1. René says

    I have a y-chromosomal question that I hope PZ — or another biologist among the Pharyngulites — can answer. One of my great-great(-great)-grandmothers had an extramarital child, that therefore came to carry her surname, in stead of the biological father’s. There exists a photograph of the man — a nephew who is into the family’s genealogy found this out. The man was an officer in the French army and stationed in the Netherlands. Military documentation might exist that can pinpoint the man’s personalia.
    Since I should share his surname, I’m curious to find out.
    If I understand inheritance correctly, I think my y-chromosome is (almost?) identical to his, and to all his male descendants. So, and here comes the question, if we can trace the man’s male descendants, can we establish that he is, or isn’t, my forefather? Or is that impossible after a number of (how much?) generations?
    I would then also know my ‘real’ surname.

  2. Reginald Selkirk says

    @4 Yes. Presuming you are descended in an all-male line from this person. The Y chromosome goes to only male children. Males typically having one Y chromosome and one X chromosome, the Y does not get mixed, there is only a slow rate of random mutation.
    This does not apply to male grandchildren of his daughters, only to the all-male lines.
    So, it is possible in theory to test biological material from this putative ancestor, if available. If not, you could test biological material from other of his all-male lineage descendants (living or dead, so long as biological material is available), who should likewise share the same Y, excepting some few mutations. The name for this in English is “paternity testing”.
    As to your “real” surname, that is not biological but cultural.

  3. birgerjohansson says

    Plant breeding has resulted in a lot of plants doubling their genomes. Obviously plants have a more robust development process. But is there any inherent advantage in a large genome size or number of chromosomes?

  4. René says

    Thank you, Reginald! Much obliged. My surname is the same as my mentioned great-great-grandmother, so yes, I’m descended in an all-male line from the man in question.
    BTW, one could consider one’s surname as the name for the y-chromosome — in patrilineal naming conventions.

  5. René says

    An afterthought. Staircase wit. Provided none of the [redacted] family “pissed beside the chamberpot.”