Why Does Evolution Allow Some People to Hear Colors?

National Geographic has a piece on the evolution of synesthesia, which is broadly defined as “a neurologically based condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway.” In the most extreme cases, this means that people can taste words or hear colors.

This article caught my eye because I realized a number of years ago that I have a mild case of grapheme color synesthsia. I basically associate a color with every letter and number. The colors don’t change, and there doesn’t seem to be a logical reason as to why each letter or number has its color. For example, 7 is green. M is red. I don’t see colors when I look at written text, but when I think about words or numbers (e.g., a phone number), each character has its respective color.

My case is so mild that I didn’t even realize this was unusual until about six years ago when I asked someone else whether the colors they associate with letters and numbers change over time and got a very confused response. I’ve since found a handful of people that have similar associations (if anyone from Sloan is reading this, Kanaka is one of them).

The article links synesthesia to creativity and artistic capability. Maybe that’s true for the types that can taste words, but I don’t think it helps me in any way. I suppose on occasion when I forget someone’s phone number I may remember that it starts out yellow. Unfortunately, both 4 and 8 are yellow.

Any readers out there have something similar going on?

The Sugar Myth

I was happy to read this via Marginal Revolution:

Let’s cut to the chase: sugar doesn’t make kids hyper. There have been at least twelve trials of various diets investigating different levels of sugar in children’s diets. That’s more studies than are often done on drugs. None of them detected any differences in behavior between children who had eaten sugar and those who hadn’t. These studies included sugar from candy, chocolate, and natural sources. Some of them were short-term, and some of them were long term. Some of them focused on children with ADHD. Some of them even included only children who were considered “sensitive” to sugar. In all of them, children did not behave differently after eating something full of sugar or something sugar-free….

In my favorite of these studies, children were divided into two groups. All of them were given a sugar-free beverage to drink. But half the parents were told that their child had just had a drink with sugar. Then, all of the parents were told to grade their children’s behavior. Not surprisingly, the parents of children who thought their children had drunk a ton of sugar rated their children as significantly more hyperactive. This myth is entirely in parents’ heads. We see it because we believe it.

Even when science shows time and again that it’s not so, we continue to persist in believing that sugar causes our kids to be hyperactive. That’s likely because there’s an association. Times when kids get a lot of sugar are often times when they are predisposed to be a little excited. Halloween. Birthday parties. Holidays. We may even be causing the problem ourselves. Some parents are so restrictive about sugar and candy that when their kids finally get it they’re quite excited. Even hyper.

The notion of sugar making people hyper always seemed ridiculous to me, but until now, I had never read any studies confirming that it was, in fact, ridiculous.

On a somewhat related note, stop telling me that I’ll get sick if I go outside in the cold without a jacket. It’s just not true.

Building Space Ships

That was quick. SpaceX, a private space ship company, will begin sending shipments to the international space station this fall:

A little less than six months after the final space shuttle launch, a private space company will launch a rocket carrying a cargo capsule bound for the International Space Station. SpaceX said this week that it plans a Nov. 30 launch date for its first rendezvous with the ISS — an encounter that will mark a major milestone in private space exploration.

We heard last month that NASA agreed to speed up SpaceX’s flight demo schedule, as SpaceX, eager to start making deliveries under its $1.6 billion NASA contract, asked NASA for permission to combine two planned missions into one. That mission is now targeted for the week after Thanksgiving, according to SpaceX.

I found SpaceX’s website to be surprisingly interesting. The Falcon Heavy is bad. ass.

“There are ‘obvious benefits’ of straight-up sex”

Well that should give my daily traffic a bump. The quote is actually referring to the benefits of “straight-up sex” (as opposed to asexual reproduction) for a type of insect — the cottony cushion scale. Via National Geographic, this is fascinating and weird (as is the picture):

An Icerya purchasi beetle and its children.

Are males necessary?

Maybe not for long, at least in an insect species whose females have begun to develop sperm-producing clones of their fathers—inside their bodies.

