Born to be what?

We're all mutants. Now, I de-glorified all Marvel comics heros/villains that posess some kind of extrordinary gift due to being a "mutant". Well, it's not that remarkable in the real world. You won't gain any cool abilities by exposing yourself to nuclear waste, except the ability to grow aggressive tumors in your body (otherwise, imagine what the flora and fauna around Chernobyl would look like at this time). Still, mutations occur all the time; in us and around us. By using the different mechanisms, that causes mutations, in the laboratory we may see glimpses of how nature could work.

In all animals, fungi and plants there are a group of genes called HOX-genes. These dictates the development from a single cell to the multicellular being that we become. Think of them as "on and off" buttons that can be connected in a huge network, giving thousands of possibilities for combining the signals. In simple words, the different combinations of HOX-genes determines the orientation of the future body, i.e. where the head should be, the legs and so on, as well as growing wings instead of an arm. This means that a small change in the combinations directs the developing body to a completely different structure than "normal". Usually, the consequences are so severe that the fetus is spontaniously aborted, but not all developmental disturbances are lethal.

The fruit fly Drosophila melanogaster have been studied to the core when it comes to the HOX-genes. By disturbing the pattern of expression of these genes, either with mutations or environmental factors (such as chemicals) a fly with antennae instead of eyes develops, or a fly with two thoraxes (see pictures further down for both). In mice you can disturb the development by turning "on" some of the HOX-genes way too much so that the new born mouse has no hair at all. So it's not as simple as just having a genome with all you need to build a being. The genome must be extremely fine-tuned in order to have all limbs in the correct places!

Sources:

http://www.musc.edu/mcbp/concentrations/geneticsdevelop.html

When I come around

I tend to dwell a lot on everything that concerns being human. I mean, what combinations of minor and major evolutionary processes have led us to this character state defined as a Homo sapiens? Things like this can easily keep my nights sleepless. You know the saying if a tree falls in the forest and no one's around to see or hear it, did it ever occur at all? If you say no, then did the world really exist before your first memory? Even better: did the world exist before the one and only "I think therefore I am" species (i.e. us) came along?

If you leave out philosophy and creation myths that place humans in the center, then yeah, there was something here before us. Actually, there were a lot of things here before us. Some, like liverworth are still here today but more species that you could ever imagine have walked and inherited the earth in thousands (or millions!) of years before us, until some cryptic event made them head towards extinction. If you dig around in the earth's crust you may come across some fossils, but we will never ever be able to know all the creatures that have existed (or that will exist in the last million years of this planet, but that's another question).

Predating the waters of the Cambrian period was a strange little being named Opabinia regalis, belonging to a group of animals that have no decendants living today. The fossil record claims that it was up to 7 cm long, had five eyes and a really remarkable feeding part of its body (which makes me think of the offspring of a trilobite, elephant and a vacuum cleaner). The Cambrian period flourished with life forms in many, many versions but this period ended with the greatest mass extintion ever, leaving behind a fraction of species that later evolved into the various life forms we are today.

I may add that the fossil record is based on fewer than twenty fossils. Now, think about a present species that's fairly abundant in our world and have been so for a couple of hundred thousand years. Imagine that only a fraction of these were fossilised and only 15 of these were discovered by some future creature that has a bias for investigating the world's history. Will that say anything about all the other species that exist today? Not really... More fossils of other species might give more but we will never know it all. And that's what's keeping me up at night. Maybe it's a weird extension of being a control freak, but it really bugs me to know that I will never know how things have been before I came around.

