Dangerous grannies

October 28th, 2009 § 0 comments

There’s a report out today that shows how important grandmothers are in the early lives of children. I’m not sure about you, but it sounds complete bollox to me…

The importance of grandmothers in the lives of their grandchildren is underlined in a study published today.

But the research showed that it was only granddaughters who were likely to do better with their paternal grandmothers involved in their early lives. In contrast, the presence of paternal grandmothers had a detrimental effect on the survival of their grandsons.

The discovery supports the idea that grandmothers have played an important role in human evolution and could explain why human females – alone among the animal kingdom – live well beyond their reproductive age.

See what I mean? Just in that first bit there are a couple of things that raises suspicions.

  1. The presence of a certain person that has no physical connection to a baby girl has a positive affect on the baby girl
  2. The same person with the same relationship to a baby boy has exactly the opposite effect. Not just no effect, but the opposite.
  3. The results differed concerning paternal and maternal grandmothers (this is the only mention of maternal grandparents in the Indepedents’ article).

How can this be? The researchers don’t know…

“We’ve only looked at infant mortality, and the mechanism itself remains mysterious. Other studies have given evidence against conscious favouritism towards one grandchild or another,”

They don’t know why, but grannies are either a help or a hinderence. It couldn’t be some other factor that they, implicitly admit, don’t know about?

The study looked at birth and death rates from populations in Africa, North America, Europe and Asia, a total of seven populations in all, and also going back to the seventeenth century. Now stop me if I’m wrong, but I would imagine that the birth and deaths recording, at least in some of the chosen study areas, in the 1600s’ would be limited and maybe not entirely accurate enough to be used in a study of this type.

Another thing to be taken into consideration is what about when the paternal grandmother is not geneolically related to the baby, due to sperm donation or plain old extra marital affairs? Is the supposed grandmother still a help/hinderance? Is this kink in the grandmother/baby relationship going to be known from records 400 years old?

It is common knowledge (common knowledge doesn’t neccerssarily make it true) that babies babies from large extended families do better because of the extra care and energy that is able to be committed to the baby. Who that care comes from, does it really make a difference?

I’m not a scientist, but I’ve read enough of Ben Goldacre, the Lay Scientist and the Canard Noir, to know that this…

The presence of a paternal grandmother in all seven of the populations had a harmful effect on grandsons because her presence was linked with an increase in mortality,” Ms Fox said.

“Meanwhile, in six out of seven populations, the paternal grandmother’s presence in her granddaughter’s early life had a beneficial effect in terms of the risk of mortality. This difference between paternal grandsons and granddaughters would explain a lot of the inconsistencies in previous studies, where the sex of the grandchild was not considered,” Ms Fox said.

is rubbish. The presence of A doesn’t mean it is the cause of B. There may be more detail in the report itself that the Independent isn’t telling us but from the quotes, I doubt it very much.

It is normally assumed that all grandchildren share about 25 per cent of their DNA with each of their four grandparents but Ms Fox, a doctoral student in Cambridge’s department of biological anthropology, pointed out that the female “X” sex chromosome of grandmothers is not inherited equally between their grandchildren, which could explain why some do better than others with each grandmother.

Ah, that would explain a lot, wouldn’t it. The older boys get the more immune they are to the girl chromosome. As a baby, the boys immune system is weak and so the X-germ is dangerous. At about the age of 6+ the X-germ merely smells and before the end of puberty, the lads immune system is fully protected and can now safely turn his parents into grandparents. What do you reckon? Sounds just as plausible as the dangerous granny thing, doesn’t it?

Another thing the Independent says is…

The study, in Proceedings of the Royal Society B, could help to explain the evolution of female longevity: grandmothers live beyond their menopause to help bring up their grandchildren.

It is widely believed that the reason human females live well beyond the menopause is so that grandmothers can invest their energy in raising their children’s children rather than risking further pregnancies of their own.

The “grandmother hypothesis” suggests that all grandchildren benefit from having either of their grandmothers involved in their early upbringing. But studies have so far failed to support the hypothesis with consistent evidence.

If this study helps to show that females live beyond menopause to help with the upbringing of their grandchildren, why have they evolved to be a danger to boy babies? It doesn’t. It just adds to the inconsistent evidence.

In my view: Grannies, give grandson a big hug. You won’t harm him and you’ll both love it.

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