Tag Archives: Evolution

The Blueberry Wars

In elementary school, the first “robin red-breast” of spring signaled warmer days, colorful flowers, and a promise that the school year wouldn’t last forever. I considered robins my friends.

Of late, I’ve come to perceive those same songbirds as my enemies.

This year, thanks to non-stop April rains, the blueberry bushes in our back yard have burst with fruits as they’ve never done before. My husband and I have inspected the branches daily with equal doses of anticipation and dismay as their output has transformed from tiny, hard, green things, to pinkish-purple promises, to blue balls of deliciousness.

Keeping vigilant over every move toward the berries’ sweet inevitability, we’ve had to do more vigorous battle with their other major, neighborhood fans, the robins.

As a delicate bird alights on a twig, I play schoolyard bully and drive her–or, is it him?–away. (I’m embarrassed to say, I don’t know my adversary’s gender.) The robin flits across my neighbor’s yard, only to return a few minutes later.

Philip wickedly points out that some wild chirping in a nearby tree might signal a nest filled with robin babies, and who’s to say I’m not depriving babies of needed nourishment?

Three baby robins in a nest, with open mouths waiting for food.  Source: http://clarksilerfamily.blogspot.com/2016/06/born-into-family.html.

Despite usually being a sucker for all things baby, I don’t buy this bid for maternal solidarity and return to my war of words.

“Shoo! Go find your meal elsewhere!” I holler, clapping my hands firmly for extra emphasis. The call of a future blueberry clafoutis dominates my decision.

*

My Biology 101 level of understanding of evolution assures me that humans sit comfortably atop something we easily term the “food chain.”

Merriam-Webster defines “food chain” as:

an arrangement of the organisms of an ecological community according to the order of predation in which each uses the next usually lower member.

When I picture the food chain, a very human-centric model readily comes to mind. (You can tell I’m not a vegetarian.)

How can my husband and I be competing as equals with a small-brained creature so much lower on the evolutionary scale?

Maybe my human arrogance is misplaced. Given that we seem to have the same taste in fruit, who’s to say birds and humans can’t be classified as equals, at least when it comes to dessert?

Then I remember an image from some fields in West Africa where I used to hang out. Come the growing season, birds showed up en masse, excited about the feast of tiny baby corn and rice kernels suddenly enticing them. But any success they enjoyed would come at the expense of the villagers–subsistence farmers, whose food supply they were stealing.

So, farmers enlisted children from the age of three on to serve as a young army. From dawn to dusk, groups of children occupied the fields. To entertain themselves during any intermittent periods of truce, the children brought along homemade flutes, drums, and dolls. Whenever some birds showed up, the kids took a break from their play time to shoot little pebbles at the flying invaders. Their aim was impressively accurate, thanks to homemade slingshots. Deployed over the course of a couple of weeks by those youthful armed forces, that simple technology–a Y-shaped piece of wood, with strips of red rubber tied to two ends and linked by a small piece of leather, to cup the pebble–saved the year’s crops.

The Beng knew what every farmer has known since the advent of agriculture. Never mind brain size or evolutionary scales. For that matter, never mind cute images of birds as characters in children’s books. (Think, Make Way for Ducklings). A food competitor is a food competitor.

It’s true that a more “live and let live” approach to the natural world might re-orient the food chain toward a more cooperative image–say, a non-hierarchical circle, rather than a tiered pyramid.

Still, like farmers everywhere, Beng villagers don’t romanticize the quest for food. Once humans figured out how to plant seeds, everything changed. We’re not just digging roots and killing animals wherever we may find them, we’re setting out clearly demarcated territories for what we consider our food sources–and defending those boundaries not only against our human neighbors, but against other species, as well. If that means chasing away cute robins from our blueberry bushes, so be it.

In the U.S. these days, it’s common for urbanites to dismiss rural residents as less sophisticated–at best, country bumpkins; at worst, ignorant racists. But knowledge comes in many forms. From their distant perch in the rain forest of West Africa, Beng farmers–as rural as they come–have, as usual, taught me a thing or two.

A Tale of Two Chins

Cell phones . . . couches . . . gyms and community centers . . . archaeologists of the future will unearth countless artifacts and buildings that will testify to the nature of our lives as social creatures.

Recently, anthropologists have argued for evidence of a different sort that tells a far earlier story of our social nature: to wit, some ancient chins.

Yes, our evolving chin shape apparently demonstrates some major alternations in our species’ profile.

Nowadays, women’s fashion magazines might dispense advice about how to choose sunglasses depending on one’s chin shape.
Screenshot 2015-04-18 19.03.20
But these small differences pale compared to that between our current, species-wide, facial shape and that of our much older ancestors.

For, before 80,000 years ago, our ancestors pretty much lacked chins altogether.
2 Chins

Left: Note the chin on this modern human; Right: No chin on this Neanderthal!
[Image: Tim Schoon]

Many changes happened in a short time. Among other notable alterations, our early ancestors’ head sizes shrank overall, while their brains grew out of all proportion. In turn, the enlarging brains of these pre-modern humans shrank the space available for their faces. (Today, most people boast faces some 15 percent shorter than the faces of Neanderthals.) In turn, those smaller faces pushed out our ancestors’ chins.

According to biological anthropologist Nathan Holton, the development of a chin—a facial feature unique to our über-social species—correlates temporally with other transformations.

For this bony shift in facial shape occurred while males’ testosterone levels lowered, social cooperation between groups heightened, and our early ancestors produced the first art.

So it’s not that our chins actually made us more sociable. Rather, their sudden appearance on the facial scene signals the development of our social nature.

Biological anthropologist Robert Franciscus explains: “modern humans had an advantage at some point to have a well-connected social network, they can exchange information, and mates, more readily, there’s innovation . . . and for that to happen, males have to tolerate each other. There had to be more curiosity and inquisitiveness than aggression, and the evidence of that lies in facial architecture.”

Nowadays, in the midst of daily headlines that scream examples of violence on scales both massive (war) and intimate (rape), we easily forget that the impulse to violence that captures our collective attention is, somewhere deep inside our genetic makeup, counterbalanced by an impulse to cooperation.

What will it take for us to reclaim that pointy-chin part of our species’ capacities?

Read more: “Feminization, Social Tolerance, and the Origins of Behavioral Modernity,” by Robert L. Cieri, et al.

P.S. A recent lecture at Harvard by my Illinois colleague, archaeologist Stan Ambrose, argues that our lineage of modern humans beat out Neanderthals some 74,000 years ago because of our close ancestors’ capacity for cooperation; he builds his argument by looking at the changing relationship between testosterone levels, face shape, deep voice, and trust (skip to 47’47 to get to the heart of the argument).