When Genes Go Weird

Some cool mutations:

Navel oranges.


Navel oranges are an orange that has another, tinier orange growing inside instead of seeds. Because of this, they're sterile. All naval oranges are clones of the original mutant tree!


Fruitflies.

The gene governing location has mutated, so that legs have been placed where the antenna would normally grow. Similar mutations can swap around eyes and wings. Flies can have legs where their eyes should be, eyes where their wings should be, and wings where their antenna should be.

Dolphins.

This is an albino dolphin. Most albino animals are white because most animals have fur. Since dolphins don't have fur, they look pink, much like albino humans.

And this...

This is a dolphin with "legs", a set of extra flippers in the place where long ago, its ancestors had limbs. In modern dolphins, the leg buds disappear before the dolphin is born.

Chickens.

Back when birds were dinosaurs, they had teeth. Teeth are much, much heavier than beaks, so birds lost their teeth, but the genes to grow teeth are still in their DNA. With a bit of tampering, scientists managed to get chickens to grow tiny teeth again.

Humans.



Our ancestors had tails and a lot of the genes for them remain. Babies in the womb all have a partial tail midway through development. In normal humans, the genes to grow a full-sized tail are turned off and the genes to break down the partial tail before birth are on. Every now and then, a mutation messes this system up.

And speaking of mutations messing up, all humans possess the genes to make vitamin C, but it's been disabled by mutations. One day, science may find a way to alter humans to fix the genes and turn it back on. Until then, we have to be sure to eat food with vitamin C in it!

Finally, here's some photos of Stumpy, the four-legged duck.

The limits of genetic instincts

Hey everyone!

We're not having class this week or next, so enjoy the break! I'll be updating today and next week with a blog post of fun facts.

Genes govern a lot of things, but they don't do everything.

For many years, science has believed animal behavior is almost entirely instinct, or set behaviors, but as we learn about genes, we learn that this is impossible. Imagine writing a book of behaviors for a person to cover every possible thing. Just telling a person what's good to eat would be the size of a dictionary. If you tried to write that in DNA, it wouldn't fit in the cell! It's much easier to write only a few short rules, like "eat sweet things", and rely on the creature to learn what food they should eat using the rule.

First, check out these animals stealing food!

In most of those images, the animals are looking at the other animal they're getting food from, suggesting they think the other animal has a mind like theirs that also desires food and might get mad they're taking the food. Meanwhile, some of the pet animals (especially the one in the first image) have no idea what's going on because they're not hungry, so they have trouble understanding the animal across from them wants food.

In other words: they're thinking about their behavior, not following a script!

Here we see a pair of squirrels who both think the stuffed animal is another squirrel. One cautiously tests to see if the fake squirrel will object to it having one of the nuts. The other assumes the fake squirrel will fight, so it attacks first.

All of this suggests animals have a very basic "theory of mind", which means they can think another animal has similar thoughts and feelings.

Humans are much, much better at this than anything else, but humans can also make mistakes with theory of mind.

Here, the human is offering a cake to the dog, but she also trained the dog to shake paws when someone puts their hand out. She made the mistake of thinking the dog would have the exact same mind as her and understands cake is not for shaking paws.

Join me next week for lots of weird stuff genetic mutation can do!

Mutation!

Today we went over the anatomy of the dragonflies torn apart last week and then examined various preserved beetles, discussing how dragonflies, like all insects, share certain common body traits. This moves us into our new unit: mutation!

Mutations are behind all the diversity of life. For more on the subject, the first episode of the currently airing Cosmos show goes into the evolution of the eye, a long and complex process.

Some other examples of mutation:
Corn, before and after human selection pressures:

Moths, before and after smog painted their habitat black:

Which would you eat first?

It's important to remember that mutations are rarely "good" or "bad". A moth mutated to have black pigment in an environment full of white things would be "bad", but if the environment changed to be full of black things, the mutation would be "good". Corn is now crippled, requiring humans to pollinate it rather than the wind and humans to separate and plant the kernels. But it's also one of the most common plants on the planet.

Two interesting side facts:

1) You may notice the black moth is not camouflaged as well on the dark surface as the white moth on the light. This is because the black is the result of a single mutation to make it solidly black. The fancy dimpling of the original moth is the result of thousands of years of chance mutation until the right combination was found. For the black moth to gain similar patterns would take thousands more years.

2) It doesn't look like they'll have thousands more years to perfect the black look. The original peppered moth has returned to most of its territory now that we have rules against factories belching endless smog, and it's thought the black moth will disappear again completely within a few more years.

But for an example of what uninterrupted mutation chains can do, enjoy this Phalera bucephala moth!

It's also known as the buff-tip moth.

Finally, the human hairball (or bezoar)! Because humans don't eat hair as quickly or as often as animals like cats, we also don't quickly vomit it all over your carpet. Left alone, bezoars will end up worn down by the acid into a tight ball. Removed before then, they're a hairy mass.

People in the past believed they cured poisoning, possibly just because they figured something so bizarre had to have some practical use. Bezoars do not cure poisoning, call Poison Control if you're poisoned instead!

The Body

Hey everyone!

We've completed our exploration of the lungs/heart and the oft-overlooked lymphatic system, then examined a squid to see how it contains similar structures, such as hearts, proportioned very differently, such as how the squid had two secondary hearts each in charge of pumping blood over its gills. Finally, we examined dead dragonflies under the dissecting scope and then dismantled them.

Here's a really interesting discovery about the interaction between a california side-gill slug and a spanish shawl. The california side-gill slug has a very simple nervous system, so it was thought to only have a sequence of behaviors much like one of the robots programmed in Robotics class, but this showed it learned to recognize the spanish shawl as bad prey. Also check out the images of the spanish shawl's amazing WHY ARE YOU BOTHERING ME NOTHING THIS COLOR IS GOOD TO EAT dance.

Next week, we'll begin learning about genes and evolution. We touched briefly upon this when talking about how a squid's beak started off as its shell and how human and squid nervous systems evolved independently, and we'll now dive in to how that information is encoded and how errors in that information is where all diversity on earth comes from.

Finally, here's a video of the song Frozen translated through many different languages and then back into English, with surprisingly few errors. It won't be long at this rate before we may have near-perfect machine translations, allowing people anywhere to communicate with each other!