Absolutely true, however the linked piece (not the study) seems to imply that there is some form of evolutionary mechanism which relates to the bonding experien

Absolutely true, however the linked piece (not the study) seems to imply that there is some form of evolutionary mechanism which relates to the bonding experience with a newborn/toddler that somehow helps the father 'stay around' to raise a child. I can see that there are mechanisms at play that favour the father to 'stay around'. But specifically for the Testosterone concentrations it seems to me that the cause could have nothing to do with an endocrine change triggered by bonding or nurturing.