Male Vs. Female (Percent)

Date: Sun, 17 Aug 2003 21:45:33 -0400
Subject: Bluebird talk
From: Maynard R Sumner <m-r-sumner"at"juno.com

Hi all, Today I give a bluebird talk at a Jr. Church and everything went good. I had one boy ask if more females or males were hatched out of the eggs. I did not know, but told him I would find out and get back to him. So I am coming to you to find out. Thank you, Maynard Sumner
Flint, MI

From: "Nancy C. Hebb" <Fencroft"at"msn.com>
Subject: M/F percentages
Date: Mon, 18 Aug 2003 11:09:01 -0400

Although the actual number hatched/fledged may not bear out the "roll of the dice" statistics, in all species there's exactly a 50/50 chance of any fertile coupling producing male or female. "Them's the facts, mam" but of course you might need an extremely broad sampling to get to that 50/50 number. For instance, I've had litters of pups that were 100% male or female; some years we seem to get more male lambs than females, etc. But if you extended the "study" population far enough, you'd reach that 50/50 level. 

From: "Bernie Daniel" <bdaniel"at"cinci.rr.com>
Subject: Re: M/F percentages
Date: Tue, 19 Aug 2003 00:23:44 -0400

Nancy Actually that is not correct. Although I am a big believer and user of statistics -- here is an example of where it does not apply. The ratio of M/F WILL depend on the ration of Y/X sperm but those are not necessarily 50:50 in production and vary from male to male. Further all kinds of things like temperature, pH, and other external factors will affect the success ratio for either X or Y sperm reaching and/or actually fertilizing the egg. In fact, in humans I believe that 106 male to 100 females are the "normal" ratio at birth and this evens out to approx 100 to 100 by around age 10 - 12 years due to higher male mortality. My numbers are may be a bit off due to the fact that I'm employing old neurons not used since grad school in the previous century.

Bernie Daniel, Ph.D.
9211 Solon Drive
Cincinnati, OH 45242-4617

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