Survival of the Sickest

1. Why not all macrophage lack iron, just some?

2. Why only iron rich individuals who develop iron poor macrophages?

More powerful armies only conquer rich lands. For example, after several US soldiers were killed in Somalia, US withdrew its troops. But after many hundreds of casualties in Iraq, US is still firm to stay there, since Iraq is oil rich.

And while we don't know whether neonatal parenting is actually changing brain development, scientists who study this epigenetic connection in animals believe it's very unlikely that humans don't share it. In fact, the total picture suggests humans should be more prone to epigenetic effects in infancy. After all, cognitive development and physical development after birth in humans are much more significant than they are in most other mammals. (p. 170)

In the months immediately after the terrorist attacks on New York and Washington on September 11, there was a dramatic spike in the number of late-term miscarriages --- in California. It would be tempting to assume that there is an obvious, behavior-related explanation for this --- higher stress made it harder for some expectant mothers to take care of themselves. It is tempting to accept this except for one thing --- the rise in miscarriage only affect male fetuses. (p. 179)

Comment: It is easy to explain. Males face higher selective pressure in a state of war. So weaker male fetuses are more likely to be aborted when expectant mothers sense future wars.

During the reunification of Germany in 1990, the birth rate in the former East Germany (where reunification was difficult, tumultuous, and anxiety-producing) skewed toward females. (p. 179)

Comment: After unification, males in East German will have harder time to find a mate because they will face stiff competition from more wealthy males from West Germany. Hence more females are born.

On the other side of the coin, there is evidence that in times after great conflict, the male birth rate goes up. That's what happened after World War I and World War II. (p. 180)

Comment: During a great conflict, many males die. So there is a scarcity of males and hence males will offer higher rate of returns.

A more recent study of six hundred mothers ... revealed that those who predicted that they would live well into old age were more likely to have male babies than those who predicted that they would die relatively young. (P. 180)

Males need a lot of financial strength to find a mate. Those who can get support from family have better chance.