A baby is an anchor. I don't mean that in an abstract sense where it keeps parents grounded and appreciative of what really matters in life; I mean a baby is dead weight. In terms of pragmatic usefulness, a baby is about on equal footing with a moderately sized stone, if stones were prone to rashes and screaming and disgorging fluids. Where a baby horse can walk before the embryonic sack has had a chance to dry, and a newborn kangaroo can climb sheer vertical ascents to its mother's pouch without any hind legs, a human baby can't even flip itself over and will occasionally try to claw its own face off. Babies are simply not prepared for the world when they arrive, and it's up to parents to make sure they stay clean, their brains stay un-poked through their ill-formed skulls and they aren't carried off by coyotes or hawks.
You stupid kid, you don't even know what horrors the world holds.
It's a big job for anyone, and even though we are a highly intelligent species that can see the importance of propagation, there must be moments when the haze of affection clears from a parent's eyes and he or she is tempted to pad a wicker basket and find the closest river.
Fortunately, nature's never willing to rely on the off chance that anyone will actually like their child. Through years of evolution, it has hidden elaborate fail-safes in our brains to ensure that we won't abandon our young. "But Soren," you harried and sleepless parents will cry in a voice just soft enough not to wake your tiny beast, "You have no children -- what makes you think you know anything about raising a kid?" Well, you just answered your own question, Jack; only the childless can objectively see the spell you're under, a spell that's meant to look and feel a lot like love.
#4. A Baby Is a Bong-Load of Oxytocin
One of the most calming and euphoric drugs you will ever feel massaging its way into your brain is oxytocin. Fortunately, you will never have to pay anything for it, because your own body is your dealer. Oxytocin is a neuromodulating hormone that's released after sex, when you fall in love and, for mothers, when a baby breast-feeds. In fact, any skin-to-skin contact between a mother and her baby, even gazing into her child's eyes, will trigger another dose of this bliss hormone, effectively turning the baby into a vehicle for a drug. Now, anyone who has seen or knows firsthand how protective and nurturing weed enthusiasts are for their vaporizers and pipes can get a sense of how nature has tricked mothers into essentially becoming addicted to their babies.
"Just this one last time and then I'll quit."
And like any drug, oxytocin can severely impair logic and judgment. It's at least partially responsible for every new mother thinking "Yes, babies are generally pretty adorable, but have you fucking seen MY baby? Why are people still fighting wars? Don't they know? Where are the news vans!?" Those of us without children have been forced to tolerate Facebook pages and Twitter accounts created on behalf of other people's babies, all while wondering how anyone could lose perspective so badly, how even close friends could become so grating and unrelatable in such a short period of time. The answer, of course, is drugs. But in this case, it's a drug that the mother doesn't even know she's taking. She's high on motherhood and can't conceive of a reason why everyone else isn't losing their shit over her newborn. Meanwhile, she spends every waking second scoring another fix, trying to snort the hairs off the baby's head like an addict huffing paint from a paper bag.
#3. Newborns Look Like the Father (Even When They Don't)
On a purely biological level, a new father will instinctively look for indications that a baby is his. Regardless of how monogamous a relationship may be, the basest part of his brain will want to know that sharing two decades of energy, time and resources with a pink pile of flesh is in his best interest. A study in 1995 aimed to prove that newborns look more like the father under the theory that, evolutionarily speaking, it's advantageous to alleviate any doubt of paternity. The study had 122 people matching pictures of babies with pictures of parents based on facial features alone. The participants managed to match up about half of the fathers with their babies but were absolutely terrible at determining which newborn belonged to which mother. While that study should prove that babies are born looking like their dad, all other attempts to replicate the first experiment have since failed.
So here's where it gets weird.
A separate study in 2000 asked new mothers and fathers which parent their baby most resembled, and the answer was resoundingly the father ... but only when the father was present during the questioning. Researchers asked 60 couples together and then 100 mothers alone whom the baby looked like, and when the mother didn't have to worry about the father overhearing, the paternal resemblance magically dropped 27 percent.
"Don't tell him, I want it to be a surprise 18 years from now."
Now, that doesn't mean that each one of those moms is trying to pull a fast one on some unassuming guy in the hopes that he'll help share the load of her new tiny black-eyed nightmare. In fact, most of those mothers probably didn't even realize that their answers would change based on whether the father was in the room. Instead, it's an evolved response built into a mother's brain after thousands and thousands of years. See, while it may be in a father's best interest to know that a baby is his, it's in the best interest of the family and the species as a whole that the father stick around to raise the next generation, whether the baby is his or not. So when it comes to propagation of the species, nature is on the side of the sluts.
Evolution isn't stupid enough to make every newborn look like the father, because that would be disastrous any time a woman happened to swap forensics with a guy who wasn't her partner. Instead, nature conditioned the minds of mothers to insist, and even believe, that the baby looks like her partner just to ensure that he doesn't abandon her, or eat the baby, or whatever it is that cuckolds do.