The ecological rationality of helping others: Potential helpers integrate cues of recipients' need and willingness to sacrifice

Why do humans help others? Many theories focus on dimensions like kinship or reciprocity. On their surface, these theories seem unable to explain help directed at fleeting strangers. In response to this puzzle, researchers have proposed that the mind has ecologically rational systems for providing aid. These systems respond to cues that predicted adaptive behavior during human evolution, regardless of whether such cues continue to be predictive in modern environments. In three studies, we test for two cues that might predict whether a potential benefactor will help a potential recipient: the need of the recipient and the extent to which the recipient is willing to sacrifice for the benefactor. Both cues, in ancestral environments, have the potential to predict whether a long-term relationship might be established. Consistent with past research, we find that both cues matter: Needy people and people willing to sacrifice are helped more. However, the cues are not merely additive: In some cases, the cue of need is ignored and only willingness to sacrifice is used. We discuss these results in terms of recent evolutionary theories of emotions.     

Recovery from insulin-induced hypoglycemia after saccharose or glucose administration

This study compared the effects of saccharose and glucose on the recovery from insulin hypoglycemia. 17 normal volunteers (12 men, 5 women, 25-40 years old) received the same dose (0.1 IU i.v.) of semisynthetic rapid-acting human insulin on two different days after an overnight fast. Blood glucose and C peptide were measured in venous blood samples before as well as at regular time intervals after insulin administration. 30 min after the injection, 20 g saccharose or 20 g glucose p.o. (diluted in water) were given. The mean glucose values were at most time intervals higher after glucose than after saccharose administration. In addition, glucose ingestion resulted in an earlier and steeper blood glucose rise (mean recovery rates during the first 5 min 3.10 and 1.38 mg/dl/min for glucose and saccharose, respectively). The C peptide values decreased progressively and did not achieve baseline levels even at 120 min in spite of blood sugar normalization. It is concluded that glucose acts faster than saccharose in insulin-induced hypoglycemia. Exogenous insulin results in a prolonged depression of C peptide which lasts longer than the hypoglycemic effect.