volume inversely correlates to sperm morphology. That is, athletes ...


1

Sperm are intricately adapted to existing alongside millions of their peers at all times, but is simply unknown if they can survive and achieve success without these peers. There simply is not enough research to know. Specifically, no one has ever tried a series of billions of trials in which they introduced a single sperm and checked if it created a ...


1

This remains a controversial issue but the evidence doesn't appear to be strong enough to conclude there is a significant decline NB I'm adding this answer because of two contradictory papers I stumbled across in recent months that illustrate just how divided the actual evidence base is and also how the stories that hit the headlines are not an unbiased ...


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