Father's primary impact is in his genetic material. Secondary impact is his parenting impact which starts to matter mostly after child is 2 years old. Before that, from conception to birth to 2 years, mother is much more important.
My daughter is two weeks old today. In the past 14 days, my wife has been responsible for providing 100% of what our baby consumes, but at least half the time, I'm the one feeding her (we're about 50/50 breastfed/pumped breastmilk in a bottle).
Aside from that, there's effectively no difference in our roles in caring for her. We both change diapers, we both bathe her, we both hold her and comfort her when she's fussy. We don't pay any particular attention to making it a 50/50 split for these activities, but it probably works out to approximately that, for all intents and purposes.
Right now her schedule seems fairly nocturnal (she seems most awake from ~2300 to ~0400), and I tend to be the one up with her during that time, since I find I'm pretty productive during those hours anyway (I've gotten pretty good at one-handed typing).
On a practical level, there's effectively no difference in the amount of care provided between her mother and I. Your statement that her impact is "much more important" is fairly offensive to me (and while I haven't bothered talking to my wife about a comment on Hacker News... I suspect she would be equally offended).
While my wife is theoretically capable of doing everything on her own we share duties like you do, if only because there's no way I could allow the woman I married to suffer the entire burden of childcare unsupported. I don't know of anyone who does things any differently.
> I've gotten pretty good at one-handed typing
In another context that would be a source of shame, not pride :)
In bearmf's defence, we do matter more to the child after 2 years old. What we're doing now is supporting the mother.
In my opinion, I don't bear any less responsibility than she does.
That said, you cannot be a mother to your child. Your roles now are approximately equal, but they will inevitably change over time. Feeding and changing diapers is enough for now, and that indeed can be split between partners, because baby cannot really tell the difference right now.
For further normal development, babies need to develop a bond with their mother. This gives them a fundamental sense of security. It is one of human baby's primary needs which is also observed in most mammals.
Children later become attached to their fathers. It is a different experience for them, which involves more "rational" thought instead of primary urge to bond with their mothers.
However, I see that there is nothing in the article specifically about primary caregiver being female. To summarize, it is better to have one primary caregiver who has established a strong attachment with child. Traditionally it has been a female role, and I do believe women are better suited for it.
Also, I am always suspisous of 2nd hand science reports, especially when they do not provide a direct link to the original paper(s). If anyone does track down some research papers on the subject, please post it here.
All due respect, but you're talking garbage. Please stop with this sexist drivel.
Uninvolved fathers of America take note, you're off the hook until age 2. Apparently prior to that you don't really matter much anyway.
</sarcasm>
Even very young babies recognize both parents and expect different things from them.
Babies are quite smart and are fully capable of bonding with multiple people, and can even assign roles to them: This person for this need, etc.