I've had two kids of my own, so my knowledge of this subject comes from first-hand observation. I claim magisterial authority on this subject...which is baby skin.
As you know, babies cry a lot for the first 6 months, then at the very minute they reach the seventh month, they immediately stop crying and act like cute little toddlers. The six months of crying is very trying for parents, and you have to wonder why nature would produce behaviors that are so potentially alienating to the baby's caregivers. I can't answer that, but I do know why parents put up with it. It is...amazingly...the quality of the little kid's skin.
Baby skin is the most pleasing thing to touch that you'll ever feel...well, apart from the obvious other pleasing sensation. Words can never adequately describe how soft and silky and alive it feels. No mink, no ermine, no fox fur can compete. It's the supreme experience for the sense of touch.
They say that the skin is an organ, just like the heart, but it doesn't seem that way, especially when it's dry and leathery like it is in adults. On a baby though, it's manifestly a fully functioning organ with a life of its own. The books say that it carries out complex respiratory functions and regulates some of the internal organs; It might even alter the electric field around it to produce a pleasing sensation in adults. I'll add that it also churns out fragrant oil...
addictive fragrant oil.
Yes, I said "addictive." Once you're hooked, if you don't touch that baby skin a zillion times a day you get depressed. No wonder adults get addicted to dangerous drugs...we're designed to be addiction prone so that we can be good parents.
So imagine that... your own baby addicts and manipulates you, and maybe you do the same to him. There you both are, manipulating each other and, amazingly, enjoying it. It's kind of nice to know that you're part of nature, flapping your wings and strutting around just like beetles and birds do.
Now here's the surprising thing...I've already made the point that living baby skin is like a flower that lives to attract bees. It'll do anything it can to attract its parents. What you may not know is that nature has built you to be vulnerable to that attraction, and that this attraction is partly located in the finger tips.
It's as if the skin contains sensors that you don't even know you have. They lay dormant til your baby's skin is first touched then they snap to wakefulness and you find yourself wanting to pick up the baby all the time and make silly sounds to it. That's true even if it's crying, and even if it puked on you a few minutes before. That sensitivity in the fingers is there even if you're a brick layer with tough, gnarled stubs for fingers; even if you're only feeling the baby's skin through pajamas.
So, that's one reason why having a baby is so much fun, even though it's admittedly stressful fun sometimes. I'll only add that, for this to work, the baby has to be your own baby, or one that you have a strong emotional attachment to.