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Name: John M.
Status: Other
Age: 50s
Location: N/A
Country: N/A
Date: July 2002

A question was asked if YY chromosome human could live. The scientists said a human with YY only could not exist yet 60% of the Salmon in the Columbia River today who are female in body are in reality, genetically XY. This is because these pseudo females are induced to grow as females due to hormonal triggers in the pesticide/fertilizer ecosystem. XY male mates with XY female and a percentage become YY. So, if it is possible in fish , then why not in humans?

I do not know if a salmon Y chromosome contains enough genetic material for the fish to live without any Y-chromosome genes present. The issue is not whether a zygote can be assembled so that its genome is YY, the issue is whether such a cell can grow into a living adult.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois

The human Y chromosome is a smidgen of a chromosome and contains virtually no genes. It only contains those genes necessary for becoming male, the SRY for example. Sex determination occurs differently in different species and I cannot say whether all Y chromosomes are so small in all species. But in humans, the X contains genes that all of need for life-in females there are two copies of each gene and in males only one (they only have one X) but most of the genes on the X have nothing to do with sex determination. Examples include genes for the ability to see color and to make blood clotting proteins. Whether these same genes are found on all species' X I do not know, but I suspect not all of them. So, at least in humans, everyone needs at least one X. Without one, life is impossible (for humans).


The arrangement of genes in the chromosomes of different animal varies. The "sex" chromosomes of a fish can have vastly different genes than those of a human. It seems in evolution that although animals that are in the same class, as in mammals, have a reasonable similarity in their genes, the way these genes are arranged and on what chromosomes varies widely. A porcupine has 40 chromosomes per cell, a goat has 60 and a chicken has 78....if I remember correctly.

Peter Faletra Ph.D.
Assistant Director
Science Education
Office of Science
Department of Energy

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