The obvious conclusion was that the pancreas controlled sugar metabolism, and for the first time scientists knew that diabetes was somehow the result of a faulty pancreas (or no pancreas at all in the case of this dog). Three decades later, Canadian researchers proved that the pancreas produces insulin, and that this chemical regulates sugar levels. Then, in 1922, insulin (derived from cattle) was used to treat diabetes in people.
More recently, the effects of insulin have illuminated an extra- ordinary conflict within the bodies of pregnant women. David Haig of Harvard University dem-onstrated that foetuses release placental lactogen, a chemical that permeates the mother's body, blocking the effect of the mother's insulin. The foetus is trying to increase its host's blood- sugar level, so that it can harvest the excess sugar for its own benefit. However, the mother cannot afford to be deprived of sugar, because this would endanger her life. Hence, she fights back by secreting more insulin.
In short, there has been an evolutionary tit for tat through the generations, whereby foetuses secrete more lactogen and mothers secrete more insulin, each trying to get ahead of the other. The escalation has been gradual, because if the foetus generates too much lactogen then it will harm the mother, which obviously is not in its own interest. Similarly, if the mother over-reacts with too much insulin then she will harm the foetus, which obviously is not what she wants to do. Consequently, although the levels of lactogen during pregnancy are 1,000 times higher than usual, this is balanced by an increase in insulin.
The insulin battle is only one aspect of the conflict between the foetus and the mother. The foetus also secretes chemicals which constrict the mother's arteries, raising blood pressure and thereby sending more blood to the placenta. This can cause hypertension in the mother. Although Haig's research is throwing new light on pregnancy, his work has not been well-received by some non-scientists. An American Professor of Rhetoric, Language and Culture attacked Haig, labelling his ideas as "male fantasies of warfare in the womb".