There seems to be a lot of varying answers on this so I was curious what people here think it would be.
If a sin is a behavior that harms or threatens to harm, and the individual knows that it is wrong, that would be a sin, right? And if one's group knows that it is wrong, it is safe to say that the individual also knows that it is wrong, right? If that is true, then I would suggest that the first "sin" predates the existence of homo sapiens.
There are documented instances where chimpanzees have punished group members for behavior that could be deemed socially unacceptable within their group.
One such example is the punishment of individuals who violate social norms, such as failing to participate in group defense or showing aggression towards infants. In some cases, chimpanzees have been observed to collectively turn against an aggressive member. For instance, research has shown that chimpanzees may attack and ostracize individuals who have exhibited extreme violence or who pose a threat to the group's stability.
Since we can see from this behavior that chimps do have a concept of sin and punish group members who sin, we can extrapolate from that, that this ability to understand and commit sins comes from an ancestor common to both chimpanzees and humans.
That would mean that the first sin, whatever it was, is so far back in time, that there is really no possible way of knowing what it was.
