An unscientific science story

Future Females — Bigger Eyes…and Bigger Breasts?

What evolution will mean for the twins is anyone’s guess

In the future, our species will undoubtedly look different.

A Forbes article explains that rapid changes in the Earth’s climate long ago caused the size of the human brain and skull to triple, making the face flatter. For fun, the magazine paired an artist and a geneticist to play a guessing game about what we might look like in 20,000, 60,000 and 100,000 years.

Bigger heads for bigger brains and larger nostrils and eyes to function better on the far flung planets we might inhabit were a few of the predictions. No mention of the pinky toe which other scientists hypothesize we might lose due to the fact that the more recently evolved big toe is picking up the slack.

In other words, unlike our brain, if we lost the little toe, we wouldn’t miss it.

That got me wondering about the evolution of other appendages — like breasts. Would there ever come a time that they would be superfluous as well?

Turns out, I’m not the first one to ponder the evolutionary significance of breasts. In a Discover Magazine article, the author explains how bigger human breasts are kind of their own thing.

“In other primate species, only pregnant or lactating females have bosoms. The animals stay flat-chested for the rest of their lives. In humans, pubescent girls accumulate fat around their milk glands, which stays for life and seems to hold sex appeal in every culture. Those permanent, alluring mounds of fat on women’s chests are indeed an evolutionary anomaly, begging for an explanation.”

Female breasts hold sex appeal in every culture? Shocking news!

Other hypotheticals for the reasons that women’s breasts exist in their current state:

• Evolution gives the nod to “pendulous” breasts that babies could cling to “like handle bars”
• A storage for fat reserves similar to a camel’s humps. Since we evolved near the equator, we didn’t need to store fat all over like those in colder climates. Males don’t get the humps because they don’t nurse the babies.

However breasts started out, man’s interest in them certainly has evolved and that’s where scientists think natural selection comes into play.

“They argue that over the course of human evolution, permanent breasts helped females attract mates. Like the ostentatious feathers of male peacocks, breasts served as a message to the opposite sex, ‘Hey, look at these! Reproduce with me!’”

Again, this probably is unsurprising to 99.9% of the population.

I’d never heard the term for it though — an “honest signal.”

The idea also supposes that some breasts are more appealing than others, from a mating perspective. For instance, Barbie — according to some studies done in the West— would make a more desirable mate. Her narrow waist and large breasts are the calling card for a successful fertilization. Really? That chick has enough body fat to get pregnant?

According to one study of Polish woman, the answer was yes.

“[The] women with large breasts and narrow waists had higher values for [the needed] hormones — and the combo of these hormones predicts pregnancy success. This led the researchers to conclude that at least among these Polish women, ‘the cultural icon of Barbie as a symbol of female beauty seems to have some biological grounding.’”

Just you wait Barbie, that 24-inch waist has a shelf life.

Other studies, however, have not replicated this outcome. And in studies where men were asked to flat out rate their breast preference, the results were all over the map. Brazilians like them larger. Czechs like them smaller. Hungry British men liked bigger breasts than those participants who were fed first. That sort of makes sense to me in a really weird way.

The gist seems to be that biology is important but culture matters too. Nature and nurture as is the case for many things.

If breasts first evolved to let mates know about the “shift” in placement of reproductive organs when we got up on two feet, what will happen to them now that everyone has the hang of things?

You would think that if big breasts were an important part of the mating call, then breast sizes would be getting bigger. And they are.

“LiveScience.com also reports an increase in the average size of breasts from 34B to 36C since 1995, although there is no explanation for the increase in size.”

Maybe there is an evolutionary explanation — even if we don’t quite understand it yet.

On the other hand, mating is a choice. According to the United Nations Populations Division, the global growth rate reached its peak of 92.9 million in 1988, but slowed to 81.3 million in 2020. And humans will continue to hit the breaks on procreation.

Long-term projections indicate that the growth rate of the human population of this planet will continue to decline, and that by the end of the 21st century, it will reach zero.

The International Institute of Sustainable Development said that this is because of the “abrupt decline” in the global total fertility rate, from 5.0 in 1960 to 2.3 in 2020.

If fewer people want to have children, maybe the clarion call of the “right” kind of breasts won’t matter. Less babies will need to breastfeed. And the “camel humps” won’t need to store fat for any offspring. If we don’t use our breasts, would we eventually lose them along with the pinky toe?

It is a question only the bug-eyed humans of the future will be able to answer for sure. In the meantime, it is business — and pleasure — as usual for the breasts.

Betsy Denson, 2022

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