Y chromosomes

[Pedigree Ann]

Part of the 'male line' worship in many cultures is, I think, based on a false analogy with agriculture. You plant a seed in the ground and what comes up depends on what kind of seed you planted; the soil can modify its health, but not its species traits - you plant wheat, what grows is wheat. The sire plants his seed in the mare; she provides the environment for it to grow, so what comes out is 'his' foal. While stallions used by the early TB breeders were clearly identified, many of the mares had no identity other than being daughters of their sire.

Why cultures would hold onto this idea in the face of obvious contradictions - children who resemble their mothers more than their fathers, for instance - is the real mystery.

[Dave C]

In humans it is advantageous for the mother and society in general for the father of the child to identify with the child. Although it is fashionable to bash patrilineal inheritance as being not in the best interests of women, reality is that this model works for women in that by ensuring a majority of men are fully vested in the system they expend a great deal of effort to maintain the system and their children. The few matrilineal social heirarchies that have survived to be studied have shown themselves to be plagued by rogue males who are not particularly helpful in raising their children or maintaining order in society. The focus on the importance of male lines is then projected onto other species (horses in this case) because it is useful for maintaining a functional (though not necessarily optimally functional) social order that works to the advantage of most though not all individuals.

[Shammy Davis]

XFactor wrote:

. . . Wild horses (true wild horses, not feral horses) have 66 chromosomes. Domestic horses 64. At some time there was a mutation that fused two chromosomes together. Because all the genetic data was present on the fused chromosome, this mutation was not fatal, and resulted in a breeding population that had horses with 66, 65, and 64 chromosomes. . .

I've been re-reading W. R. Cook's " . . . The Airflow Factors". He points out that RLN (Recurent Laryngeal Nueropathy) is 99% inherited. In his discussion of the disease, he suggests that RLN is not found in wild horses.

Until I read the above from XFactor I had not made the connection of 66 vs 64 chromosomes. Certainly makes you think about the domestication of the horse and its ancestry.

[vineyridge]

Okay, folks, new question.

I've been intrigued lately by the number of deadly cardiovascular events in eventing and steeplechasing horses during or immediately after competition. The number is not insignificant, given the relatively low number of entries. These horses tend to be older than flat racers and they always seem to be geldings--i.e males. In the US the TBs used are almost 100% ex flat racers, while in Europe the horses are bred for jumps racing.

In humans it's usually males who drop dead in situations like that. I can't think of a single instance in my personal knowledge of females who just suddenly die during a game of racquetball or driving a tractor on a hot day. You'd think if the genes were the same in males and females except for the relatively unimportant Y chromosome that the distribution of fatal CV events would be the same for both sexes.

Phalaris himself dropped dead while covering a mare at the age of 16. Didn't Nasrullah die of a CV event?

So is there anything on the Y chromosome that might activate something somewhere else to increase the risk factor for CV events?

[Dave C]

Read about the adverse effects of anabolic steroids. Endogenous sources will produce similar effects. Geldings not on a regimen of exogenous hormones will still have permanent changes to their cells and organs from pre and post natal endogenous testosterone. The 'y' chromosome provides the plan, the hormone does the deed.