Sources:

Evolution. An introduction (Stephen C. Stearns and Rolf F. Hoekstra). Second edition.

http://en.wikipedia.org/wiki/Opabinia

It's evolution, baby

Image revised from http://photography-on-the.net/forum/showthread.php?t=500821

Top news from Nature.com here! For me, this is exciting since it is a very good example of how the evolutionary forces can work. It concerns the tiger moths, which are rejected of a number of predatory species even though they'd probably make a good addition in terms of nutients. Some time ago, it was discovered that some tiger moths produces ultrasonic sounds. Now, this sound is also used by bats, which otherwise likes to eat other individuals of the Lepidoptera. But this sound it is not used to locate the moths. Instead, its used to ward them off, since the bats precive the sounds as toxicity signals (and the tiger moths don't really taste good so if the bat would take a chunk, he'd probably leave it directly which in turn leaves no gain for either the moth or the bat). Tiger moths that are around during summer, when bats are a major threat, uses this as a good way of avoiding becoming dinner. However, some other types emerges when it's springtime and the bats aren't as active. Then, there are other greedy eyes in the environment, such as birds. To cope with this other type of predator, these tiger moths rely on bright coloring to send of some statements to the birds that there's no use in eating them since they would taste unpleasant. Visual signals is also used during the summer, but mainly in day active moths since the daylight makes colors more efficiant. SO, what's cool about this is that two different predators and different light-settings have led to the divergence different antipredator defences within the same species. Like X-men, but for real.

Sources:
http://www.nature.com/nature/journal/v455/n7209/edsumm/e080904-11.html
http://www.nature.com/nature/journal/v455/n7209/full/nature07087.html

The gene that Fearnot did not have

Image revised from http://www.sciencedaily.com/releases/2007/07/070725152040.htm

I'm a horror litterature nerd. During my pre-teen summer holidays - when all my friends were out in the sun - I was at the library searching for anything spooky, written down by masters such as E. A. Poe, M. R. James, W. H. Hodgson ect. The only thing that kept me from discovering the macabre world of horror movies were infact my dear mother. She doesn't think highly of "evil flattering" so whenever I pointed my finger towards Tales from the crypt, Salems lot, or Evil dead when we were in a video store she wrinkled her nose and promptly said no.

Of course, later on I was able to get the movies myself. By the age of 12, I had a friend who kindly enough invited me over now and then for late nights with popcorn and Braindead. So early on I was accustomed to bloody flicks and gore galore.

Therefore, the findings of a gene that is linked to “why horror films make some people scream in terror while others may simply laugh” is hard to apply on people with the same horror background as me. The gene is involved in dopamine regulation, and the carriers of this variation generally response more dramatically to unpleasant images, due to the regulation affecting the startle reflex. It is completely new in evolution (which means that no other primate has it) and could be of some advantage. I would guess that being a stone age Homo sapiens, it would be better to be scared and run away than to stay and wrestle a sable toothed kittie.

If you're wondering about my title, it's from one of The storyteller episodes - Fearnot! I was obsessed with that tv-show when I were a kid. I have to buy that DVD-box soon...

Source:
http://blogs.nature.com/news/thegreatbeyond/2008/08/scaredycat_gene_will_make_you.html

No candy for you, missy!

Ever thought about why your dog has a sweet-tooth and gladly indulge in your cookies and sweets, while if you offer your cat a piece he/she stares at you as if you were stupid just for thinking that he/she would even smell at it? Well, as much as some people would like to believe that cats are smarter than dogs (which is based on the independance of most cats compared to most dogs, which in turn is a false indication of intelligence since this reasoning would state that the lone ourangutangs are much, much more smarter than us human that likes to get along with all the other kids...but that's a whoooole different entry), this is not the answer to the candy question. Actually, cats can't taste the sweetness at all. Sometime during cat evolution the kittie ancestor lost the ability to have taste receptors for all things being sugary. I would think that this is ok since their diet is more dependant on amino-acids than carbohydrates (if I didn't have my childish liking of chocolate and cookies I would gladly remove this part of my genome too!)

Since this is not exclusive for our cute little homies that cuddles with us hairless primates, but concern all cats (tigers, lions, yeah you get it now) I suppose I'll be safe on a savannah if I dress up as a lolipop? This must be tested empirically...

Sources:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2063449