The breakthrough for research into intersexual selection came in the development of a new technique for investigating female response in the laboratory.
The third, and most potent limitation is that it is not possible to be certain that the infant's response was due to the stimulus presented or to a change from no stimulus to a stimulus.
The results showed that there was slight chemical reaction between NBR and PA under high temperature and high shear rate, but the chemical reaction did not influence on the process of phase reversion.
Alain Bouillard said life vests found among the wreckage were not inflated, indicating the accident happened so quickly that the passengers had no time to react.
Since evolution has given rise to few, if any, purposeless physiological responset, it is logical to assume that crying has one or more functions that enhance survival.