Sunday, November 10, 2013

tiny dancer in my hive

(Yes, that was a Sir Elton John reference.)

I’m fixing to blow your mind.

Honey bees utilize basic geometry and perceive quantitative distances and angles.

And they communicate with each other about it.

OH look. A little poster you should print out!
Bees live socially, and the workers forage for nectar to bring back and make honey with. After a bee finds a source of nectar in a patch of flowers, it returns to the hive with the good news. But how could a little bug like a bee communicate something as complicated as an outside location? Hormones can say primal things like “me angry, me attack!” or “me horny!” But “upon exiting the hive, fly 45 degrees to the right for about 2 kilometers, at which point you will then arrive upon bountiful flowers and nectar?” How is a bee supposed to say that?

The bee does a little dance, called a waggle dance. Let’s put ourselves in a bee’s shoes for a minute. Say you just found a nectary patch of daisies and arrive back at the hive.

First step in the waggle dance is to cling to the side of the hive and acclimate yourself however many degrees from the vector for “up,” or the opposite of the pull of gravity, according to how many degrees from the direction of the sun you found the nectar. Say you went 45 degrees to the left of the sun to find your daises. In that case, you turn your body 45 degrees to the left of up. Okay- now you’re ready to boogie.

Now, you waggle your butt as fast as you possibly can and walk a straight line along your angle. It’s very important how long you take to do this; you’re telling the other bees how far away the flowers were. One second of this waggle phase represents one kilometer of distance. So, if you waggle for a quarter of a second, then you’re telling everyone that the flowers are 250 meters away.

Next, you turn to the right and walk back to your starting point. Do another waggle, and turn to the left and loop back to your starting point. However many times you do this tells everyone how worth it it is to find this nectar. If you found a butt load of nectar, you’ll want to waggle plenty of times to get your point across. Otherwise, a few waggles will do.

And this actually works. This is an actual thing that bees do. Bees are mathematically perceptive. To me, this is totally insane.

Also, what makes this story cool, is that the bees give a damn at all. So many times in the animal kingdom, you see intense resource competition amongst conspecifics. Like when an eagle finds a fish and has to fight other eagles from taking it away from him. Or when a mean girl asks me where I got my brand new cute shoes, I’m going to lie and tell her WalMart. (I’m not proud. But don’t be scamming on my cute shoes! I worked hard to find them on Why should bees give away their nectar findings to each other?

But bees are social animals, and structured into social tiers. Worker bees exist only to collect nectar for the good of the hive. Workers cannot reproduce, and therefore have no real motivation to be selfishly competitive for resources. Their instinctual interest is that of the hive, making working together essential. Ah lah, the evolution of this amazing cooperative communication system.

Saturday, November 2, 2013

lots and lots of babies

I am at that age where my Facebook feed constantly offers up pictures of engagement rings, weddings, and lots of babies. Lots and lots of babies.

While some of my fellow single ladies find this to be a tad annoying, I don’t mind so much. It’s nice to see good things happening for good people when they’re ready for said good things to happen. Even if those things are kind of red and wrinkly and a little gross looking. With weird heads.

When you look at pregnancy patterns across Mammalia, you see a wide variety of systems. Rats have a gestational period of just over two weeks, while elephants can take 2 years to develop in utero.

Humans take, on average, 40 weeks to develop before birth. It’s long been thought that this timeline is determined by female pelvis size. Basically, that babies pop out right before their heads grow too big to fit through the birth canal.

Long ago in our evolutionary history, before we stood on two legs, we were quadrapedal rodents running around birthing multiple babies at once. But as the millennia passed and we rose to walk on just two feet, our pelvises had to evolve to support an upright posture. It narrowed so as to balance our distribution of weight. The tradeoff here was females no longer being able to (comfortably) give birth to multiple, or more developed and not-so-helpless offspring.

This interpretation was long held, and even suggested that gestation had to shorten in duration especially for the human lineage as intelligence evolved. With bigger brains came bigger heads, making birth essential earlier in the pregnancy timeline. This too would be a tradeoff- a newborn with only a small percent of its brain development completed makes for a very helpless little nugget of neediness.

New findings suggest that evolving a wider pelvis would not be disadvantageous to females. Walking and running is not compromised, and only 3 extra centimeters would be needed to produce babies with 40% brain development at birth (which is more than we currently average). Though it sounds scary, an extra 3 centimeters is statistically not that far-fetched. Evolutionarily, it’s actually pretty doable.

So why end the pregnancy party so early? Why not let it bake for a little longer, ensuring a more precocial offspring?

Scientists recently took a different approach to understanding gestation length in humans. They compared body size to gestation length in different species of primates. Homo sapiens actually break the mold, gestating longer than primate patterns would predict. That’s quite different than the suggestion of the previous model: that human gestation was shortened to accommodate babies with bigger brains. So females are pushing our bodies to the limits—but if not pelvis width, what are those gestational limits?

Evidence suggests those limits are metabolic. Our bodies are capable of supporting spurts of metabolic activity about 2 times that of resting metabolism. By the third trimester, a woman’s metabolism is already running at twice its normal rate. Those last few months are extremely taxing on a woman’s body. By 40 weeks, the baby is requiring nutrients and energy at a rate that a woman simply cannot satisfy past 40 weeks or so.

The article posted on ends on a thoughtful note- suggesting that maybe helpless offspring aren’t so bad after all. And that makes sense; a brain that comes into this world with more than 60% growing capacity has room for learning through experience. There are some advantageous survival behaviors that simply cannot be programmed into your brain at birth- like the fundamentals of cellular biology that help you understand the need to clean and disinfect a cut. Or how to grow crops and feed yourself and your family. Or how to use tools that build homes and provide shelter. Our blank baby brains are part of what makes us arguably the most successful species on earth. They give us the capacity to learn.

How amazing it is that all of these factors are tied together- the evolution of bipedal locomotion, to brain size, to pelvis width, to the capacity for in utero brain development, to the evolution of higher intelligence and consequently the ability to feel emotion. Perhaps the most beautiful factor in the evolutionary story of our brains is the ability to appreciate warm fuzzy things that seemingly have no bearing on us or our chances for survival. Like cozy, happy feelings you get from Christmas time, or a bouquet of flowers from someone who loves you, or even warm fuzzies from Facebook photos of friends holding their perfectly ripened, 40-week old bundles of helplessness.

Here’s a link to the original article, written by Stephanie Pappas of She writes good stuff- read more of it.