Acquired characteristics—characteristics gained after birth —cannot be inherited.a For example, large muscles acquired by a man in a weight-lifting program cannot be inherited by his child. Nor did giraffes get long necks because their ancestors stretched to reach high leaves. While almost all evolutionists agree that acquired characteristics cannot be inherited, many unconsciously slip into this false belief. On occasion, Charles Darwin did.b
However, stressful environments for some animals and plants cause their offspring to express various defenses for the first time. New genetic traits are not acquired; instead, certain environments can switch on genetic machinery already present. Amazingly, this optimalc genetic machinery already exists to handle some contingencies, opposing the belief that time, the environment, or “a need” can produce the machinery.d
Also, rates of variation within a species (microevolution, not macroevolution) increase enormously when organisms are under stress, such as starvation.e Stressful situations would have been widespread in the centuries after a global flood.