Natural selection means that they likely are warlike and violent. Warlike and violent intelligent species destroy themselves quickly so are unlikely to exist at

Natural selection means that they likely are warlike and violent. Warlike and violent intelligent species destroy themselves quickly so are unlikely to exist at the same time as us. Only the ones that can reengineer themselves to not be warlike and violent before they destroy themselves will survive for long enough to exist at the same time as us. Therefore it is likely any intelligent species we meet will be peaceful (among themselves at least).