(CBS News) In virtually every language in every corner of the world, the first sound a baby makes that can be called a word is MAMMA. In ancient Latin MAMMA became the word for breast - our first source of nurture, comfort and love - and for all humankind a source imagery and medical challenge across the centuries. Our Cover Story is reported now by Tracy Smith:
There are few images in the Christian world more universal and more sacred than these: the Madonna by Leonardo da Vinci, doing what any mother would do: feed her newborn child at her breast.
Since the earliest forms of human expression, the breast (in Latin, Mamma) has been front and center.
Beth Rosenberg, who teaches art history at New York's School of Visual Arts, said breasts have been on artists' minds since the Venus of Willendorf - a statue dating to about 25,000 B.C.
"We see breasts throughout art history because they're about the world, they're about life," Rosenberg said.
More specifically, they're uniquely designed to feed babies.
"Human infants are different from a lot of other mammals in that we don't have this kind of protuberant snout," said science journalist Florence Williams. "And if we had really flat mammary glands and a fat infant trying to suckle that, you know, it would be like kissing a mirror. Doesn't work very well."
Williams, who wrote the book on breasts, says that researchers are still scratching their heads over them.
"It turns out that it's actually a really contentious debate about why breasts evolved," Williams said. "Because breasts, as apart from mammary glands, are very unique in the animal kingdom. They're sort of protuberant from puberty on. And it turns out that's really unusual. Other primates only have breasts while they're breastfeeding."
And since human breasts typically arrive long before they have anything to do, Williams says there is disagreement over whether they evolved for food . . . or sex.
"There's been many decades of scholarship arguing that breasts evolved as sexual signals," she said. "And then the feminist scholars came along in the 1970s and '80s and said, 'Well, wait a minute, maybe they're something to do with how breasts actually work that might help women survive or help infants survive - and maybe the interest in breasts on the part of men came later."
It's a lot more than interest; Dolly Parton was famous for attribute sother than her acting ability . . . .as was Raquel Welch. And who could forget Halle Berry in a bathing suit?
Few people understand this more than Mary Kathryn Langhamer, a veteran bra-fitter at Houston's Top Drawer Lingerie. "Most women really don't like their breasts. There's always something wrong. They're too big or they're too little. They always want the opposite of what they have."
It's no secret that women have been trying to improve on nature for generations. "There were bras that you could put all sorts of things in - wire, tissue, metal. There were even bras that you could blow up with a straw to make your breasts look bigger," said Williams."
In recent years, bigger has often been seen as better. But permanent breast enlargement was a medical puzzle, until a eureka! moment 50 years ago in a Texas blood bank.
"There was a doctor in Houston, Texas, who was holding one of these new silicone blood bags," said Williams. "Blood used to be contained in glass. And he was holding a warm bag of blood and he said, 'My, that feels good. It feels like a breast.'"