In the cottony cushion scale—a common agricultural pest that grows to about a fifth of an inch (half a centimeter) long—a new phenomenon has arisen: When some females develop in fertilized eggs, excess sperm grows into tissue within the daughters.

This parasitic tissue, genetically identical to the female’s father, lives inside the female and fertilizes her eggs internally—rendering the female a hermaphrodite and making her father both the grandfather and father of her offspring, genetically speaking.

Though this new form of reproduction hasn’t replaced cottony cushion scale sex, “this parasitic male has taken off like an epidemic in population,” said study leader Andy Gardner, an evolutionary theorist at the University of Oxford.

“Once [this trend] gets started, it’s going to sweep through the population so all the females carry it. So there’s no point for regular males to exist,” Gardner added.

“If you mate with yourself, that doesn’t generate the sort of adaptive variation that regular sex does.”

There are “obvious benefits” of straight-up sex, he said—the offspring get new combinations of genes that can make species overall more robust, he said.

Ladybug Zombies

This is twisted. I love it. From National Geographic:

“The parasitic wasp…prepares to inject a spotted ladybug with a single egg…the ladybug has been paralyzed by the wasp’s venom…”:

A picture of a parasitic wasp about to inject a ladybug with an egg

“In time the egg will hatch into a larva that will develop for a few days and then chew a small hole through the abdomen of the ladybug. The larva will then spin a cocoon between the legs of the ladybug, whose body will rest on top of the cocoon as the larva undergoes metamorphosis…”:

A picture of a wasp larva emerging from a ladybug

“…sometimes the ladybugs survive the larva’s emergence, and in those cases, the…larva then “brainwashes” the bug into defending the vulnerable cocoon from predators, said study co-author Jacques Brodeur, a biologist at the University of Montreal…”

A picture of a "bodyguard" ladybug assuming her post on top of a parasitic wasp cocoon

There you have it. Ladybug zombies.

Although my favorite parasite is the Cuckoo bird:

“The European cuckoo (Cuculus canorus) is, famously, a “brood parasite”: the female lays her eggs in other birds’ nests. Typical victims are small birds like reed warblers and wagtails. When the young cuckoo hatches, its first act is to dispose of any other eggs: it heaves them out of the nest, leaving itself as the sole occupant.

What happens next is peculiar. The foster parents don’t appear to notice they are rearing a monster. Instead, they work hard to satisfy the demands of the chick, even though it sometimes becomes so large that it no longer fits inside the nest, and has to sit on top. It’s one of the oddest sights in nature.”

For more, check out The Selfish Gene.

Yeast, Unite!

Two of my favorite topics are evolutionary biology and brewing. It’s rare that they overlap in the same article. It looks like brewer’s yeast has been coaxed to evolve to do more than make beer:

One giant leap for yeastkind (Image: Eye of Science/SPL)IN JUST a few weeks single-celled yeast have evolved into a multicellular organism, complete with division of labour between cells. This suggests that the evolutionary leap to multicellularity may be a surprisingly small hurdle.

Multicellularity has evolved at least 20 times since life began, but the last time was about 200 million years ago, leaving few clues to the precise sequence of events. To understand the process better, William Ratcliff and colleagues at the University of Minnesota in St Paul set out to evolve multicellularity in a common unicellular lab organism, brewer’s yeast.

Their approach was simple: they grew the yeast in a liquid and once each day gently centrifuged each culture, inoculating the next batch with the yeast that settled out on the bottom of each tube. Just as large sand particles settle faster than tiny silt, groups of cells settle faster than single ones, so the team effectively selected for yeast that clumped together.

Sure enough, within 60 days – about 350 generations – every one of their 10 culture lines had evolved a clumped, “snowflake” form. Crucially, the snowflakes formed not from unrelated cells banding together but from cells that remained connected to one another after division, so that all the cells in a snowflake were genetically identical relatives. This relatedness provides the conditions necessary for individual cells to cooperate for the good of the whole snowflake.