The Seven Daughters of Eve Read Online Free PDF Page A

was going to be fun.

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SO, WHAT IS DNA AND WHAT DOES IT DO?
    All of us are aware, as people must have been for millennia, that children often resemble their parents and that the birth of a child follows nine months after sexual intercourse. The mechanism for inheritance remained a mystery until very recently, but that didn’t stop people from coming up with all sorts of theories. There are plenty of references in classical Greek literature to family resemblances, and musing on the reasons for them was a familiar pastime for early philosophers. Aristotle, writing around 335 BC , speculated that the father provided the pattern for the unborn child and the mother’s contribution was limited to sustaining it within the womb as well as after birth. This idea made perfect sense to the patriarchal attitudes of Western civilization at the time. It was only reasonable that the father, the provider of wealth and status, was also the architect of all his children’s features and nature. This was not to underestimate the necessity of choosing a suitable wife. After all, seeds planted in a good soil always do better than those put into a poor one. However, there was a problem and it was one that was to haunt women for a long time to come.
    If children are born with their father’s design, how was it that men had daughters? Aristotle was challenged on this point during his lifetime, and his answer was that all babies would be the same as their fathers in every respect, including being male, unless they were somehow ‘interfered with’ in the womb. This ‘interference’ could be relatively minor, leading to such trivial variations as a child having red hair instead of black like his father; or it could be more substantial – leading to major ones such as being deformed or female. This attitude has had serious consequences for many women throughout history who have found themselves discarded and replaced because they failed to produce sons. This ancient theory developed into the notion of the homunculus , a tiny, preformed being that was inoculated into the woman during sexual intercourse. Even as late as the beginning of the eighteenth century the pioneer of microscopy, Anthony van Leewenhoek, imagined he could see tiny homunculi curled up in the heads of sperm.
    Hippocrates, whose name is commemorated in the oath that newly qualified doctors used to take (some still do), had a less extreme view than Aristotle which did give women a role. He believed that both men and women produced a seminal fluid, and that the characteristics of the baby were decided by which parts of the fluid prevailed when they mixed after copulation. A child might have its father’s eyes or its mother’s nose as a result of this process; if neither parent’s fluid prevailed for a particular characteristic, the child might be somewhere in between, having, for example, hair of a colour that was intermediate between the two parents.
    This theory was much more obviously connected to most people’s experience of real life. ‘He’s just like his father’ or ‘She’s got her mother’s smile’ and other similar observations are repeated millions of times every day throughout the world. The idea that the parents’ characteristics are somehow blended in the offspring was the predominant belief among scientists until the end of the nineteenth century. Darwin certainly knew no better, and it was one reason why he could never find a suitable mechanism to explain his theory of natural selection; for anything new and favourable would be continually diluted out by the blending process at each generation. Even though geneticists today scoff at such apparent ignorance among their predecessors, I wouldn’t mind betting that a theory of blending is, even now, a perfectly satisfactory explanation for what most people observe with their own eyes.
    Eventually, two practical developments in the nineteenth