Human's Imperfect Construction of Time

Humans have attempted to interpret time in order to gain control over it. We have constructed a 24 hour day based on the cicadian rythym in humans and animals. However, scientists have found that when they put people indoors with no time cues, their bodies naturally adjust to a 25-hour day. Similarly, the commonly used calendar adds an extra day in February (a leap year) because the astronomical year is 365.25 days. Since our calendar year has 365 days, the leap year occurs every four years to make up for this discrepancy.

Does anybody have any insight to why our interpretation of time is skewed? Is there a way to make it more accurate?

Envy and Hate

If jealousy is the wanting of the beloved object, and envy is the feeling of competition with the rival, then I think jealousy is a normal emotion that shouldn't necessarily be considered negative. However, envy seems to be more about hatred of the rival. An envious person wont be happy if he/she gets the desired object/person/thing; he/she just wants to see the rival lose it and suffer. This sounds like hatred. I'm wondering why hate is not one of the seven deadly sins and envy is. Hatred is probably at the root at most envy, so how can hate and envy be distinguished?